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写真a

ゴウシ ケンイチ
合志 憲一
GOSHI KENICHI
所属
工学研究院 エネルギー量子工学部門 准教授
最先端有機光エレクトロニクス研究センター (併任)
■廃止組織■ 水素製造研究部門(併任)
工学部 応用化学科(併任)
職名
准教授
連絡先
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外部リンク

学位

  • 博士(理工学)

経歴

  • 2008年10月 東北大学助教(工学研究科)   

研究テーマ・研究キーワード

  • 研究テーマ: 有機エレクトロニクス材料・デバイス物理の解明

    研究キーワード: 有機エレクトロニクス,有機半導体

    研究期間: 2010年11月 - 2010年12月

受賞

  • 平成24年度光電相互変換第125委員会奨励賞

    2012年12月   日本学術振興会光電変換第125委員会   遅延蛍光有機EL素子の研究開発

  • 第14回有機EL討論会講演奨励賞

    2012年11月   有機EL討論会   エキサイプレックスからの遅延蛍光および有機EL素子への応用

  • ACOE2011 Best Poster Award

    2012年11月   Exciplex states having high reverse intersystem crossing efficiency and application to organic light-emitting diodes

  • 第32回(2012年春季)応用物理学会講演奨励賞

    2012年9月   応用物理学会   エキサイプレックスを用いた遅延蛍光有機EL素子

  • コニカミノルタ画像科学進歩賞

    2011年1月   公益財団法人コニカミノルタ科学技術振興財団   エキサイプレックス状態の高い逆項間交差確率を利用した高効率有機EL素子の実現

論文

  • Triplet management for efficient perovskite light-emitting diodes 査読

    Chuanjiang Qin, Toshinori Matsushima, William J. Potscavage, Atula S. D. Sandanayaka, Matthew R. Leyden, Fatima Bencheikh, Kenichi Goushi, Fabrice Mathevet, Benoit Heinrich, Go Yumoto, Yoshihiko Kanemitsu, Chihaya Adachi

    NATURE PHOTONICS   14 ( 2 )   70 - +   2020年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Careful harvesting of triplet excitons allows the realization of efficient green-emitting quasi-2D perovskite LEDs.Perovskite light-emitting diodes are promising for next-generation lighting and displays because of their high colour purity and performance(1). Although the management of singlet and triplet excitons is fundamental to the design of efficient organic light-emitting diodes, the nature of how excitons affect performance is still not clear in perovskite(2-4) and quasi-two-dimensional (2D) perovskite-based devices(5-9). Here, we show that triplet excitons are key to efficient emission in green quasi-2D perovskite devices and that quenching of triplets by the organic cation is a major loss path. Employing an organic cation with a high triplet energy level (phenylethylammonium) in a quasi-2D perovskite based on formamidinium lead bromide yields efficient harvesting of triplets. Furthermore, we show that upconversion of triplets to singlets can occur, making 100% harvesting of electrically generated excitons potentially possible. The external quantum and current efficiencies of our green (527 nm) devices reached 12.4% and 52.1 cd A(-1), respectively.

    DOI: 10.1038/s41566-019-0545-9

  • Triplet-triplet upconversion enhanced by spin-orbit coupling in organic light-emitting diodes 査読

    Ryota Ieuji, Kenichi Goushi, Chihaya Adachi

    NATURE COMMUNICATIONS   10 ( 1 )   2019年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Triplet-triplet upconversion, in which two triplet excitons are converted to one singlet exciton, is a well-known approach to exceed the limit of electroluminescence quantum efficiency in conventional fluorescence-based organic light-emitting diodes. Considering the spin multiplicity of triplet pairs, upconversion efficiency is usually limited to 20%. Although this limit can be exceeded when the energy of a triplet pair is lower than that of a second triplet excited state, such as for rubrene, it is generally difficult to engineer the energy levels of higher triplet excited states. Here, we investigate the upconversion efficiency of a series of new anthracene derivatives with different substituents. Some of these derivatives show upconversion efficiencies close to 50% even though the calculated energy levels of the second triplet excited states are lower than twice the lowest triplet energy. A possible upconversion mechanism is proposed based on the molecular structures and quantum chemical calculations.

    DOI: 10.1038/s41467-019-13044-1

  • Indication of current-injection lasing from an organic semiconductor 査読

    Atula S. D. Sandanayaka, Toshinori Matsushima, Fatima Bencheikh, Shinobu Terakawa, William J. Potscavage, Chuanjiang Qin, Takashi Fujihara, Kenichi Goushi, Jean-Charles Ribierre, Chihaya Adachi

    APPLIED PHYSICS EXPRESS   12 ( 6 )   2019年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    In this study, we investigate the lasing properties of 4,4'-bis[(N-carbazole) styryl] biphenyl thin films under electrical pumping. The electroluminescent devices incorporate a mixed-order distributed feedback SiO2 grating into an organic light-emitting diode structure and emit blue lasing. The results provide an indication of lasing by direct injection of current into an organic thin film through selection of a high-gain organic semiconductor showing clear separation of the lasing wavelength from significant triplet and polaron absorption and design of a proper feedback structure with low losses at high current densities. This study represents an important advance toward a future organic laser diode technology. (C) 2019 The Japan Society of Applied Physics

    DOI: 10.7567/1882-0786/ab1b90

  • Toward continuous-wave operation of organic semiconductor lasers 査読 国際誌

    Atula S. D. Sandanayaka, Toshinori Matsushima, Fatima Bencheikh, Kou Yoshida, Munetomo Inoue, Takashi Fujihara, Kenichi Goushi, Jean-Charles Ribierre, Chihaya Adachi

    SCIENCE ADVANCES   3 ( 4 )   e1602570   2017年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The demonstration of continuous-wave lasing from organic semiconductor films is highly desirable for practical applications in the areas of spectroscopy, data communication, and sensing, but it still remains a challenging objective. We report low-threshold surface-emitting organic distributed feedback lasers operating in the quasicontinuous-wave regime at 80 MHz as well as under long-pulse photoexcitation of 30 ms. This outstanding performance was achieved using an organic semiconductor thin film with high optical gain, high photoluminescence quantum yield, and no triplet absorption losses at the lasing wavelength combined with a mixed-order distributed feedback grating to achieve a low lasing threshold. A simple encapsulation technique greatly reduced the laser-induced thermal degradation and suppressed the ablation of the gain medium otherwise taking place under intense continuous-wave photoexcitation. Overall, this study provides evidence that the development of a continuous-wave organic semiconductor laser technology is possible via the engineering of the gain medium and the device architecture.

    DOI: 10.1126/sciadv.1602570

  • Highly efficient organic light-emitting diodes from delayed fluorescence 査読 国際誌

    Hiroki Uoyama, Kenichi Goushi, Katsuyuki Shizu, Hiroko Nomura, Chihaya Adachi

    NATURE   492 ( 7428 )   234 - +   2012年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The inherent flexibility afforded by molecular design has accelerated the development of a wide variety of organic semiconductors over the past two decades. In particular, great advances have been made in the development of materials for organic light-emitting diodes (OLEDs), from early devices based on fluorescent molecules(1) to those using phosphorescent molecules(2,3). In OLEDs, electrically injected charge carriers recombine to form singlet and triplet excitons in a 1:3 ratio(1); the use of phosphorescent metal-organic complexes exploits the normally non-radiative triplet excitons and so enhances the overall electroluminescence efficiency(2,3). Here we report a class of metal-free organic electroluminescent molecules in which the energy gap between the singlet and triplet excited states is minimized by design(4), thereby promoting highly efficient spin up-conversion from non-radiative triplet states to radiative singlet states while maintaining high radiative decay rates, of more than 10(6) decays per second. In other words, these molecules harness both singlet and triplet excitons for light emission through fluorescence decay channels, leading to an intrinsic fluorescence efficiency in excess of 90 per cent and a very high external electroluminescence efficiency, of more than 19 per cent, which is comparable to that achieved in high-efficiency phosphorescence-based OLEDs(3).

    DOI: 10.1038/nature11687

  • Efficient organic light-emitting diodes through up-conversion from triplet to singlet excited states of exciplexes 査読 国際誌

    Kenichi Goushi, Chihaya Adachi

    APPLIED PHYSICS LETTERS   101 ( 2 )   2012年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Enhanced electroluminescence efficiency is achieved in organic light-emitting diodes through delayed fluorescence of the exciplex state formed between 4,40,4 ''-tris[3-methylphenyl(phenyl) amino]triphenylamine (m-MTDATA) as an electron-donating material and 2,8-bis(diphenylphosphoryl) dibenzo[b,d]thiophene (PPT) as an electron-accepting material. The devices exhibited maximum external electroluminescence quantum and power efficiencies of 10.0% and 47.0 lm/W, respectively. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4737006]

    DOI: 10.1063/1.4737006

  • Organic light-emitting diodes employing efficient reverse intersystem crossing for triplet-to-singlet state conversion 査読 国際誌

    Kenichi Goushi, Kou Yoshida, Keigo Sato, Chihaya Adachi

    NATURE PHOTONICS   6 ( 4 )   253 - 258   2012年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Light emission from organic light-emitting diodes that make use of fluorescent materials have an internal quantum efficiency that is typically limited to no more than 25% due to the creation of non-radiative triplet excited states. Here, we report the use of electron-donating and electron-accepting molecules that allow a very high reverse intersystem crossing of 86.5% between non-radiative triplet and radiative singlet excited states and thus a means of achieving enhanced electroluminescence. Organic light-emitting diodes made using m-MTDATA as the donor material and 3TPYMB as the acceptor material demonstrate that external quantum efficiencies as high as 5.4% can be achieved, and we believe that the approach will offer even higher values in the future as a result of careful material selection.

    DOI: 10.1038/nphoton.2012.31

  • Excitation Intensity Dependence of Power-Law Blinking Statistics in Nanocrystal Quantum Dots 査読 国際誌

    Kenichi Goushi, Toshiki Yamada, Akira Otomo

    JOURNAL OF PHYSICAL CHEMISTRY C   113 ( 47 )   20161 - 20168   2009年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We present new information that requires explanation in the study of possible mechanisms for fluorescence blinking in single nanocrystal (NC) quantum dots. By using pulse laser excitation, we investigated the excitation intensity dependence of fluorescence blinking statistics in NC quantum dots embedded in polymer matrices. Under strong excitation intensity, we observed an unexpected excitation intensity dependence of the power-law distribution in the blinking statistics. To explain the new information on the blinking statistics in the framework of the Tang-Marcus model, we propose a diffusion-controlled model based upon anharmonic potentials that originate from a nonlinear response of polarization to the electric field and is caused by an increase in the dielectric constant of host media with the excitation intensity. The validity of the proposed model is investigated by comparing the blinking statistics for two host matrices.

    DOI: 10.1021/jp811448k

  • 100% phosphorescence quantum efficiency of Ir(III) complexes in organic semiconductor films 査読 国際誌

    Y. KAWAMURA, K. GOUSHI, J. BROOKS, J. J. BROWN, H. SASABE, C. ADACHI

    APPLIED PHYSICS LETTERS   86 ( 7 )   2005年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1063/1.1862777

  • Efficient photosensitized luminescence from Eu<sup>3+</sup> in inert nanocrystals via ligand coordination

    Goushi K., Kashiwagi Y., Adachi C.

    Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers   63 ( 9 )   2024年9月   ISSN:00214922

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers  

    Luminescent lanthanide ions incorporated in sodium yttrium fluoride nanocrystals are promising as new luminescent materials in optoelectronics and bioimaging since the nonradiative transition is significantly suppressed due to the absence of high-energy vibrational modes. To prepare optically and electrically active nanocrystals, we explored organic ligands that allow efficient triplet energy transfer to Eu3+ incorporated into nanocrystals, resulting in an efficient photosensitization effect in colloidal solutions and films. Further, we applied these emitting nanocrystals to light-emitting devices and observed the electroluminescence.

    DOI: 10.35848/1347-4065/ad760d

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  • Hexacarbazolylbenzene: An Excellent Host Molecule Causing Strong Guest Molecular Orientation and the High-Performance OLEDs 国際誌

    Madushani B., Mamada M., Goushi K., Katagiri H., Nakanotani H., Hatakeyama T., Adachi C.

    Advanced Materials   36 ( 30 )   e2402275   2024年6月   ISSN:09359648

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Advanced Materials  

    Hexacarbazolylbenzene (6CzPh), which is benzene substituted by six carbazole rings, is a simple and attractive compound. Despite the success of a wide variety of carbazole derivatives in organic light-emitting diodes (OLEDs), 6CzPh has not received attention so far. Here, excellent performances of 6CzPh are revealed as a host material in OLEDs regarding conventional host materials. Various strategies are implemented to improve the performance of OLEDs, e.g., triplet utilization by thermally activated delayed fluorescence (TADF) and phosphorescence emitters for maximizing internal quantum efficiency, and molecular orientation control for increasing outcoupling efficiency. The present host material is suited for both criteria. Robustness of the structure and sufficiently high triplet energy enables a high external quantum efficiency with a long device lifetime. Besides, the host material boosts the horizontal molecular orientations of several guest emitters. It is noteworthy that disk-shaped 4CzIPN marks the complete horizontal molecular orientations (Θh = 100%, S = −0.50). These results provide an effective way of improving efficiencies without sacrificing device durability for future OLEDs.

    DOI: 10.1002/adma.202402275

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  • Effect of Multiple Acceptor Structures in Electron Transport Materials on Operational Lifetime of Blue Thermally Activated Delayed Fluorescence Organic Light-Emitting Diodes

    Kiriyama S., Mamada M., Goushi K., Madushani B., Hatakeyama T., Adachi C.

    Advanced Functional Materials   2024年4月   ISSN:1616301X

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Advanced Functional Materials  

    Recent advances in organic light-emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF)-assisted fluorescence (TAF) attest to the great promise of this technology in practical use. However, the simultaneous realization of high efficiency and device durability in blue OLEDs remains a significant challenge. Clarification of the degradation mechanisms correlated to molecular structure and device configuration is the key to extending the device lifetime. In this study, electron transport materials incorporating two triazine units in close proximity are adopted to use in hole-blocking and electron-transporting layers, resulting in superior device performances. In addition, a modified photodegradation experiment reveals that the degradation origins closely relate to charge carriers. The optimization of the device according to the obtained findings leads to 4.5 times extension in the lifetime of the TAF-OLED using a multiple resonance emitter. These results also provide guidelines for designing robust electron transport materials for blue OLEDs.

    DOI: 10.1002/adfm.202402287

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  • Indication of Intramolecular Triplet–Triplet Annihilation Upconversion in Organic Light‐Emitting Diodes

    Shoma Sasaki, Kenichi Goushi, Masashi Mamada, Shiori Miyazaki, Kiyoshi Miyata, Ken Onda, Chihaya Adachi

    Advanced Optical Materials   12 ( 3 )   2023年10月

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    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    Abstract

    It is well known that triplet–triplet annihilation upconversion (TTU) can enhance electroluminescence (EL) efficiency by converting two low‐energy triplet excitons into one high‐energy singlet exciton. However, conventional intermolecular TTU requires high doping concentration to activate, limiting device architecture. Here, six dimer molecules comprised of two anthracene units connected by a spacer unit are investigated, which have a possibility of the intramolecular TTU process. As a result, two dimer molecules show high TTU efficiencies close to the theoretical maximum even in dispersed, diluted conditions. By comparing these molecular conformations, a correlation is found between the dimer structures of two anthracene units and the TTU activity in the diluted condition, i.e., the 3D molecular structure with the exciton utilizing efficiency.

    DOI: 10.1002/adom.202301924

  • Multiple donor–acceptor design for highly luminescent and stable thermally activated delayed fluorescence emitters

    Bhagya Madushani, Masashi Mamada, Kenichi Goushi, Thanh Ba Nguyen, Hajime Nakanotani, Hironori Kaji, Chihaya Adachi

    Scientific Reports   13 ( 1 )   2023年5月

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    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    Abstract

    A considerable variety of donor–acceptor (D–A) combinations offers the potential for realizing highly efficient thermally activated delayed fluorescence (TADF) materials. Multiple D–A type compounds are one of the promising families of TADF materials in terms of stability as well as efficiencies. However, those emitters are always composed of carbazole-based donors despite a wide choice of moieties used in linearly linked single D–A molecules. Herein, we developed a multiple D–A type TADF compound with two distinct donor units of 9,10-dihydro-9,9-dimethylacridine (DMAC) and carbazole as the hetero-donor design. The new emitter exhibits high photoluminescence quantum yield (PLQY) in various conditions including polar media blend and high concentrations. Organic light-emitting diodes (OLEDs) showed a reasonably high external quantum efficiency (EQE). In addition, we revealed that the multiple-D–A type molecules showed better photostability than the single D–A type molecules, while the operational stability in OLEDs involves dominant other factors.

    DOI: 10.1038/s41598-023-34623-9

  • Highly efficient light harvesting of a Eu(iii) complex in a host–guest film by triplet sensitization 査読

    Shiori Miyazaki, Kenichi Goushi, Yuichi Kitagawa, Yasuchika Hasegawa, Chihaya Adachi, Kiyoshi Miyata, Ken Onda

    Chemical Sciences   2023年5月

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    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    Highly efficient light harvesting of a Eu(iii) complex in a host–guest film by triplet sensitization
    Very high photoluminescence intensity of a Eu(iii) complex is achieved using a host–guest system. The intensity is 400 times larger than that of the Eu(iii) complex itself.

    DOI: 10.1039/D3SC01817B

  • Artificial p–n‐like Junction Based on Pure 2D Organic–Inorganic Halide Perovskite Structure Having Naphthalene Diimide Acceptor Moieties

    Zhao Feng, Xuelong Liu, Kentaro Imaoka, Tomohiro Ishii, Ganbaatar Tumen‐Ulzii, Xun Tang, George F. Harrington, Benoît Heinrich, Jean‐Charles Ribierre, Lise‐Marie Chamoreau, Lydia Sosa Vargas, David Kreher, Kenichi Goushi, Toshinori Matsushima, Guijiang Zhou, Fabrice Mathevet, Chihaya Adachi

    Advanced Optical Materials   11 ( 10 )   2023年3月

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    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1002/adom.202202734

  • Organic Binary and Ternary Cocrystal Engineering Based on Halogen Bonding Aimed at Room‐Temperature Phosphorescence

    Ayano Abe, Kenichi Goushi, Masashi Mamada, Chihaya Adachi

    Advanced Materials   2023年3月

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    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1002/adma.202211160

  • Tailor-Made Multi-Resonance Terminal Emitters toward Narrowband, High-Efficiency, and Stable Hyperfluorescence Organic Light-Emitting Diodes

    Yi-Ting Lee, Chin-Yiu Chan, Masaki Tanaka, Masashi Mamada, Kenichi Goushi, Xun Tang, Youichi Tsuchiya, Hajime Nakanotani, Chihaya Adachi

    ADVANCED OPTICAL MATERIALS   10 ( 17 )   2022年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Multi-resonance emitters (MREs) are a promising candidate for fulfilling the harsh requirements of display applications due to their unique photophysical properties. Recently, MREs have been widely used as a terminal emitter in hyperfluorescence organic light-emitting diodes (HF-OLEDs); however, since MREs are always thermally activated delayed fluorescence (TADF)-active, possessing long triplet lifetimes in millisecond order, they result in severe chemical degradation. Instead of shortening the delayed lifetime of MREs by molecular design, herein, a low-triplet pyrene unit is introduced into an MRE scaffold to achieve narrowband emission and quick removal of triplets in MREs simultaneously. Blue HF-OLED based on the non-TADF MRE demonstrates a high external quantum efficiency of 20&#37; and a tenfold improvement in stability, compared to those of the HF-OLEDs with standard MREs. An opposite direction of molecular design of MREs for the sophisticated exciton generation and transfer system in HF-OLEDs is proposed to enhance device lifetime without sacrificing color purity and efficiency.

    DOI: 10.1002/adom.202200682

  • Highly Efficient Deep-Blue Organic Light-Emitting Diodes Based on Rational Molecular Design and Device Engineering

    Masashi Mamada, Hiroshi Katagiri, Chin-Yiu Chan, Yi-Ting Lee, Kenichi Goushi, Hajime Nakanotani, Takuji Hatakeyama, Chihaya Adachi

    ADVANCED FUNCTIONAL MATERIALS   32 ( 32 )   2022年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    There is increasing interest in thermally activated delayed fluorescence (TADF) in materials, and to understand its mechanism in the excited state dynamics. Recent challenges include color purity, efficient deep-blue emission, fast exciton decay lifetimes, high reverse intersystem crossing rates (k(RISC)), low-efficiency roll-off in organic light-emitting diodes (OLEDs), and long device lifetimes. Here, a series of compounds having benzonitrile and carbazole rings are examined, that provide a detailed understanding of the excited states, and a guideline for high-performance TADF. A dense alignment of the excited states with several different characters within a small energy range results in high k(RISC) of >2 x 10(6) s(-1), while maintaining radiative rate constants (k(r)) >10(7) s(-1). OLEDs based on the optimum compound exhibit a low-efficiency roll-off and a CIEy (y color coordinate of Commission Internationale de l'eclairage) <0.4. TADF-assisted fluorescence (TAF) OLED exhibits a maximum external quantum efficiency of 22.4&#37; with CIE coordinates (0.13,0.15). This work also provides insights for device engineering and molecular designs.

    DOI: 10.1002/adfm.202204352

  • Carbazole-2-carbonitrile as an acceptor in deep-blue thermally activated delayed fluorescence emitters for narrowing charge-transfer emissions

    Chin-Yiu Chan, Yi-Ting Lee, Masashi Mamada, Kenichi Goushi, Youichi Tsuchiya, Hajime Nakanotani, Chihaya Adachi

    CHEMICAL SCIENCE   13 ( 26 )   7821 - 7828   2022年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    This work reports a new acceptor for constructing donor-acceptor type (D-A type) blue thermally activated delayed fluorescence (TADF) emitters with narrowed charge-transfer (CT) emissions. A new acceptor core, carbazole-2-carbonitrile (CCN), is formed by the fusion of carbazole and benzonitrile. Three D-A type TADF emitters based on the CCN acceptor, namely 3CzCCN, 3MeCzCCN, and 3PhCzCCN, have been successfully synthesized and characterized. These emitters show deep-blue emissions from 439 to 457 nm with high photoluminescence quantum yields of up to 85&#37; in degassed toluene solutions. Interestingly, all CCN-based deep-blue TADF emitters result in narrow CT emissions with full-width at half-maximums (FWHMs) of less than 50 nm in toluene solutions, which are pretty narrower compared with those of typical D-A type TADF emitters. Devices based on these emitters show high maximum external quantum efficiencies of up to 17.5&#37;.

    DOI: 10.1039/d2sc02478k

  • Numerical Study of Triplet Dynamics in Organic Semiconductors Aimed for the Active Utilization of Triplets by TADF under Continuous-Wave Lasing

    Ayano Abe, Kenichi Goushi, Atula S.D. Sandanayaka, Ryutaro Komatsu, Takashi Fujihara, Masashi Mamada, Chihaya Adachi

    Journal of Physical Chemistry Letters   13 ( 5 )   1323 - 1329   2022年2月

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    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    The limitation of lasing duration less than nanosecond order has been a major problem for realizing organic solid-state continues-wave (CW) lasers and organic semiconductor laser diodes. Triplets accumulation under CW excitation has been well recognized as a critical inhibiting factor. To overcome this issue, the utilization of thermally activated delayed fluorescence (TADF) emitters is a promising mechanism because of efficient reverse intersystem crossing. Herein, we model the triplet accumulation processes under lasing and propose the active utilization of TADF for lasing based on our simulation analysis. We used the rate constants experimentally determined from the optical properties of a boron difluoride curcuminoid fluorophore showing both TADF and lasing. We demonstrate that the intersystem crossing efficiency is gradually increased after the convergence of relaxation oscillation, i.e., terminating laser oscillation. In addition, we found that when the reverse intersystem crossing rate is close to the intersystem crossing rate, CW lasing becomes dominant.

    DOI: 10.1021/acs.jpclett.1c03983

  • Hot exciplexes in U-shaped TADF molecules with emission from locally excited states

    A. Lennart Schleper, Kenichi Goushi, Christoph Bannwarth, Bastian Haehnle, Philipp J. Welscher, Chihaya Adachi, Alexander J. C. Kuehne

    NATURE COMMUNICATIONS   12 ( 1 )   2021年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Fast emission and high color purity are essential characteristics of modern opto-electronic devices, such as organic light emitting diodes (OLEDs). These properties are currently not met by the latest generation of thermally activated delayed fluorescence (TADF) emitters. Here, we present an approach, called "hot exciplexes" that enables access to both attributes at the same time. Hot exciplexes are produced by coupling facing donor and acceptor moieties to an anthracene bridge, yielding an exciplex with large T-1 to T-2 spacing. The hot exciplex model is investigated using optical spectroscopy and quantum chemical simulations. Reverse intersystem crossing is found to occur preferentially from the T-3 to the S-1 state within only a few nanoseconds. Application and practicality of the model are shown by fabrication of organic light-emitting diodes with up to 32 &#37; hot exciplex contribution and low efficiency roll-off.Molecular designs improving the performance of thermally activated delayed fluorescence (TADF) emitters are greatly desired for optoelectronic applications. The authors propose a molecular geometry with donor and acceptor moieties facing each other separated by an anthracene bridge, giving rise to hot exciplex states producing color pure and fast TADF emission.

    DOI: 10.1038/s41467-021-26439-w

  • Recycling of Triplets into Singlets for High-Performance Organic Lasers

    Chathuranganie A. M. Senevirathne, Seiya Yoshida, Morgan Auffray, Masayuki Yahiro, Buddhika S. B. Karunathilaka, Fatima Bencheikh, Kenichi Goushi, Atula S. D. Sandanayaka, Toshinori Matsushima, Chihaya Adachi

    ADVANCED OPTICAL MATERIALS   10 ( 1 )   2021年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Achieving continuous-wave (CW) lasing in organic semiconductors is known to be a difficult task because long-lived triplets quench radiative singlets via singlet-triplet annihilation (STA). To avoid STA and operate organic lasers in CW or long-pulse photoexcitation, the triplets need to be removed from an organic laser gain medium. However, this triplet removal leads to a loss of excitons. In addition to removing the detrimental triplets, here it is reported a triplet recycling process, which includes triplet scavenging and successive triplet upconversion via triplet-triplet annihilation (TTA) to regenerate emissive singlet excitons in a laser medium. An anthracene derivative of 9-(1-naphthalenyl)-10-(4-(2-naphthalenyl)phenyl)anthracene (NaNaP-A) and a laser dye of 4,4 '-bis[4-(diphenylamino)styryl]biphenyl (BDAVBi) are used as the triplet recycling sensitizer and the emitting laser dye, respectively. In this laser system, NaNaP-A can efficiently scavenge the triplets formed on BDAVBi because the triplet level is deeper for NaNaP-A than for BDAVBi, and then NaNaP-A successively recycles the triplets into the BDAVBi's singlet state via TTA. The TTA compensates and overcomes the STA in this laser system. Hence, these laser devices can be operated with long pulse widths of up to 10 ms. This unique triplet recycling behavior is confirmed by transient photoluminescence (PL) and electroluminescence (EL) studies.

    DOI: 10.1002/adom.202101302

  • Markedly Improved Performance of Optically Pumped Organic Lasers with Two-Dimensional Distributed-Feedback Gratings

    Chathuranganie A. M. Senevirathne, Atula S. D. Sandanayaka, Buddhika S. B. Karunathilaka, Takashi Fujihara, Fatima Bencheikh, Chuanjiang Qin, Kenichi Goushi, Toshinori Matsushima, Chihaya Adachi

    ACS PHOTONICS   8 ( 5 )   1324 - 1334   2021年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Continuous-wave (CW) lasing is still difficult to realize in organic laser dyes, one reason being the thermal degradation caused by intense photoexcitation. A decrease in laser threshold suppresses the thermal degradation and, therefore, leads to long-lasting lasing from organic laser dyes. Here, we show that it is possible to decrease the laser thresholds by combining the organic laser dye 4,4-bis[(N-carbazole)styryl]biphenyl, which has a small spectral overlap between the laser emission and the excited-state triplet absorption, with two-dimensional (2D) distributed-feedback (DFB) gratings. We used second-order 2D cross double and square lattice DFB gratings, which offer light feedback in two orthogonal directions, and second-order and mixed-order circular DFB gratings, which offer light feedback in radial directions. Among these grating structures, the mixed-order circular DFB grating structure led to the lowest lasing threshold of similar to 0.015 mu J cm(-2) under short-pulse photoexcitation because of the excellent optical feedback. Moreover, a low average-power threshold of 10 W cm(-2) (a peak-power threshold of 1 kW cm-2) was obtained when laser devices with this grating structure were operated under 1 s of long-pulse photoexcitation with a repetition rate of 0.01 Hz. Additionally, using the mixed-order circular DFB grating structure improved the laser stability under CW photoexcitation since shorter exciton lifetimes in the optical resonator suppress the chemical decomposition. These results demonstrate the importance of choosing an optical resonator structure for improving organic laser performance.

    DOI: 10.1021/acsphotonics.0c01728

  • Synthesis and Characterization of 5,5 '-Bitetracene

    Masashi Mamada, Kenichi Goushi, Ryota Nakamura, Hironori Kaji, Chihaya Adachi

    CHEMISTRY LETTERS   50 ( 4 )   800 - 803   2021年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    A tetracene dimer, 5,5'-bitetracene (55BT), has successfully been synthesized for the first time and its structure was confirmed by X-ray single crystal analysis. The electrochemical and optical properties of 55BT were investigated and compared to those of tetracene. Although the photoluminescence quantum yield of 55BT was slightly higher than that of tetracene, the results of the transient absorption spectroscopy suggested triplet formation by singlet fission in solution.

    DOI: 10.1246/cl.200909

  • Realizing Near-Infrared Laser Dyes through a Shift in Excited-State Absorption

    Reiko Aoki, Ryutaro Komatsu, Kenichi Goushi, Masashi Mamada, Soo Young Ko, Jeong Weon Wu, Virginie Placide, Anthony D'Aleo, Chihaya Adachi

    ADVANCED OPTICAL MATERIALS   9 ( 6 )   2021年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The development of near-infrared (NIR) light sources has attracted much interest due to their attractive applications, such as biosensing and light detection and ranging (LiDAR). In particular, organic semiconductor laser diodes with NIR emission are emerging as a next generation technology. However, organic NIR emitters have generally suffered from a low quantum yield, which has resulted in only a few examples of organic solid-state NIR lasers. In this study, the authors demonstrate a highly efficient NIR emitter based on a boron difluoride curcuminoid structure, which shows a high photoluminescence (PL) quantum yield (phi(PL)) at >700 nm and a high fluorescence radiative rate constant in a solid-state film. Amplified spontaneous emission and lasing occurs at >800 nm with very low thresholds. The large redshift of the stimulated emission is attributed to the transition from the lowest excited state to the different vibrational levels of the ground state owing to the overlap between the emission and the singlet-singlet excited-state absorption.

    DOI: 10.1002/adom.202001947

  • Suppression of external quantum efficiency rolloff in organic light emitting diodes by scavenging triplet excitons

    Buddhika S. B. Karunathilaka, Umamahesh Balijapalli, Chathuranganie A. M. Senevirathne, Seiya Yoshida, Yu Esaki, Kenichi Goushi, Toshinori Matsushima, Atula S. D. Sandanayaka, Chihaya Adachi

    NATURE COMMUNICATIONS   11 ( 1 )   2020年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Large external quantum efficiency rolloff at high current densities in organic light-emitting diodes (OLEDs) is frequently caused by the quenching of radiative singlet excitons by long-lived triplet excitons [singlet-triplet annihilation (STA)]. In this study, we adopted a triplet scavenging strategy to overcome the aforementioned STA issue. To construct a model system for the triplet scavenging, we selected 2,6-dicyano-1,1-diphenyl-lambda (5)sigma (4)-phosphinine (DCNP) as the emitter and 4,4-bis[(N-carbazole)styryl]biphenyl (BSBCz) as the host material by considering their singlet and triplet energy levels. In this system, the DCNP's triplets are effectively scavenged by BSBCz while the DCNP's singlets are intact, resulting in the suppressed STA under electrical excitation. Therefore, OLEDs with a 1wt.&#37;-DCNP-doped BSBCz emitting layer demonstrated the greatly suppressed efficiency rolloff even at higher current densities. This finding favourably provides the advanced light-emitting performance for OLEDs and organic semiconductor laser diodes from the aspect of the suppressed efficiency rolloff. Though organic light-emitting diodes are highly desirable for display and lighting applications, efficiency roll-off at high current densities limits its applicability. Here, the authors report a triplet scavenging strategy for improved triplet exciton management and reduced efficiency roll-off.

    DOI: 10.1038/s41467-020-18292-0

  • An Organic Laser Dye having a Small Singlet-Triplet Energy Gap Makes the Selection of a Host Material Easier

    Buddhika S. B. Karunathilaka, Umamahesh Balijapalli, Chathuranganie A. M. Senevirathne, Yu Esaki, Kenichi Goushi, Toshinori Matsushima, Atula S. D. Sandanayaka, Chihaya Adachi

    ADVANCED FUNCTIONAL MATERIALS   30 ( 30 )   2020年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Quenching of singlets by long-lived triplets is a serious issue for lasing from organic laser dyes, especially under long pulse excitation. As a strategy to scavenge or manage unnecessary triplets, an organic laser dye is dispersed into a host material having high singlet and low triplet energy levels [a large singlet-triplet energy gap (Delta E-ST)]. However, finding such a host material having a triplet scavenging capability is limited. In this study, an organic laser dye, 2,6-dicyano-1,1-diphenyl-lambda(5)sigma(4)-phosphinine (DCNP), having a small Delta E-ST of approximate to 0.44 eV is synthesized, and thus 4-4 '-bis[(N-carbazole)styryl] biphenyl (BSBCz) can be employed as a triplet scavenging host, i.e., the triplets formed on DCNP are easily transferred to BSBCz. A 1 wt&#37;-DCNP-doped BSBCz film is formed on a mixed-order distributed feedback grating, showing lasing with a low threshold value of approximate to 0.86 mu J cm(-2) and a full-width-at-half-maximum value of approximate to 0.5 nm. Because of the suppressed singlet-triplet annihilation, DCNP-based laser devices operating under a continuous-wave regime, with a low threshold of 72 W cm(-2) and a long laser half-lifetime of approximate to 3 min, are demonstrated. These results indicate a possibility of the wider selection of host materials, easing a material design strategy of fabricating high-performance laser devices in future.

    DOI: 10.1002/adfm.202001078

  • Intersystem Crossing Rate in Thermally Activated Delayed Fluorescence Emitters

    Takashi Kobayashi, Daisuke Kawate, Akitsugu Niwa, Takashi Nagase, Kenichi Goushi, Chihaya Adachi, Hiroyoshi Naito

    PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE   217 ( 3 )   2020年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    For a better understanding of the exciton decay process in thermally activated delayed fluorescence (TADF) emitters, the intersystem crossing rate, k(ISC), is one of the important physical constants that have to be determined. Herein, a method to calculate the k(ISC) value from photoluminescence (PL) measurements is reconsidered. The k(ISC) value can be determined at very low temperatures where delayed fluorescence (DF) is completely suppressed, as well as around room temperature where triplet excitons mainly decay into the ground state by emitting DF. However, there is a temperature range where the k(ISC) value cannot be determined accurately because the influences of nonradiative decay paths can be neither ignored nor corrected. For such a temperature range, an alternative approach, which utilizes the temperature dependence of an observed PL decay rate, is presented. In this way, k(ISC) values from 300 to 10 K are determined for thin films of two TADF emitters, i.e., 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene and 1,2-bis(carbazol-9-yl)-4,5-dicyanobenzene, which are known as 4CzIPN and 2CzPN, respectively.

    DOI: 10.1002/pssa.201900616

  • Observation of Nonradiative Deactivation Behavior from Singlet and Triplet States of Thermally Activated Delayed Fluorescence Emitters in Solution 査読

    Naoto Notsuka, Hajime Nakanotani, Hiroki Noda, Kenichi Goushi, Chihaya Adachi

    JOURNAL OF PHYSICAL CHEMISTRY LETTERS   11 ( 2 )   562 - 566   2020年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Excited states of emissive organic molecules undergo various kinds of quenching phenomena such as vibration-coupled quenching depending on their environmental conditions. Because bright singlet excitons in purely organic molecules exhibiting thermally activated delayed fluorescence (TADF) can access dark triplet excited states, photogenerated singlet excitons can decay nonradiatively through both singlet and triplet excited states. Here, we investigated nonradiative decay behavior, including internal and external exciton quenching processes, of various types of TADF materials in solution. Under air-saturated conditions, both the lowest singlet and triplet excited states of almost all of the TADF materials showed oxygen quenching. We considered the effect of oxygen quenching for both spin states to develop a method for determination of the triplet contribution to the total photoluminescence quantum yield from the transient photoluminescence profiles. Furthermore, we observed a clear energy gap law for the internal nonradiative processes.

    DOI: 10.1021/acs.jpclett.9b03302

  • Intersystem Crossing Rate in Thermally Activated Delayed Fluorescence Emitters 査読

    Takashi Kobayashi, Daisuke Kawate, Akitsugu Niwa, Takashi Nagase, Kenichi Goushi, Chihaya Adachi, Hiroyoshi Naito

    Physica Status Solidi (A) Applications and Materials Science   2019年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    For a better understanding of the exciton decay process in thermally activated delayed fluorescence (TADF) emitters, the intersystem crossing rate, kISC, is one of the important physical constants that have to be determined. Herein, a method to calculate the kISC value from photoluminescence (PL) measurements is reconsidered. The kISC value can be determined at very low temperatures where delayed fluorescence (DF) is completely suppressed, as well as around room temperature where triplet excitons mainly decay into the ground state by emitting DF. However, there is a temperature range where the kISC value cannot be determined accurately because the influences of nonradiative decay paths can be neither ignored nor corrected. For such a temperature range, an alternative approach, which utilizes the temperature dependence of an observed PL decay rate, is presented. In this way, kISC values from 300 to 10 K are determined for thin films of two TADF emitters, i.e., 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene and 1,2-bis(carbazol-9-yl)-4,5-dicyanobenzene, which are known as 4CzIPN and 2CzPN, respectively.

    DOI: 10.1002/pssa.201900616

  • スカイブルー発光を示す2CzPNの時間分解発光スペクトル

    萱苗 淳美, 石井 智也, 小林 隆史, 永瀬 隆, 合志 憲一, 安達 千波矢, 内藤 裕義

    応用物理学会学術講演会講演予稿集   2019.2   2621 - 2621   2019年9月

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    記述言語:日本語  

    Time-resolved photoluminescence spectra of 2CzPN with sky blue emission

    DOI: 10.11470/jsapmeeting.2019.2.0_2621

  • Distributed Feedback Lasers and Light-Emitting Diodes Using 1-Naphthylmethylamnonium Low-Dimensional Perovskite 査読

    Matthew R. Leyden, Shinobu Terakawa, Toshinori Matsushima, Shibin Ruan, Kenichi Goushi, Morgan Auffray, Atula S. D. Sandanayaka, Chuanjiang Qin, Fatima Bencheikh, Chihaya Adachi

    ACS PHOTONICS   6 ( 2 )   460 - 466   2019年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    This work investigates the feasibility of using low-dimensional perovskites for electrically driven lasers given the current status of perovskite light-emitting diodes and optically pumped lasers. In our progress toward electrically driven lasers, we performed a variety of measurements on bulk and low-dimensional perovskite films to give a baseline for expectations. This included the measurement of amplified spontaneous emission, lasing, and near-infrared light-emitting diodes operated at low and high current density. We considered power density thresholds needed for amplified spontaneous emission and lasing and compared this to light-emitting diodes operated at high current density to speculate on the future of electrically driven perovskite lasers. We concluded that our current perovskite devices will need current densities of similar to 4 to 10 kA/cm(2) to achieve lasing. Future devices will most significantly benefit from architectures that accommodate higher current, but meaningful reductions in threshold may also come from improved film quality and confinement.

    DOI: 10.1021/acsphotonics.8b01413

  • Enhanced Electroluminescence from Organic Light-Emitting Diodes with an Organic-Inorganic Perovskite Host Layer 査読

    Toshinori Matsushima, Chuanjiang Qin, Kenichi Goushi, Fatima Bencheikh, Takeshi Komino, Matthew Leyden, Atula S. D. Sandanayaka, Chihaya Adachi

    ADVANCED MATERIALS   30 ( 38 )   2018年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The development of host materials with high performance is essential for fabrication of efficient and stable organic light-emitting diodes (OLEDs). Although host materials used in OLEDs are typically organics, in this study, it is shown that the organic-inorganic perovskite CH3NH3PbCl3 (MAPbCl(3)) can be used as a host layer for OLEDs. Vacuum-evaporated MAPbCl(3) films have a wide band gap of about 3 eV and very high and relatively balanced hole and electron mobilities, which are suitable for the host material. Photoluminescence and electroluminescence take place through energy transfer from MAPbCl(3) to an organic emitter in films. Incorporation of an MAPbCl(3) host layer into OLEDs leads to a reduction of driving voltage and enhancement of external quantum efficiency as compared to devices with a conventional organic host layer. Additionally, OLEDs with an MAPbCl(3) host layer demonstrate very good operational stability under continuous current operation. These results can be extensively applied to organic- and perovskite-based optoelectronics.

    DOI: 10.1002/adma.201802662

  • Triplet-triplet annihilation in a thermally activated delayed fluorescence emitter lightly doped in a host 査読

    Akitsugu Niwa, Shota Haseyama, Takashi Kobayashi, Takashi Nagase, Kenichi Goushi, Chihaya Adachi, Hiroyoshi Naito

    APPLIED PHYSICS LETTERS   113 ( 8 )   2018年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Triplet-triplet annihilation (TTA) will change the ratio between fluorescence and phosphorescence in the photoluminescence spectrum of a thermally activated delayed fluorescence emitter at very low temperature. Using the resultant spectral blueshift, this study investigated the nature of TTA in 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) doped in a host material. The spectral blueshift is not caused by singlet-triplet annihilation and the emitter saturation effect and is less influenced by the emitter aggregates, particularly for the case of a lower doping concentration. Using these features, it is possible to focus on TTA. For 4CzIPN, the spectral blueshift due to TTA is recognized even in samples with the doping concentration as low as 1 wt. &#37;. Published by AIP Publishing.

    DOI: 10.1063/1.5025870

  • Emission properties of thermally activated delayed fluorescence emitters: analysis based on a four-level model considering a higher triplet excited state 査読

    Takashi Kobayashi, Akitsugu Niwa, Shota Haseyama, Kensho Takaki, Takashi Nagase, Kenichi Goushi, Chihaya Adachi, Hiroyoshi Naito

    JOURNAL OF PHOTONICS FOR ENERGY   8 ( 3 )   2018年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    A four-level model consisting of a higher triplet excited state (T-2), the lowest singlet and triplet excited states (S-1 and T-1), and the ground state was previously used to understand emission properties of a thermally activated delayed fluorescence (TADF) emitter, 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN). In this report, we discuss the four-level model in more detail and apply to the other two TADF emitters, i.e., 1,2,4,5-tetrakis(carbazol-9-yl)-3,6-dicyanobenzene (4CzTPN) and 1,2-bis(carbazol-9-yl)-4,5-dicyanobenzene(2CzPN), in order to determine their excited-state structures. It is suggested that in all the emitters T-2 lies between S-1 and T-1 and play an essential role in the emitting process. In 4CzTPN, phosphorescence from T-2 is clearly observed around 100 K as in 4CzIPN. Compared to the other two emitters, 2CzPN has a wider energy gap between S-1 and T-1 so that delayed fluorescence at room temperature is thought to be mixed with phosphorescence. Because of this mixing, the spectrum characteristic of phosphorescence from T-2 in 2CzPN cannot be identified. (C) 2018 Society of Photo-Optical Instrumentation Engineers (SPIE)

    DOI: 10.1117/1.JPE.8.032104

  • Observation of spontaneous orientation polarization in evaporated films of organic light-emitting diode materials 査読

    Kohei Osada, Kenichi Goushi, Hironori Kaji, Chihaya Adachi, Hisao Ishii, Yutaka Noguchi

    ORGANIC ELECTRONICS   58   313 - 317   2018年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The molecular orientation in organic semiconductor films determines device performances. In particular, the spontaneous orientation of a permanent dipole moment (PDM) along the surface normal direction induces a polarization charge at the hetero-interfaces of stacked multilayer devices, and the interface charge dominates the charge accumulation and injection properties. Spontaneous orientation polarization (SOP) has been observed in the "randomly oriented" films of several organic semiconductor materials, and is potentially inherent in many common materials. Herein, we report that 11 additional molecules of organic light-emitting diode materials, including thermally activated delayed fluorescence emitters, and horizontally oriented emitters and electron transporters, exhibit SOP in their evaporated films. The experimental results clearly indicate that SOP frequently occurs in "horizontally oriented" films as well as "randomly oriented" films. The factors contributing to SOP formation are discussed in terms of the figure of merit per PDM. We found that strong intermolecular interactions tend to reduce the figure of merit. Moreover, we suggest the impact of SOP on device performances.

    DOI: 10.1016/j.orgel.2018.04.026

  • Recent Advances in Molecular Electronics and Bioelectronics FOREWORD

    Kenichi Goushi, Takeshi Fukuda, Atsushi Kubono, Atsushi Miura, Kei Noda, Hiroaki Usui, Ichiro Yamashita, Yuji Yoshida

    JAPANESE JOURNAL OF APPLIED PHYSICS   57 ( 3 )   2018年3月

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    記述言語:英語  

    DOI: 10.7567/JJAP.57.03E001

  • Confinement of Long-Lived Triplet Excitons in Organic Semiconducting Host-Guest Systems 査読

    Naoto Notsuka, Ryota Kabe, Kenichi Goushi, Chihaya Adachi

    ADVANCED FUNCTIONAL MATERIALS   27 ( 40 )   2017年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Long-lived triplet excitons on organic molecules easily deactivate at room temperature because of the presence of thermally activated nonradiative pathways. This study demonstrates long-lived phosphorescence at room temperature resulting from suppression of the nonradiative deactivation of triplet excitons in conventional organic semiconducting host-guest systems. The nonradiative deactivation pathway strongly depends on the triplet energy gap between the guest emitting molecules and the host matrices. The triplet energy gap required to confine the long-lived triplet excitons (approximate to 0.5 eV) is much larger than that of conventional host-guest systems for phosphorescent emitters. By effectively confining the triplet excitons, this study demonstrates long-lived room-temperature phosphorescence under optical and electrical excitation.

    DOI: 10.1002/adfm.201703902

  • Flexible and Printed Electronics 査読

    Masatoshi Kitamura, Kenichi Goushi, Takao Ishida, Tatsuo Mori, Hiroyoshi Naito, Masaya Nogi, Kazuhito Tsukagoshi, Yukiharu Uraoka, Hirobumi Ushijima, Tsukasa Yoshida

    JAPANESE JOURNAL OF APPLIED PHYSICS   56 ( 5 )   2017年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.7567/JJAP.56.05E001

  • Control of the Singlet-Triplet Energy Gap in a Thermally Activated Delayed Fluorescence Emitter by Using a Polar Host Matrix 査読 国際誌

    Shota Haseyama, Akitsugu Niwa, Takashi Kobayashi, Takashi Nagase, Kenichi Goushi, Chihaya Adachi, Hiroyoshi Naito

    NANOSCALE RESEARCH LETTERS   12 ( 1 )   2017年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The photoluminescence properties of a thermally activated delayed fluorescence emitter, 1,2-bis(carbazol-9-yl)-4,5-dicyanobenzene (2CzPN), doped in a host matrix consisting of 1,3-bis(9-carbazolyl) benzene and a polar inert molecule, camphoric anhydride (CA), in various concentrations have been investigated. It is found that the addition of CA stabilizes only the lowest singlet excited state (S-1) of 2CzPN without changing the energy level of the lowest triplet excited state (T-1), leading to a reduction in the energy gap between S-1 and T-1. The maximum reduction of energy gap achieved in this work has been determined to be around 65 meV from the shift of the fluorescence spectrum and the temperature dependence of the photoluminescence decay rate.

    DOI: 10.1186/s11671-017-2012-1

  • Contributions of a Higher Triplet Excited State to the Emission Properties of a Thermally Activated Delayed-Fluorescence Emitter 査読 国際誌

    Takashi Kobayashi, Akitsugu Niwa, Kensho Takaki, Shota Haseyama, Takashi Nagase, Kenichi Goushi, Chihaya Adachi, Hiroyoshi Naito

    PHYSICAL REVIEW APPLIED   7 ( 3 )   2017年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The temperature dependences of photoluminescence (PL) decay rates and the PL spectrum of a thermally activated delayed-fluorescence emitter, 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN), are investigated. It is found that not only the lowest singlet (S-1) and triplet ( T-1) excited states but also an additional triplet excited state ( T-n) lying between S-1 and T-1 play an important role in the exciton decay process, particularly around 100 K. At around this temperature, some of the triplet excitons are thermally activated into Tn but not up to S-1, and they then decay into the ground state (S-0) with phosphorescence emission. Therefore, two kinds of phosphorescence, originating from T-n and T-1, are observed. The temperature dependence of the PL decay rates of 4CzIPN can be explained by a four-level model consisting of S-1, T-1, T-n, and S-0, and its energy gaps between T-n and T-1 and between S-1 and T-1 are determined to be 45 +/- 5 meV and 135 +/- 10 meV, respectively.

    DOI: 10.1103/PhysRevApplied.7.034002

  • Quasi-Continuous-Wave Organic Thin-Film Distributed Feedback Laser 査読 国際誌

    SANDANAYAKA SANGARANGE, Kou Yoshida, Munetomo Inoue, QIN CHUANJIANG, Kenichi Goushi, JEAN CHARLES MAURICE RIBIERRE, Toshinori Matsushima, Chihaya Adachi

    Advanced optical materials   4 ( 6 )   834 - 839   2016年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1002/adom.201600006

  • Quasi-Continuous-Wave Organic Thin-Film Distributed Feedback Laser 査読 国際誌

    Atula S. D. Sandanayaka, Kou Yoshida, Munetomo Inoue, Chuanjiang Qin, Kenichi Goushi, Jean-Charles Ribierre, Toshinori Matsushima, Chihaya Adachi

    ADVANCED OPTICAL MATERIALS   4 ( 6 )   834 - 839   2016年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1002/adom.201600006

  • Quasi-Continuous-Wave Organic Thin-Film Distributed Feedback Laser 査読 国際誌

    Atula S. D. Sandanayaka, Kou Yoshida, Munetomo Inoue, Chuanjiang Qin, Kenichi Goushi, Jean-Charles Ribierre, Toshinori Matsushima, Chihaya Adachi

    ADVANCED OPTICAL MATERIALS   4 ( 6 )   834 - 839   2016年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1002/adom.201600006

  • Quasi-Continuous-Wave Organic Thin-Film Distributed Feedback Laser 査読 国際誌

    Atula S. D. Sandanayaka, Kou Yoshida, Munetomo Inoue, Chuanjiang Qin, Kenichi Goushi, Jean-Charles Ribierre, Toshinori Matsushima, Chihaya Adachi

    ADVANCED OPTICAL MATERIALS   4 ( 6 )   834 - 839   2016年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1002/adom.201600006

  • Quasi-Continuous-Wave Organic Thin-Film Distributed Feedback Laser 査読 国際誌

    Atula S. D. Sandanayaka, Kou Yoshida, Munetomo Inoue, Chuanjiang Qin, Kenichi Goushi, Jean-Charles Ribierre, Toshinori Matsushima, Chihaya Adachi

    ADVANCED OPTICAL MATERIALS   4 ( 6 )   834 - 839   2016年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1002/adom.201600006

  • Quasi-Continuous-Wave Organic Thin-Film Distributed Feedback Laser 査読 国際誌

    Atula S. D. Sandanayaka, Kou Yoshida, Munetomo Inoue, Chuanjiang Qin, Kenichi Goushi, Jean-Charles Ribierre, Toshinori Matsushima, Chihaya Adachi

    ADVANCED OPTICAL MATERIALS   4 ( 6 )   834 - 839   2016年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1002/adom.201600006

  • Quasi-Continuous-Wave Organic Thin-Film Distributed Feedback Laser 査読 国際誌

    Atula S. D. Sandanayaka, Kou Yoshida, Munetomo Inoue, Chuanjiang Qin, Kenichi Goushi, Jean-Charles Ribierre, Toshinori Matsushima, Chihaya Adachi

    ADVANCED OPTICAL MATERIALS   4 ( 6 )   834 - 839   2016年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1002/adom.201600006

  • Organic light-emitting diodes (OLEDs) Materials, photophysics, and device physics 査読 国際誌

    Chihaya Adachi, Saeyoun Lee, Tetsuya Nakagawa, Katsuyuki Shizu, Kenichi Goshi, Takuma Yasuda, William J. Potscavage

    Organic Electronics Materials and Devices   43 - 73   2015年9月

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    記述言語:英語  

    Currently, organic light-emitting diodes (OLEDs) have reached the stage of commercialization, and there has been an intense drive to use them in various applications from small-and medium-sized mobile devices to illumination equipment and large television screens. In particular, room-temperature phosphorescent materials have become core OLED components as alternatives to conventionally used fluorescent materials because devices made with phosphorescent materials exhibit excellent light-emitting performance with internal electroluminescence efficiencies (ηint) of nearly 100 &#37;. However, phosphorescent materials have several intrinsic problems, such as being limited to metal-organic compounds containing rare metals, for example, Ir, Pt, Au, and Os, and difficulty in realizing stable blue light emission. As a result, researchers have attempted to develop new materials for use as emissive dopants in OLEDs that overcome these limitations. In this chapter, first we briefly review the progress of OLED materials and device architectures mainly based on fluorescent (first-generation) and phosphorescent (secondgeneration) emitters. Then, we discuss third-generation OLEDs that use a new light-emitting mechanism called thermally activated delayed fluorescence (TADF). Recently, highly efficient TADF, which had been difficult to realize with conventional molecular design, has been achieved by very sophisticated molecular structures, allowing access to the unlimited freedom of molecular design using carbon-based materials. This has led to the production of ultimate OLEDs that are made of common organic compounds without precious metals and can convert electricity to light at ηint of nearly 100 &#37;.

    DOI: 10.1007/978-4-431-55654-1_2

  • Comparison of transient state and steady state exciton-exciton annihilation rates based on Forster-type energy transfer 査読 国際誌

    Toshiya Yonehara, Kenichi Goushi, Tomoaki Sawabe, Isao Takasu, Chihaya Adachi

    JAPANESE JOURNAL OF APPLIED PHYSICS   54 ( 7 )   071601   2015年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We investigated differences between the transient state and steady state exciton-exciton annihilation rates based on Forster-type energy transfer. The exciton-exciton annihilation rate of an organic semiconductor is usually determined by transient state photoluminescence measurements using a pulsed laser or steady state photoluminescence measurements using a continuous wave laser. However, it is unclear that the respective annihilation rates determined by their rate equations are the same. In calculations with platinum-octaethylporphyrin (PtOEP) parameters, Monte Carlo simulations gave two different annihilation rates for the transient state and the steady state. The analytical models based on Forster-type energy transfer also showed the same result. These results indicate that the exciton-exciton annihilation rates in transient state and steady state are distinguished. (C) 2015 The Japan Society of Applied Physics

    DOI: 10.7567/JJAP.54.071601

  • Highly Efficient Thermally Activated Delayed Fluorescence Emitters with a Small Singlet-Triplet Energy Gap and Large Oscillator Strength 査読 国際誌

    Yuta Sagara, Katsuyuki Shizu, Hiroyuki Tanaka, Hiroshi Miyazaki, Kenichi Goushi, Hironori Kaji, Chihaya Adachi

    CHEMISTRY LETTERS   44 ( 3 )   360 - 362   2015年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    A strategy for designing highly efficient thermally activated delayed fluorescence (TADF) emitters was reported. TADF emitters with donor-acceptor-donor (D-A-D)-type structures showed highly efficient TADF because of their small singlet-triplet energy gap and large oscillator strength. An organic light-emitting diode containing a D-A-D-type TADF emitter, cis-BOX2, exhibited a high external electroluminescence quantum efficiency of 17.6&#37;.

    DOI: 10.1246/cl.141054

  • Charge carrier dynamics and degradation phenomena in organic light-emitting diodes doped by a thermally activated delayed fluorescence emitter 査読 国際誌

    Yutaka Noguchi, Hyung-Jun Kim, Ryuta Ishino, Kenichi Goushi, Chihaya Adachi, Yasuo Nakayama, Hisao Ishii

    ORGANIC ELECTRONICS   17   184 - 191   2015年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We report on the charge carrier dynamics and their degradation phenomena in an organic light-emitting diode (OLED) doped by a thermally activated delayed fluorescence emitter; (4s, 6s)-2,4,5,6-tetra(9H-carbazol-9-yl) isophthalonitrile (4CzIPN). Displacement current measurement (DCM) data revealed the presence of negative interface charge originating from the spontaneous orientation polarization of the electron transport layer (ETL), 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl) benzene. The negative interface charge acts as a hole reservoir and thus confines the recombination zone near the emission layer (EML); 4,4'-bis(N-carbazolyl)-1,1'-biphenyl (CBP):4CzIPN (5 wt&#37;)/ETL interface. By keeping the recombination zone far from the hole transport layer, 4,40-bis[N-(1-naphthyl)-N-phenylamino]- biphenyl (alpha-NPD), a better electroluminescence efficiency is expected because the Dexter energy transfer from the triplet state of 4CzIPN to that of alpha-NPD is suppressed. Moreover, we found an excellent linear relation between the accumulated hole amount and luminance losses owing to device aging. The results are consistent with hole traps originating at the degradation products of CBP as the main factor of device degradation. We suggest device architectures based on the charge carrier dynamics for better efficiency and lifetime. (C) 2014 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.orgel.2014.12.009

  • Influence of host matrix on thermally-activated delayed fluorescence: Effects on emission lifetime, photoluminescence quantum yield, and device performance 査読 国際誌

    Gabor Mehes, Kenichi Goushi, William J. Potscavage, Chihaya Adachi

    ORGANIC ELECTRONICS   15 ( 9 )   2027 - 2037   2014年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The influence of the host molecules on the photoluminescent (PL) and electroluminescent (EL) properties of organic light-emitting diode (OLED) emitters showing efficient thermally-activated delayed fluorescence (TADF) has yet to be investigated in detail. Here we demonstrate that the choice of host can cause large variations in the PL quantum yield (Phi(PL) similar to 15-70&#37;) and delayed PL transient decay (tau(del) similar to 2-70 ms) of a spiro-acridine-based TADF guest. We show that the effect of exciplex formation on Phi(PL) must be considered even at low concentrations of the TADF guest. Using the same TADF guest but changing the host layer, we are able to greatly vary the PL transient decay time from similar to 4 to similar to 70 ms while maintaining a high Phi(PL) similar to 70&#37;, which can lead to new applications. Detailed spectral characterization during PL decay reveals a gradually increasing singlet-triplet energy gap (Delta E-ST) as the origin of these observations. The time-varying Delta E-ST is explained based on dipole interactions between the host and guest molecules. Finally, PL and electrical considerations for host selection are discussed based on the performance of OLED devices. (C) 2014 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.orgel.2014.05.027

  • Temperature dependence of photoluminescence properties in a thermally activated delayed fluorescence emitter 査読 国際誌

    Akitsugu Niwa, Takashi Kobayashi, Takashi Nagase, Kenichi Goushi, Chihaya Adachi, Hiroyoshi Naito

    APPLIED PHYSICS LETTERS   104 ( 21 )   2014年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Using steady-state and time-resolved photoluminescence (PL) spectroscopy, we have investigated the temperature dependence of PL properties of 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN), which have a small energy gap between its singlet and triplet excited states and thus exhibits efficient thermally activated delayed fluorescence [H. Uoyama et al., Nature 492, 235 (2012)]. Below around 100 K, PL quantum efficiency of 4CzIPN thin films is largely suppressed and strong photoexcitation intensity dependence appears. These features can be explained by using rate equations for the densities of singlet and triplet excited states considering a triplet-triplet annihilation process. (C) 2014 AIP Publishing LLC.

    DOI: 10.1063/1.4878397

  • Reduced amplified spontaneous emission threshold in organic semiconductor laser structure with relaxed roll-off characteristics under high current densities 査読

    Munetomo Inoue, Kenichi Goushi, Kuniaki Endo, Hiroko Nomura, Chihaya Adachi

    JOURNAL OF LUMINESCENCE   143   754 - 758   2013年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We reduced the amplified spontaneous emission (ASE) threshold in an organic semiconductor laser structure by the introduction of an exciton blocking layer adjacent to the cathode layer. A phenyldipyrenylphosphine oxide (POPy2) layer with the function of an electron transport layer and the exciton blocking layer were inserted between an active layer of 4,4-bis[N-(carbazole)styrylbiphenyll (BSB-Cz) and a metal cathode layer. The electron injection barrier from POPy2 to BSB-Cz is downward, indicating no net energy barrier, and the hole injection barrier from the BSB-Cz layer into the POPy2 layer is also small because of the similarity between the highest occupied molecular orbital levels of the materials. Therefore, the proposed device structure can avoid extra carrier accumulations at the heterointerface, leading to compatibility in terms of both relaxation of the exciton-polaron annihilation and blocking of the energy transfer from the BSB-Cz layer into the cathode layer. (C) 2013 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.jlumin.2013.04.001

  • Reduced amplified spontaneous emission threshold in organic semiconductor laser structure with relaxed roll-off characteristics under high current densities 査読 国際誌

    Munetomo Inoue, Kenichi Goushi, Kuniaki Endo, Hiroko Nomura, CHIHAYA ADACHI

    Journal of Luminescence   2013年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: http://authors.elsevier.com/sd/article/S0022231313002123

  • Triplet Exciton Confinement in Green Organic Light-Emitting Diodes Containing Luminescent Charge-Transfer Cu(I) Complexes 査読 国際誌

    Qisheng Zhang, Takeshi Komino, Shuping Huang, Shigeyuki Matsunami, Kenichi Goushi, Chihaya Adachi

    ADVANCED FUNCTIONAL MATERIALS   22 ( 11 )   2327 - 2336   2012年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The temperature dependence of luminescence from [Cu(dnbp)(DPEPhos)]BF4 (dnbp = 2,9-di-n-butylphenanthroline, DPEPhos = bis[2-(diphenylphosphino)phenyl]ether) in a poly(methyl methacrylate) (PMMA) film indicates the presence of long-life green emission arising from two thermally equilibrated charge transfer (CT) excited states and one non-equilibrated triplet ligand center (3LC) excited state. At room temperature, the lower triplet CT state is found to be the predominantly populated excited state, and the zero-zero energy of this state is found to be 2.72 eV from the onset of its emission at 80 K. The tunable emission maximum of [Cu(dnbp)(DPEPhos)]BF4 in various hosts with different triplet energies is explained in terms of the multiple triplet energy levels of this complex in amorphous films. Using the high triplet energy charge transport material as a host and an exciton-blocking layer (EBL), a [Cu(dnbp)(DPEPhos)]BF4 based organic light-emitting diode (OLED) achieves a high external quantum efficiency (EQE) of 15.0&#37;, which is comparable to values for similar devices based on Ir(ppy)3 and FIrpic. The photoluminescence (PL) and electroluminescence (EL) performance of green emissive [Cu(mu I)dppb]2 (dppb = 1,2-bis[diphenylphosphino]benzene) in organic semiconductor films confirmed its 3CT state with a zero-zero energy of 2.76 eV as the predominant population excited state.

    DOI: 10.1002/adfm.201101907

  • Two-dimensional orientation control of organic semiconducting amorphous films by mechanical brushing 査読 国際誌

    Toshiharu Arai, Kenichi Goushi, Hiroko Nomura, Tomohiko Edura, Chihaya Adachi

    Appl. Phys. Lett.   99   2011年8月

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    記述言語:英語  

  • Two-dimensional orientation control of organic semiconducting amorphous films by mechanical brushing 査読

    Toshiharu Arai, Kenichi Goushi, Hiroko Nomura, Tomohiko Edura, Chihaya Adachi

    APPLIED PHYSICS LETTERS   99 ( 5 )   2011年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We demonstrate that horizontally oriented organic semiconducting molecules in amorphous films can be oriented uniaxially by mechanical brushing. The absorption of polarized light in the direction parallel to the brushing direction was higher than the absorption in the perpendicular direction. Thus, simultaneous uniaxial and in-plane molecular orientation in amorphous films was realized by brushing. In addition, we demonstrate a polarized electroluminescence from the films treated by mechanical brushing. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3608315]

    DOI: 10.1063/1.3608315

  • Improvement of Electroluminescence Performance of Organic Light-Emitting Diodes with a Liquid-Emitting Layer by Introduction of Electrolyte and a Hole-Blocking Layer 査読 国際誌

    Shuzo Hirata, Korefumi Kubota, Heo Hyo Jung, Osamu Hirata, Kenichi Goushi, Masayuki Yahiro, Chihaya Adachi

    ADVANCED MATERIALS   23 ( 7 )   889 - +   2011年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Organic light-emitting diodes containing a liquid-emitting layer that exhibit improved external electroluminescence quantum efficiency (Phi(EL)) and maximum luminance are presented. Doping the liquid-emitting layer with an electrolyte significantly decreases the turn-on voltage for electroluminescence. Insertion of a TiO2 hole-blocking layer between the liquid-emitting layer and indium tin oxide cathode improves Phi(EL).

    DOI: 10.1002/adma.201003505

  • Time-correlated single photon counting system and light-collection system for studying fluorescence emitters under high-vacuum conditions: Use of immersion objective and ionic liquid 査読 国際誌

    Toshiki Yamada, Kenichi Goushi, Akira Otomo

    THIN SOLID FILMS   518 ( 2 )   432 - 436   2009年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    In this paper, we introduce a time-correlated single photon counting system and an efficient light-collection system for studying fluorescence emitters under high-vacuum conditions; the latter system has an immersion objective, and an ionic liquid is used as a refractive index matching medium. The ionic liquid is positioned in high vacuum. The time-correlated single photon counting system has modified photomultiplier tubes that act as photon detectors. The light-collection system is designed to be simple, compact, and easy to use. In order to verify the performance of these systems, the optical properties of colloidal semiconductor nanocrystals (CdSe/ZnS) and fluorescent dye molecules are studied as examples. (C) 2009 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.tsf.2009.07.002

  • Organic Field Effect Transistor Using Pentacene Single Crystals Grown by a Liquid-Phase Crystallization Process 査読 国際誌

    Yasuo Kimura, Michio Niwano, Naohiko Ikuma, Kenichi Goushi, Kingo Itaya

    LANGMUIR   25 ( 9 )   4861 - 4863   2009年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Nearly perfect pentacene single crystals with wide terraces several micrometers in width were grown by crystallization from a pentacene-containing trichlorobenzene solution. Organic Field-effect transistors (OFETs) were fabricated with the pentacene single crystals and characterized for their electrical properties. The field effect mobility was found to be in the range of 0.4-0.6 cm(2)/V.s, which is comparable to that of OFETs fabricated with pentacene single crystals prepared by a physical vapor-phase growth method. The results described in this paper clearly demonstrate that the crystallization of organic semiconductors from solution is a promising chemical method for device processing of OFETs.

    DOI: 10.1021/la900647y

  • Time-correlated single photon counting and optical measurement systems for studying single fluorescent emitters under high vacuum conditions 査読 国際誌

    Toshiki Yamada, Kenichi Goushi, Xingsheng Xu, Akira Otomo

    THIN SOLID FILMS   517 ( 4 )   1507 - 1511   2008年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    In this paper, we introduce a modified inverted microscope system in which an objective with high NA (0.95) is located under high-vacuum conditions, and a time-correlated single photon counting system is used along with a modified photomultiplier tube for the characterization of single emitters under high-vacuum conditions. The modified inverted microscope system is designed to be simple, compact, and easy to handle. As an example, the optical properties of individual colloidal semiconductor nanocrystals (CdSe/ZnS) were studied by using these systems. (c) 2008 Elsevier B.V. All rights reserved

    DOI: 10.1016/j.tsf.2008.09.029

  • Charge-carrier injection characteristics at organic/organic heterojunction interfaces in organic light-emitting diodes 査読 国際誌

    Toshinori Matsushima, Kenichi Goushi, Chihaya Adachi

    CHEMICAL PHYSICS LETTERS   435 ( 4-6 )   327 - 330   2007年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Organic light-emitting diodes (OLEDs) having various guest molecules doped in an organic host matrix layer are fabricated [the OLED structure is anode/hole-transporting layer (HTL)/guest-host emitting layer/hole-blocking layer/electron-transporting layer/cathode], and the dependence of current density-voltage (J-V) characteristics of the OLEDs on highest occupied molecular orbital (HOMO) levels of guest molecules are investigated. From the J-V characteristics of these OLEDs, we find two important results: (1) J-V characteristics of the OLEDs are controlled by the direct hole injection from the neighboring HTL to guest molecules, and (2) HOMO level alignment between the HTL and guest molecules provides efficient hole injection at this interface. (c) 2007 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.cplett.2007.01.010

  • Phosphorescence quantum efficiency and intermolecular interaction of Iridium(III) complexes in co-deposited films with organic semiconducting hosts 査読

    Y Kawamura, K Goushi, J Brooks, JJ Brown, H Sasabe, C Adachi

    Organic and Nanocomposite Optical Materials   846   73 - 78   2005年8月

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    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

    We accurately measured the absolute photoluminescence (PL) quantum efficiency (eta(PL)) Of organic solid-state thin films by using an integrating sphere. We measured the eta(PL) Of conventional organic materials used in organic light emitting diodes, such as a tris (8-quinolionolato)aluminum(III) complex (Alq(3)), and a phosphorescent 1.5mol%-fac-tris(2-phenylpyridyl)iridium(III):4,4'-bis(carbazol-9-yl)-2,2'-biphenyl [Ir(ppy)(3):CBP] co-deposited film. Alq(3) and lr(ppy)(3):CBP showed a eta(PL) = 20 +/- 1% and 97 +/- 2%, which corresponded well to external electroluminescence efficiency using these materials. We also measured red emitting bis[2-(2'-benzothienyl)pyridinato-N,C-3'] (acetylacetonato) iridium(III) [BtP(2)Ir(acac)] with CBP, and the blue complex, bis[(4,6-difluorophenyl)pyridinato -N, C-2](picolinato)iridium(III)[FIrpic], with m-bis(N-carbazolyl)benzene. The maximum eta(PL) values for BtP(2)Ir(acac), and FIrpic were 51 +/- 1 % (at 1.4mol%), and 99 +/- 1% (1.2mol%), respectively. These results suggest that the TIEL of red phosphorescent OLEDs using BtP(2)Ir(acac) as the dopant can be as high as 10%, and blue devices using FIrpic can reach the theoretical limit of 20%.

  • 100&#37; fluorescence efficiency of 4,4’-bis[(N-carbazole)styryl]biphenyl in a solid film and the very low amplified spontaneous emission threshold 査読 国際誌

    T. AIMONO, Y. KAWAMURA, K. GOUSHI, H. YAMAMOTO, H. SASABE C. ADACHI

    APPLIED PHYSICS LETTERS   86 ( 7 )   2005年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1063/1.1867555

  • Unusual Phosphorescence Characteristics of Ir(ppy)3 in a Solid Matrix at Low Temperatures 査読 国際誌

    Goushi Kenichi, Kawamura Yuichiro, Sasabe Hiroyuki, Adachi Chihaya

    Japanese journal of applied physics. Pt. 2, Letters   43 ( 7 )   L937 - L939   2004年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We observed unusual radiative decay characteristics of a (fac-tris(2-phenylpyridine)iridium [Ir(ppy)3]) triplet-excited state doped into 4, 4&#36;'&#36;-N, N&#36;'&#36;-dicarbazole-biphenyl (CBP) and polymethylmethacrylate (PMMA) host matrices. From a measurement of the temperature dependence on the phosphorescence intensity and the lifetime of Ir(ppy)3 in these hosts, we observed that phosphorescence intensities are independent of temperature, while the lifetimes significantly increase at temperatures below &#36;T sim 50&#36; K. These results lead us to conclude that the non-radiative transition rate (&#36;k_{ ext{nr } }&#36;) from the triplet excited state is very small compared with the radiative transition rate (&#36;k_{ ext{r } }&#36;) and that the phosphorescence quantum yield (&#36;phi_{ ext{PH } }&#36;) is nearly 100&#37; even at room temperature. Based on our experimental results, we propose a possible decay mechanism to rationalize the characteristic temperature dependence on the transient phosphorescence.

    DOI: 10.1143/JJAP.43.L937

  • Triplet exciton confinement and unconfinement by adjacent hole-transport layers 査読 国際誌

    K. GOUSHI, R. KWONG, J. J. BROWN, H. SASABE, C. ADACHI

    JOURNAL OF APPLIED PHYSICS   95 ( 12 )   2004年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1063/1.1751232

  • 2つのリン光性ドーパントを含有する白色リン光デバイスの発光機構

    佐藤 喜郎, 合志 憲一, 雀部 博之, BROWN Julie J., 斉藤 正美, 安達 千波矢

    電気学会論文誌. A, 基礎・材料・共通部門誌 = The transactions of the Institute of Electrical Engineers of Japan. A, A publication of Fundamentals and Materials Society   124 ( 5 )   414 - 420   2004年5月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    High efficiency white organic light emitting diodes (WOLED) have been expected for applications of lighting, illumination and back-light sources for LCD. Recently, since organic phosphors demonstrated very high electroluminescence (EL) quantum efficiency of ˜100%, high efficiency WOLED with the organic phosphors has been anticipated. In this study, we employed an emitter layer which is doped with blue and red phosphorescence molecules. In our optimized device structure, we obtained maximum EL quantum efficiency of 4%. However, the shapes of the EL spectrum were strongly dependent on current density. With analysis of exciton decay process under optical and electrical excitations, we conclude that triplet-triplet annihilation occurs in blue and red phosphors independently, resulted in a significant change of the EL spectrum. Thus, the coincidence of the lifetimes of the blue and red phosphors is indispensable to escape change of EL spectrum with current density.

    DOI: 10.1541/ieejfms.124.414

  • Ultraviolet amplified spontaneous emission from thin films of 4,4 '-bis(9-carbazolyl)-2,2 '-biphenyl and the derivatives 査読 国際誌

    Y. KAWAMURA, H. YAMAMOTO, K. GOUSHI, H. SASABE C. ADACHI

    APPLIED PHYSICS LETTERS   84 ( 15 )   2004年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1063/1.1695091

  • High-efficiency organic electrophosphorescent diodes using 1, 3, 5-triazine electron transport materials 査読 国際誌

    H. INOMATA, K. GOUSHI, T. MASUKO, T. KONNO, T. IMAI, H. SASABE, J. J. BROWN, C. ADACHI

    CHEMISTRY OF MATERIALS   16 ( 7 )   2004年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1021/cm034689t

▼全件表示

書籍等出版物

  • 先端 有機半導体デバイス

    合志 憲一(担当:共著)

    2015年8月 

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    記述言語:日本語   著書種別:学術書

  • 有機半導体のデバイス物性

    安達千波矢(編者), 合志憲一(一部執筆)

    2012年4月 

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    記述言語:その他   著書種別:学術書

  • 有機EL材料技術

    河村祐一郎, 合志憲一, 安達千波矢

    2004年1月 

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    記述言語:日本語   著書種別:学術書

  • 有機半導体の応用展開

    安達千波矢, 合志憲一, 河村祐一郎

    シーエムシー出版  2003年12月 

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    記述言語:その他   著書種別:学術書

  • 有機ELディスプレイにおける高輝度・高効率・長寿命化技術

    合志憲一, 安達千波矢

    2003年9月 

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    記述言語:日本語   著書種別:学術書

講演・口頭発表等

  • Efficient Intramolecular Triplet-Triplet Annihilation Upconversion of Anthracene Dimers in Organic Light-Emitting Diodes 招待 国際会議

    Kenichi Goushi

    IDW23  2022年11月 

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    開催年月日: 2023年12月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Niigata   国名:日本国  

  • 三重項励起子を利用した有機光デバイスの高性能化 招待

    合志 憲一

    電子情報通信学会有機エレクトロニクス研究会  2023年3月 

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    開催年月日: 2023年3月

    記述言語:日本語  

    国名:日本国  

  • Intramolecular triplet-triplet annihilation up-conversion in organic light-emitting diodes 招待 国際会議

    Kenichi Goushi

    ICONO13/ICOPE2022  2022年11月 

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    開催年月日: 2022年11月

    記述言語:英語  

    開催地:Nara   国名:日本国  

  • Efficient organic photonic devices by manipulating triplet excited states 招待

    Kenichi Goushi

    SNU – KYUSHU JOINT SYMPOSIUM  2020年9月 

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    開催年月日: 2020年9月

    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:Kyushu University   国名:日本国  

  • 有機薄膜による新しい光エレクトロニクス 招待

    合志 憲一

    2nd Interdisciplinary Forum  2019年3月 

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    開催年月日: 2019年11月

    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:東京大学   国名:日本国  

  • 酸素濃度を変えた4CzIPN 溶液試料における発光減衰曲線

    川手 大輔, 萱苗 淳美, 石井 智也, 丹羽 顕嗣, 小林 隆史, 永瀬 隆, 合志 憲一, 安達 千波矢, 内藤 裕義

    第66回応用物理学会春季学術講演会  2019年3月 

     詳細を見る

    開催年月日: 2019年3月

    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:東京工業大学   国名:日本国  

  • 臭素置換された熱活性化遅延蛍光材料の光物性評価

    石井 智也, 川手 大輔, 小林 隆史, 永瀬 隆, 合志 憲一, 中野谷 一, 安達 千波矢, 内藤 裕義

    第66回応用物理学会春季学術講演会  2019年3月 

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    開催年月日: 2019年3月

    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:東京工業大学   国名:日本国  

  • 熱活性化遅延蛍光材料における三重項-三重項対消滅の定量的解析

    石井 智也, 丹羽 顕嗣, 川手 大輔, 小林 隆史, 永瀬 隆, 合志 憲一, 安達 千波矢, 内藤 裕義

    第79回応用物理学会秋季学術講演会  2018年9月 

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    開催年月日: 2018年9月 - 2019年9月

    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:名古屋国際会議場   国名:日本国  

  • CT性を有するアントラセン誘導体におけるTriplet-triplet upconversion特性

    家宇治 亮太, 合志 憲一, 安達 千波矢

    第79回応用物理学会秋季学術講演会  2018年9月 

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    開催年月日: 2018年9月 - 2019年9月

    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:名古屋国際会議場   国名:日本国  

  • スカイブルー発光を示す2CzPNの緩和速度の溶媒極性依存性

    川手 大輔, 石井 智也, 小林 隆史, 永瀬 隆, 合志 憲一, 安達 千波矢, 内藤 裕義

    第79回応用物理学会秋季学術講演会  2018年9月 

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    開催年月日: 2018年9月 - 2019年9月

    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:名古屋国際会議場   国名:日本国  

  • Continuous-wave lasing from organic semiconductor films

    SANDANAYAKA SANGARANGE, 松島敏則, BENCHEIKH FATIMA, 吉田 巧, 井上 棟智, 藤原 隆, 合志 憲一, RIBIERRE JEAN CHARLES MAURICE, 安達 千波矢

    第64回応用物理学会春季学術講演会  2017年3月 

     詳細を見る

    開催年月日: 2017年3月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:横浜市・パシフィコ横浜   国名:日本国  

  • 時間相関単一光子計数法を用いたTADF 材料の蛍光寿命測定

    丹羽 顕嗣, 長谷山 翔太, 小林 隆史, 永瀬 隆, 合志 憲一, 安達 千波矢, 内藤 裕義

    第64回応用物理学会春季学術講演会  2017年3月 

     詳細を見る

    開催年月日: 2017年3月

    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:横浜市・パシフィコ横浜   国名:日本国  

  • Tn準位を考慮した4準位モデルによる熱活性化遅延蛍光材料の評価

    川手 大輔, 長谷山 翔太, 丹羽 顕嗣, 小林 隆史, 永瀬 隆, 合志 憲一, 安達 千波矢, 内藤 裕義

    第64回応用物理学会春季学術講演会  2017年3月 

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    開催年月日: 2017年3月

    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:横浜市・パシフィコ横浜   国名:日本国  

  • 極性分子を添加したホストマトリックス中での TADF 材料の発光特性

    長谷山 翔太, 丹羽 顕嗣, 小林 隆史, 永瀬 隆, 合志 憲一, 安達 千波矢, 内藤 裕義

    第77回応用物理学会秋季学術講演会  2016年9月 

     詳細を見る

    開催年月日: 2016年9月

    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:新潟市・朱鷺メッセ   国名:日本国  

  • 熱活性化遅延蛍光薄膜における三重項対消滅について - 発光スペクトルの励起光強度依存性

    丹羽 顕嗣, 長谷山 翔太, 小林 隆史, 永瀬 隆, 合志 憲一, 安達 千波矢, 内藤 裕義

    第77回応用物理学会秋季学術講演会  2016年9月 

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    開催年月日: 2016年9月

    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:新潟市・朱鷺メッセ   国名:日本国  

  • 遅延蛍光型エキサイプレックスを利用した有機EL素子の高効率化

    合志 憲一, 安達 千波矢

    第64回高分子討論会  2015年9月 

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    開催年月日: 2015年9月

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    開催地:東北大学   国名:日本国  

  • Delayed fluorescence by reverse intersystem crossing from intermolecular excited states 国際会議

    Kenichi Goushi, Yuta Hirayama, Chihaya Adachi

    SpinOS 2014  2014年11月 

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    開催年月日: 2014年11月

    記述言語:英語  

    開催地:イーグレひめじ   国名:日本国  

  • Development of Donor-Acceptor-Donor Type TADF Molecules for Highly Efficient OLEDs 国際会議

    Kenichi Goushi, Yuta Sagara, CHIHAYA ADACHI

    SPIE optics + photonics 2014  2014年8月 

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    開催年月日: 2014年8月 - 2014年3月

    記述言語:英語  

    開催地:San Diego Convention Center   国名:アメリカ合衆国  

  • 九州大学 最先端有機光エレクトロニクス研究センター(OPERA)の取り組みと今後の展開-有機ELデバイス物性の最先端

    合志 憲一

    日経エレクトロニクスセミナー  2014年7月 

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    開催年月日: 2014年7月

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    開催地:UDX カンファレンス(東京・秋葉原)   国名:日本国  

  • Organic light-emitting diodes with energy transfer mechanism from intermolecular excited state into fluorescent dye 国際会議

    Yuta Hirayama, Kenichi Goushi, CHIHAYA ADACHI

    TADF International Workshop  2014年3月 

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    開催年月日: 2014年3月 - 2012年3月

    記述言語:英語  

    開催地:ACROS Fukuoka   国名:日本国  

  • Thermal activated spin conversion in excited states and application to organic light-emitting diodes 招待 国際会議

    Kenichi Goushi

    The 1st CMS International Symposium  2014年2月 

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    開催年月日: 2014年2月 - 2012年2月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Kyushu University   国名:日本国  

  • 有機半導体におけるスピン自由度と電荷ダイナミクス 招待

    合志 憲一

    日本物理学会 2013年秋季大会  2013年9月 

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    開催年月日: 2013年9月

    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:徳島大学   国名:日本国  

  • Efficient up-conversion from triplet to singlet excited states of exciplex in organic light-emitting diodes 招待 国際会議

    Kenichi Goushi

    Asian Conference on Organic Electronics 2012  2012年12月 

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    開催年月日: 2012年12月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Yamagata University   国名:日本国  

  • Controlling Carrier Recombination Line Width in Organic Single Crystal Light Emitting Transistor Having Split-Gate Electrodes 国際会議

    Hayato Kakizoe, Kenichi Goushi, Tomohiko Edura, and Chihaya Adachi

    Material Research Socieety Fall Meeting  2011年12月 

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    開催年月日: 2012年11月 - 2012年12月

    記述言語:その他   会議種別:口頭発表(一般)  

    開催地:Boston   国名:アメリカ合衆国  

  • エキサイプレックスの逆項間交差による高効率有機EL素子 招待

    合志 憲一

    第73回応用物理学会学術講演会  2012年9月 

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    開催年月日: 2012年9月

    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:愛媛大学・松山大学   国名:日本国  

  • エキサイプレックスからの遅延蛍光および有機EL素子への応用

    合志 憲一, 安達 千波矢

    有機EL討論会  2012年6月 

     詳細を見る

    開催年月日: 2012年6月

    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:日本科学未来館   国名:日本国  

  • Delayed Fluorescence by Reverse Intersystem Crossing and Application to Organic Light-Emitting Diodes 招待 国際会議

    Kenichi Goushi and Chihaya Adachi

    The Conference on Lasers and Electro-Optics  2012年5月 

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    開催年月日: 2012年5月

    記述言語:その他   会議種別:口頭発表(一般)  

    開催地:San Jose   国名:アメリカ合衆国  

  • Mechanism of two-dimensional orientation control by mechanical brushing in organic amorphous films 国際会議

    Kenichi Goushi, Toshiharu Arai, Hiroko Nomura, Tomohiko Edura, and Chihaya Adachi

    Material Research Socieety Spring Meeting  2012年4月 

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    開催年月日: 2012年4月

    記述言語:その他  

    開催地:San Francisco   国名:アメリカ合衆国  

  • Electric field-induced polaron absorption in organic semiconductors and elucidation of exciton annihilation process under electrically pumping 国際会議

    Miki Kamoto, Kenichi Goushi, Hiroko Nomura, Takuma Yasuda, and Chihaya Adachi

    Material Research Socieety Spring Meeting  2012年4月 

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    開催年月日: 2012年4月

    記述言語:その他  

    開催地:San Francisco   国名:アメリカ合衆国  

  • Suppression of propagation loss in organic semiconductor laser devices having low refractive index layers 国際会議

    Munetomo Inoue, Kenichi Goushi, Hiroko Nomura, and Chihaya Adachi

    Material Research Socieety Spring Meeting  2012年4月 

     詳細を見る

    開催年月日: 2012年4月

    記述言語:その他   会議種別:口頭発表(一般)  

    開催地:San Francisco   国名:アメリカ合衆国  

  • エキサイプレックスを用いた遅延蛍光有機EL素子

    合志憲一,野村洸子,安達千波矢

    第59回応用物理学関係連合講演会  2012年3月 

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    開催年月日: 2012年3月

    会議種別:口頭発表(一般)  

    開催地:早稲田大学   国名:日本国  

  • 遅延蛍光有機EL素子 招待

    合志憲一, 野村洸子, 安達千波矢

    学振第125委員会EL分科会 第40回研究会  2012年2月 

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    開催年月日: 2012年2月

    記述言語:その他   会議種別:口頭発表(一般)  

    開催地:金沢工業大学大学院虎ノ門キャンパス   国名:日本国  

  • Organic light-emitting diodes using exciplex states to promote high reverse intersystem crossing efficiency 国際会議

    Kenichi Goushi, Kou Yoshida, Keigo Sato, and Chihaya Adachi

    The Nanotech Revolution  2011年12月 

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    開催年月日: 2011年12月

    記述言語:その他  

    開催地:Paris   国名:フランス共和国  

  • UV absorption measurement of electric field-induced polaron in organic semiconductors and elucidation of the process of exciton annhilation caused by electrically pumping 国際会議

    Miki Kamoto, Kenichi Goushi, Hiroko Noumura, Takuma Yasuda, and Chihaya Adachi

    The 3rd Asian Conference on Organic Electronics  2011年11月 

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    開催年月日: 2011年11月

    記述言語:その他  

    開催地:Taipei   国名:台湾  

  • Exciplex states having high reverse intersystem crossing efficiency and application to organic light-emitting diodes 国際会議

    Kenichi Goushi, Kou Yoshida, Keigo Sato, and Chihaya Adachi

    The 3rd Asian Conference on Organic Electronics  2011年11月 

     詳細を見る

    開催年月日: 2011年11月

    記述言語:その他  

    開催地:Taipei   国名:台湾  

  • Light emitting organic single crystal OFET having split gate structure aiming for high current density with high external quantum efficiency 国際会議

    Hayato Kakizoe, Kenichi Goushi, Tomohiko Edura, and Chihaya Adachi

    The 3rd Asian Conference on Organic Electronics  2011年11月 

     詳細を見る

    開催年月日: 2011年11月

    記述言語:その他  

    開催地:Taipei   国名:台湾  

  • 高効率熱活性化遅延蛍光の実現と新しい有機ELデバイスの構築へ 招待

    合志憲一, 安達千波矢

    第6回超分子研究会講座  2011年10月 

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    開催年月日: 2011年10月

    記述言語:その他   会議種別:口頭発表(一般)  

    開催地:金沢工業大学大学院虎ノ門キャンパス   国名:日本国  

  • スプリットゲート発光トランジスタの発光特性 -スプリット幅依存性とキャリア再結合過程の解明-

    垣添勇人, 合志憲一, 江面知彦, 安達千波矢

    第72回 応用物理学会学術講演会  2011年8月 

     詳細を見る

    開催年月日: 2011年8月 - 2011年9月

    記述言語:その他  

    開催地:山形大学   国名:日本国  

  • 有機アモルファス薄膜のブラッシングによる配向制御機構

    荒井俊晴, 合志憲一, 江面知彦, 野村洸子, 安達千波矢

    第72回 応用物理学会学術講演会  2011年8月 

     詳細を見る

    開催年月日: 2011年8月 - 2011年9月

    記述言語:その他  

    開催地:山形大学   国名:日本国  

  • 有機半導体におけるポーラロン状態の吸収過程の測定

    嘉本美希, 合志憲一, 野村洸子, 安田琢磨, 安達千波矢

    第72回 応用物理学会学術講演会  2011年8月 

     詳細を見る

    開催年月日: 2011年8月 - 2011年9月

    記述言語:その他  

    開催地:山形大学   国名:日本国  

  • DELAYED FLUORESCENCE BY REVERSE INTERSYSTEM CROSSING AND APPLICATION TO ORGANIC LIGHT-EMITTING DIODES 招待 国際会議

    Kenichi Goushi and Chihaya Adachi

    FINELUMEN International Summer School  2011年5月 

     詳細を見る

    開催年月日: 2011年5月

    記述言語:その他   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    開催地:Lochow   国名:ポーランド共和国  

  • S1-T1間ゼロギャップ有機発光材料の創出とOLEDへの応用

    佐藤圭悟, 合志憲一, 宮崎浩, 吉村和明, 甲斐孝弘, 川田敦, 安達千波矢

    第58回春季応用物理学会  2011年3月 

     詳細を見る

    開催年月日: 2011年3月

    記述言語:その他   会議種別:口頭発表(一般)  

    開催地:神奈川工科大学   国名:日本国  

  • スプリットゲート構造を有する発光型有機単結晶トランジスタ

    垣添勇人, 合志憲一, 江面知彦, 安達千波矢

    第58回春季応用物理学会  2011年3月 

     詳細を見る

    開催年月日: 2011年3月

    記述言語:その他   会議種別:口頭発表(一般)  

    開催地:神奈川工科大学   国名:日本国  

  • ブラッシングによる有機半導体薄膜の分子配向制御

    荒井俊晴, 合志憲一, 江面知彦, 安達千波矢

    第58回春季応用物理学会  2011年3月 

     詳細を見る

    開催年月日: 2011年3月

    記述言語:その他   会議種別:口頭発表(一般)  

    開催地:神奈川工科大学   国名:日本国  

  • 高い発光効率を有するエキサイプレックス発光の探索とOLEDへの展開

    吉田巧, 合志憲一, 佐藤圭悟, 安達千波矢

    第58回春季応用物理学会  2011年3月 

     詳細を見る

    開催年月日: 2011年3月

    記述言語:その他   会議種別:口頭発表(一般)  

    開催地:神奈川工科大学   国名:日本国  

  • 逆項間交差による遅延蛍光を利用した有機ELの開発 招待

    合志 憲一, 遠藤 礼隆, 佐藤 圭悟, 吉田 巧, 安達 千波矢

    日本学術振興会第142委員会  2011年3月 

     詳細を見る

    開催年月日: 2011年3月

    記述言語:その他   会議種別:口頭発表(一般)  

    開催地:東京理科大学 森戸記念館   国名:日本国  

  • Organic Light Emitting Diode Having a Liquid Emitting Layer Doped with an Organic Salt 国際会議

    Heo Hyo Jung, Shuzo Hirata, Korefumi Kubota, Osamu Hirata, Kenichi Goushi, Masayuki Yahiro, and Chihaya Adachi

    MRS  2010年11月 

     詳細を見る

    開催年月日: 2010年11月 - 2010年12月

    記述言語:その他  

    開催地:Boston   国名:アメリカ合衆国  

  • Organic Magnetoresistance Based onto Exciplex States 国際会議

    Kenichi Goushi and Chihaya Adachi

    MRS  2010年11月 

     詳細を見る

    開催年月日: 2010年11月 - 2010年12月

    記述言語:その他  

    開催地:Boston   国名:アメリカ合衆国  

  • High Reverse Intersystem Crossing Efficiency Using Exciplex Formation 国際会議

    Kenichi Goushi, Kou Yoshida, Keigo Sato, and Chihaya Adachi

    MRS  2010年11月 

     詳細を見る

    開催年月日: 2010年11月 - 2010年12月

    記述言語:その他   会議種別:口頭発表(一般)  

    開催地:Boston   国名:アメリカ合衆国  

  • エキサイプレックス状態の高い逆項間交差確率の検証

    吉田 巧, 合志憲一, 佐藤圭悟, 安達千波矢

    応用物理学会学術講演会  2010年9月 

     詳細を見る

    開催年月日: 2010年9月

    記述言語:その他   会議種別:口頭発表(一般)  

    開催地:長崎大学   国名:日本国  

  • エキサイプレックス形成に基づく有機磁気抵抗

    合志憲一, 安達千波矢

    応用物理学会学術講演会  2010年9月 

     詳細を見る

    開催年月日: 2010年9月

    記述言語:その他   会議種別:口頭発表(一般)  

    開催地:長崎大学   国名:日本国  

  • 液体有機半導体のキャリア電導機構の解析

    久保田是史, 平田修造, 合志憲一, 安達千波矢

    応用物理学会学術講演会  2010年9月 

     詳細を見る

    開催年月日: 2010年9月

    記述言語:その他   会議種別:口頭発表(一般)  

    開催地:長崎大学   国名:日本国  

  • 液体半導体を発光層に有する有機EL素子の発光効率の改善

    平田修造, 久保田是史, Jung Heo Hyo, 平田 修, 合志憲一, 八尋正幸, 安達千波矢

    応用物理学会学術講演会  2010年9月 

     詳細を見る

    開催年月日: 2010年9月

    記述言語:その他   会議種別:口頭発表(一般)  

    開催地:長崎大学   国名:日本国  

▼全件表示

MISC

  • スピン軌道相互作用による三重項-三重項消滅アップコンバージョンの高効率化 査読

    合志憲一

    電気学会誌 141(5), 277-279, 2021   2021年5月

     詳細を見る

    記述言語:日本語   掲載種別:記事・総説・解説・論説等(学術雑誌)  

    DOI: 10.1541/ieejjournal.141.277

  • 遅延蛍光を用いた高効率有機EL素子

    合志 憲一, 魚山 大樹, 志津 功將, 野村 洸子, 安達 千波矢

    Molecular electronics and bioelectronics   2013年5月

     詳細を見る

    記述言語:日本語  

  • エキサイプレックスを用いた遅延蛍光有機EL素子の研究開発 (特集 有機ELの最新技術とトレンド)

    合志 憲一, 安達 千波矢

    ディスプレイ   2012年9月

     詳細を見る

    記述言語:日本語  

    Delayed Organic Electroluminescence Devices using an Exciplex State

  • 革新的有機半導体材料を用いた有機発光デバイスへの挑戦

    安達千波矢, 合志憲一

    2012年5月

     詳細を見る

    記述言語:日本語  

  • 強リン光性分子薄膜の開発と発光デバイスへの応用

    安達千波矢, 河村祐一郎, 合志憲一, 遠藤礼隆

    2006年12月

     詳細を見る

    記述言語:日本語  

  • Irppy誘導体のホストーゲスト, ゲストーゲスト分子間相互作用

    河村 祐一郎, 合志 憲一, 安達 千波矢

    Molecular electronics and bioelectronics   2005年2月

     詳細を見る

    記述言語:日本語  

  • 高効率有機リン光ダイオードの材料開発動向 (特集 有機ELディスプレイと関連部材)

    安達 千波矢, 河村 祐一郎, 合志 憲一

    ディスプレイ   2004年9月

     詳細を見る

    記述言語:日本語  

  • 有機金属リン光材料のPL及びEL過程

    河村 祐一郎, 合志 憲一, 高橋 教悦, 安達 千波矢

    Molecular electronics and bioelectronics   2004年2月

     詳細を見る

    記述言語:日本語  

  • 有機リン光デバイスの発光メカニズムと展望

    合志 憲一, 猪股 寛子, 安達 千波矢

    Molecular electronics and bioelectronics   2003年3月

     詳細を見る

    記述言語:日本語  

▼全件表示

所属学協会

  • 光化学協会

  • 応用物理学会

  • Materials Reserch Society

委員歴

  • 応用物理学会 有機分子・バイオエレクトロニクス分科会   幹事   国内

    2024年4月 - 2026年3月   

  • 電子情報通信学会   有機エレクトロニクス研究専門委員   国内

    2022年6月 - 2024年6月   

  • CLEO EUROPE 2015   Program committee   国際

    2014年2月 - 2015年6月   

  • CLEO EUROPE 2015   Program committee   国際

    2014年2月 - 2015年6月   

  • 応用物理学会 有機分子・バイオエレクトロニクス分科会   幹事   国内

    2013年4月 - 2015年3月   

学術貢献活動

  • Organizing Committee 国際学術貢献

    2023 KJF-International Conference on Organic Materials for Electronics and Photonics (KJF-ICOMEP2023)  ( Centennial Hall Kyushu University School of Medicine, Fukuoka, Japan Japan ) 2023年8月 - 2023年9月

     詳細を見る

    種別:大会・シンポジウム等 

  • 学術論文等の審査

    役割:査読

    2023年

     詳細を見る

    種別:査読等 

    外国語雑誌 査読論文数:12

    日本語雑誌 査読論文数:0

    国際会議録 査読論文数:0

    国内会議録 査読論文数:0

  • Local Committee 国際学術貢献

    ICONO13/ICOPE2020  ( Nara Kasugano International Forum IRAKA, Nara Japan ) 2022年11月

     詳細を見る

    種別:大会・シンポジウム等 

  • 学術論文等の審査

    役割:査読

    2022年

     詳細を見る

    種別:査読等 

    外国語雑誌 査読論文数:12

    日本語雑誌 査読論文数:0

    国際会議録 査読論文数:0

    国内会議録 査読論文数:0

  • 学術論文等の審査

    役割:査読

    2021年

     詳細を見る

    種別:査読等 

    外国語雑誌 査読論文数:18

    日本語雑誌 査読論文数:0

    国際会議録 査読論文数:0

    国内会議録 査読論文数:0

  • 学術論文等の審査

    役割:査読

    2020年

     詳細を見る

    種別:査読等 

    外国語雑誌 査読論文数:9

    日本語雑誌 査読論文数:0

    国際会議録 査読論文数:0

    国内会議録 査読論文数:0

  • Organizing Committee 国際学術貢献

    10th International Conference on Molecular Electronics and Bioelectronics (M&BE9)  ( Nara Kasugano International Forum IRAKA, Nara Japan ) 2019年6月

     詳細を見る

    種別:大会・シンポジウム等 

  • Organizing Committee 国際学術貢献

    10th International Conference on Molecular Electronics and Bioelectronics (M&BE9)  ( Nara Kasugano International Forum IRAKA, Nara Japan ) 2019年6月

     詳細を見る

    種別:大会・シンポジウム等 

  • 学術論文等の審査

    役割:査読

    2019年

     詳細を見る

    種別:査読等 

    外国語雑誌 査読論文数:12

    日本語雑誌 査読論文数:0

    国際会議録 査読論文数:0

    国内会議録 査読論文数:0

  • 学術論文等の審査

    役割:査読

    2018年

     詳細を見る

    種別:査読等 

    外国語雑誌 査読論文数:10

    日本語雑誌 査読論文数:0

    国際会議録 査読論文数:0

    国内会議録 査読論文数:0

  • Organizing Committee 国際学術貢献

    9th International Conference on Molecular Electronics and Bioelectronics (M&BE9)  ( Ishikawa Ongakudo and ANA Crowne Plaza Kanazawa, Kanazawa Japan ) 2017年6月

     詳細を見る

    種別:大会・シンポジウム等 

  • 世話人

    第38回光化学若手の会  ( 休暇村志賀島 ) 2017年6月

     詳細を見る

    種別:大会・シンポジウム等 

  • 学術論文等の審査

    役割:査読

    2017年

     詳細を見る

    種別:査読等 

    外国語雑誌 査読論文数:12

    日本語雑誌 査読論文数:0

    国際会議録 査読論文数:0

    国内会議録 査読論文数:0

  • 座長(Chairmanship)

    第64回高分子討論会  ( 東海大学 ) 2015年9月

     詳細を見る

    種別:大会・シンポジウム等 

  • 座長(Chairmanship) 国際学術貢献

    CLEO EUROPE 2015  ( ACROS Fukuoka Japan ) 2015年6月

     詳細を見る

    種別:大会・シンポジウム等 

  • Japanese Journal of Applied Physics 国際学術貢献

    2015年4月 - 2019年3月

     詳細を見る

    種別:学会・研究会等 

  • 座長(Chairmanship) 国際学術貢献

    TADF International Workshop  ( ACROS Fukuoka Japan ) 2014年3月

     詳細を見る

    種別:大会・シンポジウム等 

  • 座長(Chairmanship)

    第74回応用物理学会秋季学術講演会  ( 同志社大学 ) 2013年9月

     詳細を見る

    種別:大会・シンポジウム等 

  • 座長(Chairmanship)

    第59回応用物理学関係連合講演会  ( 早稲田大学 ) 2012年3月

     詳細を見る

    種別:大会・シンポジウム等 

  • 座長(Chairmanship)

    第62回応用物理学会春季学術講演会  ( 東海大学 ) 2012年3月

     詳細を見る

    種別:大会・シンポジウム等 

  • 座長(Chairmanship)

    第58回春季応用物理学会  ( 神奈川工科大学 ) 2011年3月

     詳細を見る

    種別:大会・シンポジウム等 

  • 座長(Chairmanship) 国際学術貢献

    The 5th Yeungnam University-Kyushu University Joint Symposium  ( Inamori Hall, Kyushu University Japan ) 2011年2月

     詳細を見る

    種別:大会・シンポジウム等 

▼全件表示

共同研究・競争的資金等の研究課題

  • 分子内三重項-三重項アップコンバージョンのデバイス物理

    研究課題/領域番号:24K01572  2024年4月 - 2027年3月

    科学研究費助成事業  基盤研究(B)

    合志 憲一

      詳細を見る

    資金種別:科研費

    低いエネルギーの励起三重項状態を高いエネルギーの励起一重項状態に変換できる三重項-三重項消滅機構によるアップコンバージョンは有機発光ダイオード、太陽電池、有機レーザーなど、その応用範囲は幅広く、デバイスを構築する上で重要なコア技術になりつつある。本研究課題においては、三重項-三重項消滅アップコンバージョンの新しい概念として、分子内に二つの励起三重項状態が占有することで生じる分子内三重項-三重項消滅アップコンバージョン機構に着目する。分子内であることに由来した固有の特性を発現させ、利用することでデバイスの高性能化および多機能化を実現することを目的とする。

    CiNii Research

  • 低閾値発振を目指した電流励起有機半導体レーザーの構築

    研究課題/領域番号:23H05406  2023年 - 2027年

    日本学術振興会  科学研究費助成事業  特別推進研究

      詳細を見る

    担当区分:研究分担者  資金種別:科研費

  • 電子分極効果を活用した積層薄膜型超伝導体の創製

    研究課題/領域番号:21K18210  2021年7月 - 2023年3月

    科学研究費助成事業  挑戦的研究(開拓)

    安達 千波矢, 松島 敏則, 合志 憲一, 中野谷 一

      詳細を見る

    資金種別:科研費

    電子分極誘電層(P)/導電層(C)/電子分極誘電層(P)の3層を基本構造とし、薄膜導電層中の伝導電子と誘電層内の分極性分子との間で電子分極効果に基づく“クーパー対”形成を目指す。電子分極誘電層には、様々なドナー及びアクセプター分子骨格を含有したπ電子系化合物を用いることでCT強度を精密に調整し、電子分極により伝導層内のクーパー電子対形成を目指す。基礎的な材料設計及びデバイス構造設計を確立し、①電子分極強度とクーパー対形成の相関、②超伝導転移温度(Tc)向上の可能性を探る。電子分極構造と導電層の網羅的な材料検討・最適化によるTc向上について研究を進め、室温有機超伝導体の可能性に繋げる。

    CiNii Research

  • 熱活性化遅延蛍光材料を発光層に有する有機ELデバイスの劣化機構解析

    研究課題/領域番号:17H01232  2017年 - 2019年

    日本学術振興会  科学研究費助成事業  基盤研究(A)

      詳細を見る

    担当区分:研究分担者  資金種別:科研費

  • 分子内三重項エネルギー移動の制御によるTADF type-IIの実現

    研究課題/領域番号:16H06057  2016年 - 2017年

    科学研究費助成事業  若手研究(A)

      詳細を見る

    担当区分:研究代表者  資金種別:科研費

  • 遅延蛍光型エキサイプレックスにおける励起子拡散に関する研究

    2014年

    公益財団法人カシオ科学振興財団 研究助成

      詳細を見る

    担当区分:研究代表者  資金種別:受託研究

  • 研究助成金

    2013年

      詳細を見る

    資金種別:寄附金

  • 学術奨励金

    2013年

      詳細を見る

    資金種別:寄附金

  • エキサイプレックス状態の高い逆項間交差確率を利用した高効率有機EL素子の実現

    2011年

      詳細を見る

    資金種別:寄附金

  • 有機半導体界面での電荷移動を用いたキャリアドープの実現

    研究課題/領域番号:22750163  2010年 - 2011年

    科学研究費助成事業  若手研究(B)

      詳細を見る

    担当区分:研究代表者  資金種別:科研費

  • 有機半導体・完全単結晶の成長機構の解明と電子デバイスの応用

    研究課題/領域番号:20245038  2008年 - 2010年

    日本学術振興会  科学研究費助成事業  基盤研究(A)

      詳細を見る

    担当区分:研究分担者  資金種別:科研費

  • 有機半導体・完全単結晶の成長機構の解明と電子デバイスの応用

    研究課題/領域番号:20245038  2008年 - 2010年

    日本学術振興会  科学研究費助成事業  基盤研究(A)

      詳細を見る

    資金種別:科研費

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担当授業科目

  • G30コース3年次・後学期

    2023年10月 - 2024年3月   後期

  • 物質科学工学実験第一

    2023年10月 - 2024年3月   後期

  • G30コース3年次・前学期

    2023年4月 - 2023年9月   前期

  • 物質科学工学実験第二

    2023年4月 - 2023年9月   前期

  • G30コース3年次・後学期

    2022年10月 - 2023年3月   後期

  • 物質科学工学実験第一

    2022年10月 - 2023年3月   後期

  • G30コース3年次・前学期

    2022年4月 - 2022年9月   前期

  • 物質科学工学実験第二

    2022年4月 - 2022年9月   前期

  • 科学英語3

    2021年10月 - 2022年3月   後期

  • G30コース3年次・後学期

    2021年10月 - 2022年3月   後期

  • 物質科学工学実験第二

    2021年10月 - 2022年3月   後期

  • 物質科学工学実験第一

    2021年10月 - 2022年3月   後期

  • G30コース3年次・前学期

    2021年4月 - 2021年9月   前期

  • 科学英語3

    2020年10月 - 2021年3月   後期

  • 物質科学工学実験第一

    2020年10月 - 2021年3月   後期

  • G30コース3年次・前学期

    2020年10月 - 2021年3月   後期

  • 物質科学工学実験第三

    2020年10月 - 2021年3月   後期

  • G30コース3年次・後学期

    2020年4月 - 2020年9月   前期

  • G30コース3年次・前学期

    2019年10月 - 2020年3月   後期

  • 科学英語3

    2019年10月 - 2020年3月   後期

  • 物質科学工学実験第一

    2019年10月 - 2020年3月   後期

  • G30コース3年次・後学期

    2019年4月 - 2019年9月   前期

  • 物質科学工学実験第二

    2019年4月 - 2019年9月   前期

  • 科学英語3

    2018年10月 - 2019年3月   後期

  • 物質科学工学実験第一

    2018年10月 - 2019年3月   後期

  • G30第7期生3年次・前学期

    2018年10月 - 2019年3月   後期

  • G30第6期生3年次・後学期

    2018年4月 - 2018年9月   前期

  • 物質科学工学実験第二

    2018年4月 - 2018年9月   前期

  • 分析化学演習

    2017年10月 - 2018年3月   後期

  • 科学英語3

    2017年10月 - 2018年3月   後期

  • 物質科学工学実験第一

    2017年10月 - 2018年3月   後期

  • G30第6期生3年次・前学期

    2017年10月 - 2018年3月   後期

  • 物質科学工学実験第二

    2017年4月 - 2017年9月   前期

  • G30第5期生3年次・後学期

    2017年4月 - 2017年9月   前期

  • 科学英語3

    2016年10月 - 2017年3月   後期

  • G30第5期生3年次・前学期

    2016年10月 - 2017年3月   後期

  • 物質科学工学実験第一

    2016年10月 - 2017年3月   後期

  • 物質科学工学実験第二

    2016年4月 - 2016年9月   前期

  • G30第4期生3年次・後学期

    2016年4月 - 2016年9月   前期

  • 物質科学工学実験第一

    2015年10月 - 2016年3月   後期

  • G30第3期生3年次・前学期

    2015年10月 - 2016年3月   後期

  • 物質科学工学実験第三

    2015年10月 - 2016年3月   後期

  • G30第2期生3年次・後学期

    2015年4月 - 2015年9月   前期

  • G30第3期生3年次・後学期

    2015年4月 - 2015年9月   前期

  • G30第4期生3年次・後学期

    2015年4月 - 2015年9月   前期

  • 物質科学工学実験第三

    2014年10月 - 2015年3月   後期

  • G30第3期生3年次・前学期

    2014年10月 - 2015年3月   後期

  • G30第2期生3年次・後学期

    2014年4月 - 2014年9月   前期

  • G30第2期生3年次・前学期

    2013年10月 - 2014年3月   後期

  • 物質科学工学実験第三

    2013年10月 - 2014年3月   後期

  • コアセミナー

    2013年4月 - 2013年9月   前期

  • G30第1期生3年次・後学期

    2013年4月 - 2013年9月   前期

  • 物質科学工学実験第三

    2012年10月 - 2013年3月   後期

  • 物質科学工学実験第三

    2011年10月 - 2012年3月   後期

  • 物質科学工学実験第三

    2010年10月 - 2011年3月   後期

▼全件表示

FD参加状況

  • 2016年6月   役割:参加   名称:ハラスメント防止のための研修会

    主催組織:部局

  • 2010年4月   役割:参加   名称:第1回全学FD.

    主催組織:全学

社会貢献活動

  • OPERAクリスマスサイエンスレクチャーにおける実験体験コーナーの企画・運営

    OPERA  九州大学伊都キャンパス  2013年12月

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    対象:社会人・一般, 学術団体, 企業, 市民団体, 行政機関

    種別:講演会

  • 高等学校の化学クラブへの支援活動

    九州大学社会連携化学クラブ活動支援フォーラム  九州大学伊都キャンパス  2013年11月

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    対象:社会人・一般, 学術団体, 企業, 市民団体, 行政機関

    種別:セミナー・ワークショップ

  • 城南高校スーパーサイエンスハイスクール事業の一環で行っている、化学クラブ活性化のために課題研究と提案および指導を行った。

    福岡県立城南高校  最先端有機光エレクトロニクス研究センター  2012年12月

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    対象:社会人・一般, 学術団体, 企業, 市民団体, 行政機関

    種別:セミナー・ワークショップ

  • 化学クラブ生徒等を対象にした研修会

    九州大学社会連携化学クラブ活動支援フォーラム  九州大学伊都キャンパス  2010年11月

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    対象:社会人・一般, 学術団体, 企業, 市民団体, 行政機関

    種別:セミナー・ワークショップ

メディア報道

  • レアメタルを使用せずに高効率な有機EL素子を構成できる技術開発について 新聞・雑誌

    西日本新聞  2012年3月

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    レアメタルを使用せずに高効率な有機EL素子を構成できる技術開発について

  • レアメタルを使用せずに高効率な有機EL素子を構成できる技術開発について 新聞・雑誌

    日経産業新聞  2012年3月

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    レアメタルを使用せずに高効率な有機EL素子を構成できる技術開発について

  • レアメタルを使用せずに高効率な有機EL素子を構成できる技術開発について 新聞・雑誌

    日刊工業新聞  2012年3月

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    レアメタルを使用せずに高効率な有機EL素子を構成できる技術開発について