Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Electrochemical Society of Japan  

<p>3,6-diphenyltetrazine (DPT) is an electron-deficient π-conjugated molecule with a perfectly planar structure and high crystallinity. In this study, discharge-charge tests of crystalline DPT as a cathode material for sodium ion batteries were conducted. DPT showed an initial reversible capacity of 102 mAh/g (theoretical capacity 114 mAh/g), corresponding to one electron reaction. The plateau of the discharge-charge profiles was observed at 1.9–2.1 V vs. Na/Na⁺. According to the ex-situ XRD, FT-IR, and XPS measurements to investigate the discharge-charge mechanism, the redox center was identified as the conjugated tetrazine ring. DPT was in a crystalline form in both the charged and discharged state and indicated the potential as a reversible Na ion host.</p>

DOI： 10.5796/electrochemistry.22-00100

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

A new design concept of a dendritic ligand with regulated number coordination sites is proposed, and capability as a template for nanoparticle synthesis is demonstrated.

DOI： 10.1039/d1sc05661a

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry ({RSC})  

Carbazole dendrimers with a benzophenone core and bulky terminal substituents were synthesized, and their thermally activated delayed fluorescence (TADF) properties were investigated. The adamantane (Ad) substituted dendrimer showed green TADF emission with a PLQY of 40% in the neat film. The tetraphenylphenyl (TPPh) substituted dendrimer showed blue emission with a PLQY of 11% in the neat film but did not show effective TADF. The dendrimer and dendron (fragment) phosphorescence measurement revealed that the TPPh substituted carbazole dendron has low triplet energy. This will reduce the TADF efficiency. Also a new deactivation path due to the large freedom in the rotation of TPPh substituents leads to non-radiative deactivation and quenches the TADF emission. Simple terminal modification can minimize the intermolecular interaction and tune the on-off of the TADF, which gives insights for designing efficient TADF materials.

DOI： 10.1039/d2py00255h

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1126/sciadv.abd9887

Repository Public URL： http://hdl.handle.net/2324/4783631

Publisher：ACS Applied Optical Materials  

Carbazole dendrimers are promising materials for realizing highly efficient solution-processed organic light-emitting diodes (OLEDs). Merging carbazole dendrimers with a light-metal complex enables the development of solution-processable materials with excellent optical properties. In this work, highly luminescent Al complexes with carbazole-based dendritic ligands were developed. Metal complexation enhances photoluminescence quantum yields (PLQYs) and thermally activated delayed fluorescence (TADF) properties compared with the corresponding dendritic ligands. Consequently, the Al complex containing symmetric dendritic ligands exhibited a high PLQY of 70% with a delayed fluorescence lifetime of 16 μs in the doped film. Solution-processed OLEDs using these Al complexes as emitters exhibited excellent performance with an external electroluminescence quantum efficiency of 10.6% at a luminance of 100 cd m-2. These results present a strategy to improve the TADF properties and contribute to expanding the chemical space of the TADF materials.

DOI： 10.1021/acsaom.4c00178

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

Organic luminescent radicals are a new class of materials. New water-soluble tris(2,4,6-trichlorophenyl)methyl (TTM) radicals were synthesized, and potential as fluorescence and magnetic resonance imaging agent was investigated.

DOI： 10.1039/d4tb00940a

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Publisher：Journal of Energy Storage  

Herein, we report the fabrication of an electrode composite with an ultra-high active material content (90 wt%). This composite was possible because of the utilization of TiH2 as an anode active material that forms a solid electrolyte (LiH) in situ and functions as an electronic conductor, enabling a substantial reduction of the amount of conductor additive in the electrodes. The electrochemical performance of the TiH2-based electrodes with a high active material content was comparable to that of electrode composites that include a solid electrolyte because of sufficient Li+-ion conduction pathways provided by the LiH formed in situ. To further increase the capacity of the TiH2-based electrode, MgH2 (theoretical capacity: 2036 mAh/g) was mixed with TiH2 to function as an active material. TiH2, which is known to exhibit high electron conductivity and a high density, is expected to be used as a partial substitute for low-density carbon additives to increase the volumetric energy density of batteries and their active material content. Hence, the xMgH2-(1 − x)TiH2-AB (AB: acetylene black) electrode composite exhibited a high active material content (90 wt%) and improved volumetric energy density (1687 Wh/L, based on the anode) compared with a MgH2-AB (70:30 wt%) electrode composite (1157 Wh/L), even when the AB content of the xMgH2-(1 − x)TiH2-AB composite was 10 wt%. In addition, a MgH2-TiH2-VGCF (VGCF: vapor-grown carbon fiber) based electrode composite exhibited the highest volumetric and gravimetric energy density (2154 Wh/L, 1888 Wh/kg) among the investigated composites, facilitated by sufficient electron pathways provided by VGCF.

DOI： 10.1016/j.est.2024.111286

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Publisher：Electrochimica Acta  

MgH2 conversion anodes are considered promising anode active materials for use in lithium batteries because of their high theoretical lithium storage capacity and suitable redox potential. In a previous study, MgH2 was clarified to function as an anode material that forms a solid electrolyte in situ and to work without an electrolyte added to the composite electrode because of the in situ formation of LiH with an ionic conductivity of 10−7 S cm−1 at 120 °C. In the present study, to improve the energy density, cells with thick MgH2 electrodes were prepared and the reaction mechanism was investigated. With increasing thickness of the MgH2 electrode from 84 to 420 μm, the capacity decreased from 1628 to 425 mAh g−1 and the initial lithiated areal capacity was constant among cells with electrodes thicker than 140 μm. In addition, the unreacted MgH2 was found to be mainly distributed near the current collector by ex situ XPS (X-Ray Photoelectron Spectroscopy) measurement. This result differs substantially from that observed for a thick Mg(BH4)2 anode, which can self-generate LiBH4 with a high ionic conductivity of 10−3 S cm−1. The results of the present study indicate that the ionic conductivity of the in-situ-formed electrolyte strongly influences the relationship between battery performance and electrode thickness of an anode that forms an electrolyte in situ.

DOI： 10.1016/j.electacta.2024.144083

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Publishing type：Research paper (scientific journal)   Publisher：Batteries and Supercaps  

All-solid-state batteries have gained considerable attention due to their high safety and energy density. However, solid state electrolytes which contribute to the ionic conductivity component of a composite electrode, are not utilized during the electrode reaction and cannot directly contribute to capacity. This study focuses on decreasing the amount of electrolyte in the electrode by utilizing Ca(BH4)2 as an active electrode material. In this work, the charge-discharge properties of Ca(BH4)2 as an electrode material were determined for the first time. The lithiation of the Ca(BH4)2 anode creates LiBH4 within the electrode mixture, providing new Li-ion conduction pathways within the composite electrode in situ. An electrode fabricated only from Ca(BH4)2 and acetylene black (AB) showed an initial capacity of 473 mAh g−1 at 120 °C, which is comparable to the performance obtained from a composite electrode additionally containing electrolyte. Evidently, Ca(BH4)2 is a promising candidate negative electrode for increased energy density all-solid-state Li-ion batteries.

DOI： 10.1002/batt.202300550

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Language：English   Publisher：Faraday Discussions  

DOI： 10.1039/d4fd90006e

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DOI： 10.1039/d4fd90008a

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Language：English   Publisher：Faraday Discussions  

DOI： 10.1039/d4fd90007c

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Publisher：Journal of Magnesium and Alloys  

MgH2 and TiH2 have been extensively studied as potential anode materials due to their high theoretical specific capacities of 2036 and 1024 mAh/g, respectively. However, the large volume changes that these compounds undergo during cycling affects their performance and limits practical applications. The present work demonstrates a novel approach to limiting the volume changes of active materials. This effect is based on mechanical support from an intimate interface generated in situ via the reaction between MgH2 and Ti within the electrode prior to lithiation to form Mg and TiH2. The resulting Mg can be transformed back to MgH2 by reaction with LiH during delithiation. In addition, the TiH2 improves the reaction kinetics of MgH2 and enhances electrochemical performance. The intimate interface produced in this manner is found to improve the electrochemical properties of a MgH2-Ti-LiH electrode. An exceptional reversible capacity of 800 mAh/g is observed even after 200 cycles with a high current density of 1 mA/cm2 and a high proportion of active material (90 wt%) at an operation temperature of 120 °C. This study therefore showcases a new means of improving the performance of electrodes by limiting the volume changes of active materials.

DOI： 10.1016/j.jma.2024.08.006

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

Surface modification by carbazole dendrimers, in particular, 9-phenylcarbazole, enhances electrochemical CO₂ conversion to CO on gold.

DOI： 10.1039/D3CC00350G

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DOI： 10.1039/D1CC04350A

Language：Others   Publishing type：Research paper (scientific journal)  

DOI： 10.1038/s42004-020-00364-3

Repository Public URL： http://hdl.handle.net/2324/4783642

Language：English   Publishing type：Research paper (scientific journal)  

Microcrystallites are promising minute mirrorless laser sources. A variety of luminescent organic compounds have been exploited along this line, but dendrimers have been inapplicable owing to their fragility and extremely poor crystallinity. Now, a dendrimer family that overcomes these difficulties is presented. First-, second-, and third-generation carbazole (Cz) dendrimers with a carbon-bridged oligo(phenylenevinylene) (COPV2) core (GnCOPV2, n=1-3) assemble to form microcrystals. The COPV2 cores align uni/bidirectionally in the crystals while the Cz units in G2- and G3COPV2 align omnidirectionally. The dendrons work as light-harvesting antennas that absorb non-polarized light and transfer it to the COPV2 core, from which a polarized luminescence radiates. Furthermore, these crystals act as laser resonators, where the lasing thresholds are strongly coupled with the crystal morphology and the orientation of COPV2, which is in contrast with the conventional amorphous dendrimers.

DOI： 10.1002/anie.202000712

Language：English   Publishing type：Research paper (scientific journal)  

This study presents the inkjet printing of a novel OLED device with fully solution-processed organic layers that employ TADF material as an emitting layer. The ink was formulated using new TADF material, triazine core carbazole dendrimers with tert-butyl group at the periphery (tBuG2TAZ), dissolved in a mixture of two non-chlorinated solvents. The influence of the print resolution and the substrate temperature on morphology of the printed films was studied and optimized in ambient conditions. The optimized TADF dendrimer layer was then incorporated in the OLEDs as the emitting layer. The best-printed OLEDs exhibited a maximum current efficiency of 18 cd/A and maximum luminance of 6900 cd/m². Such values are comparable to the values obtained in spin coated devices made of the same TADF dendrimer. Further, the mobility of charge carriers extracted from transient electroluminescence measurements of printed OLEDs, when compared to reference OLEDs made by spin coating technique, showed similar values. Finally, we have demonstrated the possibility of patterning of emission the area of complex shapes merely by selectively printing the emission layer. These results demonstrate the potential application of the new dendrimer TADF emitters for the fabrication of efficient OLEDs by an inkjet printing technique.

DOI： 10.1016/j.orgel.2019.07.011

Language：English   Publishing type：Research paper (scientific journal)  

Tin oxide quantum dots (QDs) have attracted much attention because of their low toxicity and the absence of cadmium and other poisonous elements. In this paper, we report the novel synthetic method for size-controlled tin oxide QDs using dendrimers as a template, and their electronic and structural properties. Hemispherical tin oxide QDs with a size below 2 nm and small size distribution were synthesized on silica glass substrates by the dendrimer-templated synthesis method (Sn₁₂, Sn₂₈, and Sn₆₀ oxide QDs). The structures of the tin oxide QDs were composed not only of Sn(IV) sites, but also Sn(II) sites due to the restriction of the coordination environment to stabilize the structure. Density functional theory calculation showed that a bare tin oxide cluster with a mixed valence state (Sn(II) + Sn(IV)) is more stable than those only with Sn(II) or Sn(IV). The synthesized tin oxide QDs showed the quantum confinement effect caused by the spatial confinement of an electron. The Urbach tail parameter, expressing the disorderliness of the QDs, decreased with the reduced QD size, although the value of each tin oxide QD was higher than that of bulk SnO₂. The experimental band gap energy was compared with the effective mass approximation models, which are theoretical models for the quantum confinement effect. We found that the experimental values of Sn₂₈ and Sn₆₀ oxide QDs were consistent with the theoretical values, while Sn₁₂ oxide QDs had a lower value compared to the predicted band gap energy. This could be attributed to the change in the physical parameters of Sn₁₂ oxide QDs, which are not the same as those of Sn₂₈, Sn₆₀ oxide QDs or the bulk SnO₂. These results indicate that small tin oxide QDs have a different structure and different electronic properties compared to bulk or conventional nanoparticles and have potential applications in such fields as catalysis and optical and electronic devices.

DOI： 10.1021/acs.chemmater.9b01925

Language：English   Publishing type：Research paper (scientific journal)  

Formation of nanospheres that consist of π-conjugated dendrimers (phenylazomethine and carbazole) is reported. The nanospheres can be prepared by spin-casting a solution of dendrimers in a proper good/poor solvent mixture as kinetically trapped amorphous products. This method could be applied to metallodendrimer and fluorescent dendrimer. By controlling the kinetic process, the size of the spheres could be controlled and the fluorescent dendrimer sphere, with a few ¯m in size, displayed whispering gallery mode (WGM) photoluminescence.

DOI： 10.1246/cl.190511

Language：English   Publishing type：Research paper (scientific journal)  

Current-voltage characteristics of single molecule junctions are governed both by the energy level alignment of molecular orbitals with respect to the Fermi level of the electrodes and by the hybridization of electronic structures at the interface between the molecule and the electrodes. While there have been many studies on tuning the former, only a few works intended to control the latter. In the present study, we demonstrate that molecular junctions based on carbazole oligomers showed a current rectification behavior due to asymmetric-symmetric control of electronic hybridization between the molecule and electrodes at the both terminals. The carbazole oligomers originally showed an asymmetric molecular orbital and, hence, electronic hybridization with the electrodes because of the electric dipole moment. Symmetric electronic hybridization was achieved when the applied electric field between electrodes deformed molecular orbital to be symmetric. This is a novel way to control charge transport in single-molecule junctions.

DOI： 10.1039/c8nr06049e

Language：English   Publishing type：Research paper (scientific journal)  

A series of second-generation carbazole-benzophenone dendrimer substituted by several functional groups at terminal positions (subG2B) was investigated toward a thermally activated delayed fluorescence (TADF) emitter for nondoped emissive layer (EML) application in a solution-processed organic light-emitting diode (OLED). Substitution was found to dramatically alter the photophysical properties of the dendritic TADF emitters. The introduction of tert-butyl and phenyl group endows the subG2Bs with aggregation-induced emission enhancement character by suppression of internal conversion in singlet excited states. In the meantime, the introduction of a methoxy group resulted in aggregation-caused quenching character. The device performance of the OLED, where subG2B neat films were incorporated as nondoped EMLs, was found to be highly enhanced by adopting fully solution-processed organic multilayer architecture in comparison to the devices with a vacuum-deposited electron transporting layer (ETL), achieving a maximum external quantum efficiency of 17.0%. Such improvement was attributable to the improved carrier balance via intermixing at solution-processed EML/ETL interfaces. It was also found that the post-thermal annealing of the OLED at appropriate temperatures could be beneficial to enhance OLED performance by promoting the intermixing EML/ETL interface to some extent. Our findings emphasize the potential utility of dendritic TADF emitters in the solution-processed TADF-OLED and increase the importance to manipulate dendrimer/small molecule interfaces.

DOI： 10.1021/acsami.8b09451

Language：English   Publishing type：Research paper (scientific journal)  

A thermally activated delayed fluorescence (TADF) carbazole dendrimer (tBuG2TAZ) doped in a carbazole dendrimer host (G3Ph, G4Ph) was employed as an emissive layer (EML) in an OLED device with fully solution processed organic layers. Green (l
_MAX
= 502 nm) emission with a maximum external efficiency (EQE
_MAX
) of 16.1% was achieved when tBuG2TAZ was doped in G3Ph. This value was higher than the previously reported OLED device with a neat film of tBuG2TAZ as an EML because of the higher PLQY due to suppressed concentration quenching. The TADF-active carbazole dendrimer doped in a carbazole host film shows excellent miscibility and solvent resistance to ethanol. On the other hand, when a small molecule (rubrene) was doped in the carbazole dendrimer, significant dissolution of rubrene was observed after rinsing the doped film with ethanol. This shows the importance of the solvent resistivity of a dopant emitter when another film is solution-processed onto the doped film. The ''doping dendrimer in dendrimer'' concept is a new concept to allow fabrication of fully solution-processed TADF OLEDs.

DOI： 10.1039/C7QM00579B

Language：English   Publishing type：Research paper (scientific journal)  

The CO oxidation reaction is an industrially important reaction; however, the practical catalysts are limited to noble metals. In this paper, we report a systematic study of the CO oxidation ability on cheap and less noble tin oxide clusters with the aim of quantitatively understanding the active sites. We synthesized size-controlled tin oxide clusters in mesoporous silica using the dendrimer templating method, employing dendritic phenylazomethine with a tetraphenylmethane core (TPMG4) as the template molecule. The clusters had different sizes depending on the added amount of SnCl₂ as a precursor to TPMG4. The synthesized tin oxide clusters contained not only stable tetravalent Sn(IV) but also metastable divalent Sn(II) due to the structural stability and had a size-dependent composition. The CO oxidation activity of the tin oxide clusters increased with decreasing cluster size depending on the Sn(II)/Sn(IV) ratio. We also found the correlation between the Sn(II) fraction and the CO oxidation activity, clearly indicating that the partially reduced Sn(II) acted as the active site for the CO oxidation in the tin oxide clusters. This knowledge give a clue on how to design a highly active CO oxidation catalyst with base metal oxides.

DOI： 10.1021/acscatal.7b02981

Language：English   Publishing type：Research paper (scientific journal)  

Anisotropic dendrimers with bipolar shapes were systematically obtained using a heteroleptic metal-organic polyhedron (MOP) as a robust core scaffold. The structure of one of these polyhedral shapes was unambiguously determined by single-crystal X-ray analysis, which revealed that the bulky dendrons converge to both axial positions of the heteroleptic MOP core.

DOI： 10.1039/c8cc02460j

Language：English   Publishing type：Research paper (scientific journal)  

A self-assembled crystalline microporous dendrimer framework (MDF) exhibits novel turn-on and ratiometric fluorescence upon exposure to solvent vapours. The donor-acceptor character, combined with the large surface area (>650 m
²
g
^-1
), allows the MDF to discriminate vapours of volatile solvents with turn-on and colour change of photoluminescence.

DOI： 10.1039/c7cc09342j

Language：English   Publishing type：Research paper (scientific journal)  

Light-emitting electrochemical cells (LECs) are composed of blends of semiconducting polymers and electrolytes, in which a unique cooperative action of ions and electrons induces a dynamic p-n junction for efficient emission. One of the crucial issues remaining in LECs is uniformity in blends of polymer and electrolyte; phase separation in between the two components results in poor performance or failure of operation. Here, we overcome this issue by developing an ionic liquid-based electrolyte of alkylphosphonium-phosphate that shows notable compatibility high enough to dissolve even light-emitting polymers. This exceptional compatibility enabled us to prepare uniform film blends with various blue to red emitting polymers, and offered bright and efficient LECs. Especially, a blue-emitting LEC showed excellent performance: the luminance reached ∼20 000 cd m^-2 with a high luminance efficiency of ∼5 cd A^-1, of which performances significantly exceed a light-emitting diode using the same polymer. The ionic liquid was further applied to the LECs with state-of-the-art light-emitting dendrimers showing thermally activated delayed fluorescence under electrical excitation, giving a high efficiency of 11 cd A^-1. These demonstrations remind us of the great importance of the polymer-electrolyte compatibility and the usefulness of ILs for electrolyte of LECs.

DOI： 10.1021/acs.chemmater.7b02128

Language：English   Publishing type：Research paper (scientific journal)  

By the covalent linkage of two bent bisanthracene amphiphiles with a biphenyl spacer bearing hydrophilic pendants, we synthesized a new molecular clip with a C-shaped conformation. The molecular clip provides an acyclic, open cavity surrounded by four anthracene panels in water. In contrast to previous clip- and tweezers-like compounds as well as cage-shaped compounds, the C-shaped polyaromatic cavity displays unusual wide-ranging capturing abilities toward not only planar perylene-based pigments and cylindrical single-walled carbon nanotubes but also highly branched macromolecules (carbazole dendrimers).

DOI： 10.1002/anie.201612489

Language：English   Publishing type：Research paper (scientific journal)  

Thermally activated delayed fluorescence (TADF) materials emerged as promising light sources in third generation organic light-emitting diodes (OLED). Much effort has been invested for the development of small molecular TADF materials and vacuum process-based efficient TADF-OLEDs. In contrast, a limited number of solution processable high-molecular weight TADF materials toward low cost, large area, and scalable manufacturing of solution processed TADF-OLEDs have been reported so far. In this context, we report benzophenone-core carbazole dendrimers (GnB, n = generation) showing TADF and aggregation-induced emission enhancement (AIEE) properties along with alcohol resistance enabling further solution-based lamination of organic materials. The dendritic structure was found to play an important role for both TADF and AIEE activities in the neat films. By using these multifunctional dendritic emitters as non-doped emissive layers, OLED devices with fully solution processed organic multilayers were successfully fabricated and achieved maximum external quantum efficiency of 5.7%.

DOI： 10.1038/srep41780

Language：English   Publishing type：Research paper (scientific journal)  

We developed a procedure for fabricating sub-1 nm gap Au electrodes using a metal mask for electrode patterning. Self-aligned nanogap formation was achieved using an electromigration method during metal deposition. We also measured the electric conductivities of organic molecules using the new nanogap electrodes. Because the new procedure does not involve wet processing, the ranges of possible electrode and substrate materials for the nanogap electrodes are greatly expanded. Finally, we discussed the molecular orbital energies of bridging and nonbridging 1,4-benzenedithiol molecules between Au electrodes. The new procedure for the fabrication of nanogap electrodes is expected to be useful for measuring the electrical properties of various nanoscale materials.

DOI： 10.1039/c7ra10873g

Language：English   Publishing type：Research paper (scientific journal)  

New solution processable and laminatable terminally modified carbazole-triazine thermally activated delayed fluorescence (TADF) dendrimers are reported. An OLED device with fully solution processed organic layers exhibited an external quantum efficiency of up to 9.4% at 100 cd m⁻².

DOI： 10.1039/c6cc09275f

Language：English   Publishing type：Research paper (scientific journal)  

The phenylazomethine dendrimer (DPA) has a layer-by-layer electron density gradient that is an analog of the Bohr atom (atom mimicry). In combination with electron pair mimicry, the polymerization of this atom-mimicking dendrimer was achieved. The valency of the mimicked atom was controlled by changing the chemical structure of the dendrimer. Bymimicking a divalent atom, a one-dimensional (1D) polymer was obtained, and by using a planar tetravalent atom mimic, a 2D polymer was obtained. These poly(dendrimer) polymers could store Lewis acids (SnCl₂) in their unoccupied orbitals, thus indicating that these poly(dendrimer) polymers consist of a series of nanocontainers.

DOI： 10.1126/sciadv.1601414

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2494/photopolymer.29.323

Language：English   Publishing type：Research paper (scientific journal)  

Recently, thermally activated delayed fluorescence (TADF) materials have received increasing attention as effective emitters for organic light-emitting diodes (OLEDs). However, most of them are usually employed as dopants in a host material. In this report, carbazole dendrimers with a triphenyl-s-triazine core are reported, which are the first solution-processable, non-doped, high-molecular-weight TADF materials. The dendrimers were obtained by a new and facile synthetic route using the tert-butyldimethylsilyl moiety as a protecting group. All dendrimers showed TADF in toluene. Measurements of the temperature-dependent luminescence lifetime revealed that spin-coated neat films also showed TADF with moderate quantum yields. OLED devices incorporating these dendrimers as spin-coated emitting layers gave external quantum efficiencies of up to a 3.4%, which suggests that this device is harvesting triplet excitons. This result indicates that carbazole dendrimers with attached acceptors are potential TADF materials owing to their polarized electronic structure (with HOMO-LUMO separation). Fluorescent dendrimers: Carbazole dendrimers with a triphenyl-s-triazine core have been developed as the first solution-processable, non-doped, and high-molecular-weight thermally activated delayed fluorescence (TADF) materials. OLED devices with such dendrimers as the spin-coated emitting layer displayed external quantum efficiencies of up to 3.4%, which suggests that this device is harvesting triplet excitons.

DOI： 10.1002/anie.201500203

Language：English   Publishing type：Research paper (scientific journal)  

Phenylazomethine dendrimer (DPA) is a dendritic ligand that coordinates to various Lewis acids in a stepwise radial fashion. Second generation para-substituted and meta-substituted phenylazomethine dendrimers with p-phenylenediamine and m-phenylenediamine core were synthesized and the coordination sequence was investigated by UV–vis titration. Stepwise radial complexation from the outer layer was observed for the m-phenylenediamine core meta-substituted phenylazomethine dendrimer (m-mG2). Other three dendrimers showed stepwise radial complexation from the inner layer. The reason could be explained with the binding constant of the 1st generation dendrimer (model of the 1st layer). This is suggesting that for controlling the coordination sequence of DPA, not only the dendron structure is important, but also the structure of the core is an important factor.

DOI： 10.1007/s10904-014-0116-y

Language：English   Publishing type：Research paper (scientific journal)  

A para-substituted phenylazomethine dendrimer (pGnA) coordinates to Lewis acids in a stepwise radial fashion from the inner layer to the outer layer. The inversion of this coordination sequence was achieved for the first time by just changing the substitution position of the phenylazomethine group from the para position to the meta position (mGnA). This journal is

DOI： 10.1039/c4cc05007j

Language：English   Publishing type：Research paper (scientific journal)  

The pyridine ring-introduced phenylazomethine dendrimer (PyDPA) was synthesized by a dehydration reaction using titanium(IV) chloride. The ultraviolet-visible absorption and the electrochemical study showed that the introduction of the pyridine ring produces a smaller band gap by increasing the highest occupied molecular orbital level and decreasing the lowest unoccupied molecular orbital level. A crystal of a PyDPA-PdCl₂ complex was also prepared. Traditional phenylazomethine dendrimers cannot form a complex with palladium, indicating that PyDPA can potentially coordinate with various metal salts such as Co, Ni, Ru, and Mn and can be used for catalytic or electronic applications.

DOI： 10.1080/00397911.2014.891746

Language：English   Publishing type：Research paper (scientific journal)  

A relationship between the size of metal particles and their catalytic activity has been established over a nanometer scale (2-10 nm). However, application on a subnanometer scale (0.5-2 nm) is difficult, a possible reason being that the activity no longer relies on the size but rather the geometric structure as a cluster (or superatomic) compound. We now report that the catalytic activity for the oxygen reduction reaction (ORR) significantly increased when only one atom was removed from a magic number cluster composed of 13-platinum atoms (Pt₁₃). The synthesis with an atomic-level precision was successfully achieved by using a dendrimer ligand as the macromolecular template strictly defining the number of metal atoms. It was quite surprising that the Pt₁₂ cluster exhibited more than 2-fold catalytic activity compared with that of the Pt₁₃ cluster. ESI-TOF-mass and EXAFS analyses provided information about the structures. These analyses suggested that the Pt₁₂ has a deformed coordination, while the Pt₁₃ has a well-known icosahedral atomic coordination as part of the stable cluster series. Theoretical analyses based on density functional theory (DFT) also supported this idea. The present results suggest potential activity of the metastable clusters although they have been "missing" species in conventional statistical synthesis.

DOI： 10.1021/ja405922m

Language：English   Publishing type：Research paper (scientific journal)  

The effect of axial coordination of pyridine derivatives to the core porphyrin on the fullerene encapsulation of the 4th generation carbazole-phenylazomethine dendrimer (ZnPG2-2) was investigated. The axial coordination of large (bulky) pyridine derivatives affects the cavity in an allosteric manner, and the size-selectivity of the fullerene association could be controlled.

DOI： 10.1039/c3cc43249a

Language：English   Publishing type：Research paper (scientific journal)  

A fourth generation carbazole-phenylazomethine dendrimer with a porphyrin core was investigated as a new host for fullerenes (C₆₀, C ₇₀, and C₈₄). This dendrimer has a significantly higher association constant compared to the lower generation dendrimers, and the encapsulation is achieved by the cooperation of the dendron and the core.

DOI： 10.1039/c2cc36451d

Language：English   Publishing type：Research paper (scientific journal)  

A new type of phenylazomethine dendrimer (DPA) that has one more coordination site compared to the tetraphenylmethane core DPA was synthesized for the magic number 13 metal cluster template that has cubic or hexagonal densely packed structures. The stepwise complexation property was revealed, and this property is expected to be the magic number 13 metal cluster template.

DOI： 10.1246/cl.2012.828

Language：Japanese  

Polymeric (high molecular weight) semiconducting materials are expected as a key material for low cost, flexible and printable organic electronics. Especially, due to the unique and uniform molecular structure, dendritic materials have been a focus of constant attention. For example, several dendrimers that have charge transporting units at the terminal and chromophores at the core have been developed. However, laminating polymeric and dendritic materials is difficult, and the application to high-performance devices was limited. In this review, the progress of the semiconductive dendritic materials will be briefly reported, followed by the introduction of new classes of dendrimers containing phenylazomethine (for metal assembling) and carbazole (for photocrosslinking).

DOI： 10.1295/koron.69.251

Language：English   Publishing type：Research paper (scientific journal)  

The synthesis of double-layer-type dendrimers with carbazole and phenylazomethine as the dendron with a symmetric tetraphenylmethane core is reported. Structural modeling studies showed that the G3 dendrimer has a rigid and spherical structure. These dendrimers were thermally stable (T _d10% over 500 °C) with the TGA-MS study revealing a degradation mechanism occurring first at the inner-layer phenylazomethine group. The metal (Lewis acid) complexation property of these dendrimers was also studied. Electrochemical measurements showed that these dendrimers have the appropriate HOMO level as a hole-transporting material with electropolymerizability on the peripheral carbazole groups. A photo-cross-linking property of the dendrimer film was also observed. Finally, electro-nanopatterning with conducting AFM and photopatterning of the dendrimer film were demonstrated. Thus, the new dendrimer is a potential hole-transporting material that is patternable through oxidation of the peripheral carbazole units by either photochemical or electrochemical methods.

DOI： 10.1021/ma202485h

Language：English   Publishing type：Research paper (scientific journal)  

The fluorescence properties of double layer-type dendrimers with carbazole as the outer layer and phenylazomethine as the inner layer of the dendron with a zinc porphyrin core were studied. Based on the fluorescence quantum yield (solution), the effect of the bulky dendron to inhibit the interaction of the chromophores was confirmed. Additionally, the efficient light-harvesting property of the double layer-type dendron was revealed by the fluorescence measurement at several excitation wavelengths. These dendrimers were used as an emitting-layer in an OLED device. The electroluminescence of the core porphyrin was observed and it was shown that the double layer-type dendrimer with a luminescent core has the potential to be a hole-transporting/emitting material.

DOI： 10.1007/s10904-008-9239-3

Language：English   Publishing type：Research paper (scientific journal)  

A new synthetic route for carbazole dendrimers was discovered using the copper-catalyzed N-arylation reaction. This synthetic route allowed synthesizing the fourth generation carbazole dendrimer and several derivatives for the first time. The crystal structure, Mark-Houwink-Sakurada plots, and UV-vis and fluorescence studies showed that the dendritic carbazole backbone has a rigid and highly twisted structure. From the measurement of the redox potential of the ferrocene derivatives, the IR spectra of the benzophenone derivatives, and complexation behavior of the phenylazomethine derivatives, the inductive electron-withdrawing effect of the carbazole dendron was revealed. This suggested that the summation of this electron withdrawal from each layer may produce a potential gradient such that the outer layer is electron-rich and the inner layer is electron-poor in the carbazole dendron. By assignment of the ¹H and ¹³C NMR spectra of the dendron, the existence of this kind of potential gradient was proved. Overall, these data show the π-polarization substituent effect of the carbazole unit, and their summation determines the potential gradient in the repeating dendritic structure of the carbazole dendrimer.

DOI： 10.1021/ja807312e

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2494/photopolymer.21.181

Language：English   Publishing type：Research paper (scientific journal)  

A new double layer-type dendrimer with carbazole as the outer layer and phenylazomethine as the inner layer of the dendron was synthesized using the Ullmann reaction and dehydration reaction in the presence of titanium tetrachloride. In this dendrimer, the carbazole units act as excellent hole-transporters, the phenylazomethine units act as metal assembling sites, and the combination of both units provides a thermally stable shell for which the 10% weight loss temperature was over 550°C. The dendrimers were used as the hole-transporting layer in an OLED device. The OLED device performance increased when the generation of the carbazole increased, corresponding to the higher HOMO level. Additionally, the enhancement of the hole-transporting property was observed by simple complexation of the metal ions to the imine site. Next, the effect of the generation of phenylazomethine was observed and compared to the asymmetric-type carbazole-phenylazomethine dendrimers. When the generation of phenylazomethine increased in the asymmetric-type dendrimer, the device performance decreased. In contrast, the performance did not change using the double layer-type dendrimer. This indicates that the outer layer carbazole works as a hole-transporting shell, and the double layer-type architecture is an ideal structure.

DOI： 10.1021/ma800265h

Language：English   Publishing type：Research paper (scientific journal)  

The interface modification of dye-sensitized solar cells (DSSCs) in order to remove I₃ ^- on the TiO₂ electrodes is important for improving their performance. The suppression of the back electron transfer by a modified interface improves the open-circuit voltage. In this study, we demonstrated that the suppression mechanism using phenylazomethine dendrimers with a triarylamine core (TPA-DPAs) and two other dendrimers, which are a carbazole dendrimer containing a cyclic phenylazomethine of the third generation (CPA-Cz G3) and a half-dendritic phenylazomethine of the fifth generation (Half-DPA G5). Removing I₃ ^- and producing I^- on the TiO₂ electrode by complexation is critical for the suppression of the back electron transfer and promoting the regeneration of the dye in dendrimers having an inner space. Additionally, the presence of various metal compounds in the dendrimers decreased the resistance of the DSSCs, improving fill factor and energy conversion efficiency. We studied that the dendrimer property is changed by the quantitative metal complexation. The fill factor and energy conversion efficiency of the DSSCs are maximized with 0.5 equiv. of SnCl₂ in the TPA-DPAs.

DOI： 10.1021/cm703279u

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2494/photopolymer.19.175

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2494/photopolymer.19.141

Language：English  

Venue：日本大学 船橋キャンパス  

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Venue：日本大学 船橋キャンパス  

Venue：日本大学 船橋キャンパス  

Venue：日本大学 船橋キャンパス  

Venue：日本大学船橋キャンパス  

Venue：名古屋国際会議場  

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Venue：Changchun, China  

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Venue：Pattaya (Thailand)  

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Venue：仙台国際センター  

Venue：北海道大学 札幌キャンパス  

Venue：名古屋国際会議場  

Venue：タワーホール船堀  

Venue：金森ホール(函館)  

Language：English  

Venue：National Physical Laboratory (Delhi, India)  

Language：English  

Venue：Boston Convention and Exhibition Center (Boston, USA)  

Venue：甲南大学 岡本キャンパス  

Venue：甲南大学 岡本キャンパス  

Venue：甲南大学 岡本キャンパス  

Venue：大阪大学　豊中キャンパス  

Venue：大阪府立国際会議場  

Venue：WISTA convention center(Berlin, Germany)  

Venue：東京国際交流館プラザ平成  

Venue：Kyushu University, Ito Campus (Fukuoka, Japan)  

Venue：九州大学 筑紫キャンパス  

Venue：北海道大学　札幌キャンパス  

Venue：東北大学片平キャンパス  

Venue：九州国立博物館  

Venue：Guido Mine and Coal Mining Museum(Zabrze, Poland)  

Venue：北海道大学  

Venue：名古屋工業大学  

Venue：東京理科大学　野田キャンパス  

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Venue：Tokyo University of Science(Chiba, Japan)   Country：Japan  

Venue：福岡国際会議場  

Venue：オンライン  

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Venue：オンライン  

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Venue：オンライン  

Venue：オンライン  

Venue：オンライン  

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Venue：オンライン  

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Venue：オンライン＋名古屋大学  

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Venue：オンライン  

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Venue：オンライン  

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Venue：Technical University of Munich(Straubing, Germany)  

Venue：大阪府立大学  

Venue：大阪府立大学  

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Venue：Vancouver Convention center (Vancouver)   Country：Canada  

Venue：北九州国際会議場  

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Venue：Warsaw (Poland)   Country：Poland  

Venue：オンライン  

Venue：北海道大学　札幌キャンパス  

Venue：北海道大学札幌キャンパス  

Venue：北海道大学  

Venue：京都大学桂キャンパス  

Venue：福岡工業大学  

Language：English  

Venue：オンライン  

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Venue：オンライン  

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Venue：Osaka University (Osaka, Japan)  

Venue：上智大学  

Venue：上智大学  

Venue：上智大学  

Venue：上智大学  

Venue：東京理科大学 野田キャンパス  

Venue：東京理科大学 野田キャンパス  

Venue：東京工業大学 八木山キャンパス  

Language：English  

Venue：Daejeon Convention Center (Daejeon, Korea)   Country：Korea, Republic of  

Venue：日本大学 船橋キャンパス  

Venue：日本大学理工学部 船橋キャンパス  

Venue：オンライン  

Venue：名古屋大学　VBL３階 ベンチャーホール  

Venue：九州大学 伊都キャンパス  

Venue：下呂温泉  

Venue：大阪府立国際会議場  

Venue：大阪国際会議場  

Language：English  

Venue：Max-Planck-Institute for Polymer Research (MPIP)(Mainz, Germany)  

Language：English  

Venue：九州大学筑紫キャンパス  

Language：English  

Venue：Osaka City Central Public Hall(Osaka, Japan)  

Language：English  

Venue：Keio University, Hiyoshi campus (Yokohama, Japana)  

Venue：宮崎大学工学部講義棟2階　D204  

Language：English  

Venue：慶應義塾大学 日吉キャンパス  

Venue：宮崎大学工学部  

Venue：宮崎大学工学部  

Venue：九州大学　伊都キャンパス  

Language：English  

Venue：Lodz University of Technology(Lodz, Poland)  

Venue：北九州国際会議場  

Venue：北九州国際会議場  

Venue：北九州国際会議場  

Language：English  

Venue：国立陽明交通大学(台湾, 新竹)  

Language：English  

Venue：Suntec Singapore Convention & Exhibition Centre(Singapore)  

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Venue：Raleigh Convention Center  

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Venue：Raleigh Convention center(Raleigh, USA)  

Language：English  

Venue：Ulm University(Ulm, Germany)  

Venue：九州大学　伊都キャンパス  

Venue：横浜研修センター  

Language：English  

Venue：パシフィコ横浜  

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Venue：パシフィコ横浜  

Venue：Chiba, Japan  

Venue：東大  

Venue：慶大  

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Venue：大阪市大  

Venue：大阪市大  

Venue：日大船橋キャンパス  

Venue：日大船橋キャンパス  

Venue：日大船橋キャンパス  

Venue：神戸国際会議場  

Language：English  

Venue：Department of Fibreand Polymer Technology, KTH, Stockholm, Sweden  

Venue：晴海グランドホテル  

Venue：熊本大学  

Venue：近畿大学本部キャンパス  

Venue：近畿大学本部キャンパス  

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Venue：近畿大学本部キャンパス  

Venue：パシフィコ横浜  

Venue：パシフィコ横浜  

Language：English  

Venue：京都国際会館  

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Venue：I & I Land (大阪府四條畷市)  

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Venue：Hawaii Convention center  

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Venue：Kamehameha Halls II and III (Convention Center)  

Language：English  

Venue：神奈川大学横浜キャンパス  

Venue：神奈川大学  

Venue：沖縄コンベンションセンター  

Language：English  

Venue：大阪国際会議場  

Venue：大阪国際会議場  

Venue：戸倉上山田温泉 ホテル園山荘  

Venue：岡山大学津島キャンパス  

Venue：岡山大学津島キャンパス  

Language：English  

Venue：Keio University  

Venue：慶應義塾大学矢上キャンパス  

Venue：慶應義塾大学 日吉キャンパス  

Venue：パシフィコ横浜  

Venue：パシフィコ横浜  

Venue：パシフィコ横浜  

Language：English  

Venue：Pacifico Yokohama  

Venue：横浜テクノタワーホテルファミール  

Venue：兵庫県民会館  

Venue：兵庫県民会館  

Venue：名古屋  

Venue：名古屋工業大学  

Venue：富山大学  

Language：English  

Venue：Nagoya Insititute of Technology  

Venue：東京工業大学 大岡山キャンパス  

Venue：東京工業大学  

Language：English  

Venue：神戸国際会議場  

Language：English  

Venue：Kobe  

Venue：東北大学片平キャンパス  

Venue：立命館大学 びわこ・くさつキャンパス  

Venue：立命館大学 びわこ, くさつキャンパス  

Venue：立命館大学 びわこ, くさつキャンパス  

Venue：立命館大学 びわこ・くさつキャンパス  

Venue：立命館大学 びわこ, くさつキャンパス  

Venue：神奈川工科大学  

Language：English  

Venue：Tokyo Tech Front  

Venue：京都国際会館  

Venue：京都国際会館  

Venue：金沢大学角間キャンパス  

Language：English  

Venue：The University of Tokyo  

Venue：名古屋大学 東山キャンパス  

Venue：名古屋大学 東山キャンパス  

Venue：名古屋大学 東山キャンパス  

Language：English  

Venue：Nagoya University (Nagoya, Japan)  

Venue：名古屋国際会議場  

Venue：名古屋国際会議場  

Venue：名古屋国際会議場  

Venue：名古屋国際会議場  

Language：English  

Venue：San Francisco  

Venue：東京理科大学神楽坂キャンパス  

Venue：北海道大学 札幌キャンパス  

Venue：長崎大学 文教キャンパス  

Language：English  

Venue：タワーホール船堀  

Venue：大阪大学豊中キャンパス  

Venue：大阪大学 吹田キャンパス  

Venue：日本大学 船橋キャンパス  

Venue：日本大学 船橋キャンパス  

Venue：日本大学 船橋キャンパス  

Venue：日本大学 船橋キャンパス  

Venue：日本大学 船橋キャンパス  

Venue：日本大学 船橋キャンパス  

Venue：日本大学 船橋キャンパス  

Venue：日本大学 船橋キャンパス  

Venue：日本大学 船橋キャンパス  

Venue：千葉大学 西千葉キャンパス  

Venue：東北大学 片平さくらホール  

Venue：札幌コンベンションセンター  

Venue：札幌コンベンションセンター  

Venue：札幌コンベンションセンター  

Venue：大坂市中央公会堂  

Venue：兵庫県民会館  

Language：English  

Venue：知床グランドホテル 北こぶし  

Language：English  

Venue：知床グランドホテル 北こぶし  

Venue：東北大学 川内キャンパス  

Venue：名古屋国際会議場  

Venue：東京工業大学 大岡山キャンパス  

Venue：東北大学 川内キャンパス  

Venue：タワーホール船堀  

Language：English  

Venue：タワーホール船堀  

Venue：タワーホール船堀  

Venue：京都大学桂キャンパス ローム記念館  

Venue：京都大学桂キャンパスローム記念館  

Venue：六甲保養荘  

Venue：六甲保養荘  

Venue：九州大学伊都キャンパス 椎木講堂  

Venue：九州大学伊都キャンパス 椎木講堂  

Language：English  

Venue：Grand Hyatt Resort and Spa Kauai, Hawaii USA  

Language：English  

Venue：ハワイ コンベンションセンター  

Language：English  

Venue：Hawaii convention center, Honolulu, Hawaii, USA  

Language：English  

Venue：Hawaii convention center, Honolulu, Hawaii, USA  

Language：English  

Venue：Hawaii convention center, Honolulu, Hawaii, USA  

Language：English  

Venue：Hawaii convention center, Honolulu, Hawaii, USA  

Venue：東京工業大学 大岡山キャンパス  

Language：English  

Venue：同志社大学 京田辺キャンパス  

Venue：同志社大学 京田辺キャンパス  

Venue：同志社大学 京田辺キャンパス  

Language：English  

Venue：同志社大学 京田辺キャンパス  

Venue：同志社大学 京田辺キャンパス  

Venue：同志社大学 京田辺キャンパス  

Venue：同志社大学 京田辺キャンパス  

Language：English  

Venue：Community Center Urawa  

Venue：神戸国際会議場  

Venue：神戸国際会議場・国際展示場  

Venue：神戸国際会議場  

Venue：北九州国際会議場  

Venue：幕張メッセ  

Language：English  

Venue：ACROS Fukuoka, Japan  

Venue：朱鷺メッセ  

Venue：朱鷺メッセ  

Venue：神奈川大学  

Venue：神奈川大学 横浜キャンパス  

Venue：朱鷺メッセ  

Venue：神奈川大学  

Venue：北海道教育大学旭川校  

Venue：東北大学 片平キャンパス さくらホール  

Venue：北海道大学 フロンティア応用科学研究棟  

Venue：北海道大学 フロンティア応用科学研究棟  

Venue：石川県 ゆのくに天祥  

Venue：大阪大学シグマホール(豊中キャンパス)  

Language：English  

Venue：仙台市 秋保岩沼屋  

Language：English  

Venue：Kyoto convention center (Japan)  

Language：English  

Venue：Kyoto convention center (Japan)  

Venue：神戸大学百年記念館  

Language：English  

Venue：Fukuoka convention center (Japan)  

Language：English  

Venue：Fukuoka convention center (Japan)  

Language：English  

Venue：Nagoya University (Japan)  

Language：English  

Venue：Lisbon, Portugal  

Venue：パシフィコ横浜  

Venue：慶應義塾大学 日吉キャンパス  

Venue：パシフィコ横浜  

Venue：慶應義塾大学 日吉キャンパス  

Venue：慶應義塾大学 日吉キャンパス  

Language：English  

Venue：慶應義塾大学 日吉キャンパス  

Venue：慶應義塾大学 日吉キャンパス  

Venue：慶應義塾大学 日吉キャンパス  

Venue：慶應義塾大学 日吉キャンパス  

Language：English  

Venue：慶應義塾大学 日吉キャンパス  

Venue：北海道立道民活動センターかでる２・７  

Language：English  

Venue：Masurian Lake District, Poland  

Venue：幕張メッセ  

Language：English  

Venue：Ho Chi Minh City, Vietnam  

Venue：福岡市 休暇村志賀島  

Venue：Ishikawa Ongakudo (Kanazawa)  

Venue：Kyushu University, Fukuoka, Japan  

Venue：Kyushu University, Fukuoka, Japan  

Venue：アカデミーハウス館山  

Venue：東京工業大学 すずかけ台キャンパス  

Language：English  

Venue：Waseda University (Tokyo)  

Venue：福岡国際会議場  

Language：English  

Venue：愛媛大学  

Venue：愛媛大学  

Language：English  

Venue：愛媛大学  

Venue：タワーホール船堀  

Venue：タワーホール船堀  

Venue：東京工業大学 大岡山キャンパス  

Venue：東京工業大学 大岡山キャンパス  

Venue：愛媛大学  

Venue：愛媛大学  

Venue：愛媛大学