Language：English   Publisher：Advanced Science  

This study demonstrates that optical absorption of the CsPbBr<inf>3</inf> quantum dots can be significantly enhanced through monolithic integration with the Tamm plasmon (TP) structure. This integration enables the resulting TP photodetector to achieve a higher photocurrent and a more linear power dependence compared to the reference device with a nonresonant configuration. The enhancement is confined to the designed resonant energy, while photons with off-resonance energies are fully reflected, making the TP photodetector an ideal candidate for compact and efficient image sensors, eliminating the need for additional filters or bulky microlenses for color discrimination or photon collection. Furthermore, the photocurrent generated by the TP photodetector can be regulated by varying light pulse stimulations, enabling it to mimic the synaptic dynamics of the human brain. By integrating the functions of perception, processing, and memorization of visual images, its potential for facial recognition through simulation based on a 64 × 64 array of TP photodetectors under the artificial neural network-based weight-update expectation thresholding model is demonstrated. These findings mark a significant step forward in utilizing all-inorganic perovskite materials for compact, color-filter-free image sensors and open new avenues for photonic neural computations on a single platform.

DOI： 10.1002/advs.202503464

Web of Science

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PubMed

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

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACS Applied Materials and Interfaces  

The formation of periodic arrangements of two types of nanoparticles (NPs), i.e., binary NP superlattices (BNSLs), provides a versatile approach to control their physical properties through interparticle interactions. However, achieving highly ordered BNSLs is still challenging because of the difficulty of combining two distinct NPs without phase segregation. In this work, plasmonic Au NPs and CdS quantum dots (QDs) modified with dodecanethiol ligands were assembled into binary multilayered structures by alternately laminating their monolayers onto a single substrate. Grazing-incidence small-angle X-ray scattering analysis confirmed the long-range ordered arrangement of the NPs, demonstrating the successful fabrication of 3D structures with Au NPs and CdS QDs. The formation of close-packed monolayers and entropic stabilization by surface ligands were identified as key factors in artificially constructing such 3D arrays via multilayering. The formation of defect-free BNSLs was also optically identified by a systematic increase in the intensities of the photoluminescence (PL) and plasmon extinction intensities, as well as perfect control of respective band positions. Based on finite-difference time-domain simulations, this PL behavior was attributed to the formation of a layered superstructure with a homogeneous dielectric function in the repeat unit of a Au NP-CdS QD-Au NP layer. This work demonstrates that simple alternative lamination of NP monolayers offers a facile yet effective strategy to obtain BNSLs with well-defined physical properties for broader application of NP array-based materials.

DOI： 10.1021/acsami.5c02956

Web of Science

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PubMed

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Nanoscale  

本研究では、ペロブスカイトナノ粒子の自己組織化単粒子膜を自在に積層・パターン形成することを可能にする、ポリジメチルシロキサン（PDMS）膜を用いた膜転写手法を提案した。
具体的には、転写元および転写先基板の表面エネルギーをシランカップリングにより制御することで、ナノ粒子への追加処理を行うことなく、効率的な膜転写が可能であることを実証した。本成果は、様々なナノ光デバイスへの応用展開に資するものである。

DOI： 10.1039/D4NR05088F

Web of Science

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PubMed

Publishing type：Research paper (international conference proceedings)   Publisher：Proceedings of SPIE the International Society for Optical Engineering  

Semiconductor optical refrigeration utilizes the energy upconversion of light via anti-Stokes (AS) photoluminescence (PL), which occurs through a phonon-assisted optical absorption process. This process is advantageous for semiconductors with strong electron-phonon (e-ph) interactions, such as lead halide perovskites. We discuss the significance of short-range e-ph interactions in the AS-PL process, rather than the long-range Fröhlich interactions. Short-range e-ph interactions induce Urbach tail absorption, which is experimentally evaluated via the steepness parameter. We simulate the impact of the steepness parameter on the photo-cooling gain and efficiency. We also focus on halide perovskite CsPbBr3 quantum dots embedded in a Cs4PbBr6 host crystal, which possess both near-unity PL quantum efficiency and strong e-ph interactions, and quantitatively evaluate their AS-PL properties. Based on the spectroscopic results, we discuss the possibility of semiconductor optical refrigeration using halide perovskite quantum dots.

DOI： 10.1117/12.2655039

Scopus

Event date： 2025.3

Presentation type：Oral presentation (general)  

Venue：東京理科大 野田キャンパス  

Event date： 2025.2

Presentation type：Oral presentation (invited, special)  

Venue：Sakure Hall, Sendai, Japan  

Event date： 2024.7

Presentation type：Symposium, workshop panel (public)  

Venue：日本学術会議講堂  

Event date： 2024.7

Presentation type：Oral presentation (general)  

Venue：Shimane, JAPAN  

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京都市大学 世田谷キャンパス   Country：Japan