Carrier dynamics in a perovskite solar cell observed with light-triggered time domain reflectometry

Ryuichi Tokuyama, Ryuya Inakawa, Haruki Nakashima, Rikuto Matsumoto, Takeru Tsuchihashi, Yuto Ishimatsu, Ruoxue Zhang, Tatsuya OMORI, Hirofumi Mino, MASATOSHI SAKAI

Japanese Journal of Applied Physics 2025年4月30日査読有り

Abstract The carrier dynamics of photogenerated holes in perovskite solar cells were observed using light-triggered time-domain reflectometry. The distribution of photogenerated holes in the perovskite layer began to expand immediately (within the time resolution) after light illumination. The hole frontline arrived at the perovskite/hole transport layer interface in 30 ns and at the hole transport layer/anode interface in 90 ns. Afterwards, the distribution of the photogenerated holes continued to grow and reached the steady photogeneration state in approximately 30 μs.
High-sensitive vector visualization of nonlinear harmonic responses generated in RF-SAW devices

Yasuhiro Kawaguchi, Hiroki Gai, Tatsuya Omori

2024 IEEE Ultrasonics, Ferroelectrics, and Frequency Control Joint Symposium (UFFC-JS) 1-4 2024年9月22日
Vector Measurement of Nonlinear Responses Generated by SAW/BAW RF Devices Using Lock-in Amplifiers

Temma Doi, Tatsuya Omori

2024 IEEE Ultrasonics, Ferroelectrics, and Frequency Control Joint Symposium (UFFC-JS) 1-4 2024年9月22日
High sensitive vector measurement of nonlinear harmonic responses in surface acoustic wave/bulk acoustic wave radio frequency devices

Seiya Himata, Tatsuya Omori

Japanese Journal of Applied Physics 62(SJ) SJ8003-SJ8003 2023年2月6日

Abstract This paper proposes a high-sensitive measuring method for nonlinear harmonic responses in radio frequency (RF) SAW/BAW devices using a lock-in amplifier. The proposed system could detect the nonlinear complex harmonic responses generated in an RF SAW resonator, even if the responses are weaker than −140 dBm. The detection limit is extended by around 10 dB compared with the conventional technique using a cross-domain analyzer.
Initial Photocarrier Generation Process in Organic Photovoltaics Observed with Light-Triggered Time-Domain Reflectometry

Tomoaki Mashiko, Koki Takano, Akira Kaino, Sou Kuromasa, Shintaro Fujii, Tatsuya Omori, Masatoshi Sakai, Kazuhiro Kudo, Hirofumi Mino

Physica Status Solidi (A) Applications and Materials Science 2023年

Herein, a time-resolved electrical measurement is developed to observe the transient impedance of organic photovoltaics (OPV) and traced the initial photocarrier generation dynamics with the time region from 10 ns to 190 μs. A light-triggered time-domain reflectometry is adopted to observe the initial carrier dynamics in OPV by synchronizing rectangular light pulses from LED with a transient impedance probe pulse. Both the rising and recovery processes of OPV are observed in detail. The time evolution of the photocarrier distribution is calculated based on the diffusion–recombination scheme and is discussed in the initial process of photocarrier generation.

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MISC

147

千葉支所における最近の活動状況

大森達也

電気学会誌 144(11) 730-730 2024年11月1日
高周波弾性表面波デバイスにおける高調波の高感度複素振幅測定

43 99-99 2022年11月
超高速弾性振動可視化装置の高性能・高機能化に関する研究

大森達也

研究報告書フジクラ財団 [編] 1-5 2020年
Performance enhancement with applying FSS and ASB method for MU-MIMO

Fumiaki Ukaji, Chang Jun Ahn, Tatsuya Omori, Ken Ya Hashimoto

Proceedings of the IEEE International Conference on Industrial Technology 2016-May 860-865 2016年5月19日

Multi-user multi-input multi-output (MU-MIMO) can achieve more transmission speed and multi-user diversity. Furthermore, since frequency symbol spreading (FSS) can mitigate the effect of frequency selective fading, it is useful for improving the BER performance. However, FSS cannot be applied to MIMO system with adding forward error correction (FEC) due to interference of the transmit antennas. In this paper, we consider the difference of the transmitted power for each user and the difference of the distance from base station (BS) to each user in general mobile wireless communications, we propose that applying FSS and adaptive subcarrier block (ASB) method with considering the imbalanced transmitted power for MU-MIMO. From the simulation results, it is shown that the proposed scheme can achieve a superior BER and throughput performance.
Channel compensation based on VPS and time-frequency interferometry for massive MIMO-OFDM

Masaya Okamura, Chang Jun Ahn, Tatsuya Omori, Ken Ya Hashimoto

2015 International Symposium on Intelligent Signal Processing and Communication Systems, ISPACS 2015 532-536 2016年3月11日

Massive MIMO has been recognized as promising ways to provide high speed data transmission. However, since the number of pilot symbol is proportionally depending on the number of transmit antenna, the total transmission rate of massive MIMO would be degraded. To solve this problem, channel estimation by virtual pilot signal (VPS) with a few pilot signals has been proposed. However, since the conventional method iteratively identifies the channel state information (CSI), the complexity is considerable work. Then again, time-frequency interferometry (TFI)-OFDM has been proposed. This method can achieve a good BER performance with a few pilot symbols. In this paper, we propose a novel channel compensation based on VPS and TFI for massive MIMO without increasing the system complexity. The proposed scheme has a low complexity, with improving BER performance to compared with the conventional method using linear interpolation and FFT/IFFT after specific operations. From the simulation results, the proposed scheme can improve BER performance to compared with the conventional method in 4 × 4 and 8 × 8MIMO systems.