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Photocarrier dynamics in CIGS, CZTS, and related materials revealed by ultrafast optical spectroscopy
Author(s) -
Okano Makoto,
Phuong Le Quang,
Kanemitsu Yoshihiko
Publication year - 2015
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201400260
Subject(s) - czts , materials science , copper indium gallium selenide solar cells , semiconductor , optoelectronics , solar cell , relaxation (psychology) , spectroscopy , cadmium telluride photovoltaics , photoluminescence , femtosecond , thin film , chemical physics , nanotechnology , chemistry , optics , laser , physics , psychology , social psychology , quantum mechanics
We discuss the photocarrier dynamics in emerging thin‐film solar‐cell materials, Cu(In,Ga)Se 2 (CIGS), Cu 2 ZnSnS 4 (CZTS), and CdTe‐based nanocrystals (NCs), using time‐resolved photoluminescence and femtosecond pump–probe spectroscopy. In CIGS and CZTS samples, we found long‐lived free photocarriers and slow intraband relaxation at room temperature. These distinctive behaviors of the free carriers are considered common features in multinary semiconductors and are related to the complicated near‐band edge structure due to potential fluctuations, which might affect solar‐cell efficiencies. We revealed the relationship in CdTe‐based type‐II NCs between hot carrier transfer and intraband relaxation, providing a better understanding of the charge separation mechanism in multinary semiconductors. We also demonstrated the usefulness of ultra‐fast optical spectroscopy techniques for clarifying the photocarrier dynamics in various semiconducting bulk and nano‐structure materials for solar cells.