期刊
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
卷 136, 期 39, 页码 13818-13825出版社
AMER CHEMICAL SOC
DOI: 10.1021/ja506936f
关键词
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资金
- KAKENHI grant from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan
- Precursory Research for Embryonic Science and Technology (PRESTO) program of the Japan Science and Technology Agency (JST)
- Murata Science Foundation
- Grants-in-Aid for Scientific Research [25288084] Funding Source: KAKEN
The intriguing photoactive features of organic-inorganic hybrid perovskites have enabled the preparation of a new class of highly efficient solar cells. However, the fundamental properties, upon which the performance of these devices is based, are currently under-explored, making their elucidation a vital issue. Herein, we have investigated the local mobility, recombination, and energetic landscape of charge carriers in a prototype CH3NH3PbI3 perovskite (PVK) using a laser-flash time-resolved microwave conductivity (TRMC) technique. PVK was prepared on mesoporous TiO2 and Al2O3 by one or two-step sequential deposition. PVK on mesoporous TiO2 exhibited a charge carrier mobility of 20 cm(2)V(-1)s(-1), which was predominantly attributed to holes. PVK on mesoporous Al2O3, on the other hand, exhibited a 50% lower mobility, which was resolved into balanced contributions from both holes and electrons. A general correlation between crystal size and mobility was revealed irrespective of the fabrication process and underlying layer. Modulating the microwave frequency from 9 toward 23 GHz allowed us to determine the intrinsic mobilities of each PVK sample (60-75 cm(2) V-1 s(-1)), which were mostly independent of the mesoporous scaffold. Kinetic and frequency analysis of the transient complex conductivity strongly support the superiority of the perovskite, based on a significant suppression of charge recombination, an extremely shallow trap depth (10 meV), and a low concentration of these trapped states (less than 10%). The transport mechanism was further investigated by examining the temperature dependence of the TRMC maxima. Our study provides a basis for understanding perovskite solar cell operation while highlighting the importance of the mesoporous layer and the perovskite fabrication process.
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