Organometal Halide Perovskite Solar Cell Materials Rationalized: Ultrafast Charge Generation, High and Microsecond-Long Balanced Mobilities, and Slow Recombination

作者：Carlito S. Ponseca, Tom J. Savenije, Mohamed A. Abdellah, Kaibo Zheng, Arkady P. Yartsev, Tobjörn Pascher, Tobias Harlang, Pavel Chábera, Tõnu Pullerits, Andrey L. Stepanov, Jean‐Pierre Wolf, Villy Sundström · 发表于：Journal of the American Chemical Society · 年份：2014 · DOI：10.1021/ja412583t · 被引用次数：1259 · 研究领域：Perovskite Materials and Applications、Conducting polymers and applications、Chalcogenide Semiconductor Thin Films

Organometal halide perovskite-based solar cells have recently been reported to be highly efficient, giving an overall power conversion efficiency of up to 15%. However, much of the fundamental photophysical properties underlying this performance has remained unknown. Here, we apply photoluminescence, transient absorption, time-resolved terahertz and microwave conductivity measurements to determine the time scales of generation and recombination of charge carriers as well as their transport properties in solution-processed CH3NH3PbI3 perovskite materials. We found that electron-hole pairs are generated almost instantaneously after photoexcitation and dissociate in 2 ps forming highly mobile charges (25 cm(2) V(-1) s(-1)) in the neat perovskite and in perovskite/alumina blends; almost balanced electron and hole mobilities remain very high up to the microsecond time scale. When the perovskite is introduced into a TiO2 mesoporous structure, electron injection from perovskite to the metal oxide is efficient in less than a picosecond, but the lower intrinsic electron mobility of TiO2 leads to unbalanced charge transport. Microwave conductivity measurements showed that the decay of mobile charges is very slow in CH3NH3PbI3, lasting up to tens of microseconds. These results unravel the remarkable intrinsic properties of CH3NH3PbI3 perovskite material if used as light absorber and charge transport layer. Moreover, finding a metal oxide with higher electron mobility may further increas...