Quantifying Charge Carrier Mobilities and Recombination Rates in Metal Halide Perovskites from Time-Resolved Microwave Photo-conductivity Measurements.

The unprecedented rise in power conversion efficiency of solar cells based on metal halide perovskites (MHPs) has led to enormous research effort to understand their photo-physical properties. In this paper, we review the progress in understanding the mobility and recombination of photo-generated charge carriers from nanosecond to microsecond time scales, monitored using electrodeless transient photoconductivity techniques. In addition, we present a kinetic model to obtain rate constants from transient data recorded using a wide range of laser intensities. For various MHPs the temperature dependence of the mobilities and recombination rates are evaluated. Furthermore, we show how these rate constants can be used to predict the upper limit for the open-circuit voltage Voc of the corresponding device. Finally, we discuss photo-physical properties of MHPs that are not yet fully understood, and make recommendations for future research directions.