Steady-state microwave conductivity reveals mobility-lifetime product in methylammonium lead iodide

Abstract

Many time-resolved techniques to study charge carrier recombination involve pulsed high-power optical excitation and photo-generated carrier densities many orders of magnitude higher than present under typical solar cell operating conditions. In this report, we demonstrate a steady-state contactless microwave conductivity technique to evaluate the photoconductivity of carriers in semiconductors at low illumination intensity, as a function of optical power density. We studied characteristics of both thin films and single crystals of a hybrid halide perovskite compound, methylammonium lead iodide (MAPbI3). The aggregate mobility-lifetime product of majority and minority carriers in thin films of MAPbI3 was determined and found to be highly-dependent on incident optical power density, even at sub-1-sun illumination intensities, and attributed to trap states within the films.