Many optoelectronic properties have been reported for lead halide perovskite polycrystalline films. However, ambiguities in the evaluation of these properties remain, especially for long-range lateral charge transport, where ionic conduction can complicate interpretation of data. Here we demonstrate a new technique to measure the long-range charge carrier mobility in such materials. We combine quasi-steady-state photo-conductivity measurements (electrical probe) with photo-induced transmission and reflection measurements (optical probe) to simultaneously evaluate the conductivity and charge carrier density. With this knowledge we determine the lateral mobility to be ~ 2 cm2/Vs for CH3NH3PbI3 (MAPbI3) polycrystalline perovskite films prepared from the acetonitrile/methylamine solvent system. Furthermore, we present significant differences in long-range charge carrier mobilities, from 2.2 to 0.2 cm2/Vs, between films of contemporary perovskite compositions prepared via different fabrication processes, including solution and vapour phase deposition techniques. Arguably, our work provides the first accurate evaluation of the long-range lateral charge carrier mobility in lead halide perovskite films, with charge carrier density in the range typically achieved under photovoltaic operation.
@article{arxiv.1812.06322,
title = {Elucidating the long-range charge carrier mobility in metal halide perovskite thin films},
author = {Jongchul Lim and Maximilian T. Hoerantner and Nobuya Sakai and James M. Ball and Suhas Mahesh and Nakita K. Noel and Yen-Hung Lin and Jay B. Patel and David P. McMeekin and Michael B. Johnston and Bernard Wenger and Henry J. Snaith},
journal= {arXiv preprint arXiv:1812.06322},
year = {2018}
}