Elucidating the Long-range Charge Carrier Mobility in Metal Halide Perovskite Thin Films
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Various charge carrier mobility under different carrier densities regime have been reported for lead halide perovskite polycrystalline films. However, time-dependent change of internal carrier population due to early-time recombination should be reflected in long-range lateral charge transport through intragrains and grain boundaries. Here we demonstrate a new transient photo-conductivity technique and accurately estimate the internal free carrier density using simulation of charge population rise and decay with the early-time recombination. With this knowledge we determine carrier density invariable lateral mobilities to be in the range from 8.9 down to 0.2 cm2/Vs for Cs0.17FA0.83Pb(I0.9Br0.1)3, Cs0.05(FA0.83MA0.17)0.95Pb(I0.9Br0.1)3 and CH3NH3PbI3 polycrystalline perovskite films depending upon the preparation route and free carrier density. Our results provide the first accurate evaluation of the carrier density invariable lateral mobility in lead halide perovskite films.