title: Spectral dependence of direct and trap-mediated recombination processes in lead halide perovskites using time resolved microwave conductivity.
abstract: Elucidating the decay mechanisms of photoexcited charge carriers is key to improving the efficiency of solar cells based on organo-lead halide perovskites. Here we investigate the spectral dependence (via above-, inter- and sub-bandgap optical excitations) of direct and trap-mediated decay processes in CH3NH3PbI3 using time resolved microwave conductivity (TRMC). We find that the total end-of-pulse mobility is excitation wavelength dependent - the mobility is maximized (172 cm(2) V(-1) s(-1)) when charge carriers are excited by near bandgap light (780 nm) in the low charge carrier density regime (10(9) photons per cm(2)), and is lower for above- and sub-bandgap excitations. Direct recombination is found to occur on the 100-400 ns timescale across excitation wavelengths near and above the bandgap, whereas indirect recombination processes displayed distinct behaviour following above- and sub-bandgap excitations, suggesting the influence of different trap distributions on recombination dynamics.
authors.affiliation: School of Physics, UNSW, Sydney, NSW 2052, Australia. dane.mccamey@unsw.edu.au.
authors.forename: Joanna A
authors.initials: JA
authors.lastname: Guse
authors.affiliation: Australian Centre for Advanced Photovoltaics (ACAP), School of Photovoltaic and Renewable Energy Engineering, UNSW, Sydney, NSW 2052, Australia.
authors.forename: Arman M
authors.initials: AM
authors.lastname: Soufiani
authors.affiliation: Department of Materials Engineering, Monash University, Melbourne, Victoria 3800, Australia.
authors.forename: Liangcong
authors.initials: L
authors.lastname: Jiang
authors.affiliation: Australian Centre for Advanced Photovoltaics (ACAP), School of Photovoltaic and Renewable Energy Engineering, UNSW, Sydney, NSW 2052, Australia.
authors.forename: Jincheol
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Materials Engineering, Monash University, Melbourne, Victoria 3800, Australia.
authors.forename: Yi-Bing
authors.initials: YB
authors.lastname: Cheng
authors.affiliation: School of Chemistry, UNSW, Sydney, NSW 2052, Australia.
authors.forename: Timothy W
authors.initials: TW
authors.lastname: Schmidt
authors.affiliation: Australian Centre for Advanced Photovoltaics (ACAP), School of Photovoltaic and Renewable Energy Engineering, UNSW, Sydney, NSW 2052, Australia.
authors.forename: Anita
authors.initials: A
authors.lastname: Ho-Baillie
authors.affiliation: School of Physics, UNSW, Sydney, NSW 2052, Australia. dane.mccamey@unsw.edu.au.
authors.forename: Dane R
authors.initials: DR
authors.lastname: McCamey