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Excitations Partition into Two Distinct Populations in Bulk Perovskites
Author(s) -
Wang Lili,
Brawand Nicholas P.,
Vörös Márton,
Dahlberg Peter D.,
Otto John P.,
Williams Nicholas E.,
Tiede David M.,
Galli Giulia,
Engel Gregory S.
Publication year - 2018
Publication title -
advanced optical materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.89
H-Index - 91
ISSN - 2195-1071
DOI - 10.1002/adom.201700975
Subject(s) - polaron , perovskite (structure) , charge carrier , halide , materials science , chemical physics , ab initio quantum chemistry methods , recombination , absorption (acoustics) , molecular physics , condensed matter physics , optoelectronics , crystallography , chemistry , physics , inorganic chemistry , biochemistry , organic chemistry , quantum mechanics , molecule , gene , electron , composite material
Organolead halide perovskites convert optical excitations to charge carriers with remarkable efficiency in optoelectronic devices. Previous research predominantly documents dynamics in perovskite thin films; however, extensive disorder in this platform may obscure the observed carrier dynamics. Here, carrier dynamics in perovskite single‐domain single crystals is examined by performing transient absorption spectroscopy in a transmissive geometry. Two distinct sets of carrier populations that coexist at the same radiation fluence, but display different decay dynamics, are observed: one dominated by second‐order recombination and the other by third‐order recombination. Based on ab initio simulations, this observation is found to be most consistent with the hypothesis that free carriers and localized carriers coexist due to polaron formation. The calculations suggest that polarons will form in both CH 3 NH 3 PbBr 3 and CH 3 NH 3 PbI 3 crystals, but that they are more pronounced in CH 3 NH 3 PbBr 3 . Single‐crystal CH 3 NH 3 PbBr 3 could represent the key to understanding the impact of polarons on the transport properties of perovskite optoelectronic devices.