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Photophysics of Organic–Inorganic Hybrid Lead Iodide Perovskite Single Crystals
Author(s) -
Fang HongHua,
Raissa Raissa,
AbduAguye Mustapha,
Adjokatse Sampson,
Blake Graeme R.,
Even Jacky,
Loi Maria Antonietta
Publication year - 2015
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201404421
Subject(s) - materials science , photoluminescence , exciton , perovskite (structure) , luminescence , halide , phase transition , tetragonal crystal system , chemical physics , saturation (graph theory) , semiconductor , atmospheric temperature range , condensed matter physics , optoelectronics , crystallography , crystal structure , chemistry , physics , thermodynamics , inorganic chemistry , mathematics , combinatorics
Hybrid organometal halide perovskites have been demonstrated to have outstanding performance as semiconductors for solar energy conversion. Further improvement of the efficiency and stability of these devices requires a deeper understanding of their intrinsic photophysical properties. Here, the structural and optical properties of high‐quality single crystals of CH 3 NH 3 PbI 3 from room temperature to 5 K are investigated. X‐ray diffraction reveals an extremely sharp transition at 163 K from a twinned tetragonal I4/mcm phase to a low‐temperature phase characterized by complex twinning and possible frozen disorder. Above the transition temperature, the photoluminescence is in agreement with a band‐edge transition, explaining the outstanding performances of the solar cells. Whereas below the transition temperature, three different excitonic features arise, one of which is attributed to a free‐exciton and the other two to bound excitons (BEs). The BEs are characterized by a decay dynamics of about 5 μs and by a saturation phenomenon at high power excitation. The long lifetime and the saturation effect make us attribute these low temperature features to bound triplet excitons. This results in a description of the room temperature recombination as being due to spontaneous band‐to‐band radiative transitions, whereas a diffusion‐limited behavior is expected for the low‐temperature range.