Year: 2015
Type: article
Abstract: 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.
Source: Advanced Functional Materials
Authors: Hong‐Hua Fang, Raissa Raissa, Mustapha Abdu‐Aguye, Sampson Adjokatse, Graeme R. Blake, Jacky Even, Maria Antonietta Loi
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $5,790
OpenAlex ID: W2100526315