Characterization of an abnormal photoluminescence behavior upon crystal-phase transition of perovskite CH3NH3PbI3

Abstract

Solution-processed hybrid perovskite of CH₃NH₃PbI₃ (MAPbI₃) exhibits an abnormal luminescence behavior at around the tetragonal–orthorhombic phase transition temperature. The combination of time resolved photoluminescence (PL), variable excitation power PL, and variable-temperature X-ray diffraction (XRD) allows us to clearly interpret the abnormal luminescence features in the phase transition region of MAPbI₃. Both PL and XRD results unambiguously prove the coexistence of the tetragonal and orthorhombic phases of MAPbI₃ in the temperature range of 150 to 130 K. The two luminescence features observed in the orthorhombic phase at T < 130 K originate from free excitons and donor–acceptor-pair (DAP) transitions, respectively. The comprehensive understanding of optical properties upon phase transition in MAPbI₃ will benefit the development of new optoelectronic devices.