Temperature-dependent photoluminescence of CH₃NH₃PbBr₃ crystal powder

In this work, the temperature-dependent behavior of CH₃NH₃PbBr₃ (MAPbBr₃) crystal powder is experimentally investigated using steady-state photoluminescence (PL) spectroscopy. Under 405 nm continuous-wave laser excitation, the fluorescence peak is at 560 nm with a full width at half maximum of 123 meV. There is a good linear increase in the luminescence intensity with increasing pump laser fluence, which indicates induced single-photon absorption. The MAPbBr₃ crystal powder-induced PL exhibits different temperature-dependent behaviors at temperatures ranging from 80−310 K. As the temperature increases, the photon energy of the line width gets greater and the PL integral intensity gradually decreases because of the enhanced exciton phonon interaction. The peak of the PL spectrum shows a linear blue shift at 80−145 K. There is a very shallow slot around 150 K, while the peak position of the spectrum remains almost constant when the temperature exceeds 150 K. These temperature-dependent induced PL behaviors are mainly due to the contribution of phase transition and thermal expansion from orthogonal to tetragonal phases occurring at around 150 K. In addition, exciton binding energies of about 49.8 meV and longitudinal optical phonon energies of about 60.4 meV are derived from the temperature dependent PL experimental dataset.