Dendebera M. Electron and excitone states in CsPbBr3 perovskite

The relevance of the research topic is due to the unique properties of halide perovskites, which make them promising materials for creation of various applications, such as the LEDs, photovoltaic devices, and high-speed scintillation detectors. Understanding the energy structure of the CsPbBr3 crystal, as a model object of halide perovskites, will make it possible to improve and expand the possibility of their use. For this purpose, a set of spectral-kinetic studies of the luminescence properties of a single-crystal sample of CsPbBr3, particles in a crystalline and polymer matrix in the temperature range of 12-300 K was carried out. The obtained spectra and luminescence decay made it possible to interpret the edge emission bands as direct transitions of free excitone and transitions from Rashba minima. The characteristic two emission bands of the CsPbBr3 single crystal are interpreted as free exciton emission and transitions from Rashba minima. The broad luminescence band is associated with defects emission. CsPbBr3 particles in the KBr crystal matrix show similarities with both nanoparticles (one intense luminescence band at room temperature) and single crystals (splitting of the luminescence band into two at liquid nitrogen temperature, presence of a broad low-energy band). The analysis of temperature dependences made it possible to assume the presence of direct and Rashba exciton in the ensemble of nanoparticles. Intense luminescence and short luminescence decay times of the polystyrene-based composite with embedded nanoparticles CsPbBr3 at temperature of liquid nitrogen demonstrate its promise as a high-speed scintillator for positron emission tomography.