Anomalous variable-temperature photoluminescence of CsPbBr3 perovskite quantum dots embedded into an organic solid
All-inorganic lead halide perovskite quantum dots (PQDs) of CsPbBr3 were synthesized at room tem-perature via a facile solution-based procedure. Cubic phase structure of the synthesized PQDs was judiciously identified through examining high-resolution transmission electron microscope (TEM) images, selected area electronic diffraction (SAED) patterns and scanning TEM images of the PQDs. Variable-temperature photoluminescence (PL) spectra of the CsPbBr3 PQDs randomly embedded into a frozen solid of methylbenzene were measured in a temperature range of 5-180 K. It is found that both linewidth and peak position of the measured PL spectra are abnormally almost temperature independent in the interested temperature range. Some competing mechanisms, such as a competition between bandgap blue shift induced by thermal lattice expansion and red shift by thermal escaping of localized excitons, and a competition between lineshape broadening by phonon scattering and narrowing by thermal escaping of localized excitons, are proposed to interpret the phenomena. Good agreement between the theoretical fitting and the experimental data leads to a state-of-the-art understanding of the temperature-dependent luminescence of the CsPbBr3 PQDs in solid matrix.