Boziki, AriadniDar, M. IbrahimJacopin, GwenoleGratzel, MichaelRothlisberger, Ursula2021-04-102021-04-102021-04-102021-03-1810.1021/acs.jpclett.1c00263https://infoscience.epfl.ch/handle/20.500.14299/177090WOS:000631413800029CsPbBr3 has received wide attention due to its superior emission yield and better thermal stability compared to other organic-inorganic lead halide perovskites. In this study, through an interplay of theory and experiments, we investigate the molecular origin of the asymmetric low-temperature photoluminescence spectra of CsPbBr3. We conclude that the origin of this phenomenon lies in a local dipole moment (and the induced Stark effect) due to the preferential localization of Cs+ in either of two off-center positions of the empty space between the surrounding PbBr6 octahedra. With increasing temperature, Cs+ ions are gradually occupying positions closer and closer to the center of the cavities. The gradual loss of ordering in the Cs+ position with increasing temperature is the driving force for the formation of tetragonal-like arrangements within the orthorhombic lattice.Chemistry, PhysicalNanoscience & NanotechnologyMaterials Science, MultidisciplinaryPhysics, Atomic, Molecular & ChemicalChemistryScience & Technology - Other TopicsMaterials SciencePhysicstext::journal::journal article::research article