PL spectra and PL dynamics of CsPbBr 3 quantum dots in solution and film

Abstract Temperature dependent photoluminescence (PL) and time-resolved PL (TRPL) of CsPbBr 3 quantum dots (QDs) in solution and film are investigated. The electron−phonon coupling strength of quantum dots in solution is found two times larger than that of thin films. The averaged phonon energy involved in luminescence is also significantly higher than that of thin films, indicating that ligands’ phonons are involved in optical processes in solution but not in film. TRPL shows that the luminescence lifetime of the solution (22.5 ns) is longer than that of the thin film (5 ns) at room temperature, and both decrease abnormally with decreasing temperature, ascribing to the thermally activated trap states for PL, the further analysis shows that the trap energy levels in the thin film are deeper (~20 meV) compared to ~4 meV in solution. Our work proves that the morphology of organic ligands can regulate electron−phonon interactions and optoelectronic properties in CsPbBr 3 QDs, providing fundamental insights into its photophysics.