Tuning Electron–Phonon Coupling Interaction for the Efficient Wide Blue Emission of Pb2+-Doped Cs2InCl5·H2O

Lead-free perovskites exhibit unique crystal structures and optical properties due to their low-dimensional structure. However, the 0D structure of Cs 2 InCl 5 ·H 2 O usually demonstrates poor optical properties at room temperature due to their extremely strong electron–phonon coupling interaction. In this study, a doping strategy is employed by introducing Pb 2+ into Cs 2 InCl 5 ·H 2 O, resulting in the achievement of an efficient broadband blue emission, with a photoluminescence quantum yield (PLQY) of 58%. The temperature-dependent PL spectra reveal that the efficient emission is attributed to the weakening of the electron–phonon coupling strength in the lattice and the inhibition of the phonon-assisted non-radiative recombination process through Pb 2+ doping. The validity of this deduction is further corroborated by the results of the Raman spectra. The results of the first-principle calculation demonstrate that the broadband emission originates from multiple emission paths in In 3+ and Pb 2+ polyhedrons. In addition, Pb 2+ -doped Cs 2 InCl 5 ·H 2 O can realize the transformation from sky-blue emission to deep-blue emission by absorbing water in the air. Remarkably, this change is reversible during the heating–cooling cycles, demonstrating excellent optical stability with repeatable recyclability.