Stable Luminescence of CsPbBr₃/nCdS Core/Shell Perovskite Quantum Dots with Al Self-Passivation Layer Modification

Perovskite quantum dots (PQDs) are among the most important luminescent semiconducting materials; however, they are unstable. Exposure to light, heat, and air can lead to irreversible degradation, which results in fluorescence quenching. Therefore, defects in PQDs significantly limit their practical application. Herein, we describe a simple method to enhance the photostability of CsPbBr₃/nCdS QDs, which involves doping their shells with aluminum. The temperature-dependent photoluminescence (PL) of colloidal CsPbBr₃/nCdS/Al₂O₃ QDs is investigated, and the thermal quenching of PL, blue shift of the optical band gap, and PL line width broadening are observed in each QD sample. Al₂O₃ layers on the CsPbBr₃/nCdS QDs can effectively prevent photodegradation. Nonlinear, temperature-dependent exciton-phonon coupling and lattice dilation leads to radiative and nonradiative relaxation processes at temperatures ranging from 10 to 300 K; moreover, changes in the band gap and PL spectral line broadening are observed.