Optimizing optical properties of hybrid core/shell perovskite nanocrystals

Abstract

Hybrid perovskite nanocrystals (NCs) are widely used in various applications, due to their desirable optoelectronic characteristics. However, the related applications are usually hindered by their poor long-term stability. In this work, we have synthesized one kind of CH₃NH₃PbBr₃ (MAPbBr₃) NC that is heteroepitaxially grown with an MA_1−xCs_xPbBr₃ shell, with the aim to optimize the optical properties of the former. It is found that the MAPbBr₃/MA_1−xCs_xPbBr₃ core/shell NCs possess optimized optical stability. Through the measurement of the temperature-dependent photoluminescence spectrum, it is confirmed that the core/shell NCs exhibit weaker electron–phonon coupling strength and larger exciton binding energy than the bare MAPbBr₃ NCs. Interestingly, the core/shell NCs display significantly prolonged biexciton Auger lifetime and enlarged two-photon absorption. Impressively, two-photon pumped amplified stimulated emission is only observed in the core/shell NCs but not in the bare NCs, enabling the former to be promising for application in nonlinear optoelectronic devices.