Optimizing optical properties of hybrid core/shell perovskite nanocrystals

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 (MAPbBr(3)) NC that is heteroepitaxially grown with an MA(1-x)Cs(x)PbBr(3) shell, with the aim to optimize the optical properties of the former. It is found that the MAPbBr(3)/MA(1-x)Cs(x)PbBr(3) 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 MAPbBr(3) 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.