Pressure Effect on Luminescence Characteristics and Energy Transfer in CsPbBr3/ZnS Nanocrystal Heterostructures

All-inorganic perovskite CsPbX3 (X = Cl, Br, or I) and related materials have shown great potential for applications in solar cells, light-emitting diodes, and photodetectors. A kind of heterostructure was proposed comprising CsPbBr3/ZnS nanocrystals in order to enhance the luminescence properties of CsPbBr3 nanocrystals. The incorporation of ZnS induces recombination at the interface, facilitating charge transfer and the formation of a type-II heterostructure. The luminescence characteristics of this heterostructure can be modulated by applying pressure. The photoluminescence intensity of the CsPbBr3/ZnS nanocrystals is significantly enhanced up to 0.29 GPa. With further pressure increase, these nanocrystals exhibit a red shift in emission wavelength, resulting in a high sensitivity (dλ/dP) of 9.59 nm GPa–1 and an absolute sensitivity (dFWHM/dP) of 6.07 nm GPa–1. Photoluminescence quenching occurs until the completely undetectable emission at a pressure of 2.38 GPa. The observed anomalous enhancement and wavelength red shift indicate that pressure can promote the transition from free excitons to self-trapping excitons, leading to energy transfer between ZnS and CsPbBr3. This study enhances the understanding effect of high pressure on luminescent materials in heterostructures.