Core–Shell CsPbBr₃@CdS Quantum Dots with Enhanced Stability and Photoluminescence Quantum Yields for Optoelectronic Devices

Optimizing the stability and improving photoluminescence quantum yields (PLQYs) of all-inorganic halide perovskite nanocrystals has become an urgent and challenging task to promote its application in the field of optoelectronic devices. Lead halide perovskite CsPbX3 (X = Br, I, Cl) often suffers from many serious issues, mainly from changes in the environment (thermal, chemical, light excitation). To better solve these thorny problems, two different core–shell heterostructures were proposed to protect CsPbX3, and the changes of photoluminescence (PL) characteristics under different external conditions were studied. Here, a more stable CdS with adjacent absorption bands was selected as the shell protection layer, and the CsPbBr3@CdS core–shell quantum dots (QDs) were prepared by epitaxial growth strategy. To confirm the comprehensive stability of the CsPbBr3@CdS QDs, the integrated CsPbBr3@Cs4PbBr6 core–shell nanocrystals (NCs) were taken as a reference. Interestingly, the results show that individual CsPbBr3@CdS QDs not only show excellent comprehensive (thermal, chemical, light excitation) stability compared to integrated CsPbBr3@Cs4PbBr6 but also offer improved PLQY of naked CsPbBr3 from 81 to 86% in the presence of a CdS shell. Our results will promote the further commercial development of inorganic perovskite materials in optoelectronic devices.