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, CI) 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.