Exploring optimal in situ fabrication conditions to realize core-shell CsPbBr3 QDs with high PLQYs and structural stability by dual-defect passivation

Abstract

Core-shell CsPbBr3 QDs (core-shell M-CsPbBr3 QDs) with high structural stability and excellent optical properties were developed through dual-defect passivation, with simultaneous application of in situ thiol ligand passivation and a core-shell structure using SiO2 as a shell. When MPTES was injected immediately before Cs-oleate injection, the formation of by-products (PbS and trigonal-Cs4PbBr6 nanocrystals) was suppressed/minimized and effective surface defect passivation was achieved, resulting in defect-less core-shell M-CsPbBr3 QDs. The thiol group of MPTES effectively passivated uncoordinated Pb2+ defects, while the SiO2 shell formed by the hydrolysis reaction of three silyl ethers inhibited the formation of defects (vacancies) by preventing the penetration of moisture. The core-shell M-CsPbBr3 QDs exhibited a PLQY of similar to 82.9 +/- 3.8%, much higher than that of pristine CsPbBr3 QDs (similar to 65.3 +/- 3.8%). Furthermore, they also showed more than 5 times higher structural stability in DI water compared to pristine CsPbBr3 QDs. These results demonstrated that the synergistic effect of surface passivation with the thiol group and the core-shell structure can significantly improve the PLQYs and structural stability of CsPbBr3 QDs.