Enhanced photoluminescence quantum yield and stability of CsPbBr3 perovskite nanocrystals by post-synthetic treatment with tin (II) bromide

Surface vacancies are commonly formed during the synthesis and purification of perovskite nanocrystals (NCs), which usually lower the photoluminescence quantum yield (PLQY) and stability. In this study, we demonstrate a facile post-synthetic treatment with SnBr2 to passivate the existing Pb2+ and Br vacancies on the surface of CsPbBr3 NCs. The PLQY of passivated NCs in the solution increases from 73% to 94%, and the average fluorescence lifetime of CsPbBr3 NC film is prolonged from 7.77 to 9.78 ns, indicating a higher degree of radiative recombination of electron-hole pairs. The CsPbBr3 NCs treated by SnBr2 present higher stability with 82% of the original PLQY after two weeks of storage in ambient atmosphere, while the PLQY of untreated NCs drastically drops to 58%. Furthermore, the maximum current efficiency of the light-emitting diode based on the modified CsPbBr3 NCs is enhanced by a factor of 2.5. It is believed that the proposed post-synthetic treatment method is promising in enhancing the PLQY and stability of perovskite NCs, as well as promoting the efficiency of the electroluminescent device.