Investigating the transformation of CsPbBr₃ nanocrystals into highly stable CsPbBr₃/Cs₄PbBr₆ nanocrystals using ethyl acetate in a microchannel reactor

Abstract

The nanocrystals (NCs) of inorganic perovskites CsPbX₃ and Cs₄PbX₆ (X = Cl, Br, I) are showing a great development potential due to their versatility of crystal structure. Here, we used a microchannel reactor to synthesize both CsPbBr₃ NCs (CsPbBr₃ NCs) and Cs₄PbBr₆ NCs with embedded CsPbBr₃ (CsPbBr₃/Cs₄PbBr₆ NCs). Via speed control of the precursor, ligands around the surface of NCs were effectively regulated by ethyl acetate, allowing the transformation from CsPbBr₃ NCs to CsPbBr₃/Cs₄PbBr₆ NCs in a short time, an outstanding stability of NCs, and a better crosslinking between NCs and polymer for the application of LEDs. Without any protection, the CsPbBr₃/Cs₄PbBr₆ NCs, with a production rate of 28 mg min^-1, retain more than 90% of the PL intensity after 84 d. Finally, the CsPbBr₃/Cs₄PbBr₆ NCs were used to produce an LED device, and a wide color gamut of 122.8% NTSC or 91.7% Rec 2020 was attained.