Stable and\nBright CsPbX₃ Nanocrystals in\nMetal–Organic Frameworks for White Light-Emitting Diodes

Abstract

The stability of metal halide perovskite (CsPbX₃, X\n= Cl, Br, and I) nanocrystals (NCs) is crucial for their practical\napplications. In this paper, perovskite NCs were synthesized in situ\nin lead-based metal–organic frameworks (Pb-MOFs: [Pb₂(1,3,5-HBTC)₂(H₂O)₄]·H₂O), and we obtained stable and bright luminescence composites\nwith different colors. Namely, CsPbBr₃@Pb-MOF composites\nwere created by the in situ growth of CsPbBr₃ crystals\n(NCs) on Pb-MOF, which had high ion resistance, bright photoluminescence\n(PL), and excellent stability. The composites still had bright luminescence\nafter 11 months of storage. The PL intensity of green-emitting CsPbBr₃@Pb-MOF composites was increased compared with as-prepared\nCsPbBr₃ NCs. Bright and stable blue- and red-emitting CsPbX₃@Pb-MOF composites were obtained by adjusting the amount of\nPbX₂ (X = Cl, Br, and I) in the synthesis process. These\nCsPbX₃ NCs were homogeneously distributed in Pb-MOF substrates.\nThe growth of CsPbX₃ NCs in Pb-MOFs prevented NC aggregation\nand decreased surface defects against nonradiative recombination during\nemitting. Thus, the PL lifetime and stability were improved. Furthermore,\nwhite light-emission diodes were prepared using three color CsPbX₃@Pb-MOF composites with Commission Internationale de I’Eclairage\ncolor coordinates of (0.296, 0.316). This result provided an efficient\nway to overcome the limitation of chemical solution synthesis and\nimprove the stability of CsPbX₃ NCs.