0D Cs₃Cu₂X₅ (X = I, Br, and Cl) Nanocrystals: Colloidal Syntheses and Optical Properties

Abstract

Abstract 0D lead‐free metal halide nanocrystals (NCs) are an emerging class of materials with intriguing optical properties. Herein, colloidal synthetic routes are presented for the production of 0D Cs 3 Cu 2 X 5 (X = I, Br, and Cl) NCs with orthorhombic structure and well‐defined morphologies. All these Cs 3 Cu 2 X 5 NCs exhibit broadband blue‐green photoluminescence (PL) emissions in the range of 445–527 nm with large Stokes shifts, which are attributed to their intrinsic self‐trapped exciton (STE) emission characteristics. The high PL quantum yield of 48.7% is obtained from Cs 3 Cu 2 Cl 5 NCs, while Cs 3 Cu 2 I 5 NCs exhibit considerable air stability over 45 days. Intriguingly, as X is changed from I to Br and Cl, Cs 3 Cu 2 X 5 NCs exhibit a continuous redshift of emission peaks, which is contrary to the blueshift in CsPbX 3 perovskite NCs.