Highly Photostable Mixed‐Halide Blue CsPbBr1.5Cl1.5 Perovskite Quantum Dots via Surface Treatment

Abstract Due to its excellent optical properties, perovskite materials have a wide range of application prospects in the field of optoelectronics. Nevertheless, traditional Pb‐based perovskite quantum dots (QDs), especially blue‐emission quantum dots, have attracted more attention because of their poor stability. Moreover, the poorly passivated quantum dots surfaces is highly susceptible by the external environment, so finding suitable surface ligands not only enhances the photoluminescence (PL) performance but also improves the optical stability. In this work, mixed‐halide blue CsPbBr 1.5 Cl 1.5 perovskite quantum dots are synthesized rapidly by the hot‐injection method. The SCN − (thiocyanate) also modifies the surface of QDs to enhance PL intensity. Then, the short‐chain ligand thiol can be exchanged with the traditional long‐chain ligand for improving stability. After a series of surface treatments, the morphology of the quantum dots always maintains the cubic phase and the fluorescence intensity increases by 34.8%. The photostability of the experimental sample is improved.