Blue-emitting 0D Cs3ZnX5 (X = Cl, Br) perovskite nanocrystals based on self-trapped excitons.

All-inorganic Pb-free halide perovskites have recently received extensive attention due to their unique structures and optoelectronic properties. However, the realization of pure-blue emitting perovskite nanocrystals (NCs) with satisfactory stability and rational interpretation for their corresponding self-trapped excitons (STEs) emissions remains an arduous task. Herein, a modified hot-injection method is proposed to prepare a new family of zero-dimensional (0D) Cs 3 ZnX 5 (X = Cl, Br) perovskite NCs with pure-blue and sky-blue photoluminescence (PL) emissions. Benefitting from the 0D tetragonal-phase structure, the Cs 3 ZnX 5 NCs possess outstanding long-term stability in ambient air conditions. We employ the experimental results and first-principles calculations to confirm that the blue STEs emission of Cs 3 ZnX 5 NCs is dominated by the halide vacancies (V X) in [ZnX 4 ]2- tetrahedra. Our findings not only provide a simple and valid method to control the synthesis of blue-emitting 0D Zn-based perovskite NCs, but also clarify their underlying PL mechanism. • A new family of zero-dimensional Cs 3 ZnX 5 (X = Cl, Br) perovskite nanocrystals. • Perovskites with stable pure-blue and sky-blue photoluminescence emissions. • Self-trapped excitons luminescence induced by halide vacancies of perovskites. • A universal luminescence mechanism for zero-dimensional Zn-based halide perovskites. [ABSTRACT FROM AUTHOR]