Bright and Stable Zero-Dimensional Hexagonal Organic–Inorganic Tin Iodide Perovskites for High Color Rendering Index White Light-Emitting Diodes

Lead-free tin halide perovskites are promising environmentally friendly alternatives to the heavy metal lead-based counterparts for light-emitting diode (LED) applications. However, their poor stability and low photoluminescence quantum yields (PLQYs) pose major challenges to their practical applications. In this work, we report a new zero-dimensional (0D) hexagonal organic–inorganic hybrid tin halide perovskite, synthesized via a one-step antisolvent diffusion method. The optimized material exhibits outstanding solid-state emission with a PLQY exceeding 80% in the orange-red spectral region, along with enhanced stability compared to conventional 3D and 2D tin halide perovskites. Comprehensive structural, optical, and photophysical characterizations, combined with theoretical calculations, reveal that the enhanced emission arises from self-trapped excitons. By exploiting its broad and intense emission, we demonstrate UV-pumped white LEDs with tunable color coordinates. Most notably, our WLED devices achieve a high color rendering index of 94─positioning this material as a viable solution for high-precision lighting applications.