Highly stable Se-doped CsSnCl perovskite: self-trapped dual-emission from a single component enabling tunable white light-emitting diodes.

Commercial tunable white light-emitting diodes (WLEDs) fabricated through multi-component mixing encounter high costs, complex control systems, and color-shift issues. Therefore, developing innovative single-component tunable luminescent materials is expected to overcome these limitations. In recent years, the vacancy-ordered perovskite CsSnCl has attracted considerable research interest in the luminescence field due to its lead-free composition, notable chemical stability, inherent self-trapped excitons (STEs) emission behavior, and modifiable optical characteristics. In this work, Se-doped CsSnCl microcrystals were prepared via a one-step solvothermal method. The doping of Se can introduce a new luminescence center featuring a yellow emission band compared with the single blue emission of the pristine CsSnCl. Based on the experimental findings and the density functional theory (DFT) calculations, the blue and yellow emissions stem from the STEs luminescence caused by the excitons within the [SnCl] and [SeCl] octahedral lattices, respectively. Notably, the tunable white light can be achieved by adjusting the excitation wavelength and precisely controlling the relative intensities of blue and yellow emissions. Furthermore, the Se-doped CsSnCl microcrystals exhibit excellent structural and luminescent stability, demonstrating their remarkable capacity to withstand harsh environments, including immersion in water and exposure to high temperatures. Importantly, the single-component tunable WLEDs ranging from cool white to warm white were fabricated by combining 3 % Se-doped CsSnCl with NUV chips. Overall, this study provides novel perspectives on the dual emission of single-ion doped lead-free perovskites. It also presents a new route to achieving stable and tunable white light, effectively surmounts multi-component WLEDs limitations, and holds promise for high-end lighting and display applications.