Broadband and warm white emission in Cs2In1−xCl5·H2O:xAg+ phosphors enabled by H3PO2-mediated stabilization

Abstract

The quest for lead-free materials capable of emitting white light has been a focal point in the realm of luminescent materials due to their potential applications in lighting and display technologies. This study presents a novel approach to achieving broadband white-light emission through the doping of Ag⁺ in the zero-dimensional (0D) lead-free inorganic metal halide Cs₂InCl₅·H₂O (CICH), and the strategic addition of H₃PO₂ (HPA) to facilitate the substitution of Ag⁺ for In³⁺. The PL spectra revealed that the emission intensity and the corresponding lifetime of the Ag⁺-doped CICH samples increased with Ag⁺ concentration, reaching a maximum at 7% Ag⁺ doping. This enhancement is attributed to the suppression of non-radiative recombination and the enhancement of self-trapped exciton (STE) emission, which is a direct result of the structural deformation induced by Ag⁺ substitution for In³⁺. The large Stokes shift of 255 nm and the long luminescence lifetime of 20.56 μs observed in the optimized sample S7-CICH:Ag⁺ underscore the high quality of the STE emission. The significance of this research lies in the development of a new class of lead-free luminescent materials that combine high efficiency, broad emission, and thermal stability.