Elucidating Insights on La3+ Doping on Distorted Double-Perovskite Cs2Ag0.5K0.5InCl6 by Structural, Optical, and Theoretical Investigations

The fluorescence properties of the double perovskites (DPs) can be tuned by creating luminescent-active centers in the host material or distorting the perovskite structure by incorporating external atoms or creating defect states. Incorporation of K+ ions into DPs induces short-range structural disorder and multiphase formation. Further, La3+ doping on a distorted DP (Cs2Ag0.5K0.5InCl6) helps to enhance and tune the emission spectrum. A rare-earth ion such as La3+ is spectroscopically innocent, but it can reduce the energy of the whole system by decreasing the width of the conduction band from the hybrid effect of La 6s. In this study, the structural and electronic properties of La3+-doped distorted DP systems were investigated using theoretical calculations and optical characterization techniques. XRD and Raman studies confirm the distorted DP structure; from the photoluminescence measurements, it is clear that the introduction of La into the distorted DPs is giving a very broad emission, i.e., FWHM increased from 148 to 193 nm with a PLQY of 19.93%. These fully inorganic La3+-doped distorted DP compounds can be demonstrated as a bright emissive material for stable lighting applications.