Compact ultrabroadband light-emitting diodes based on lanthanide-doped lead-free double perovskites Abstract Impurity doping is an effective approach to tuning the optoelectronic performance of host materials by imparting extrinsic electronic channels. Herein, a family of lanthanide (Ln 3+ ) ions was successfully incorporated into a Bi:Cs 2 AgInCl 6 lead-free double-perovskite (DP) semiconductor, expanding the spectral range from visible (Vis) to near-infrared (NIR) and improving the photolumin...