Sb3+–Er3+‐Codoped Cs2NaInCl6 for Emitting Blue and Short‐Wave Infrared Radiation

Cs2NaInCl6 double perovskite is stable, environmentally benign and easy to prepare. But it has a wide band gap (5.1 eV), and therefore, does not show optical and optoelectronic properties in the visible and short‐wave infrared (SWIR) region. Here we introduce such functionalities in Cs2NaInCl6 by codoping Sb3+ (s‐electron doping) and Er3+ (f‐electron doping) ions. Sb3+ doping introduces optically allowed 5s2→ 5s15p1 electronic absorption at the sub‐band gap level, which then emits blue photoluminescence with ≈93 % quantum yield. But f‐f electronic absorption of Er3+ is parity forbidden. Codoping Sb3+–Er3+, leads to transfer of excitation energy from Sb3+ to Er3+, yielding SWIR emission at 1540 nm. Temperature (6 to 300 K) dependent photoluminescence measurements elucidate the excitation and emission mechanism. A phosphor converted light emitting diode (pc‐LED) fabricated by using the codoped sample emits stable blue and SWIR radiation over prolonged (84 hours) operation at 5.1 V. Cs2NaInCl6 double perovskite was codoped with Sb3+ (s‐electron) and Er3+ (f‐electrons). Sb3+ provides sub‐band gap (s to p) optical excitation, which de‐excites via both emitting intense blue light and non‐radiatively exciting f‐electrons of Er3+. Then Er3+ emits 1540 nm short‐wave infrared (SWIR) radiation. Phosphor converted light emitting diode (pc‐LED) show stable performance under ambient conditions.