Sb 3+ -Er 3+ -Codoped Cs 2 NaInCl 6 for Emitting Blue and Short-Wave Infrared Radiation.

Cs 2 NaInCl 6 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 Cs 2 NaInCl 6 by codoping Sb 3+ (s-electron doping) and Er 3+ (f-electron doping) ions. Sb 3+ doping introduces optically allowed 5s 2 → 5s 1 5p 1 electronic absorption at the sub-band gap level, which then emits blue photoluminescence with ≈93 % quantum yield. But f-f electronic absorption of Er 3+ is parity forbidden. Codoping Sb 3+ -Er 3+ , leads to transfer of excitation energy from Sb 3+ to Er 3+ , 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.