Sb -Er -Codoped Cs NaInCl for Emitting Blue and Short-Wave Infrared Radiation.

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