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 5s(2)-> 5s(1)5p(1) electronic absorption at the sub-band gap level, which then emits blue photoluminescence with approximate to 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.