The synthesis of lead-free double perovskite Cs2Ag0.4Na0.6InCl6 phosphor with improved optical properties via ion doping

Abstract

Lead-free double perovskite (DP) phosphors with nontoxicity and excellent moisture, light, and heat stability are promising alternatives to lead halide perovskites for wide uses in optoelectronic applications. As known, their photoluminescence (PL) quantum yield (PLQY) is low in normal. Here, the optical properties of orange-emitting Cs2Ag0.4Na0.6InCl6 DP via doping Bi3+, Sm3+, or Mn2+ ions in the host lattices are proposed and remarkably enhanced. For the Bi3+-doping, the optical band gap of the Cs2Ag0.4Na0.6In1−xBixCl6 DP could be tuned from 3.82 to 2.74 eV and the optimized sample shows a markedly high PLQY of 97.33%. Sm3+-doped Cs2Ag0.4Na0.6InCl6 microcrystals (MCs) are endowed with broad emission derived from self-trapped excitons (STEs) of host. The orange-red emissions at 570, 608, and 655 nm from the transitions of 4G5/2 to 6HJ (J = 5/2, 7/2, and 9/2) of Sm3+, are demonstrated the first observation of PL from the Sm3+-doped lead-free halide DP. The Mn2+-doped Cs2Ag0.4Na0.6InCl6 MCs show dual emission peaks centered at 538 nm and 618 nm, owing to the STEs emission of Cs2Ag0.4Na0.6InCl6 host and 4T1 → 6A1 transition of Mn2+, respectively. It is interesting that the PLQY of Cs2Ag0.4Na0.6InCl6 MCs is dramatically enhanced from 21% to 41% via doping Mn2+.