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

• Synthesis of ions doped lead-free perovskites Cs 2 Ag 0.4 Na 0.6 InCl 6 microcrystals with a simpler precipitation approach. • Bi 3+ -doped Cs 2 Ag 0.4 Na 0.6 InCl 6 MCs show a significant improvement of PLQY from 21.22% to 97.33%. • The optical property of Sm 3+ -doped Cs 2 Ag 0.4 Na 0.6 InCl 6 MCs has been first studied. • The Mn 2+ -doped Cs 2 Ag 0.4 Na 0.6 InCl 6 MCs show dual-emission with an increasing PLQY from 21% to 41%. 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 Cs 2 Ag 0.4 Na 0.6 InCl 6 DP via doping Bi 3+ , Sm 3+ , or Mn 2+ ions in the host lattices are proposed and remarkably enhanced. For the Bi 3+ -doping, the optical band gap of the Cs 2 Ag 0.4 Na 0.6 In 1−x Bi x Cl 6 DP could be tuned from 3.82 to 2.74 eV and the optimized sample shows a markedly high PLQY of 97.33%. Sm 3+ -doped Cs 2 Ag 0.4 Na 0.6 InCl 6 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 4 G 5/2 to 6 H J ( J = 5/2, 7/2, and 9/2) of Sm 3+ , are demonstrated the first observation of PL from the Sm 3+ -doped lead-free halide DP. The Mn 2+ -doped Cs 2 Ag 0.4 Na 0.6 InCl 6 MCs show dual emission peaks centered at 538 nm and 618 nm, owing to the STEs emission of Cs 2 Ag 0.4 Na 0.6 InCl 6 host and 4 T 1 → 6 A 1 transition of Mn 2+ , respectively. It is interesting that the PLQY of Cs 2 Ag 0.4 Na 0.6 InCl 6 MCs is dramatically enhanced from 21% to 41% via doping Mn 2+ .