Remarkable luminescence regulation covering full visible wavelength range of zero-dimensional indium-based metal halides

Recently, there has been a lot of research into the use of zero-dimensional (0D) metal halides as new luminous materials. However, the wide-range tunability of luminescence properties by structural engineering need to be explored. Here, we report the vacuum solid-state reaction synthesis of a series of indium-based A3InX6 (A = K, Rb, or Cs; X = Cl, Br, or their mixture) 0D metal halide single crystals (SCs). Alkali metal substitution at A site leads to similar luminescence properties but very different stability, among which Rb3InCl6 was the most air stable. Halogen alloying at the X site of Rb3InX6 can produce a luminescence wavelength modulation from 436 to 505 nm. The luminescence wavelength was further extended by Sb3+ doping to the 509–622 nm region. Finally, due to the high luminescence tunability covering the full visible wavelength range, we achieved pure white light-emitting diodes utilizing a combination of Rb3InBr2Cl4 and Rb3InBr2Cl4:Sb3+ SCs. This work provides a strategy with simultaneous substitution, alloying, and doping to modulate the luminescence properties of 0D lead-free metal halides for a variety of applications.