Tunable Efficient White Emission in Holmium Doped Double Perovskites Cs2KInCl6 via Antimony Sensitization

Recently, ns2 metal ions (such as Bi3+ and Sb3+) doped double perovskites have captured intense attention for their efficient emission, however, achieving efficient and tunable white light emission is always an enormous challenge. Herein, Sb3+/Ho3+ co‐doped Cs2KInCl6 double perovskites are proposed, and the photoluminescence results show that there are two emission bands, one broad cyan emission band stems from self‐trapped exciton (STE) in [SbCl6]3‐ octahedron, while another red emission band derives from the f‐f transitions of Ho3+. The emission processes for Sb3+/Ho3+ co‐doped Cs2KInCl6 show that Sb3+ can act as the sensitizer to activate Ho3+ emission, which is due to the energy transfer channel from STE to Ho3+. As the Ho3+ concentration increases, the luminous color of Sb3+/Ho3+ co‐doped Cs2KInCl6 can be modulated from cyan to orange under 315 nm light irradiation, and the white emission can even be obtained with a photoluminescence quantum yield of 90 ± 2% when the energy‐transfer efficiency is 50%. Finally, single compound white‐light emitting diodes and fluorescent anti‐counterfeiting labels based on 0.5%Sb3+/60%Ho3+ co‐doped Cs2KInCl6 are fabricated. This work provides an effective strategy to achieve efficient tunable white emission in lead‐free double perovskites through ns2 metal and lanthanide ion co‐doping. A strategy based on Sb3+/Ho3+ co‐doped lead‐free Cs2KInCl6 double perovskite is developed. The effective energy transfer channel between self‐trapped exciton and Ho3+ is constructed, resulting in efficient tunable white emission with an amazing photoluminescence quantum yield of 90 ± 2%.