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

Abstract Recently, ns 2 metal ions (such as Bi 3+ and Sb 3+ ) 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, Sb 3+ /Ho 3+ co‐doped Cs 2 KInCl 6 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 [SbCl 6 ] 3‐ octahedron, while another red emission band derives from the f‐f transitions of Ho 3+ . The emission processes for Sb 3+ /Ho 3+ co‐doped Cs 2 KInCl 6 show that Sb 3+ can act as the sensitizer to activate Ho 3+ emission, which is due to the energy transfer channel from STE to Ho 3+ . As the Ho 3+ concentration increases, the luminous color of Sb 3+ /Ho 3+ co‐doped Cs 2 KInCl 6 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%Sb 3+ /60%Ho 3+ co‐doped Cs 2 KInCl 6 are fabricated. This work provides an effective strategy to achieve efficient tunable white emission in lead‐free double perovskites through ns 2 metal and lanthanide ion co‐doping.