radiation can lead to the overgrowth of perovskite quantum dots and the destruction of the surface structure. [7][8][9][10] Another major challenge for lead halide perovskites is the potential environmental hazard of lead element, which is not suitable for the sustainable development. Therefore, it is of great significance to explore nontoxic and stable perovskite alternatives.In lead-free perovskites, Sn (II)-based and Ge (II)-based perovskites are not satisfactory candidates for optoelectronic devices, because Sn 2+ and Ge 2+ are easily oxidized to Ge 4+ and Sn 4+ in the normal environment. [11,12] Another type of perovskite alternatives is to replace Pb with Sb or Bi, such as Cs 3 Sb 2 Br 9 and Cs 3 Bi 2 Br 9 . These perovskites have layered 2D structure, which limits their development in terms of stability and more efficient luminescence. [13][14][15] In recent years, the lead-free double perovskite structures (A 2 B″B″"X 6 ) with mixed cations (B" = B + , B″″ = B 3+ ) instead of B position has attracted extensive attention because of its high stability and low toxicity. [15][16][17][18][19] Double perovskite Cs 2 AgBiBr 6 and Cs 2 AgBiCl 6 have also been proposed. [20][21][22][23] At present, there are many kinds of cations can synthesize double perovskites. [24] In various double perovskite structures, Cs 2 AgInCl 6 has received the most attention because of its direct bandgap character, long carrier lifetimes, and easy solution processability. [25] The PLQY of Cs 2 AgInCl 6 is less than 0.1%, which is caused by parity-forbidden transitions. [26] Tang's group reported that adding Na + and a small amount of Bi 3+ ions into the Cs 2 AgInCl 6 lattice can change the symmetry of the crystal system, which can break the prohibition of parity-forbidden transitions and increase PLQY to 86%. [27] Furthermore, Xia and Yella's groups confirmed that the single-doped Bi element can improve the PLQY of Cs 2 AgInCl 6 . [28,29] Locardi et al. reported that the key to optimizing the luminescence of the Cs 2 AgInCl 6 nanocrystalline system lies in the partial substitution of Na + , resulting in an AgCl 6 energy level higher than the maximum value of valence band. Doping Bi 3+ causes the BiCl 6 energy level to be lower than the minimum value conduction band. [30] Our group found that the emission of Cs 2 AgInCl 6 can also be improved on structural adjustment by SiO 2 . Adding SiO 2 to Cs 2 AgInCl 6 changed Lead-free halide double perovskites continue to draw increasing attention in view of their nontoxicity and stability compared to lead-based perovskites. High-end full-color displays and white light illumination are based on blue-light excitation. However, the excitation of blue light of lead-free halide double perovskites Cs 2 AgInCl 6 at room temperature faces a great challenge, which is crucial to its commercial application. In this study, Cs 2 Ag 0.6 Na 0.4 In 0.8 Bi 0.2 Cl 6 /xKBr(KI), which can be excited under blue light, have been synthesized by solid-phase compression method. Under blue-light excitation, Cs 2 Ag 0.6 ...