Tunable Color Temperatures and Efficient White Emission from Cs2Ag1−xNaxIn1−yBiyCl6 Double Perovskite Nanocrystals

Recently, Bi-doped Cs 2 Ag 0.6 Na 0.4 InCl 6 lead-free double perovskites demonstrating efficient warm-white emission have been reported. To enable the solution processing and enrich the application fields of this promising material, here a colloidal synthesis of Cs 2 Ag 1− x Na x In 1− y Bi y Cl 6 nanocrystals is further developed. Different from its bulk states, the emission color temperatures of the nanocrystal can be tuned from 9759.7 to 4429.2 K by Na + and Bi 3+ incorporation. Furthermore, the newly developed nanocrystals can break the wavefunction symmetry of the self-trapped excitons by partial replacement of Ag + ions with Na + ions and consequently allow radiative recombination. Assisted with Bi 3+ ions doping and ligand passivation, the photoluminescence quantum yield of the Cs 2 Ag 0.17 Na 0.83 In 0.88 Bi 0.12 Cl 6 nanocrystals is further promoted to 64%, which is the highest value for lead-free perovskite nanocrystals at present. The new colloidal nanocrystals with tunable color temperature and efficient photoluminescence are expected to greatly advance the research progress of lead-free perovskites in single-emitter-based white emitting materials and devices.