Tunable Color Temperatures and Efficient White Emission from Cs Ag Na In Bi Cl Double Perovskite Nanocrystals.

Recently, Bi-doped Cs Ag Na InCl 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 Ag Na In Bi Cl 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 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 ions doping and ligand passivation, the photoluminescence quantum yield of the Cs Ag Na In Bi Cl 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.