Synthesis and characterization of Cu–doped Cs2KBiBr6 double perovskite phosphors for photoluminescent applications

In the present study, we report on the synthesis and photo-luminescent applications of hexagonal double perovskite Cs2BIBiBr6 (where BI = K, Li) doped with Cu 2+ ions. Powder XRD patterns were used to confirm the formation of single-phase compounds. Near-UV light was significantly assimilated by localized excitations focused on Bi 3+ ions in the host lattice. Only very faint photoluminescence was detected in the undoped host lattice, while energy transfer from Bi 3+ to Cu 2+ causes immense green photoluminescence in copper-doped materials. A photoluminescence emission peak was obtained at 415 nm for Cs2KBiBr6. PL peaks were gradually red-shifted to higher wavelengths of 417 nm and 419 nm for Cu-doped Cs2 Li0.5K0.5BiBr4Cl2 and Cu-doped Cs2KBiBr4Cl2, respectively. Their capacity to modify a phosphor system's excitation and emission spectrum has enhanced these novel classes of material.