Eu^(3+)-Bi^(3+)Codoping Double Perovskites for Single-Component White-Light-Emitting Diodes

Double perovskites(DPs)with Cs_(2)AgInCl_(6) composition,as one of the lead-free perovskites,have been in the spotlight owing to their intriguing optical properties,namely,self-trapped exciton(STE)emission and dopant-induced photoluminescence.However,the current DPs still face the challenge of low photoluminescence efficiency and cannot be applied in practice.Herein,we synthesize the Bi^(3+)and Eu^(3+)codoped Cs_(2)AgInCl_(6) DPs,which displays enhanced STE and Eu^(3+)ions characteristic emissions.Our results indicate that the Eu^(3+)ions mainly substitute the In sites and can increase the radiative recombination rate and exciton binding energy of STEs,which is discovered that Eu^(3+)ions can promote the localization of STEs by breaking the inversion symmetry of the Cs_(2)AgInCl_(6) lattice.The existence of Bi^(3+)ions decreases the excitation(absorption)energy,provides a new absorption channel,and increases the energy transfer rate to Eu^(3+)ions.Through adjusting the Bi^(3+)and Eu^(3+)concentrations,a maximum photoluminescence quantum yield of 80.1%is obtained in 6%Eu^(3+)and 0.5%Bi^(3+)codoped Cs_(2)AgInCl_(6) DPs.Finally,the high-quality single-component white-light-emitting diodes based on Bi^(3+)and Eu^(3+)codoped Cs_(2)AgInCl_(6) DPs and a 410-nm commercial ultraviolet chip are fabricated with the optimum color rendering index of 89,the optimal luminous efficiency of 88.1 lm/W,and a half-lifetime of 1,493 h.This work puts forward an effective lanthanide and transition metals codoping strategy to design single-component white-light emitter,taking a big step forward for the application lead-free DPs.