Lead-free double perovskite nanocrystals(NCs),such as Cs2AgInCl6,have attracted considerable attention as stable and non-toxic alternatives to lead-based perovskites.However,the low photoluminescence(PL)intensity of p...Lead-free double perovskite nanocrystals(NCs),such as Cs2AgInCl6,have attracted considerable attention as stable and non-toxic alternatives to lead-based perovskites.However,the low photoluminescence(PL)intensity of pristine Cs_(2)AgInCl_(6)limits its practical applications.In this study,a series of Cs_(2)AgIn_(1−γ−x)Bi_(x)La_(γ)Cl_(6)NCs were synthesized to break the parity-forbidden transition and modify the associated optical functionalities.A broadband bright warm-white emission in the visible region was achieved,with an excellent PL quantum yield of 60%.The dynamic mechanism,involving ultrafast transient absorption,suggests that high-efficiency PL is induced by triplet self-trapping exciton emission.The incorporation of La^(3+)-Bi^(3)+facilitated the singlet–triplet transition by increasing the lifetime and quickening the intersystem crossing process.This finding provides a reliable method for optimizing the optical properties of emerging lead-free halide perovskite NCs.展开更多
基金the National Key Research and Development Program of China(2017YFA0204800)the National Natural Science Foundation of China(21833009,21533010,and 21525315)+2 种基金the Scientific Instrument Developing Project of the Chinese Academy of Sciences(YJKYYQ20190003)Liaoning Revitalization Talents Program(XLYC1802126)Dalian City Foundation for Science and Technology Innovation(2019J12GX031).
文摘Lead-free double perovskite nanocrystals(NCs),such as Cs2AgInCl6,have attracted considerable attention as stable and non-toxic alternatives to lead-based perovskites.However,the low photoluminescence(PL)intensity of pristine Cs_(2)AgInCl_(6)limits its practical applications.In this study,a series of Cs_(2)AgIn_(1−γ−x)Bi_(x)La_(γ)Cl_(6)NCs were synthesized to break the parity-forbidden transition and modify the associated optical functionalities.A broadband bright warm-white emission in the visible region was achieved,with an excellent PL quantum yield of 60%.The dynamic mechanism,involving ultrafast transient absorption,suggests that high-efficiency PL is induced by triplet self-trapping exciton emission.The incorporation of La^(3+)-Bi^(3)+facilitated the singlet–triplet transition by increasing the lifetime and quickening the intersystem crossing process.This finding provides a reliable method for optimizing the optical properties of emerging lead-free halide perovskite NCs.
