Efficient Self-Trapped Exciton Emission in Ruddlesden-Popper Sb-Doped Cs3Cd2Cl7 Perovskites

Metal halide perovskites (MHPs) have attracted extensive attention due to their excellent optoelectronic properties. Among them, layered two-dimensional (2D) metal halide materials with special structures have attracted extensive attention due to their superior stability and optoelectronic properties. Here, we report the 2D Ruddlesden-Popper (RP) phase Cs3Cd2Cl7 synthesized by a solvothermal method, and the photoluminescence quantum yields (PLQYs) of the pristine Cs3Cd2Cl7 sample (PLQY ~ 10%) can be increased to 68 +/- 5% through appropriate Sb(3+ )doping. This should be the highest PLQY of all reported all doping. highest inorganic RP-phase Cd-based perovskites so far. Our results indicate that the highly efficient cyan emission can be attributed to the common self-trapped exciton (STE) emission of the triplet states of Cd2+ and Sb3+ induced by strong electron-phonon coupling, and Sb3+:Cs3Cd2Cl7 has excellent structural and spectral stability. This new material should be a promising candidate for optoelectronic applications in the future.