Codoped 2D All-Inorganic Halide Perovskite Cs₃Cd₂Cl₇:Sb³⁺:Mn^{2+ with Ultralong Afterglow}

Herein, we synthesized a Sb3+/Mn2+-codoped2D all-inorganic halide perovskite Cs3Cd2Cl7:Sb3+:Mn2+ with ultralong afterglowemission at 579 nm. High-quality sheet-like single crystals are obtainedby solvent evaporation and have an average crystal size of about 100 & mu;m. We also synthesized Sb3+ and Mn2+ single-dopedcrystals by the same method so as to better understand the photophysicalmechanism of the long afterglow phenomenon of the double-doped crystals.Through the codoping of Sb3+ and Mn2+, energytransfer occurs between the self-trapped exciton (STE) energy levelof Sb3+ and the T-4(1)-(6)A(1) transition of Mn2+, resulting in a visibleafterglow of over 10 s. It is revealed that the changes in afterglowproperties originate from the introduction of doping elements. Andthen, photoluminescence (PL) decay spectra and temperature-dependentPL spectra were tested to further illustrate the mechanism. Finally,it is proved that the codoped crystal has excellent stability andcan meet various needs. All of the results demonstrate the uniqueafterglow properties and provide new examples for the developmentof all-inorganic halide afterglow materials. We successfully developed a novel 2D-codopedCd-(II)-basedmetal halide long afterglow materials. The single crystal of Cs3Cd2Cl7:Sb3+:Mn2+ features a special Ruddlesden-Popper (R-P) structure.It exhibits a bright orange-red light emission peak at 579 nm witha long afterglow of up to 10 s, which is attributed to the fact thatenergy transfer occurs between the self-trapped exciton energy levelof Sb3+ and the T-4(1)-(6)A(1) of Mn2+. It is proved that the long afterglowemission of all-inorganic metal halides can be achieved by codoping.