Codoped 2D All-Inorganic Halide Perovskite Cs₃Cd₂Cl₇:Sb³⁺:Mn²⁺ with Ultralong Afterglow

Herein, we synthesized a Sb³⁺/Mn²⁺-codoped 2D all-inorganic halide perovskite Cs₃Cd₂Cl₇:Sb³⁺:Mn²⁺ with ultralong afterglow emission at 579 nm. High-quality sheet-like single crystals are obtained by solvent evaporation and have an average crystal size of about 100 μm. We also synthesized Sb³⁺ and Mn²⁺ single-doped crystals by the same method so as to better understand the photophysical mechanism of the long afterglow phenomenon of the double-doped crystals. Through the codoping of Sb³⁺ and Mn²⁺, energy transfer occurs between the self-trapped exciton (STE) energy level of Sb³⁺ and the ⁴T₁-⁶A₁ transition of Mn²⁺, resulting in a visible afterglow of over 10 s. It is revealed that the changes in afterglow properties originate from the introduction of doping elements. And then, photoluminescence (PL) decay spectra and temperature-dependent PL spectra were tested to further illustrate the mechanism. Finally, it is proved that the codoped crystal has excellent stability and can meet various needs. All of the results demonstrate the unique afterglow properties and provide new examples for the development of all-inorganic halide afterglow materials.