Impact of trivalent Sb ³⁺ -ion doping on charge carrier recombination dynamics of cesium lead bromide perovskite quantum dots

Metal-ion doping of perovskites has proven to enhance their photoluminescence (PL) properties and stability; however, the underlying charge carrier dynamics remain unclear. We synthesized a cesium lead bromide (CsPbBr₃) perovskite quantum dot (PQD) incorporating a heterovalent Sb³⁺ ion dopant and its pristine counterpart and performed time-resolved single-particle PL spectroscopy. The PL intensity and lifetime of the Sb-CsPbBr₃ PQD were remarkably enhanced compared to those of the pristine-CsPbBr₃ PQD because of diminished nonradiative charge carrier recombination dynamics. The charge carrier trapping (detrapping) rate was lower (higher) for the Sb-CsPbBr₃ PQD than for the pristine-CsPbBr₃ PQD, as the Sb³⁺ doping contributed to hindering the formation of the structural defects responsible for charge carrier trap states and increasing the exciton binding energy. The replacement of Pb²⁺ with Sb³⁺, which has a smaller ionic radius, in the CsPbBr₃ structure effectively increased the tolerance factor, enabling the doped PQD to exhibit more stable local structures and, thus, suppressing its decomposition.