Modulating Charge-Carrier Dynamics in Mn-Doped All-Inorganic Halide Perovskite Quantum Dots through the Doping-Induced Deep Trap States

Abstract

Transition metal ions doping has been demonstrated effective to tune the photoluminescence properties of perovskite quantum dots (QD). However, it would inevitably introduce defects in the lattice. As the Mn concentration increases, the Mn dopant PL quantum yield (PLQY) first increases and then decreases. Herein, the influence of the dopant and the defect states on the photophysics in Mn doped CsPbCl3 QDs was studied by time-resolved spectroscopies, while the energy levels of the possible defect states were analyzed by Density Functional Theory (DFT) calculations. We reveal the formation of deep interstitials defects (Cli) by Mn2+ doping. The depopulation of initial QDs exciton states is a competition between exciton-dopant energy transfer (ET) and defect trapping at an early time-scale (< 100 ps), which determines the final PLQY of the QDs. The present work establishes a robust material optimization guideline for all the emerging applications where high PLQY is essential.