Mn2+-Doped CsPbBr2I Quantum Dots Photosensitive Films for High-Performance Photodetectors

The variable bandgap and high absorption coefficient of all-inorganic halide perovskite quantum dots (QDs), particularly CsPbBr2I make them highly promising for photodetector applications. However, their high defect density and poor stability limit their performance. To overcome these problems, Mn2+-doped CsPbBr2I QDs with varying concentrations were synthesized via the one-pot method in this work. By replacing Pb2+ ions, moderate Mn2+ doping caused lattice contraction and improved crystallinity. At the same time, Mn2+-doping effectively passivated surface defects, reducing the defect density by 33%, and suppressed non-radiative recombination, thereby improving photoluminescence (PL) intensity and carrier mobility. The optimized Mn:CsPbBr2I QDs-based photodetector exhibited superior performance, with a dark current of 1.19 × 10−10 A, a photocurrent of 1.29 × 10−5 A, a responsivity (R) of 0.83 A/W, a specific detectivity (D*) of 3.91 × 1012 Jones, an on/off ratio up to 105, and the response time reduced to less than 10 ms, all outperforming undoped CsPbBr2I QDs devices. Stability tests demonstrated enhanced durability, retaining 80% of the initial photocurrent after 200 s of cycling (compared to 50% for undoped devices) and stable operation over 20 days. This work offers a workable strategy for rational doping and structural optimization in the construction of high-performance perovskite optoelectronic devices.