High-performance photodetectors based on low-defect CsPb_1-xZn_xBr₃ quantum dots

All-inorganic CsPbBr₃ perovskite quantum dots (QDs) have broad applications of optoelectronics field due to their high photoluminescence quantum yield, high charge carrier mobility, and bandgap tunability. However, the combination of the abundant trap states generated by purification and the instability caused by external factors such as water, oxygen, light, and heat poses a critical hurdle for the fabrication of high-performance photodetectors. In this work, CsPb_1-xZn_xBr₃ QDs with low defect and high performance were prepared by passivating the CsPbBr₃ lattice through Zn²⁺ doping. The approach of doping not only increases the effective Goldschmidt tolerance factor and improves the tolerance of phase changes caused by purification, but also acquires QDs with lower defect density and stable cubic phase. In the self-powered mode, the CsPb_0.95Zn_0.05Br₃ QDs photodetectors have an extremely low dark current of 1.85 × 10^–12 A, an ultrahigh on/off ratio of 10⁷. Compared with CsPbBr₃ QDs photodetectors, the responsivity(R) of CsPb_0.95Zn_0.05Br₃ QDs photodetectors is increased by 200% from 0.08 A/W to 0.24 A/W, and the specific detectivity (D*) rate up to 6.19 × 10¹³ Jones which is more than an order of magnitude higher than that of the pristine photodetector.