Tuning Halide Composition Allows Low Dark Current Perovskite Photodetectors With High Specific Detectivity

Tuning halide composition in perovskites is a powerful approach demonstrated to enhance the performance of perovskite photovoltaic devices where such compositional modifications drive improvements in open-circuit voltage (V-oc) and a reduction in nonradiative voltage losses. Similarly, photodetectors (PDs) operate as light to current conversion devices hence it is relevant to investigate whether performance enhancements can be achieved by similar strategies. Herein, perovskite PDs are fabricated with an inverted photodiode configuration based on a MAPb(I1-xBrx)(3) perovskite (MA = methylammonium) active layer over the x = 0-0.25 composition range. Interestingly, it has been found that increasing the Br content up to 0.15 (15%) leads to a significant reduction in dark current (J(d)), with values as low as 1.3 x 10(-9) A cm(-2) being achieved alongside a specific detectivity of 8.7 x 10(12) Jones. Significantly, it has been observed an exponential relationship between the J(d) of devices and their V-oc over the 0-15% Br range. The superior performances of the 15% Br-containing devices are attributed to the reduction of trap states, a better charge extraction of photogenerated carriers, and an improvement in photoactive layer morphology and crystallinity.

Automated summary

Tuning the halide composition in perovskites has been shown to enhance the performance of perovskite photovoltaic devices. This study investigates whether similar strategies can improve the performance of perovskite photodetectors. The results show that increasing the bromide content leads to a reduction in dark current and improved detection performance. The superior performances of bromide-containing devices are attributed to reduced trap states, better charge extraction, and improved morphology and crystallinity of the photoactive layer.