Pseudohalide Additives Enhanced Perovskite Photodetectors

Abstract Hybrid organic–inorganic perovskites have made considerable progress for optoelectronic applications in recent years. In particular, novel hybrid perovskites and materials combinations have been devised to overcome the materials and device stability challenges. Recently, pseudohalide salts have emerged as promising additives to enhance the long‐term stability of the photovoltaic devices. It is found that these pseudohalide ions can effectively passivate the crystal grains and hinder the degradation, which also places perovskites in a very interesting space for the consideration of reducing dark current and noise for photodetection. These possibilities provide strong incentives for a detailed study on the performance metrics of perovskite photodetectors with pseudohalide additives. In this work, photodiodes based on formamidinium lead iodide (FAPbI₃) with/without pseudohalide ions are fabricated, and the device performance both at room temperature and cooled with liquid nitrogen is evaluated. Interestingly, it is found that the photodetectors incorporated with pseudohalide ions exhibit not only better stability but also hugely improved figure of merit, including extremely low dark current of ≈10 pA, fast response of ≈50 ns, and high detectivity of >10¹² Jones. More importantly, compared with control perovskite photodetectors, the devices with pseudohalide additives demonstrate less temperature‐dependence and superior repeatability.