Pyroelectric effect in high detectivity self-powered photodetector based on Cs2AgBiBr6

The ferroelectric perovskite material Cs2AgBiBr6 has received much attention because of its low poisonous nature and environmental stability. In this paper, we prepared high-quality Cs2AgBiBr6 thin films for self-powered photodetectors using a low-pressure-assisted method, investigated their optical, electrical, and pyroelectric properties, and characterized the film morphology and crystallization. The device modulates the photoelectric process without an external power supply, and has a maximum switching ratio of 1.72×106, a response rate of 0.158 A/W, a specific detectivity of 1.39×1011 Jones, an external quantum efficiency of 52.8%, and a fast response time of 15.4/16.8 μs when irradiated with 532 nm light, which is much better than that of previous self-powered devices with the same material on/off ratio and specific detectivity. It is worth mentioning that the pyroelectric effect was observed in the infrared band. In addition, the devices exhibited high stability to water and oxygen in an air environment (25 °C, 60% humidity), retaining more than 95% of the initial performance after one month of placement. Our study demonstrates that the lead-free perovskite Cs2AgBiBr6 is a promising and environmentally friendly alternative for the preparation of highly stable self-powered photodetectors and is also of great research value in the field of pyroelectric detection.