High-Stability Flexible X-ray Detectors Based on Lead-Free Halide Perovskite Cs₂TeI₆ Films

Abstract

Normal flat panel X-ray detectors are confined in imaging of curved surfaces and three-dimensional objects. Except that, their rigid panels provide uncomfortable user experience in medical diagnosis. Here, we report a flexible X-ray detector fabricated by the combination of a lead-free Cs₂TeI₆ perovskite film and a polyimide (PI) substrate. High-quality Cs₂TeI₆ polycrystalline films are prepared by a low-temperature electrospraying method. The resistivity even remained at the level of 10¹¹ Ω·cm after 100 cycles of bending tests with a low bending radius of 10 mm. The resulting flexible Cs₂TeI₆ detectors exhibit better response stability than those based on rigid SnO₂:F glass (FTO), which is attributed to the superior crystallization of films and the growth stress relief of flexible substrates. Furthermore, an X-ray sensitivity of 76.27 μC·Gy_air^-1·cm^-2 and a detection limit of 0.17 μGy_air·s^-1 are achieved. A series of distortion-free clear X-ray images are obtained for objects with different materials and densities. These findings provide insights into flexible X-ray detectors based on perovskite films and motivate research in wearable X-ray detectors for medical radiography and dose monitoring.