Oriented preparation of Large-Area uniform Cs₂TeI₆ perovskite film for high performance X-ray detector

Large-area flexible perovskite films are attracting widespread research interest for applications in wearable solar cells, portable photodetectors, bendable X-ray imaging detectors and other implantable optoelectronic devices. In this work, a facile mobile platform assisted electrospray method is developed to prepare large-area (100 cm²) lead-free Cs₂TeI₆ film on flexible polyimide substrate. The spraying parameters are coupled with the growth temperature to achieve a dynamic balance. The as-prepared film by optimized process shows high uniformity in grain size, thickness and X-ray response without pinholes and cracks. Moreover, oriented nucleation is more likely to occur on the flexible organic substrates for less growth stress and mismatch stress, leading to preferred (222) plane orientation. X-ray detectors prepared with the films exhibit a resistivity of 1.9 × 10¹¹ Ω·cm, an X-ray sensitivity of 226.8 μC⋅Gy_air^-1⋅cm^-2 and a transient response rise time as fast as 42 ms under 50 kV X-ray at an electrical field of 6.67 × 10³ V·mm^-1. The modified electrospray method shows great potential applications for large-area devices of radiography, solar cell and other optoelectronic devices.