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 (2 2 2) 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.