Supple Formamidinium-Based Low-Dimension Perovskite Derivative for Sensitive and Ultrastable X-ray Detection

Halide perovskite materials possess excellent optoelectronic properties and have shown great potential for direct X-ray detection. Perovskite wafers are particularly attractive among various detection structures due to their scalability and ease of preparation, making them the most promising candidates for X-ray detection and array imaging applications. However, device instability and current drift caused by ionic migration are persistent challenges for perovskite detectors, especially in polycrystalline wafers with numerous grain boundaries. In this study, we examined the potential of one-dimensional (1D) δ-phase (yellow phase) formamidinium lead iodide (δ-FAPbI₃) as an X-ray detection material. This material possesses a suitable band gap of 2.43 eV, which makes it highly promising for X-ray detection and imaging using compact wafers. Moreover, we found that δ-FAPbI₃ has low ionic migration, low Young's modulus, and excellent long-term stability, making it an ideal candidate for high-performance X-ray detection. Notably, the yellow phase perovskite derivative exhibits exceptional long-term atmospheric stability (RH of ≈70 ± 5%) over six months, as well as an extremely low dark current drift (3.43 × 10^-4 pA cm^-1 s^-1 V^-1), which is comparable to that of single-crystal devices. An X-ray imager with a large-size δ-FAPbI₃ wafer integrated on a thin film transistor (TFT) backplane was further fabricated. Direct 2D multipixel radiographic imaging was successfully performed, demonstrating the feasibility of δ-FAPbI₃ wafer detectors for sensitive and ultrastable imaging applications.