One-Dimensional orthorhombic CsPbI₃ polycrystalline thick film for efficient and highly stable direct X-ray detection and imaging

An ideal direct X-ray detector should convert a low dose of X-ray photons into large quantity of electrical signals, coupled with sustained long-term stability. Nevertheless, a notable conflict arises between X-ray absorption efficiency and carrier transport in thick polycrystalline perovskite films. Moreover, conventional perovskite materials exhibit inherent challenges regarding the stability of their crystal phase and the consistency of the photocurrent. To circumvent these limitations, a polycrystalline perovskite thick film is proposed using orthorhombic CsPbI₃ (δ-CsPbI₃) as a highly stable active material. Combined with the liquid epitaxy process, δ-CsPbI₃ prefers one-dimensional growth along the carrier transportation direction, which suppresses the formation of grain boundaries, enabling high carrier mobility while maintaining X-ray absorption for a thick polycrystalline film. Consequently, the polycrystalline δ-CsPbI₃ based detector exhibits a highest sensitivity of 1768.46 μC Gy_air^-1 cm⁻² at an electric field of 432 V mm⁻¹ which is 88.42-fold higher than α-Se based detectors and 190-fold higher than the single crystalline δ-CsPbI₃ based detector, respectively. The sensitivity maintains 91.34 % of its initial state after 7 days exposure in the air. Combing with a thin-film transistor array, the detector achieves 8-bit imaging within a 64 × 64 matrix. This work provides a feasible method for commercialized production of high-performance direct X-ray detectors.