Stereochemically Active Lone-Pair Electrons Driven High-Performance and Self-Powered X-Ray Detection in Cs₂TeMo₃O₁₂...

X-ray detection is crucial for medical imaging and industrial non-destructive testing. However, conventional materials face limitations such as low absorption efficiency, high dark current, and the necessity for external power bias. This study presents a novel inorganic polar oxide crystal, Cs₂TeMo₃O₁₂, as a high-performance direct-conversion X-ray detector material, particularly for self-powered applications. The stereochemically active lone-pair electrons of Te⁴⁺ induce a non-centrosymmetric polar structure, which generates a built-in electric field that enables efficient charge carrier separation under zero bias. Along the polar Z-direction, the crystal exhibits a high resistivity of 5.08 × 10¹⁴ Ω cm, a considerable mobility-lifetime product of 1.08 × 10^‒3 cm² V^‒1, and an excellent sensitivity of 436 µC Gy_air ^‒1 cm^‒2 under a 2000 V cm^-1 electric field. Most notably, the device operates effectively in a self-powered mode, achieving a sensitivity of 178 µC Gy_air ^‒1 cm^‒2 and an ultralow detection limit of 10.5 nGy_air s^‒1. Furthermore, it demonstrates exceptional operational stability with negligible dark current drift. This work not only introduces Cs₂TeMo₃O₁₂ as an exceptional candidate for low-dose and self-powered X-ray detection but also provides a novel design strategy leveraging lone-pair electrons for developing advanced photoelectric materials.