Synergistic Effect of Double Lone-Pair Electrons Cations toward Enhancing X-ray Detection Performance in Novel Oxide...

Oxide semiconductors are highly promising materials for X-ray detection applications due to their robust absorption, outstanding physicochemical stability, and excellent crystal growth habits. However, most of them exhibit poor detection performance, limiting their applications in X-ray imaging. Here, the synergistic effect of double lone-pair electrons cations is proposed to enhance X-ray detection of oxide semiconductors. These lone-pair electrons facilitate the generation of more charge carriers, enhance charge-carrier mobility, and increase the effective collection of charge carriers, resulting in excellent detection performance. High-quality Bi₂Te₂O₇ with two lone-pair electron cations (Bi³⁺ and Te⁴⁺), and Bi₂Ti₂O₇, which contains one (Bi³⁺), are grown through the flux method. As expected, the Bi₂Te₂O₇ crystal exhibits better carrier transport than the Bi₂Ti₂O₇ crystal due to the synergistic effect of double lone-pair electron cations. The Bi₂Te₂O₇ crystal detector achieves an ultrahigh sensitivity (1202 µC Gy_air ^‒1 cm^‒2) and an ultralow detection limit (2.71 nGy_air s^-1). At 200°C, its sensitivity increases to 1670 µC Gy_air ^‒1 cm^‒2. Additionally, the Bi₂Te₂O₇ array detector offers spatial resolution of 2.37 lp mm^-1 and performs well in high-temperature X-ray imaging. Our work confirms that the synergistic effect of double lone-pair electrons cations is a highly efficient strategy for enhancing X-ray detection performance.