Metal halide perovskites offer exceptional sensitivity for direct x-ray detection through direct current (DC) signals, but their soft lattices and mobile ions lead to signal instability and nonlinear current responses under direct current (DC) bias.
A team led by LI Yunlong from the Shenzhen Institutes of Advanced Technology (SIAT) of the Chinese Academy of Sciences, together with ZHU Ziyao and XU Xiumin from Anhui University, recently proposed an alternating current (AC) bias capacitance readout approach for metal halide perovskite X-ray detectors. This method replaces the conventional DC bias with a low-amplitude AC bias and reads out the accompanying capacitance modulation, effectively reducing the influence of ion migration on signal output.
Numerical analysis of Poisson’s equation indicates that high-ionic-concentration perovskites display distinct interfacial capacitance variations between dark and irradiated conditions. Building on this understanding, the researchers designed detectors that operate under AC bias, achieving stable signal responses and avoiding performance degradation associated with ionic motion. The detector demonstrated a theoretical readout rate of 500 Hz per pixel under 1 kHz AC bias, comparable to that of commercial a-Se/TFT imaging systems while maintaining lower material and fabrication costs.
Using this capacitance readout approach, the team reconstructed three-dimensional internal structures with polycrystalline MAPbI3 detectors. The results show improved signal stability and spatial resolution and suggest a potential route toward reliable, cost-efficient perovskite-based X-ray detection and computed tomography.
