Hybrid metal halide perovskites have emerged as promising materials for X-ray detection due to their scalable, cost-effective, and robust solution growth, combined with their capability to detect single gamma photons under high applied bias voltages. Despite these advantages, their practical application has been limited by rapid degradation under strong electric fields, a consequence of mixed electronic-ionic conduction, which undermines the long-term stability and efficiency of perovskite-based X-ray detectors.

To address this limitation, we previously demonstrated a photovoltaic mode of operation at zero-voltage bias, utilizing thick methylammonium lead iodide (MAPbI₃) single-crystal films (up to 300 µm) grown directly on hole-transporting electrodes through the space-confined inverse temperature crystallization (ITC) method [1]. These devices exhibited near-ideal performance, long-term operational stability, 88% detection efficiency, and a noise equivalent dose of 90 pGyair with 18 keV X-rays. However, we observed that the performance of MAPbI₃ devices deteriorates significantly when the crystal thickness exceeds 200 µm, presenting a challenge for applications that require thicker absorbers to achieve higher detection sensitivity.

Building upon this foundation, we now present [2] advances in compositional engineering that enable nearly 100% charge extraction in perovskite single crystals with thicknesses reaching up to 0.92 mm. These high-quality crystals exhibit significantly prolonged charge carrier lifetimes, enabling efficient X-ray absorption and complete charge collection for both 18 keV and 45 keV photons while maintaining excellent material stability. Remarkably, these devices operate without any external bias, representing a breakthrough in direct X-ray detection technology. In contrast to conventional semiconductor X-ray detectors, which typically require hundreds of volts to establish strong electric fields for efficient charge collection, our perovskite detectors achieve unity charge extraction under zero-bias conditions. This achievement sets a new benchmark, combining high performance, operational simplicity, and enhanced stability.

In conclusion, this study introduces a novel approach to perovskite-based X-ray detectors by integrating compositional engineering with advanced solution growth techniques. The resulting devices exhibit superior charge collection efficiency, extended carrier lifetimes, and robust long-term stability, opening new pathways for cost-effective, high-performance X-ray imaging technologies with simplified device architectures.

[1] Sakhatskyi, K.† Turedi, B.†, Bakr, O. M, Kovalenko, M. V. et al. Nature Photonics 2023, 17(6), 510-517.

†equal first-authors

[2] unpublished