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 ability to detect single gamma-photons under high applied bias voltages. Despite these advantages, their rapid degradation under high electric fields, a result of mixed electronic-ionic conduction, has hindered the development of stable and efficient perovskite-based X-ray detectors.

To address this limitation, we previously demonstrated a photovoltaic mode of operation at zero-voltage bias, using thick methylammonium lead iodide (MAPbI₃) single-crystal films (up to 300 µm) grown directly on hole-transporting electrodes via the space-confined inverse temperature crystallization (ITC) method [1].  These devices exhibited near-to-ideal performance, long-term stability, 88% detection efficiency, and a noise equivalent dose of 90 pGyair with 18 keV X-rays. However, we observed experimentally that the performance of MAPbI₃ devices degrades significantly beyond thicknesses of 200 µm, presenting a challenge for their application in scenarios requiring thicker crystals for higher sensitivity.

Building upon this foundation, we now present [2] advances in compositional engineering that enable up to 100% charge extraction in perovskite single crystals with thicknesses reaching 900 µm. These high-quality crystals exhibit extended charge carrier lifetimes, enabling efficient absorption of X-rays at energies of both 18 keV and 45 keV and complete charge collection. This marks a significant step forward in perovskite detector technology, as the thicker crystals allow for higher detection sensitivity while maintaining excellent material stability. Uniquely, these devices operate with no external bias, a breakthrough in X-ray detection technology. Unlike other semiconductor direct X-ray detectors, which require extremely high electric fields generated by hundreds of volts to achieve efficient charge collection, our perovskite detectors achieve 100% charge extraction under zero-voltage bias. This sets a new standard for X-ray detectors, combining superior performance with simplicity in operation.

In conclusion, this study introduces a novel approach to perovskite X-ray detectors by combining compositional engineering with advanced solution growth techniques. This results in devices with enhanced charge extraction efficiency, superior carrier lifetimes, and robust long-term stability, paving the way for cost-effective, high-performance X-ray imaging technologies.

[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