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Abstract Lead halide perovskites have made remarkable progress in the field of radiation detection owing to the excellent and unique optoelectronic properties. However, the instability and the toxicity of lead‐based perovskites have greatly hindered its practical applications. Alternatively, lead‐free perovskites with high stability and environmental friendliness thus have fascinated significant research attention for direct X‐ray detection. In this review, the current research progress of X‐ray detectors based on lead‐free halide perovskites is focused. First, the synthesis methods of lead‐free perovskites including single crystals and films are discussed. In addition, the properties of these materials and the detectors, which can provide a better understanding and designing satisfactory devices are also presented. Finally, the challenge and outlook for developing high‐performance lead‐free perovskite X‐ray detectors are also provided.

Perovskite-based X-ray detector, which is widely applied in fields of scientific research and medical diagnosis, has drawn much attention for its superior optoelectrical properties. To improve the detection performance, band engineering is becoming the hot topic for perovskite properties modulation. In this article, we review the recent progress of perovskite-based X-ray detectors with band engineering process from three aspects, which are background introduction, band theory of heterojunction devices, and optimized electrode contact devices. Lastly, research status and strategies are summarized and perspectives of future progress are analyzed. We hope this review can provide constructive instructions and suggestions for future development of band engineering for perovskite-based high-performance X-ray detector.

Abstract Mixed‐dimensional (2D/3D) van der Waals (vdW) heterostructures made with complementary materials hold a lot of promise in the field of optoelectronic devices. Beyond simple mechanical stacking, directly growing the single‐crystal perovskite on 2D materials to construct a high‐quality vdW heterojunction can better promote carrier transport. In this work, a monolithic integrated graphene/perovskite heterojunction device is fabricated by directly growing a single‐crystal hybrid perovskite on monolayer graphene. Due to the strong interface coupling, the hybrid device achieves self‐powering behavior and exhibits prominent photoresponse properties with a fast response speed of up to 2.05 μs. Moreover, the responsivity and detectivity can be boosted to up to 10.41 A W−1 and 4.65 × 1012 Jones under the actuation of −3 V bias. This technique not only improves the device performance, but also provides an effective guideline for the development of next‐generation directly integrated vdW optoelectronic devices.