Gradient Distributed\nand Tightly Integrated Perovskite\nHeterojunction Constructed by Electric Field-Driven Ion Deposition\nfor High-Performance X‑ray Detection

Perovskite heterojunctions combine the advantages of\ntwo different\ncomponents but suffer difficulties in the tightness of interconnection\nand limitation of material selection. Here we report an electric field-driven\nion deposition (EFID) strategy that controllably deposits perovskite\nions on heterogeneous single crystals to form a gradient heterojunction\nwith tight integration. The interconnection force of the gradient\nheterojunction by the EFID method is much better than that of the\nsolution-grown heterojunction, which is easily decomposed. An EFID-enabled\nheterojunction was constructed by depositing the 3D MAPbI<sub>3</sub> perovskite on the 2D (FPEA)<sub>2</sub>PbI<sub>4</sub> perovskite,\nexhibiting an excellent X-ray sensitivity of 2.12 × 10<sup>4</sup> μC Gy<sup>–1</sup> cm<sup>–2</sup> under an\nelectric field of 500 V mm<sup>–1</sup> and a low limit of\ndetection (LoD) less than 12.01 nGy s<sup>–1</sup>, substantially\nbetter than that of the pristine 2D or 3D counterparts. This work\nexpands the methodology for constructing perovskite heterojunctions,\noffering new perspectives for future perovskite heterojunction engineering.