Controlled Epitaxial Growth of Perovskite Single-Crystal Heterojunction Arrays for Self-Powered Imaging

Perovskite single-crystal heterojunction arrays exhibit significant application potential in advanced optoelectronics, however, achieving comprehensive control over crystallographic and spatial properties of the array remains challenging. Here, we report a selective epitaxial growth strategy for fabricating single-crystal MAPbCl3/MAPbBr3 and MAPbBr3/MAPbI3 heterojunction arrays. This method employs patterned polymer templates to define the pixel dimension and arrangement, while the underlying single-crystal substrate guides the crystal orientation of the heterojunction array, enabling precise control over the pixel size, pixel arrangement angle and crystal plane. The self-powered photodetector arrays were fabricated based on these heterojunctions, showing a specific detectivity of 6.0 × 1011 Jones, a weak-light detection limit of 9 nW cm−2 and long-term operation stability under zero bias. Furthermore, the light pattern with different illumination intensities could be clearly imaged by the device array in the self-powered mode. This work establishes a robust method of fabricating the single-crystal heterojunction arrays for advanced optoelectronic applications.