Direct photopatterning of perovskite nanocrystal films for building pixelated photodetector arrays

Metal halide-based perovskites, with their exceptional photoelectric conversion efficiency, are promising materials for photodetectors and image sensors. Achieving high-definition optical imaging requires not only high-quality perovskite materials but also effective patterning methods. Here, we show the fabrication of pixelated photodetector arrays through a two-step process: (1) direct optical patterning of CsPbBr₃ perovskite nanocrystal films using ligand cross-linkers, and (2) post-patterning ligand-exchange process. The direct optical patterning achieves high-resolution (≈2 μm in pixel sizes), uniform CsPbBr₃ nanocrystal film patterns over 2-inch wafers. The ligand-exchange process replaces the long hydrocarbon ligands and cross-linkers with compact ionic ligands, which enhance the charge transport efficacy without compromising the quality of the patterned films. Consequently, the patterned photodetectors, in the photoconductor configuration, show responsivity (0.11 A W⁻¹) and specific detectivity (1.81×10¹¹ Jones) on par with their non-patterned counterparts. These features permit the creation of pixelated photodetector arrays that minimize the charge-sharing crosstalk effect and enable improved imaging capabilities. This work shows a promising approach in building high-performance perovskite image sensors.