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.