Organic Active-Matrix Imager with Ultra-low Illumination Detection Capacity for Lens-Free Optical Analysis

Solution-processed organic photodiodes (OPDs) based imager arrays have great potential in large-area optical sensing. Here, a novel structure of hole transporting layer (HTL)-free is developed for OPDs by depositing a quasi-planar heterojunction active layer on a self-assembled-molecule modified electrode. This strategy effectively reduces the dark current densities and boosts the photocurrent simultaneously compared to the conventional structure. Significantly improved specific detectivity of 5.16 × 10 ¹³ Jones and superior long-term stability are realized. An imager array prototype with a resolution of 64 × 64 is developed by integrating such HTL-free OPDs and an a-Si TFT backplane, which can authentically reproduce the images clearly under an ultra-low light intensity of 4 nW cm ⁻² . Our demo equipment shows versatile applicability for lens-free optical analysis, such as thin film characterization, display screen inspection, and fluorescence detection.