Solution-Based Integration of Vertically Stacked Organic Photodetectors Toward Easy-To-Fabricate Filterless Multi-Color Light Sensors

Solution-processed, color-selective organic photodetectors are uniquely positioned to deliver high-performance, low-cost, multicolor light sensors/imagers beyond the limitations of conventional, color-filter-based technologies. To realize such potential, however, a prominent challenge has been the solution-based, monolithic integration of vertically stacked organic photodetectors, which would enable multicolor sensing with optimum light collection while benefiting from the scalability, cost, and sustainability edges of solution-based manufacturing. To tackle this challenge, this paper demonstrates, for the first time, the monolithic integration of vertically stacked solution-processed organic photodetectors for independent, multicolor light sensing within the same pixel area. The solvent orthogonality challenge is tackled by selecting polymer-based photoactive layers and an insulating polymeric spacer-for independent biasing and photocurrent readout-with compatible processing conditions. Based on the suitable characteristics of blue- and green-sensitive standalone devices, the vertically stacked, monolithic device architecture is optimized by also incorporating semitransparent electrodes for photons to reach deep into the stack. The resultant device architecture enables efficient blue- and green-selective photodetection with state-of-the-art linearity, alongside speed of response adequate for real-world applications. Based on its solution-processability and modularity, this approach paves the way for the facile, solution-based fabrication of organic imagers covering multiple spectral regions with high sensitivity and resolution.