Chlorophyll Derivative Enables High-Performance Self-Powered Organic Photodetectors for Full-Color Imaging

Conventional photodetectors are typically limited to monochromatic image sensing, which is increasingly inadequate for modern applications. In this work, we demonstrate full-color image sensing using an organic photodetector (OPD) based on a ternary heterojunction comprising 13¹-deoxo-13¹-dicyanomethylene-pyropheophorbide-<i>a</i> (Chl), poly(3-hexylthiophene-2,5-diyl) (P3HT), and [6,6]-phenyl-C₆₁-butyric acid methyl ester (PC₆₁BM). Compared with the PC₆₁BM:P3HT device, incorporating Chl effectively enhances the external quantum efficiency. This is mainly attributed to the lowest unoccupied molecular orbital and highest occupied molecular orbital energy levels of Chl lying between those of PC₆₁BM and P3HT, which facilitates efficient extraction of electrons and holes. Moreover, by leveraging the device's distinct responses at 475, 530, and 730 nm, color image sensing is realized in the self-powered mode, with the reconstructed images achieving a structural similarity index of up to 97% based on external RGB reconstruction. This study offers a new strategy for developing flexible and high-performance color imaging devices.