Bioderived Establishment of Three-Dimensional Type-I Ag2S/ZnIn2S4 Heterojunction for High-Efficacy Organic Photoelectrochemical Transistor Biomolecular Detection

Advanced optoelectronic devices have attracted extensive interdisciplinary interest but lags far behind in bio-molecular detection. The nascent organic photoelectrochemical transistor (OPECT) is expected to become a versatile platform to this end. Herein, using biological derivation of type-I Ag2S/ZnIn2S4 heterojunction, a light-fueled high-efficacy OPECT system with zero-gate-biased operation is successfully developed for biomolecular detection. Exemplified by a sandwich immunocomplexing towards mouse IgG (MIgG) with Ag nanoparticles (Ag NPs) as the label, steering the acidolysis-release of Ag+ toward ZnIn2S4 could induce the in-situ formation of type-I Ag2S/ZnIn2S4 heterojunction, increasing the recombination of light-activated excitons and thus inhibiting the photo-responsibility of ZnIn2S4, as sensitively monitored by the amplified OPECT response. The proposed device could achieve good analytical performance in terms of high specificity and sensitivity, with a detection limit as low as 33.7 fg mL-1. This OPECT device based on bio-induced formation of type-I heterojunction can provide a novel route to biomolecular detection, and offered a new perspective for the optoelectronic sensors to be used in futuristic physiological and pathological detection.