Radu A. Sporea

With growing interest in organic phototransistors, as not only sensors but also neuromorphic computing elements, the vast majority of research investigates structures comprising Ohmic source/drain contacts. Here, it is shown how source‐gated transistors (SGTs), in which a source contact barrier dominates electrical characteristics, can be implemented as phototransistors. Organic photo‐SGTs (OPSGTs) based on vacuum‐processed small‐molecule dinaphtho[2,3‐b:2′,3′‐f]thieno[3,2‐]thiophene (DNTT) demonstrate low saturation voltage, exceptional tolerance to channel length variation, and photo‐to‐dark current ratio (PDCR) peaks over 10 6 for 819 µW broad spectrum incident light power. At zero gate‐source voltage, the PDCR reaches 10 4 , showing promise for simple sensor circuit implementation in medical and wellbeing applications.