Adaptive organic phototransistor for light-suppressed regulation

Abstract

Light-adaptive synapse devices rely on physical mechanisms capable of dynamically responding to light intensity changes, where the negative photoconductivity (NPC) effect is crucial for achieving light-suppressed regulation. This study constructs an adaptive organic phototransistor (AOPT) based on a pentacene/PTCDI-C13 p–n heterojunction, systematically investigating the NPC mechanism and its regulation of photosynaptic plasticity. The device employs PVN and P(VDF-TrFE-CFE) as the capture layer and dielectric layer, respectively. The recombination of photogenerated carriers at the p–n interface, coupled with the capture effect of PVN, jointly induces a significant NPC response. Based on this mechanism, the device achieves synaptic inhibitory plasticity regulation dependent on light pulse intensity, duration, number, and frequency, while exhibiting wavelength selectivity. By integrating electrically driven long-term potentiation with optically driven long-term depression, the device successfully simulates the human eye's light–dark adaptation process. In artificial vision systems, the AOPT array achieved image recognition accuracies of 86.88% and 86.31% under light and dark adaptation conditions, respectively. This study provides a mechanistic foundation and design strategy for photo-electro-optic cooperative plasticity in organic optoelectronic devices, demonstrating their potential for visual information processing under complex illumination conditions.