Fine-control of electron trapping for photomultiplication in organic photodetectors by modulating the insulating properties of nonfullerene acceptors

), and Schottky barrier height (0.334-0.229 eV) under illumination. Higher concentrations of trapped electrons accumulated at the P3HT/Al interface, leading to a thinner Schottky barrier, reduced depletion region, and enhanced band bending, improving hole injection from the cathode. Among the NFAs, A-BTP-DT, with the highest insulating properties, exhibited superior PM effects, achieving a maximum external quantum efficiency of 7520% at -10 V (compared to 564% for the Y6-based device). This work represents the first successful demonstration of fine-tuning of electron trapping and PM effects, not by adjusting energy levels, but by modifying the insulating properties.