Light-activated electric bistability for evaporated silver nanoparticles in organic field-effect transistors

Evaporated naked silver nanoparticles (Ag-NPs) were embedded in the isolated layer of PTB7-based organic field-effect transistors (OFETs), where their electric bistability behavior was successfully activated by photo-irradiation. These devices showed no obvious memory behavior in the dark; while under weak photo-irradiation (0.015 mW cm^-2), memory windows of 12.5-35 V have been achieved. Different operation modes have been designed to exhibit the memory behavior and to explore the origin of the formation of a stable charge state. The immobilized photo-generated electrons supplied an additional photo-generated electric field, which confined the trapped charge in the charge storage media after the gate voltage and photo-irradiation being removed. The photo-irradiation created more charges at the interface, and the presence of Ag-NPs allowed effective charge storage of the majority carriers, which increased the drain current and lowered the gate-operating voltage. This method is a novel approach to light-activated electric bistability based charge storage.