Memory and Photovoltaic Elements in Organic Field Effect Transistors with Donor/Acceptor Planar-Hetero Junction Interfaces

Interfacial charge transfer at organic/organic planar-hetero junctions allows access to device structures that create new opportunities for flexible electronic devices. Fundamental characteristics of a pentacene/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) interface are explored via a comprehensive study of charge transfer between these two materials using the field-effect transistor (FET) geometry both in the dark and under illumination. Organic memory elements in a field effect transistor are demonstrated for a device fabricated with a pentacene/PCBM interface. Electric field induced charge transfer at the interface, in the dark, induced a nonvolatile memory effect with a large hysteresis characterized by a memory window of 43 V in the transfer characteristics. A photoinduced threshold voltage shift induced by exciton dissociation at the interface, in the absence of a gate electric field, is consistent with the formation of the photoinduced conducting channel in pentacene.