Influence of heterogeneous layers of graphene oxide on bottom-connected organic field effect transistors

Abstract

Organic field-effect transistors (OFETs) with a bottom-contact structure and a heterojunction layer of graphene oxide (GO) were investigated. GO films of different concentrations were prepared on gold electrodes using the spin coating method. Subsequently, the active layers of copper phthalocyanine (CuPc) were deposited by thermal evaporation to obtain GO/CuPc OFETs. For comparison, CuPc OFETs with a bottom-contact structure were fabricated. In GO/CuPc OFETs, carrier mobility is enhanced at different GO concentrations and the threshold voltage is reduced by approximately 5.3 V at low GO concentrations. These performances are superior to those of CuPc OFETs. Morphological analysis of GO/CuPc films revealed the role of the heterogeneous structure of GO in the device. GO/CuPc OFETs exhibited no hysteresis and a low threshold shift over time, indicating improved stability. Thus, the addition of GO films enhances the interaction between CuPc and GO molecules, improves the carrier transport, and increases resistance to water molecules. Incorporating GO films is an effective means to enhance the performance of organic semiconductor devices.