Performance enhancement of p-type organic field-effect transistor through introducing organic buffer layers

Top contact organic field-effect transistors (OFETs) based on pentacene active layer, which employed the organic buffer layers of subphthalocyanine, triphenyldiamine derivative, and 4,4',4aEuro(3)-tris[3-methylphenyl(phenyl)amino] triphenylamine (m-MTDATA) as the hole injection layers were fabricated. The results showed that the electrical performance of these OFETs, including the saturation current, the field-effect mobility, the on/off current ratio, and the threshold voltage, were all significantly improved by introducing the organic hole injection buffer layers. By optimizing the film thickness of these organic buffer layers to the appropriate thickness, the charge injection from gold source/drain electrodes to pentacene film could be effectively improved. Also, the interfacial properties and the contact resistance between gold source/drain electrodes and pentacene film was analyzed, and the results indicated that the interface property was significantly improved. Moreover, it was found that OFET with m-MTDATA hole injection layer exhibited the best performance compared to other two kinds of materials, and the intrinsic reason was further revealed.