Improving organic transistor performance through contact-area-limited doping

Organic thin film transistors (OTFTs) with different concentrations of tetrafluorotetracyanoquinodimethane (F4-TCNQ) doped pentacene interlayer were fabricated. When a 2 wt% F4-TCNQ doped pentacene layer was incorporated between gold electrodes and a pentacene layer, the performance of the OTFT was significantly improved. The saturation mobility increased from 0.21 to 0.63cm2/Vs, the threshold voltage was reduced from −31.9 to −7.6 V, and the threshold swing varied from 5.09 to 2.40 V/dec as compared with an OTFT without interlayer. This improvement was ascribed to the reduction of the hole-injection barrier and contact resistance. Our results indicated that contact-area-limited doping is an effective way to improve OTFT performance.