Performance enhancement of organic thin-film transistors using WO3-modified drain/source electrodes

Pentacene-based organic thin film transistors (OTFTs) with WO 3 /Au as source/drain (S/D) electrodes were fabricated. In comparison with the pentacene-based OTFT having Au-only S/D electrodes, the performance of a device having WO 3 /Au S/D electrodes has been considerably improved. The saturation mobility increased from 0.39 to 2.8 cm 2 (V s) −1 , the threshold voltage reduced from −21.3 to −11.2 V, the on/off ratio shifted from 6.7 × 10 5 to 1.5 × 10 7 and the threshold swing varied from 3.75 to 1.82 V dec −1 . The improvement was attributed to (i) the significant reduction of contact resistance by using the WO 3 interlayer and (ii) the strong heat radiation during the thermal evaporation of WO 3 . Our results indicated that using WO 3 /Au as S/D electrodes is an effective approach to improving pentacene-based OTFT's performance.