Abstract
We fabricated top-contact pentacene-based organic thin-film transistors (OTFTs) with bilayer WO 3 /Au electrodes. Compared with those of a device without a WO 3 layer, the performance characteristics including field-effect mobility, threshold voltage, and On/Off ratio were highly improved in a device with a 5 nm WO 3 hole injection layer inserted. The field-effect mobility was increased from 0.47 to 0.69 cm 2 V -1 s -1 and the On/Off ratio was also increased from $1.8\times 10^{4}$ to $4.1\times 10^{4}$. From the results of evaluating the temperature dependence of $I_{\text{D}}$--$V_{\text{D}}$ characteristics and the surface morphology of pentacene, the improved device performance was attributed to reductions in barrier height and surface roughness after inserting a suitable WO 3 layer between the pentacene and gold electrodes.