Metal Oxide Buffer Layer Thickness Influence on the Performance of Pentacene Thin Film Transistors

High performance top contact organic thin-film transistors (TC OTFTs) with bilayer electrodes (MoO3/Au) are fabricated. The interface properties of metal electrodes with organic active layer have an important effect on the OTFTs performance. We demonstrate the MoO3 layer is working as a buffer layer which can lower the charge injection barrier and reduce the contact resistance, and study the devices characteristics changing with the buffer layer thickness. Comparing with conventional TC OTFTs, the organic transistor with 10nm buffer layer shows the highest performance with field-effect mobility increasing from 0.17 to 0.69 cm2/V·s, threshold voltage downshifts from –13 to –5.3 V, and the on/off current ratio is about 50 times higher.