Optimal structure for high-performance and low-contact-resistance organic field-effect transistors using contact-doped coplanar and pseudo-staggered device architectures

A low contact resistance achieved on top-gated organic field-effect transistors by using coplanar and pseudo-staggered device architectures, as well as the introduction of a dopant layer, is reported. The top-gated structure effectively minimizes the access resistance from the contact to the channel region and the charge-injection barrier is suppressed by doping of iron(III)trichloride at the metal/organic semiconductor interface. Compared with conventional bottom-gated staggered devices, a remarkably low contact resistance of 0.1-0.2 kΩ cm is extracted from the top-gated devices by the modified transfer line method. The top-gated devices using thienoacene compound as a semiconductor exhibit a high average field-effect mobility of 5.5-5.7 cm ² V ^-1 s ^-1 and an acceptable subthreshold swing of 0.23-0.24 V dec ^-1 without degradation in the on/off ratio of ≈10 ⁹. Based on these experimental achievements, an optimal device structure for a high-performance organic transistor is proposed.