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Keywords:

  • organic field-effect transistors (OFETs);
  • contact resistance;
  • FeCl3;
  • thienoacene

Abstract

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 cm2 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 ≈109. Based on these experimental achievements, an optimal device structure for a high-performance organic transistor is proposed.