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 0.10.2 k Omega 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 5.55.7 cm(2) V-1 s(-1) and an acceptable subthreshold swing of 0.230.24 V dec(-1) without degradation in the on/off ratio of approximate to 10(9). Based on these experimental achievements, an optimal device structure for a high-performance organic transistor is proposed.