Аннотация:Ambipolar organic field-effect transistors (OFETs) based on single-crystals attract many researchers as they can lead to efficient light-emitting devices (LEFETs) with higher emission efficiencies compared to the organic light emitting diodes. Among various types of ambipolar OFETs, single-crystal bottom-gate top-contact devices based on thiophenephenylene co-oligomers (TPCOs) show the best performance combining efficient charge transport and high luminescence quantum yield. However, the LEFET energy efficiency is still very low. One of the biggest challenges for high performance single-crystal ambipolar OFETs is to overcome their high threshold voltages, which can be associated with high contact resistance. New approaches for deposition of ohmic contacts with low contact resistance have to be developed. In this work, we compare evaporated and laminated gold electrodes on top of the thiophene/phenylene (TMS-PTTP-TMS) and furan/phenylene (BPFB) co-oligomer single crystals grown using physical vapor transport (PVT) technique. OFETs based on this crystal were fabricated in the bottom-gate top-contact geometry and their performance was compared. Figure 1 presents transfer characteristics of OFETs with laminated and evaporated electrodes. Laminated gold contacts resulted in the reduced threshold voltage down to 0 V compared to the devices with evaporated gold electrodes. We analyze ambipolar OFETs with
asymmetrical top contacts: an electron-injecting electrode formed by evaporation of low work function metals (Ca, Al) and a hole-injecting laminated gold electrode. Thus, the laminated gold electrodes resulted in ohmic contact providing zero threshold voltages and are promising for efficient single-crystal OFETs.