Critical Factors to Achieve High Performance Organic Field-Effect Transistors

초록

We reports that OFETs including low-Ci dielectrics can be operated at low voltages if highly conjugated organic semiconducting layers are introduced to the hydroxyl-free dielectric surfaces, which can be produced via introducing organic layers onto either oxide dielectrics or gate electrodes. We have investigated both solution- and vacuum-processed organic semiconducting layers on grafted or cured polymer-assisted oxide dielectrics, including pentacene, triethylsilylethynyl anthradithiophene (TES-ADT), 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS pentacene), and poly(3-hexyl thiophene) (P3HT).[1-3] Particularly, solution-processed TES-ADT crystals on polymer-assisted oxide dielectrics were observed easily by the naked eye compared to micron-sized pentacene crystals. The resulting TES-ADT OFETs operated with a low voltage (|V| ≤ 5 V) showed high electrical performance (μFET , Vth, and SS values up to 1.3 cm2V−1s−1 , approximately −0.5 V and ∼ 0.2 Vdecade−1 , respectively). In contrast, polycrystalline pentacene-based OFETs requireㅇ much higher operating voltages (|V| > 20 V).[1.3] Comparing these semiconducting crystals, it was found that TES-ADT could be tuned intrinsically with better π-conjugated structures to transfer the charge-carriers, as determined by atomic force microscopy (AFM), grazing-incidence X-ray diffraction, and in-situ photo-excited charge-collection spectroscopy (PECCS).[3]