Critical Factors to Achieve Low Voltage- and Capacitance-Based 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 can be introduced to the hydroxyl-free dielectric surfaces. On grafted or cured polymer-assisted SiO2 dielectrics showing Ci = 10 – 11 nFcm−2, solution-processed triethylsilylethynyl anthradithiophene (TES-ADT) crystals 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 require much higher operating voltages (| V | > 20 V). TES-ADT could be tuned intrinsically with better π-conjugated structures to transfer the charge-carriers, as determined by atomic force microscopy (AFM), X-ray diffraction, and in situ photo-excited charge-collection spectroscopy (PECCS).