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 b3e introduced to the hydroxyl-free dielectric surfaces. On grafted or cured polymer-assisted SiO2 dielectrics showing Ci = 10 - 11 nFcm-2, solutionprocessed triethylsiylethynyl 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 (uFET, 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 pi-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).