Electrolyte-gated (EG) transistors, based on electrolyte gating media, are powerful device structures to modulate the charge carrier density of materials by orders of magnitude, at relatively low operating voltages (sub-2 V). Tungsten trioxide (WO 3 ) is a metal oxide semiconductor well investigated for applications in electrochromism, sensing, photocatalysis, and photoelectrochemistry. In this work, we report on EG transistors making use of mesoporous nanostructured WO 3 thin films easily permeated by the electrolyte as the transistor channel and bis(trifluoromethylsulfonyl)imide ([TFSI])-based ionic liquids as the gating media. The WO 3 EG transistors operate at ca. 1 V. Using a combination of cyclic voltammetry, X-ray diffraction, and transistor performance characterizations, complemented by spectroscopic (Raman and infrared) investigations, we correlate the metal oxidation state and the charge transport properties of the metal oxide, shedding light on the doping process in electrically biased WO 3 nanostructured thin films exposed to electrolytes.

Novel inner-core dithienothiophene S-oxide and S,S-dioxide oligomers were designed and synthesized. The controlled oxidation at the central sulfur of the dithienothiophene core allows the combined tailoring of the HOMO-LUMO energies, thermal properties, and thin film morphology. Electrochemical measurements indicate that a marked decrease in electron affinity is obtained by addition of the first oxygen at the central sulfur, while addition of the second oxygen induces only minor effects on both the oxidation and reduction potentials. The newly synthesized materials exhibit high solubility in common organic solvents together with good film forming properties when deposited on SiO 2 by solution-based techniques. Similar hole field effect transistor (FET) mobility for solutiondeposited and thermally-evaporated films together with FET performances independent of film morphology and molecular orientation call for non-conventional charge transport mechanisms.

No abstract

No abstract

We report on ambipolar thin film transistors based on solution-deposited films of a pentacene derivative, 2,3-dicyano-6,13-bis-(triisopropylsilylethynyl)pentacene (2,3-CN2-TIPS-Pn). The ambipolar charge transport observed in this material is well balanced; the values of the hole and electron mobility are both about 2 × 10−3 cm2/Vs. The position of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of 2,3-CN2-TIPS-Pn with respect to the work function of the Au charge-injecting electrode and the arrangement of the molecules in the film, as deduced by grazing incidence x-ray diffraction analysis, contributes to explain the charge transport properties of 2,3-CN2-TIPS-Pn films.