Low‐Operating‐Voltage Organic Transistors Made of Bifunctional Self‐Assembled Monolayers |
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Authors: | M Mottaghi P Lang F Rodriguez A Rumyantseva A Yassar G Horowitz S Lenfant D Tondelier D Vuillaume |
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Affiliation: | 1. ITODYS, CNRS‐UMR 7086, University Denis‐Diderot, 1 rue Guy de la Brosse, 75005 Paris, France;2. Present address: LPICM, école Polytechnique, 91128 Palaiseau, France;3. IEMN, CNRS‐UMR 8520, Avenue Poincaré, 59652 Villeneuve d'Ascq, France |
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Abstract: | Self‐assembled monolayers (SAMs) are molecular assemblies that spontaneously form on an appropriate substrate dipped into a solution of an active surfactant in an organic solvent. Organic field‐effect transistors are described, built on an SAM made of bifunctional molecules comprising a short alkyl chain linked to an oligothiophene moiety that acts as the active semiconductor. The SAM is deposited on a thin oxide layer (alumina or silica) that serves as a gate insulator. Platinum–titanium source and drain electrodes (either top‐ or bottom‐contact configuration) are patterned by using electron‐beam (e‐beam) lithography, with a channel length ranging between 20 and 1000 nm. In most cases, ill‐defined current–voltage (I–V) curves are recorded, attributed to a poor electrical contact between platinum and the oligothiophene moiety. However, a few devices offer well‐defined curves with a clear saturation, thus allowing an estimation of the mobility: 0.0035 cm2 V–1 s–1 for quaterthiophene and 8 × 10–4 cm2 V–1 s–1 for terthiophene. In the first case, the on–off ratio reaches 1800 at a gate voltage of –2 V. Interestingly, the device operates at room temperature and very low bias, which may open the way to applications where low consumption is required. |
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Keywords: | Electron‐beam lithography Field‐effect transistors organic (OFETs) Oligothiophenes Organic electronics Self‐assembled monolayers |
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