An Electrochemical Transducer Based on a Pentacene Double‐Gate Thin‐Film Transistor

Abstract

We report an electrochemical transducer based on an organic double-gate transistor. The bottom-gate is given by a p-doped silicon substrate, which is covered by 300 nm thermal oxide. A 20 nm pentacene film acts as the semiconducting layer, and a 50 nm tetratetracontane (TTC) alkane film is used as a top-gate dielectric. An aqueous ionic solution acts as top-gate. We record the transistor transfer characteristics by variation of the electrolyte potential via a Ag/AgCl electrode for various bottom-gate settings. A change of the electrolyte potential results in a change of the transistor current and the characteristic behaviour of the device is in good agreement with the expected behaviour of a double-gate transistor. The top-gate capacitance of the alkane layer is as high as 2.6 10 À8 F cm À2 determined by impedance measurements, indicating that TTC is a good choice as an organic top-gate dielectric. The suitability of this transducer configuration for sensing in aqueous media is demonstrated by the detection of hexanoic acid and stearic acid molecules adsorbing to the alkane interface, respectively. We show that the transducer easily achieves a concentration sensitivity in the range of 100 nM.

Towards flexible organic thin film transistors (OTFTs) for biosensing

“…The source-drain voltage is set to À0.6 V. The leakage current through the bottom gate dielectric is negligible and for the top gate dielectric, the source-drain current is corrected for the gate leakage current, as previously reported. 17 The transistors can be measured several hours, until nally breakdown of the top gate dielectric occurs.…”

“…16 In the line of sensors employing organic semiconductors, we demonstrated a transducer resembling the architecture of conventional doublegate thin lm transistors (DGTFTs). 17 To realise this experiment, it was essential to identify tetratetracontane (TTC) as a top gate dielectric.…”

Impact of subgrid‐scale vertical turbulent mixing on eyewall asymmetric structures and mesovortices of hurricanes

“…Additional control of doping levels also allows to tailor the depletion width with respect to the Debye length 35, 36. We assume that pentacene and C60 used here are unintentionally doped semiconductors, as confirmed for pentacene before in double gate experiments 37–39. In turn, the Fermi levels of pentacene and C60 are expected to align via interface charging, i.e., by formation of depletion zones or accumulation of charges, depending on the detailed values of the respective Fermi levels.…”

Ammonia sensing for enzymatic urea detection using organic field effect transistors and a semipermeable membrane

“…46 This effect gives rise to the high resistance of lipid bilayers. 47 This principle also applies to the case of an nonpolar organic semiconductor (e E 80 for water 46 and e E 3 for pentacene 14 ) or nonpolar encapsulation layers such as parylene. In practice, defects, e.g.…”

“…In Organic Electrochemical Transistors (OECTs), ions diffuse into the semiconducting film and dope or de-dope the transistor channel. 13 In Organic Field Effect Transistors (OFETs), the charge carrier concentration in the transistor channel is manipulated via capacitive coupling, [14][15][16] resulting in a change of the current through the device. The source drain current I SD of the transistor in saturation mode is given by: 16…”