Ambipolar transport in solution-deposited pentacene transistors enhanced by molecular engineering of device contacts

Abstract

We report ambipolar transport in bottom gold contact, pentacene field-effect transistors (FETs) fabricated by spin-coating and thermally converting its precursor on a benzocyclobutene/SiO2 gate dielectric with chemically modified source and drain electrodes. A wide range of aliphatic and aromatic self-assembled thiolate monolayers were used to derivatize the electrodes and all enhanced electron and hole currents, yet did not affect the observable thin film morphology. Hole and electron mobilities of 0.1–0.5 and 0.05–0.1 cm2/V s are achieved, though the threshold for electron transport was >80 V. These ambipolar FETs are used to demonstrate inverters with gains of up to 94.

Electron and hole transport in ambipolar, thin film pentacene transistors

“…On the contrary, when the gate voltage was swept from positive to negative bias, significant hysteresis was observed. 18,19 In the supplemental information, 28 the full transfer characteristics for a representative ambipolar pentacene FET (L ¼ 200 lm and W ¼ 2 mm) with a continuous V GS sweep from À50 V to 50 V is shown. Measurements in the unipolar saturation regimes ensured the minimum effect of hysteresis on the extracted mobilities.…”

“…18 SAM modification of electrodes improved both hole and electron currents. In our previous report, we demonstrated that in constant aspect ratio devices (W/L ¼ 15), both electron and hole currents increase with channel width.…”

“…Recently, we demonstrated ambipolar transport in solution-deposited bottom contact-bottom gate pentacene transistors by dual interface engineering. 18,19 Hydrophobic polymers such as parylene and benzocylcobutene were used as gate dielectric materials to support electron transport and self-assembled thiolate and carbodithiolate 20 monolayers were employed to modify the source-drain electrodes and thereby lower the contact resistance and improve charge carrier injection. In this paper, we report variable temperature and gate voltage dependent transport measurements in ambipolar transistors based on solution-deposited, thin-film pentacene.…”

Flexible organic electronics for use in neural sensing

“…Pentacene thin film transistors (TFTs) were fabricated in bottom-gate, bottom-contact configuration on a Kapton® substrate according to the method described in [18] and [19]. A schematic of the device is illustrated in Fig.…”

Device Configurations for Ambipolar Transport in Flexible, Pentacene Transistors

“…One of the best examples is the typical observation of unipolar transport in organic field‐effect transistors (OFETs) and therefore the classification of organic p‐ and n‐type materials. It is only recently that theoretical2 and experimental3–5 reports have shown that the intrinsic properties of organic semiconductors can support both electron and hole transport. Theoretical calculations have predicted that organic semiconductors such as pentacene and tetracene can be as good electron conductors as hole conductors.…”