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HL: Fachverband Halbleiterphysik

HL 85: Organic Semiconductors: Transistors and OLEDS

HL 85.3: Vortrag

Donnerstag, 29. März 2012, 15:30–15:45, EW 203

Tuning the Surface Properties of Gold Electrodes in Organic Field-Effect Transistors Using Self-Assembled Monolayers — •Janusz Schinke¹, Sebastian Hietzschold³, Rebecca Saive^2,3, Lars Müller³, Manuel Hamburger⁴, Wolfgang Kowalsky^1,2, and Michael Kröger^1,2 — ¹TU Braunschweig, Institut für Hochfrequenztechnik — ²Innovation Lab GmbH — ³Universität Heidelberg, Kirchhoff-Institut für Physik — ⁴Universität Heidelberg, Organisch-Chemisches Institut

In organic electronic devices, charge injection at the contacts is crucial for better electrical performance. In bottom-contact p-channel organic field-effect transistors (OFET), Au electrodes are very often used for drain and source contacts. A smart way of enhancing the device's performance is the use of self-assembled monolayers (SAMs) to tune the electrodes' work function or substrate conditions for deposition of the organic semiconductor. We have studied the properties of SAM-treated gold surfaces via Atomic Force Microscopy (AFM), Kelvin Probe (KP) and contact angle measurements. SAMs used for this work include fluorinated and non-fluorinated alkyl thiols. We compare the characteristics of SAM-treated OFETs using TIPS-pentacene as an organic semiconductor to standard devices. The gold electrode is subsequently treated by several SAM solutions to manipulate the effective work function and the device performance. Comparing to untreated OFETs, we see an enhancement of the mobility by two orders of magnitude and a significant reduction of the threshold voltage.