Berlin 2005 – wissenschaftliches Programm

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SYOO: Organic Optoelectronics and Photonics

SYOO 6: Poster

SYOO 6.32: Poster

Montag, 7. März 2005, 18:00–20:00, Poster TU A

Ambipolar field-effect transistors based on mixed organic layers — •Markus Bronner, Josh Askin, Andreas Opitz, and Wolfgang Brütting — Experimentalphysik IV, Universität Augsburg, 86135 Augsburg, Germany

So far organic field-effect transistors (OFETs) are only available as unipolar devices (mostly p-channel transistors). These devices have inherent drawbacks compared to complementary logic devices, among them: limited performance, high power consumption and low tolerance to parameter variations. OFETs based on ambipolar materials are one possibility to realize complementary logic and thus improve the functionality of organic electronic circuits.

We present first results on ambipolar OFETs and inverters based on low-molecular weight p-conducting and n-conducting materials. Using co-evaporated mixed layers of rubrene or pentacene together with fullerene OFETs with ambipolar characteristics have been realized. Due to favourable band bending at the Au/C₆₀ interface, Au contacts can be used for both electron and hole injection. Although only moderate charge carrier mobilities of 10⁻³ cm²/Vs have been obtained so far, ambipolar inverters from these materials show an improved noise margin of about 8 V and a high gain of about 12. Further optimisation of layer growth and morphology is expected to lead to even better performance of these ambipolar OFETs.