Ambipolar charge carrier transport in mixed organic layers of phthalocyanine and fullerene

TL;DR

This paper investigates how mixing copper-phthalocyanine and fullerene in organic layers enables ambipolar charge transport in OFETs, with tunable mobilities and threshold voltages, demonstrated through device fabrication and analytical modeling.

Contribution

It introduces a detailed analysis of mobility and threshold voltage variation with mixing ratio, and demonstrates ambipolar inverters using these mixed layers.

Findings

Mobility and threshold voltage depend on mixing ratio.

Ambipolar inverters are successfully demonstrated.

Analytical models align with experimental results.

Abstract

Mixed layers of copper-phthalocyanine (p-conductive) and fullerene (n-conductive) are used for the fabrication of organic field-effect transistors (OFETs) and inverters. Regarding the electrical characteristics of these donor-acceptor blends they show ambipolar charge carrier transport, whereas devices made from only one of the materials show unipolar behavior. Such mixed films are model systems for ambipolar transport with adjustable field-effect mobilities for electrons and holes. By variation of the mixing ratio it is possible to balance the transport of both charge-carrier types. In this paper we discuss the variation of mobility and threshold voltage with the mixing ratio and demonstrate ambipolar inverters as a leadoff application. The gained results were analyzed by simulations using an analytical model for ambipolar transistors and subsequently compared to complementary inverters.