An ambipolar to n-type transformation in pentacene-based organic field-effect transistors

Abstract

We report an ambipolar to n-type transformation in pentacene-based organic field-effect transistors (OFETs) of aluminum (Al) source–drain electrodes. The hole currents of the ambipolar OFETs were decreased by over two orders of magnitude within 24h after the device fabrication, but the electron currents remained unchanged, which makes the devices present n-type only characteristics. The transformation is correlated with the interfacial interactions between Al electrodes and pentacene, as characterized by analyzing near-edge X-ray absorption fine structure spectra and Micro-Raman spectra. This study highlights the importance of metal/organic interfaces in the performance of OFETs, and demonstrates decent n-type pentacene-based OFETs with electron mobility of 0.1cm2/V/s with proper annealing treatment.