Degradation of organic field-effect transistors made of pentacene

This article reports degradation experiments on organic thin film transistors using the small organic molecule pentacene as the semiconducting material. Starting with degradation inert p-type silicon wafers as the substrate and SiO2 as the gate dielectric, we show the influence of temperature and exposure to ambient air on the charge carrier field-effect mobility, on-off-ratio, and threshold-voltage. The devices were found to have unambiguously degraded over 3 orders of magnitude in maximum on-current and charge carrier field-effect mobility, but they still operated after a period of 9 months in ambient air conditions. A thermal treatment was carried out in vacuum conditions and revealed a degradation of the charge carrier field-effect mobility, maximum on-current, and threshold voltage.