Effects of UV/ozone treatment of a polymer dielectric surface on the properties of pentacene thin films for organic transistors

Abstract

Ultraviolet photoelectron spectroscopy and atomic force microscopy (AFM) were used to investigate the energy level alignment and growth morphology of pentacene (Pn) films deposited on a PMMA derivative-based dielectric surface with and without ultraviolet/ozone treatment. The treated surface exhibited higher offset values for the highest occupied molecular orbital levels between Pn and the polymer, which would result in higher threshold voltages for the device. However, aligned vacuum levels of the treated surface and the Pn at the interface were observed, suggesting that the dipole field would be reduced in the Pn film on the treated surface. The hydrophilic nature of the treated surface, observed by water contact angle measurement, allowed for a larger grain size of the Pn film, as confirmed by the AFM measurements, which will also favorably contribute to device mobility.