Organic field-effect transistors with density of states modified by polymer-enhanced solvent vapor annealing

Abstract

Solvent vapor annealing (SVA) is a post-fabrication process commonly utilized to reduce the structural or energetic disorder of organic semiconductor. In this work, pentacene organic field-effect transistors were treated by different solvent vapors. Methyl ethyl ketone (MEK) vapor was found to substantially improve device performance. The threshold voltage was lowered to be just −0.2 V and the subthreshold swing was steep at 200 mV/dec. Such improvements were interpreted in terms of the density of states. Quantitative analyses indicated that the SVA with MEK reshaped the density of states of the pentacene film; in particular, the localized tail states decreased considerably. Our finding suggests that our SVA method can repair water-induced defects in grain boundaries, which commonly has a negative effect on carrier transport, i.e., lessening charge localization in deep traps and thus ameliorating charge transport in electron devices. Therefore, polymer-enhanced SVA is a powerful post-fabrication technique to manufacturing high-performance organic devices.