High mobility solution-processed C8-BTBT organic thin-film transistors via UV-ozone interface modification

Abstract

The interface between the dielectric and the active layer plays a critical role on the performance of solution-processed organic thin-film transistors (OTFTs). However, the creation of a high quality interface still represents a considerable challenge because it requires the balancing of surface energy with surface wettability. This study shows that UV-ozone treatment is very effective to obtain a high quality interface between a dielectric SiO₂ film and a solution-processed 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C₈-BTBT) semiconductor film. After only one minute UV-ozone exposure on the SiO₂ surface, the hole mobility at room temperature reaches 6.50 cm² (V s)⁻¹ for a solution-processed C₈-BTBT-OTFT. UV-ozone treatment can not only modify both surface energy and surface wettability but also clean the SiO₂ surface. Consequently, it changes the degree of ordered growth, grain sizes, and grain boundaries in C₈-BTBT films. Hence, UV-ozone treatment is a simple and efficient way to produce the desirable interface qualities that enable the highly ordered growth of C₈-BTBT films. Using this method it is also very promising to produce a high-quality interface between the dielectric film and other solution-processed organic semiconductors to fabricate other high-performance OTFT applications.