Lateral confinement effect on crystallization behavior of a small molecule semiconductor during capillary force lithography for use in OFETs

Abstract

Solution-processed organic field-effect transistors (OFETs) have been an attractive research topic due to their applicability to future electronic devices. Several issues like high quality material synthesizing, and patterning process are firstly considered to commercialize the OFETs. Especially, the patterning issues are strongly related with the crosstalk and performance of device in solution-processed OFETs. Therefore, we report the analyzation of micropatterned 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene) crystals using capillary force lithography (CFL) by UV curable polyurethane acrylate (PUA) templates to investigate the lateral confinements effect on the crystallization. More aligned and free-grain boundary crystalline morphology was observed in narrow patterned width condition, and the electrical performance was also more improved than those of wide pattern width condition (0.58 cm2/(V∙s) in 100 μm and 1.66 cm2/(V∙s) in 5 μm). These consequences demonstrate that the lateral confinements caused by CFL can induce the highly aligned TIPS-pentacene crystals having advanced charge transport path way. Therefore, CFL, one type of soft lithography, should have a considerable potential to facilitate the commercialization of solution-processed OFETs, and to ensure the reproducibility of the crystallinity and the orientation.