Organic thin-film transistors (OTFTs) based on biocompatible blends of poly(3-hexylthiophene) (P3HT) and poly(2-hydroxyethyl methacrylate) (PHEMA) derivative

Abstract

In an attempting to overcome the limitation of the use of conducting polymers in biomedical areas, the blends of poly(3-hexyl thiophene) (P3HT) and poly (2-hydroxyethyl methacrylate) (PHEMA) derivative, poly(2-(2-acetoxyacetyl) ethyl methacrylate) (PHEMAAA) were prepared as a function of P3HT content. (the weight ratio of P3HT/PHEMAAA

100/0, 75/25, 50/50, 25/75, and 0/100). Surface properties of the spin-coated blend films, such as surface composition, morphology and molecular structure were investigated by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and grazing incidence wide-angle X-ray diffraction (GIWAXD). The blend films have a distinct morphology that PHEMAAA dominantly exists at the top surface, whereas P3HT having well-ordered structure is mainly located at the bottom surface. The influence of the surface properties on the electrical and biocompatible properties was demonstrated from organic thin-film transistor (OTFT) performances and cytotoxicity tests. The blend film having only 25 wt % of P3HT showed the similar hole mobility with that of pure P3HT due to no significant interruption of PHEMAAA in the phase-separated morphology. Furthermore, the cell viability of the blend film for human dermal fibroblast (HDF) cell is on a similar level as pure PHEMAAA, and it could be attributed to the abundant amount of PHEMAAA and high roughness on the top surface. In particular, when the content of P3HT was 25 wt %, the blend film showed the high field-effect mobility of P3HT and the excellent cell viability of PHEMAAA at the same time.