Controllable electrical performance of spray-coated semiconducting small molecule/insulating polymer blend thin film for organic field effect transistors application

Abstract

A systematic study on solution content and solvent effect of spray-coated 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-PEN)/poly(α-methylstyrene) (PαMS) semiconducting blends for organic field effect transistors (OFETs) application was investigated based on different concentrations (10, 15 and 20mgml−1), different compositions (TIPS-PEN/PαMS of 7/3, 5/5 and 3/7) and three different solvents, toluene (TOL), chlorobenzene (CB), and 1,2,3,4-tetrahydronaphthalene (THN). Polarized optical microscopy (POM), atomic force microscopy (AFM) and grazing-incidence X-ray diffraction (GIXRD) were used to evaluate the film morphology and chain orientation. The blend film can contribute to large coverage of TIPS-PEN carrier pathway across the OFETs channel if higher TIPS-PEN composition with suitable total blend concentration was introduced in the blend. Besides, the blend film processed from high boiling point THN can reduce the rate of evaporation which provides more time for TIPS-PEN migration to form a large grain of TIPS-PEN crystal. The resulting OFETs based on spray-coated from TIPS/PαMS (7/3) blend solution in THN exhibit maximum mobility of 3.23×10−1cm2V−1s−1 and ON/OFF ratio of >104.