Environmentally stable organic thin-films transistors: Terminal styryl vs central divinyl benzene building blocks for p-type oligothiophene semiconductors

A series of linear oligomers combining thiophene, phenyl and vinyl units were designed and synthesized to investigate the influence of the number and sequence of the π-conjugating groups on the stability and performance of organic thin-film transistors. The optical and electrochemical properties of oligomers in solution were investigated by UV–vis absorption and photoluminescence spectroscopies, and cyclic voltammetry. High vacuum evaporated thin films were investigated by optical absorption, X-ray diffraction and AFM, and implemented as p-type semiconducting layers into organic thin-film transistors (OTFTs). Furthermore, shelf-live tests (under ambient conditions) of the OTFTs based on the distyryl-substituted oligomer, DS-2T, show that the mobility was almost unchanged for 100 days, indicating a high environmental stability and the great importance of end-substitution to provide stability against air-oxidation.