Effect of end-substitutions of distyryl-oligothiophenes by hexyl chains on environmental stability in organic thin film transistors

• Published in: Organic electronics 2008-10, Vol.9 (5), p.591-601
• Main Authors: Videlot-Ackermann, C., Brisset, H., Ackermann, J., Zhang, J., Raynal, P., Fages, F., Mehl, G.H., Tnanisawa, T., Yoshimoto, N.
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Applied sciences; Chemistry; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electrochemical methods; Electronics; Exact sciences and technology; Oligothiophene derivative; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Organic semiconductor; Organic thin film transistor; Photoluminescence; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Stability; Transistors
• ISSN: 1566-1199; 1878-5530
• DOI: 10.1016/j.orgel.2008.03.007

In this study, solution and solid-state properties as well as the organic thin film transistor (OTFT) behaviour of two α,ω-hexyl-distyryl-oligothiophenes ( DH-DS nT , n = 2, 4) are presented. The optical and electrochemical properties of the oligomers in solution were investigated by UV–vis absorption and photoluminescence spectroscopies, and cyclic voltammetry. Liquid crystal properties were studied by differential scanning calorimetry (DSC) and optical polarising microscopy (OPM). High-vacuum evaporated thin films were studied by optical absorption, X-ray diffraction and atomic force microscopy (AFM), and implemented as p-type semiconducting layers into organic thin film transistors (OTFTs). The results are investigated to study the influence of alkyl chains on the α,ω-end positions of the distyryl-oligothiophene skeleton ( DS nT ). Furthermore, detailed shelf-live tests of hole mobility ( μ), threshold voltage ( V t), on current ( I ON) and off current ( I OFF) under atmospheric conditions (air, temperature) of OTFTs based on DS4T and DH-DS4T show that the presence of alkyl chains in α,ω-end positions of distyryl-oligothiophenes is detrimental to the environmental stability of OTFTs over time.