Structural, spectroscopic and device characteristics of octithiophene

As a step further in the design of efficient organic semiconductors, we report here on the structural, spectroscopic and device characterization of octithiophene (8T), the linear conjugated octamer of thiophene. The X-ray structure and optical spectra under polarized light of the 8T single crystal are described for the first time. Vapor deposited 8T behaves as a p-type semiconductor whose transport properties are investigated in thin film transistors (TFTs). In particular, we show that the use of high purity 8T enhances by two orders of magnitude its field-effect mobility in TFTs to reach mu(FET) = 1.8x10(-2) cm(2)/V.s, a value similar to that of non-substituted sexithiophene (6T).