| Three new series of diperfluoroalkyl-functionalized thiophene-based oligomers have been developed: α,ω- and β,β′ -diperfluorohexyl-substituted oligothiophenes and para-diperfluorooctyl-substituted phenylene-thiophene oligomers. The introduction of fluorine results in a shift of the majority carrier in thin films of these materials from holes to electrons, and these series comprise the first known thiophene-based n-type semiconductors. In addition to drastically affecting the electrical properties, fluorine substitution enhances thermal stability and volatility as well as chemical stability in comparison to the alkyl-substituted analogs. Optimization of film growth conditions has led to a correlation of high device performance with a balance of texture and interconnected morphology in the thin films. The perfluoroalkyl-functionalized oligomers are attractive for device applications requiring n- as well as p-type organic materials.; A series of phenylene-thiophene oligomers functionalized with solubilizing hexyl substituents has been developed for solution-processable device applications. A reliable method has been developed for casting these compounds as thin films from solution, and the performance of devices based on such films rivals that of devices employing vacuum-evaporated films. In addition, some of the compounds exhibit a substantial memory effect, the stability, tenability, and reversibility of which have been well defined. For the first time, completely solution-processed nonvolatile memory elements have been fabricated. The combination of ease of synthesis, high solubility, and reliable device performance makes this series of oligomers attractive for inexpensive organic electronics. |
