Optical and charge transport properties of a new n-type solution-processible quinoidal oligothiophene

Quinoidal oligothiophenes have recently emerged as a promising class of organic semiconductors for organic electronics. In this study, solution-processed neat films of a novel n-type quinoidal quaterthiophene modified with electron-withdrawing groups [QQT(OMe)₂] are characterized in details by absorption spectroscopy, ultraviolet photoelectron spectroscopy, atomic force microscopy, Raman spectroscopy and field-effect transistor characteristics. Top-contact transistor with Au source/drain electrodes shows in the saturation regime a field-effect electron mobility of 5 × 10^-4 cm² V^-1 s^-1 with a threshold voltage of -34 V. The results indicate that QQT(OMe)₂ is a promising candidate for future solutionprocessed transparent organic electronic devices. This study provides relevant information about the influence of the substituents along the thiophene backbone on the intermolecular interactions and the electronic properties of these oligomers. The results should be taken into account in the development of novel high mobility quinoidal oligothiophenes.