Fused H-shaped tetrathiafulvalene–oligothiophenes as charge transport materials for OFETs and OPVs

Abstract

A series of hybrid tetrathiafulvalene–oligothiophene compounds has been synthesised, where the tetrathiafulvalene unit is fused at each side to an end-capped oligothiophene chain of varying length (terthiophene, quinquithiophene and septithiophene). Each hybrid structure (1–3) has been studied by cyclic voltammetry and triple EPR-UV-Vis-NIR spectroelectrochemistry in the case of the quinquithiophene compound (2). Comparison is made with the corresponding half-units, which lack the fulvalene core and contain just one oligothiophene chain. The highest hole mobility of quinquithiophene–TTF 2 was obtained from field effect transistors (8.61 × 10⁻³ cm² V⁻¹ s⁻¹); its surface morphology was characterised by tapping mode atomic force microscopy and a power conversion of 2.5% was achieved from a bulk heterojunction organic solar cell device using PC₇₁BM as the acceptor.