Molecular and electronic-structure basis of the ambipolar behavior of naphthalimide-terthiophene derivatives: Implementation in organic field-effect transistors

A new family of naphthalimide-fused thienopyrazine derivatives for ambipolar charge transport in organic field-effect transistors is presented. Their electronic and molecular structures were elucidated through optical and vibrational spectroscopy aided by DFT calculations. The results indicate that these compounds have completely planar molecular skeletons which promote good film crystallinity and low reorganization energies for both electron and hole transport. Their performance in organic field-effect transistors is compared with twisted and planar naphthaleneamidine monoimide-fused terthiophenes in order to understand the origin of ambipolarity in this new series of molecular semiconductors. Tailoring ambipolarity: A new family of completely planar naphthalimide-fused thienopyrazine derivatives in which coplanarity is enforced by intramolecular S×××N interactions has been synthesized for ambipolar charge transport in organic field-effect transistors and analyzed by vibrational spectroscopy and DFT calculations. Their data are compared with those previously reported for a series of planar and twisted thiophene-naphthalene derivatives (see figure) and afford new understanding of OFET performance in this general class of molecular semiconductors.