Synthesis and characterization of thiophene-based push-pull chromophores for tuning the electrical and optical properties of surfaces with controlled SAM formation

International audienceDue to their efficient light absorption properties and their electronic dipole, “push-pull” chromophores with thiophene-based spacer between donor and acceptor groups are very promising for potential use in optoelectronics, photovoltaics, non-linear optics, or electronics. Such applications could benefit from chromophore deposition on a surface in an ordered way with oriented dipoles. For this purpose, self-assembled monolayers (SAMs) constitute an interesting approach. In this work we present a multi-step synthesis of a series of push-pull structures based on 2,2′-bithiophene or dithieno[3,2-b:2′,3′-d]thiophene frameworks born on an alkyl chain terminated with an anchoring group for further use in surface modification. Obtained molecules and SAMs were analyzed by cyclic voltammetry, spectroscopy and scanning probe microscopy. We show that varying the acceptor moiety allows to tune the absorption band in a wide spectral range, and that a longer chain length improves the organization of the dipole-oriented chromophore SAM