Synthesis and functional properties of donor-acceptor pi-conjugated oligomers

Novel donor−acceptor oligophenylenevinylenes (OPVs) bearing an electron-donating 2-(2-butoxyethoxy)ethoxy group at one end and various electron-withdrawing groups including alkylsulfonyl, cyano, and nitro functionalities at the other end have been synthesized for investigation of structure−functional property relationships. Depending on the nature of the electron-withdrawing group, the newly synthesized donor−acceptor OPVs can exhibit an efficient light-emitting property or a large photovoltaic effect. The asymmetrically disubstituted OPV bearing 2-(2-butoxy-ethoxy)ethoxy-hexylsulfonyl functionalities possesses superior molecular properties for light-emitting applications than the symmetrically 2-(2-butoxyethoxy)ethoxy-disubstituted counterparts. In addition, our first observation and investigation on the photovoltaic response in polyalkyleneoxy-nitro disubstituted OPV series is reported. The spectral responsivity of the photovoltaic device corresponds to the absorption characteristics of the oligomer. Most importantly, the photocurrent responsivity increases with an extension of the conjugated length of the oligomer.