An alternating polyfluorene (APFO) with low band-gap segments named APFO-Green1 has been designed and synthesized for use in optoelectronic devices. The low band-gap segment consists of an electron acceptor (A), fenced by electron donors (D). This D-A-D configuration leads to a partial charge transfer in the polymer backbone, and thereby a low band-gap (1.3 eV). Results obtained from characterization of APFO-Green1 include light absorption and emission at extended wavelengths as well as high hole mobility. Furthermore, blends of the polymer with different fullerene derivatives exhibit unusually high photovoltaic performance at long wavelengths, making this type of conjugated polymers promising for plastic solar cell applications. (c) 2006 Elsevier Ltd. All rights reserved.