A new series of low-bandgap alternating polyfluorenes with different donor-acceptor-donor moieties have been synthesized. Electrochemical and optical absorption measurement show that onset bandgaps of these polymers range from 1.2 to 1.5 eV. These polymers, blended with a C-70-derivative as acceptor, are used for solar cell fabrication. Devices show promising photovoltaic properties, and the spectral response of photocurrent covers all visible and near-infrared wavelength regions with its onset extended to 1 mu m. The best data gives a photocurrent density of 3.4 mA/cm(2), open circuit voltage of 0.58 V and power conversion efficiency of 0.7% under illumination of AM1.5 (1000 W/m(2)) from a solar. simulator. (c) 2005 Elsevier B.V. All rights reserved.