A novel low-bandgap conjugated polymer (PTPTB, E g = ∼ 1.6 eV), consisting of alternating electron-rich N-dodecyl-2,5-bis(2'-thienyl)pyrrole (TPT) and electron-deficient 2,1,3-benzothiadiazole (B) units, as a donor material is studied together with a soluble fullerene derivative (PCBM) as acceptor to prepare bulk heterojunction photovoltaic cells. Photoinduced absorption (PIA) and fluorescence spectroscopy on blends of PTPTB and PCBM gave direct spectral evidence of the photogeneration of a charge-separated state. Preliminary results on photovoltaic cells prepared using thin PTPTB:PCBM films as an active layer, sandwiched between ITO/PEDOT:PSS and Al electrodes, showed promising characteristics.