A conjugated polymer consisting of alternating octyldodecyldiketopyrrolo[3,4-c]pyrrole (DPP) and diethoxynaphthalene (EN) units (PDPP-TENT) with thiophene (T) spacers, was synthesized (M-n 19000), which showed a typical absorption of conjugated polymers (lambda(max) =720 nm, solid state). Based on the calculated geometry, PDPP-TENT is only slightly bent (170 degrees) and extensively conjugated. The optical band gap and highest occupied molecular orbital (HOMO) level of the polymer were determined to be 1.61 eV and -5.46 eV, respectively. The polymer-based photovolatic devices (ITO/PED:PSS/PDPP-TENT:PC71BM:diiodooctane/LiF/Al) exhibited the power conversion efficiencies of up to 1.6%. (C) 2015 Elsevier B.V. All rights reserved.