Hyperbranched conjugated polymers for photovoltaic applications

Three hyperbranched phenylene vinylenes (HPVs)—H‐mn, H‐es, and H‐py—were used in fabricating polymer photovoltaic cells (PVCs). PVCs with photoactive layers composed of pure HPV, a blend of HPV and C 60 , and a blend of HPV, poly(2‐methoxyl‐5,2′‐ethylhexyoxyl‐1,4‐phenylene vinylene) (MEH‐PPV), and C 60 , were fabricated, and their current–voltage characteristics were measured and investigated. The PVC with photoactive layers composed of H‐es and C 60 showed promising photovoltaic characteristics, with an energy‐conversion efficiency of 0.035%, when illuminated under 85 mW/cm 2 white light. The short‐circuit current and energy‐conversion efficiency of the PVCs based on H‐mn/C 60 and H‐py/C 60 were greatly improved when they were blended with a small amount of MEH‐PPV. The incident photon‐to‐collected‐electron efficiency of the HPV/MEH‐PPV/C 60 PVCs indicated that both HPVs and MEH‐PPV contributed to the photocurrent. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1459–1466, 2004