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 C60, and a blend of HPV, poly(2‐methoxyl‐5,2′‐ethylhexyoxyl‐1,4‐phenylene vinylene) (MEH‐PPV), and C60, were fabricated, and their current–voltage characteristics were measured and investigated. The PVC with photoactive layers composed of H‐es and C60 showed promising photovoltaic characteristics, with an energy‐conversion efficiency of 0.035%, when illuminated under 85 mW/cm2 white light. The short‐circuit current and energy‐conversion efficiency of the PVCs based on H‐mn/C60 and H‐py/C60 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/C60 PVCs indicated that both HPVs and MEH‐PPV contributed to the photocurrent.