High-efficiency polymer photovoltaic devices from regioregular-poly(3-hexylthiophene-2,5-diyl) and [6,6]-phenyl-C61-butyric acid methyl ester processed with oleic acid surfactant

Abstract

Bulk heterojunction photovoltaic cells, comprised of regioregular-poly(3-hexylthiophene-2,5-diyl) (P3HT) and[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) in the presence of the surfactant, oleic acid (OA), have been studied. The device with OA after thermal annealing has a power conversion efficiency (ηe) of 4.3%, while the devices without OA after thermal annealing have ηe=3.1%. Based on atomic force microscopy, x-ray diffraction investigation found that with OA, the P3HT-PCBM films have better molecular local ordering after thermal annealing resulting in larger donor and acceptor interfaces and higher mobility, thereby higher performance of the photovoltaic cell.