Heterojunction Photovoltaics Using GaAs Nanowires and Conjugated Polymers

We demonstrate an organic/inorganic,solar cell architecture based on a blend of poly(3-hexylthioptene) (P3HT) and narrow bandgap GaAs nanowires. The measured increase of device photocurrent with increased nanowire loading is correlated with structural ordering within the active layer that enhances charge transport. Coating the GaAs nanowires with TiOx shells passivates nanowire surface states and further improves the photovoltaic performance. We find that the P3HT/nanowire cells yield power conversion efficiencies of 2.36% under white LED illumination for devices containing 50 wt % of TiOx-coated GaAs nanowires. Our results constitute important progress for the use of nanowires in large area solution processed hybrid photovoltaic cells and provide insight into the role of structural ordering in the device performance.