The photovoltaic performance of ZnO nanorods in bulk heterojunction solar cells

A novel approach has been followed for synthesizing vertically aligned ZnO nanorods (ZONRs) on indium tin oxide (ITO) coated glass substrates for photovoltaic applications. The fabricated ZONR arrays have been used to construct bulk heterojunction photovoltaic devices together with pristine poly-(3-hexylthiophene) (P3HT) or (6,6)-phenyl C61 butyric acid methyl ester (PCBM) and P3HT blends, respectively. Scanning electron microscopy, X-ray diffraction, photoluminescence, UV-vis absorption spectroscopy, and photovoltaic measurements were performed to study the morphology and device performance of the prepared structures. The typical microstructure of the vertically aligned ZONR arrays plays an important role in collecting the photo-generated electrons and acts as conducting paths to the ITO electrode. Fill factor of the devices increased from 35% to 47% when the PCBM was introduced, which directly contributed to the enhancement of the power conversion efficiencies up to 1.23%.