Hybrid inverted bulk heterojunction solar cells with nanoimprinted TiO2 nanopores

Photovoltaic devices with highly ordered nanoporous titanium dioxide (titania; TiO2) were fabricated to improve the photovoltaic performances by increasing TiO2 interface area. The nanoimprinting lithography technique with polymethyl methacrylate (PMMA) mold was used to form titania nanopores. The solar cell with poly(3-hexylthiophene) (P3HT):[6,6]-phenyl C61 butyric acid methyl ester (PCBM) active layer on nanoporous titania showed higher power conversion efficiency (PCE) of 1.49% than on flat titania of 1.18%. The improved efficiency using nanoporous titania is interpreted with the enhanced-charge separation and collection by increasing the interface area between TiO2 and active layer.