Published online by Cambridge University Press: 22 June 2011
Fabrication of TiO2 nanofibers and their applications as the electron transporting layer for hybrid photovoltaic cells were studied. TiO2 nanofibers were electrospun onto an indium tin oxide (ITO) on glass substrate with a thin TiO2 blocking layer from a precursor solution [polyvinylpyrrolidone (PVP), titanium(IV) butoxide (TiBu), and acetylacetone (ACA)] in methanol. Many sources of precursor for fabrication of the thin TiO2 blocking layer, i.e. sintered TiO2 nanoparticle paste, sintered TiO2 nanoparticle-dispersed solution, TiBu solution with ACS in methanol, and titanium isopropoxide solution in ethanol were studied. The thin TiO2 blocking layer/nanofiber electrode was subjected to calcination at 450 °C for 3 h. The nanofiber electron transporting matrix was penetrated by blended poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). Thermal annealing and deposition of Au electrode were then carried out. After photovoltaic characterizations, it was found that hybrid organic-inorganic photovoltaic cells made of TiO2 nanofibers exhibited remarkable improvement of the cell efficiencies as compared with that of TiO2 flat film. Maximum power conversion efficiency (PCE) of hybrid organic-inorganic photovoltaic cells made of TiO2 nanofibers of 1.11% could be obtained (efficiency of flat TiO2 device = 0.28%).