Electrospun TiO_2 Nanofibers for Organic-Inorganic Hybrid Photovoltaic Cells

摘要

Fabrication of TiO_2 nanofibers and their applications as the electron transporting layer for hybrid photovoltaic cells were studied. TiO_2 nanofibers were electrospun onto an indium tin oxide (1TO) on glass substrate with a thin TiO_2 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 TiO_2 blocking layer, i.e. sintered TiO_2 nanoparticle paste, sintered TiO_2 nanoparticle-dispersed solution, TiBu solution with ACS in methanol, and titanium isopropoxide solution in ethanol were studied. The thin TiO_2 blocking layeranofiber electrode was subjected to calcination at 450 ℃ for 3 h. The nanofiber electron transporting matrix was penetrated by blended poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C_(61)-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 TiO_2 nanofibers exhibited remarkable improvement of the cell efficiencies as compared with that of TiO_2 flat film. Maximum power conversion efficiency (PCE) of hybrid organic-inorganic photovoltaic cells made of TiO_2 nanofibers of 1.11% could be obtained (efficiency of flat TiO_2 device = 0.28%).