Chemical bath deposition of ZnO nanowire–nanoparticle composite electrodes for use indye-sensitized solar cells

Abstract

ZnO nanowire (NW)-layered basic zinc acetate (LBZA)/ZnO nanoparticle(NP) composite electrodes with different NP occupying extents have beensynthesized using a simple wet-chemical route for use in dye-sensitized solar cells(DSSCs). By employing mercurochrome as the sensitizer, superior efficiencies(η) of 1.27–2.37% are obtained using the ZnO NW-LBZA/ZnO NP composite electrodes composed ofa 5.5 µm thick NW array with different NP occupying extents in comparison with the ZnO NW DSSC(η = 0.45%). It suggests that the ZnO NW-LBZA/ZnO NP composite films which possess aconsiderable enlarged surface area by NPs growth, without sacrificing electron transportefficiency of single-crystalline ZnO NWs at the same time, are promising photoanodes foruse in DSSCs. In addition to the extent of NP occupation, the overall efficiency of the ZnONW-LBZA/ZnO NP composite DSSC is also influenced by the thickness of the compositefilm as well as the LBZA fraction and the cracks within the composite. The fraction ofLBZA affected by the NP growth period and post-annealing conditions is found to play acrucial role in electron transport through the composite anode. Up to now, ahigh efficiency DSSC of 3.2% is achieved using a mercurochrome-sensitized and6.2 µm thick NW–NP composite film.