Sensitization of ZnO in Stacked Structures Containing Multiple Dyes Grown Using Liquid Phase Molecular Layer Deposition

Abstract

Sensitization by two-dye-stacked structures of p-type dye/n-type dye adsorbed on ZnO can be applied to dye-sensitized solar cells. We attempted sensitization by stacked structures containing three or four kinds of dyes for further spectral widening. The structures were fabricated by liquid-phase molecular layer deposition (LP-MLD) using the electrostatic force between p-type dyes accepting electrons (rose bengal (RB), eosine (EO)) and n-type dyes donating electrons (crystal violet (CV), brilliant green (BG)). After p-type dyes of p1 and p2 were deposited on ZnO, n-type dyes of n1 and n2 were deposited to connect them to p1 or p2. [ZnO/EO/CV+BG] exhibited a broad photocurrent spectrum extending to the long wavelength region beyond 600 nm. In [ZnO/RB+EO/CV+BG], although a strong sensitization was observed in the long wavelength region, the photocurrent decreased in the short wavelength region. These results will be explained by the energy-level schemes determined using the photoemission yield spectroscopy in air.