Dye-Sensitized Solid-State Photovoltaic Cells Based on Dye Multilayer−Semiconductor Nanostructures

The efficiency of dye-sensitized solar cells may be further improved if ways are found to broaden the spectral response resolving the fundamental issues involved. Here we report construction of dye-sensitized solid-state photovoltaic cells with heterostructure configurations: [1] n-TiO 2 /D 1 /p-CuSCN, [2] n-TiO 2 / p-CuSCN /D 2 / p-CuSCN and [3] n-TiO 2 /D 1 / p-CuSCN /D 2 /p-CuSCN, where n-TiO 2 is a ∼10 μm thick nanocrystalline film of titanium dioxide, p-CuSCN and p-CuSCN are thin (∼ 2 nm) and thick (∼ 10 μm) films of copper(I) thiocyanate. Monolayers of the dyes D 1 (Fast Green) and D 2 (Acridine Yellow) are coated on TiO 2 and p-CuSCN, respectively. The cell of configuration [3] delivered the highest efficiency, open-circuit voltage, and short-circuit photocurrent as it effectively utilizes the light adsorbed by D 1 and D 2 . The mechanism of operation involves tunneling of energetic electrons and holes liberated in photoexcitations of dyes through a thin barrier of p - CuSCN . The strategy adopted indicates the possibility of designing more efficient dye-sensitized solar cells, widening the spectral response.