Dye-sensitized solar cells: improvement of spectral response by tandem structure

A tandem structure was introduced to improve the spectral response of dye-sensitized solar cells (DSC) without loosing their high external quantum yield. Light absorption models of DSC were proposed, and light harvesting efficiency (LHE) and incident photon-to-current conversion efficiency (IPCE) were calculated using absorption spectra of dye-adsorbed TiO2 electrode, electrolyte, and conducting glass support. The IPCE of single DSCs fabricated using two typical ruthenium complexes were measured to present the improvement of the spectral response without loosing their high external quantum yield by tandem structure. As a result, the tandem structured cell exhibited higher photocurrent and conversion efficiency than each single DSC mainly caused from its extended spectral response.