Structural alternation of tandem dye-sensitized solar cells based on mesh-type of counter electrode

Tandem dye-sensitized solar cells (DSCs) are very effective to improve light absorption characteristics and overall performance. The structure of conventional tandem DSC is an assembly of two independent DSCs. Therefore, additional TiO₂ layer, Pt film, and transparent conductive oxide (TCO) electrodes weaken incident light to the bottom cell and complicate the fabrication as compared with standard DSCs. Here, this work proposed the structural alternation of tandem DSC as a solution. Mesh type of counter electrode was inserted between top and bottom cells instead of TCO electrodes. Two photo electrodes shared electrolyte and counter electrode in this structure. High aperture ratio of mesh increased light penetration into bottom cell and led to the performance improvement. Structural alternation also simplified the fabrication. It could be fabricated like standard DSCs. After dye arrangement and TiO₂ layer of bottom cell were controlled, the photovoltaic performance of proposed tandem DSC was enhanced and it was higher than conventional tandem DSC. Finally, the long-term stability of proposed tandem DSC was secured by the control of sealing walls.