Tandem dye-sensitized solar cells consisting of floating electrode in one cell

Tandem dye-sensitized solar cells (Cell TAN) consisting of a floating electrode (bottom cell) and a TiO2 electrode prepared on a F-doped SnO2 glass (top cell) are reported. The floating electrode is a flexible and self-standing composite film consisting of a porous titania/dye layer supported by a mesh electrode. The floating electrode was inserted between the TiO2 electrode and the counter electrode in a conventional single dye-sensitized solar cell to fabricate the Cell TAN. Therefore, the Cell TAN is completely different from previously reported tandem cells where two cells are merely accumulated and connected to each other. The Incident Photon to Current Conversion Efficiency (IPCE) curve for the Cell TAN had two peaks corresponding to those of the two single cells. The open circuit voltage (Voc) of the Cell TAN (0.88 V) was higher than that of the corresponding single cell (0.6–0.66 V). These two results strongly demonstrated that the Cell TAN has a potential for tandem cells.