Development of Lower Cost Monolithic Dye-Sensitized Solar Cell with Carbon Counter-Electrode

Abstract

Dye-sensitized solar cells (DSSCs) were developed as low-cost and environmentally friendly alternatives to other types of solar cells. However, due to efficiency and stability shortcomings, and also because of the cost reductions in crystalline Si cells, DSSCs are not yet commercially successful. Several parameters have to be improved, one of which is the cost that should be reduced further. There are two ideas to achieve this: the platinum electrode can be substituted by a cheaper carbon electrode, and the sandwich structure of the cells, with two glass substrates with a transparent conducting oxide (TCO) layer on them, can be changed to a monolithic structure, in which only one TCO-coated glass substrate is used. In the present project the performance of such monolithic cells with carbon counter-electrode is compared to the performance of cells with sandwich structure that are otherwise identically constructed. The performance assessment was done by means of an I-V curve measurement. The main result is that monolithic cells have a lower efficiency. The data indicate that the internal serial resistance of the monolithic cells was higher than in the sandwich cells. In a further step, three monolithic cells were interconnected in series in a submodule, and the performance of this submodule was assessed. The result indicates that the serial resistance of the three cells that were interconnected in the submodule, including the contacts, was lower than three times the serial resistance of the individual cells including the contacts. This shows that there is a potential for a more efficient usage of monolithic cells by means of a module design that allows for lower resistances in the interconnection of the cells within the module as well as in the module contacts. This should be pursued in further research, as well as the reduction of the internal resistance of the monolithic cells.