Professor Marsan and his team have been working for several years on the design of an electrochemical solar cell. His work has involved novel technologies, for which he has received numerous patents. In considering the problems of the cell developed by his Swiss colleague, Professor Marsan realized that two of the technologies developed for the electrochemical cell could also be applied to the Graetzel solar cell, specifically:
* For the electrolyte, entirely new molecules have been created in the laboratory whose concentration has been increased through the contribution of Professor Livain Breau, also of the Chemistry Department. The resulting liquid or gel is transparent and non-corrosive and can increase the photovoltage, thus improving the cell’s output and stability.
* For the cathode, the platinum can be replaced by cobalt sulphide, which is far less expensive. It is also more efficient, more stable and easier to produce in the laboratory.
Dye-sensitized solar cells (DSCs) have achieved impressive conversion efficiencies for solar energy of over 11% with an electrolyte that contains triiodide/iodide as a redox couple. Although triiodide/iodide redox couples work efficiently in DSCs, they suffer from two major disadvantages: electrolytes that contain triiodide/iodide corrode electrical contacts made of silver (which reduces the options for the scale up of DSCs to module size) and triiodide partially absorbs visible light. Here, we present a new disulfide/thiolate redox couple that has negligible absorption in the visible spectral range, a very attractive feature for flexible DSCs that use transparent conductors as current collectors. Using this novel, iodide-free redox electrolyte in conjunction with a sensitized heterojunction, we achieved an unprecedented efficiency of 6.4% under standard illumination test conditions. This novel redox couple offers a viable pathway to develop efficient DSCs with attractive properties for scale up and practical applications.
A Novel Organic Redox Electrolyte Rivals Triiodide/iodide in Dye-Sensitized Solar Cells