Degradation chemistry of RuLL´(NCS)2 complexes in the Dye-sensitized solar cell

In the last decade dye-sensitized solar cells (DSCs) have extensively been studied. From an economical point of view DSCs are of high interest because the manufacturing costs of DSCs devices are significantly lower in contrast to the costs of other solar devices such as silicon cells. One of the success criteria required for commercial use of DSCs is high stability under light soaking and thermal stress conditions. The dye sensitizer is one of the key components of a DSC device. Consequently, the stability of DSCs is directly linked to the dye stability which is in turn linked to its degradation on the surface of a semiconductor anode (TiO2). In order to be able to predict the life time of the dye during solar cell operation it is essential to map all the possible side reactions and their rates initiated from the excited (S*), oxidized (S+) and ground state of the sensitizer (S). In my lecture I will present and overview of our degradation investigations of the ruthenium dyes N719, Z907 and C106 with the general structure RuLL´(NCS)2 and show how detailed degradation mechanistic knowledge is important in the developing of DSC cells with improved thermal dye stability. The various ruthenium dye degradation products have been identified and quantified by extensive use of HPLC coupled to electro spray mass spectrometry (LC-ESI-MS).