The solar power is one of the most attractive energy sources from all types of renewable energy sources. Nowadays, the conversation of sunlight to electrical power by using of photoelectrochemical cells is the promising functional approach. In the given article we consider the operation principles of these devices. The issues of possible replacement of widely used mediators on the basis of iodide/triiodide redox electrolyte, possessing a number of shortcomings, on new redox mediators on the basis of transitional metals complexes are discussed.
