Ultrafast photoinduced processes of organic dyes in IL/molecular solvent mixtures designed for dye solar cells – UPPiL_2_Ukraine

Among all the renewable energy sources, solar energy is the most powerful source far ahead wind or geothermal energies. The possibility of an efficient and low-cost direct conversion of the sunlight energy into electricity is a clear scientific and technological stakes. Dye-sensitized solar cell (DSSC) is a type of thin film solar cell. It provides a technically and economically viable concept. The state-of-the-art DSSCs' low efficiency and instability are the shortcomings of these promising devices. The foundation of UPPiL emerged from an important observation: changing the solvent of electrolytes may reduce drastically the power efficiency and affect the stability of DSSCs. Which dye/solvent interaction dominates these profound effects? What are the molecular rearrangements in the solvents of electrolytes influencing the stability and the efficiency? To answer this problematic, UPPiL aims at studying the effect of solvents of electrolytes (solvation dynamics) on the efficiency and on the long-term stability of DSSCs. UPPiL proposes to use a new class of tuneable media/solvents for electrolytes combined with three state-of-the-art sensitizers in DSSCs. UPPiL will take 2 steps (i) the study of the molecular rearrangements of solvent around the sensitizer after the photoexcitation and (ii) the simultaneous monitoring of time-resolved spectroscopic and electrical characteristics of DSSCs. UPPiL works at two interfaces: the interface of experimental with theoretical for the solvent’s characteristics investigations and the interface of ultrafast photophysical processes of the sensitizers (electron injection, regeneration) with transient electrical signals of DSSCs. UPPiL will benefit from the high degree of competence of LASIR in ultrafast time-resolved spectroscopy and will call upon the high expertise of LRCS in the realm of DSSCs conception and characterization. Indeed, LASIR is one of the largest time-resolved spectroscopy platforms in Europe (Raman, infrared, UV-Vis, fluorescence) and LRCS is a photovoltaic unit, recognized at the European level. Starting from our previous observations and generating new types of results, UPPiL will pave the way to new sensitizers and new optimized solvents development allowing the conception of high efficiency and long-term stability DSSCs.