Photoelectrochemically polymerized polythiophene layers on ruthenium photosensitizers in dye-sensitized solar cells and their beneficial effects

Beneficial effects of polythiophen layers on ruthenium (Ru) photosensitizer in dye-sensitized solar cells (DSSCs) are observed. The thiophene is photoelectrochemically polymerized by the photoexcitation of Ru photosensitizers on TiO2. In situ polymerization enables the formation of uniform polythiophene layers on Ru-complexes/TiO2. The polythiophene layers have hydrophobic nature and bridge the energy level between Ru-complexes and iodine/iodide, which suppress the recombination reaction and improve the concentration of photoinjected electron in TiO2 layers. The DSSCs with polythiophene protecting layers shows a power conversion efficiency of 6.01%, which is a 30% increase compared to one without polythiophene layers.