Investigation of Dye Regeneration Kinetics in Sensitized Solar Cells by Scanning Electrochemical Microscopy

Sensitizers are responsible for the light harvesting and the charge injection in dye‐sensitized solar cells (DSSCs). A fast dye‐regeneration process is necessary to obtain highly efficient DSSC devices. Herein, dye‐regeneration rates of two DSSC device types, that is, the reduction of immediately formed photo‐oxidized sensitizers (ruthenium complex C106TBA and porphyrin LD14, kox′) by iodide ions (I−) and [Co(bpy)3]2+, and the oxidation of formed photo‐reduced sensitizers (organic dye P1, kre′) by triiodide ions (I3−) and the disulfide dimer (T2) are investigated by scanning electrochemical microscopy (SECM). We provide a thorough experimental verification of the feedback mode to compare the kinetics for dye‐regeneration by using the above mentioned mediators. The charge recombination at the dye/semiconductor/electrolyte interface is further investigated by SECM. A theoretical model is applied to interpret the current response at the tip under short‐circuit conditions, providing important information on factors that govern the dynamics of dye‐regeneration onto the dye‐sensitized heterojunction. Watching regeneration: Dye‐regeneration and charge recombination at the dye‐sensitized nanocrystal/electrolyte heterojunction in dye‐sensitized solar cells are investigated by scanning electrochemical microscopy. A theoretical model is applied to interpret the current response at the tip under short‐circuit conditions providing important information on factors that govern the dynamics of dye‐regeneration.