title: New approach to the reduction of recombination in dye-sensitised solar cells via complexation of oxidised species.
abstract: Although dye-sensitised solar cells (DSSCs) have received great attention as low-cost and clean energy conversion devices, their conversion efficiency still lags behind that of inorganic solar cells. One of the reasons is due to the recombination of injected electrons with the oxidised species of the redox couple that are present in the electrolyte near the surface of the bare TiO2 particles. While most research has focused on blocking the bare surface of the TiO2 nanoparticles, we have introduced a new approach that can directly reduce the concentration of the oxidised species of the redox couple present in the electrolytes through complex formation. Recombination was reduced by the addition of cyclodextrins (CDs) to a polyethyleneglycol dimethyl ether (PEGDME) electrolyte containing iodide/triiodide redox couples that can form a complex with the triiodide. Experimental and theoretical investigation of the complex formation between triiodide and the CD in PEGDME matrix was performed. Increase in total power conversion efficiency was achieved using the alpha-CD as an additive in a low volatile PEGDME based electrolyte. Electrochemical impedance spectra and intensity modulated photovoltage spectroscopy measurements showed that the increase in the short-circuit current density is due to the suppression of surface recombination by the complex formation between the CDs and the triiodide ions.
authors.affiliation: Department of Chemistry, Sejong University, 98 Gunja, Gwangjin, Seoul 143-747, Korea.
authors.forename: Hong-Kyu
authors.initials: HK
authors.lastname: Song
authors.forename: Jinsun
authors.initials: J
authors.lastname: Yoon
authors.forename: Jongok
authors.initials: J
authors.lastname: Won
authors.forename: Heeyoung
authors.initials: H
authors.lastname: Kim
authors.forename: Min Sun
authors.initials: MS
authors.lastname: Yeom
mesh_terms: D004396:Coloring Agents / Q000737:chemistry*; D011211:Electric Power Supplies; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008422:Materials Testing; D049329:Nanostructures / Q000737:chemistry* / Q000528:radiation effects / Q000648:ultrastructure; D009930:Organic Chemicals / Q000737:chemistry*; D010084:Oxidation-Reduction; D012993:Solar Energy
chemical_list: D004396:Coloring Agents; D009930:Organic Chemicals