Electrolytes Based on Binary-Redox Couples for High Voltage Dye-Sensitized Solar Cells

Tuesday, 7 October 2014: 08:40
Expo Center, 2nd Floor, Gama Room (Moon Palace Resort)
N. C. D. Nath (School of Energy Engineering, Kyungpook National University), I. S. Jeong, J. C. D. Kim, C. C. D. Kim, and J. J. Lee (Konkuk University)
We prepared the interhalogen and halogen-pseudohalogen based electrolytes with multiple redox couples for high voltage dye-sensitized solar cells (DSSCs) and it was characterized by different electrochemical techniques. It was found that the additional interhalogen or halogen-pseudohalogen based redox systems, (I-, Br-)/I2Br- or (I-, SCN-)/I2(SCN)- can be formed by both chemically and electrochemically. The electrochemical redox potential for these both couples is more positive than that of conventional iodide-triiodide system while the redox reaction involved with these ions were essentially comparable to that of I-/I3- in the conventional DSSC. Therefore, the formation of these redox couples produces extra redox states at more positive potential than I-/I3- couple, which contributed to increase the open circuit voltage (Voc) of DSSCs by shifting positively the equilibrium potential of solution phase. The interhalogen based redox couple increased open circuit voltage (Voc) significantly regardless of sensitizing dyes, which corresponded to 14% higher overall power conversion efficiency (h) compared to that with conventional iodine based redox couple. However, the degree of potential shift, so the corresponding Voc, can be controlled by adjusting the ratio of the concentrations of these redox species in the solution phase. This study is offering a very promising strategy to develop a novel electrolyte of which the energy level can be controlled by introducing an additional redox species with more positive potentials without compromising the rate of regeneration of dyes.