Lee, K.-M.K.-M.LeeChen, P.-Y.P.-Y.ChenLee, C.-P.C.-P.LeeHo, K.-C.K.-C.HoKUO-CHUAN HO2018-09-102018-09-102009http://www.scopus.com/inward/record.url?eid=2-s2.0-65049089488&partnerID=MN8TOARShttp://scholars.lib.ntu.edu.tw/handle/123456789/347908In this study, binary ionic liquids (bi-IL) of imidazolium salts containing cations with different carbon side chain lengths (C = 2, 4, 6, 8) and anions such as iodide (I-), tetrafluoroborate (BF4-), hexafluorophosphate (PF6-) and trifluoromethansulfonate (SO3CF3-) were used as electrolytes in dye-sensitized solar cells (DSSCs). On increasing the side chain length of imidazolinium salts, the diffusion coefficients of I3- and the cell conversion efficiencies decreased; however, the electron lifetimes in TiO2 electrode increased. As for different anions, the cell which contains 1-butyl-3-methyl imidazolium trifluoromethansulfonate (BMISO3CF3) electrolyte has better performance than those containing BMIBF4 and BMIPF6. From the impedance measurement, the cell containing BMISO3CF3 electrolyte has a small charge transfer resistance (Rct2) at the TiO2/dye/electrolyte interface. Moreover, the characteristic frequency peak for TiO2 in the cell based on BMISO3CF3 is less than that of BMIBF4 and BMIPF6, indicating the cell with bi-IL electrolyte based on BMISO3CF3 has higher electron lifetime in TiO2 electrode. Finally, the solid-state composite was introduced to form solid-state electrolytes for highly efficient DSSCs with a conversion efficiency of 4.83% under illumination of 100 mW cm-2. The long-term stability of DSSCs with a solidified bi-IL electrolyte containing SiO2 nanoparticles, which is superior to that of a bi-IL electrolyte alone, was also presented. © 2009 Elsevier B.V. All rights reserved.Dye-sensitized solar cells; Electrochemical impedance spectroscopy; Ionic liquid; Long-term stability; Solid-state electrolyte[SDGs]SDG7Cell conversion efficiencies; Cell-based; Characteristic frequencies; Diffusion coefficients; Dye-sensitized solar cells; Electron lifetimes; Hexafluorophosphate; Imidazolinium salts; Imidazolium; Imidazolium salts; Impedance measurements; Long-term stability; Room-temperature ionic liquids; Side chain lengths; Small charges; Solid-state electrolyte; Tetrafluoroborate; Cells; Charge transfer; Conversion efficiency; Electrochemical corrosion; Electrochemical impedance spectroscopy; Electrolysis; Ion exchange; Ionization of liquids; Nanoparticles; Negative ions; Photoelectrochemical cells; Photovoltaic cells; Salts; Silicon compounds; Solar cells; Solid electrolytes; Ionic liquidsjournal article10.1016/j.jpowsour.2009.01.080