Preparation Of Hydroxyl Ion Liquid Compound Electrolyte And Application Of It In The Dye Sensitized Solar Cells

Gel composite electrolyte is higher conductivity than the solid electrolyte and more stability than liquid electrolyte, due to liquid electrolyte has defections, such as easy leakage and hard to be sealed. Then conductivity of solid electrolyte is low and cann’t satisfy application in reality. However, gel composite electrolyte has advantages of liquid electrolyte and solid electrolyte, it has been always widely used in research and application about lithium-ion batteries and dye-sensitized solar cells. Thanks to a high conductivity, improved mechanical properties and thermal stability, gel composite electrolyte containing ionic liquids becomes one of the recent research focuses. Gel composite electrolyte ionic conductivity is lower than ionic liquids, and adding ionic liquids lead to larger ionic conductivity, but the mechanical strength of composite electrolyte membrane mechanical becomes weak. So the focus of research is enhancing conductivity of gel composite electrolyte. Dye sensitized solar cell has such advantages:stable performance, simple production process, low prices, etc. For those advantage, dye sensitized solar cell has become a new hot research area of photoelectric conversion. Because gel composite electrolyte as electrolyte in the dye sensitized solar cell has lower photoelectric conversion efficiency than silicon solar cells, improving the dye sensitized solar cell photoelectric conversion efficiency is the most important task. In this paper, the room temperature ionic liquid of1-(1-Hydroxyl-propane)-3-methylimidazolium tetrafluoroborate ([C3OHMIM]BF4) by two-steps were synthesized. Then a novel gel composite electrolytes containing the ionic liquid and polymers (PMMA and PHEMA) were prepared. The structures and properties of the gel composite electrolytes were characterized by FT-IR, AC and TG. The results show that with the m(polymer)/m([C3OHMIM]BF4) up to3:7, the maximum ionic conductivity of gel composite electrolyte with PHEMA-based is3.06×10-3S·cm-1, gel composite electrolyte with PMMA-based is6.43×10-3S·cm-1and gel composite electrolyte with P(HEMA-MMA)-based is3.87×10-3S·cm-1at room temperature. The conductive behaviour of the gel composite electrolytes follows the Arrhenius equation. The gel composite electrolytes had the maximum thermal decomposition with temperature over300℃. Those illustrate that gel composite electrolytes have great thermal stability.On the basis of the above, nano-SiO2and nano-TiO2particles to modifly PMMA-PC-[C3OHMIM]BF4, PHEMA-PC-[C3OHMIM]BF4, P(HEMA-MMA)-PC-[C3OHMIM]BF4were used as a kind of modiflied gel composite electrolytes with ionic liquid. The structure and properties of the gel composite electrolytes were tested by FT-IR, AC and TG. The results show that the maximum ionic conductivities of PMMA-PC-SiO2-[C3OHMIM]BF4, PHEMA-PC-SiO2-[C3OHMIM]BF4, P(MMA-HEMA)-PC-SiO2-[C3OHMIM]BF4, PMMA-PC-TiO2-[C3OHMIM]BF4, PHEMA-PC-TiO2-[C3OHMIM]BF4and P(MMA-HEMA)-PC-SiO2-[C3OHMIM] BF4are8.11×10-3S·cm-1,5.26×10-3S·cm-1,7.32×10-3S·cm-1,8.31×10-3S·cm-1,5.31×10-3S·cm-1and7.98×10-3S·cm-1at room temperature, respectively. The conductive behaviour of the gel composite electrolytes follows the Arrhenius equation. While the maximum thermal decomposi-tion has a temperature above300℃, the thermal stability of gel composite electrolytes are quite well.With PMMA, PHEMA, P(MMA-HEMA) as matrix and redox electricity of I-/I3-by KI and I2, the gel composite electrolyte was prepared to assemble Dye sensitized solar cells (DSSC). When the content of is10%(wt.), the total of optical efficiency is1.28%. With the higher of light intensity, η becomes larger. The different solvents have an impact on η, and the η is the greatest in the same conditions with ethanol and acetonitrile as the mixture solvents. The greatest optical efficiency of the Dye sensitized solar cells by gel composite electrolyte is that the content of P(MMA-HEMA) is10%(wt). Under irradiation simulated sunlight of100mW·cm-2, the open-circuit voltage of cell is0.70V, the short-circuit current density is1.104mA·cm-2and the total of optical efficiency is1.61%.