Study On The Synthesis Of Multifunctional Conductive Gel Electrolytes And The Performances On Quasi-solid State Dye-sensitized Solar Cells

At present, liquid electrolyte, which is commonly used in DSSC, reduces the long-term stability of the cell and limits the commercialization of DSSC due to the volatile, difficult packaging and other shortcomings. In order to improve the long-term stability and the photoelectric conversion efficiency of DSSC, quasi-solid conductive gel electrolyte are synthesised based on poly(acrylic acid)-cetyltrimethylammonium bromide (PAA-CTAB) and polyacrylate/poly (ethylene glycol) (PAA-PEG) matrix and I-/I3- redox is loaded. The preparation progress, reaction mechanisms, characterization and so on are detailed.In order to solve easily leaks, volatile problems of the liquid electrolyte and enhance the long-term stability, electrochemical properties of entire cell device, the conductive polymer Polyaniline (PANi) or Polypyrrole (PPy) was added in the PAA-CTAB matrix to form PAA-CTAB/PANi, PAA-CTAB/PPy, PAA-CTAB conductive gel electrolyte, respectively. The results show that the interconnecting conductive paths in the PAA-CTAB matrix, formed by PANi, PPy, are in favor of shorting the transmission distance of electrons, increasing the reduction reaction area between I3- ions and electrons and improving the transmission rate of electrons. At room temperature, the ionic conductivities of PAA-CTAB/PANi, PAA-CTAB/PPy and PAA-CTAB is 8.55,7.93,6.38 mS cm-1, respectively. In comparison with 6.07% for pure PAA-CTAB based DSSC, the power conversion efficiencies of 7.11% and 6.39% are recorded from PAA-CTAB/PANi and PAA-CTAB/PPy based DSSCs, respectively. This showed that PANi, PPy can significantly improve the electrical conduction and electrocatalytic performances of the electrolyte. Conductive polymers are introduced into quasi-solid-state electrolyte in the study and this provide a new way for the study of electrolyte. The application of the conductive polymers in the quasi-solid DSSC can be conducive to preparing DSSC with high-performance.Nano-carbon materials have many advantages, such as:excellent conductivity, small particle size which help molecular diffuse into PAA-CTAB matrix, wide material source and so on. In this study, PAA-CTAB matrix was prepared by free radical polymerization, then the freeze-dried matrix was immersed in a saturated liquid electrolyte solution containing grapheme (G), graphene oxide (GO), nanographite (NG), while the freeze-dried substrate was immersed in a liquid electrolyte containing no nano-carbon material as a reference. The liquid electrolyte was diffused into the PAA-CTAB matrix under the osmotic pressure and the capillary action and PAA-CTAB/G, PAA-CTAB/GO and PAA-CTAB/NG conducting gel electrolytes were obtained after adsorption equilibrium. Ionic conductivities of 10.56, 9.91 and 7.33 mS.cm"1 were recorded from PAA-CTAB/G, PAA-CTAB/GO and PAA-CTAB/NG at room temperature. This indicates that graphene, graphene oxide, nanographite effectively improve the electrical properties of the electrolyte. Power conversion efficiencies of 7.11% and 6.39% are recorded from PAA-CTAB/PANi and PAA-CTAB/PPy based DSSCs, respectively, in comparison with 6.07% from pure PAA-CTAB based DSSC. This shows, graphene, graphene oxide, nanographite can improve the electrochemical properties of the electrolyte.As can be seen from the above two-stage fabrication, graphene has the potential to significantly improve the electrochemical properties of the electrolyte. In order to preparation the quasi-solid electrolyte with excellent properties, graphene was doped into Polyacrylic acid-polyethylene glycol (PAA-PEG) matrix to fabricate the PAA-PEG/G conducting gel electrolyte. To optimize the experimental program, the graphene contents were controlled:0%-5%(m石墨储/m单体), with the other experimental conditions keeping unchanged. The results showed that the conductive gel electrolyte which graphene content was 3% had excellent electrical conductivity, and power conversion efficiencie of 7.41% was recorded. To increase the content of graphene in the conductive gel electrolyte and enhance the electrochemical performance of the electrolyte, porous PAA-PEG/G with diffent content of graphene were immersed in a liquid electrolyte containing graphene. Photoelectric conversion efficiency of 8.30% was obtained from the DSSC assembled by the electrolyte which graphene content was 3%.In this study, PAA-CTAB and PAA-PEG were prepared by free radical polymerization. The influence of the conductive material and nano-carbon material on the electrical, electrochemical performance of electrolyte was discussed. And applied the electrolyte to DSSC, measured photoelectric conversion efficiency, open up a new direction for the pioneering of electrolyte, pushing the DSSC research process.