Peg Matrix Polymer Electrolyte Dye-sensitized Solar Cells And Low Platinum Loading Of The Electrodes

Dye-sensitized solar cells (DSSC) have been one of hot-spots in the field of materials for photoelectric conversion and nanotechnology because of its low-cost, easy-made and high-efficiency. It makes sense in research dye-sensitized solar cells not only in the aspect of groping the manufacture way for low cost and high performance solar cells but also in the aspect of its scientific values in the fields such as semiconductor photoelctronics, nanometer porous material, organic electrolytes and photo-electric chemistry. In this paper, the research progress of DSSC in domestic and overseas was reviewed. In order to solving present problems of the electrolyte and the electrode in DSSC, the polymer electrolyte of PEG matrix and the counter electrode with low platinum loading were studied. In this dissertation, different kinds of polymer matrix electrolytes were researched in order to improve the overall solar energy conversion efficiency and long-term stability of the DSSC. The transmission mechanism of the ionic conductivity in the polymer electrolyte and the affects of various compositions of the polymer electrolyte on the performances of DSSC were discussed. The counter electrodes of low platinum loading were also prepared and researched in order to obtaining the counter electrodes with high activity and low cost for application in DSSC. There are some major works in the following:1. Polyblend electrolytes consisting of KI and I2 dissolved in a blending polymer of polyvinyl pyrrolidone (PVP) and polyethylene glycol (PEG) were prepared and applied to DSSC. And the effects of polyblend electrolytes were investigated to improve the photovoltaic performance of DSSC. The influence of KI concentration on ionic conductivity of the polymer electrolyte was studied. Its result has also been proved by estimation using the ion pair model. By study different inorganic salts, it is concluded that the high solubility and good performance can be attained when potassium iodide was used. By study the character of conductivity-temperature for polymer electrolyte, it was found that followed the Arrhenius principle. The formation of I3? in polymer electrolytes had been characterized by XPS. The effects of polyblend polymer electrolytes on the DSSC were also evaluated. The light-to-electricity conversion efficiency of the DSSC assembled with optimized electrolyte composition was calculated to be 4.01%. The polyblend electrolyte showed the more stable than the liquid electrolyte, the total efficiency changes in the range of±5% for two month.2. The cross-linked PEG-1000 was prepared by condensation reaction with tetraethoxysilane (TEOS). With the cross-linked PEG-1000 as polymer host, the highest ionic conductivity of the polymer electrolyte was achieved 3.12 mS·cm-1. FT-Raman spectra were obtained to confirm the formation of I3? and polyiodides (I2n+3?, here n = 1, 2, 3,…) and complete dissolution of iodine in the polymer electrolyte. Based on the optimized cross-linked PEG electrolyte, the best result of the quasi-solid state dye-sensitized solar cell (QS-DSSC) was the light-to-electricity conversion efficiency of 4.97%. The polymer electrolyte also showed the good stable for application in DSSC.3. Platinum nanoparticles were electrodeposited on FTO conducting glass substrate as counter electrode for application in dye-sensitized solar cells (DSSC). Images of TEM and SEM showed that platinum nanoparticles were with the mean size of 20-30 nm and homogeneously distributed on the surface of the FTO conductive glass sheet. Using such a counter electrode, DSSC showed 6.40% overall energy conversion efficiency under one sun illumination. It exhibited the same high-performance as the DSSC with a platinum counter electrode prepared by electroplating. Furthermore, the present preparation method for the platinum counter electrode has the advantage of low platinum loading.4. Pt/Carbon black counter electrode was prepared for application in DSSC. The image of TEM and XRD pattern showed that platinum was successfully supported and homogeneously dispersed on the carbon black powder. The cyclic voltammetry reveals that the Pt/Carbon black electrode showed high electrocatalytic activity in iodide/triiodide redox reaction. Using such a counter electrode with low platinum loading (1.5 wt% platinum loading on carbon black), DSSC achieved 6.72% overall energy conversion efficiency under one sun illumination. It exhibited the same high-performance as the DSSC with a platinized counter electrode.Based on above result of the research, we hope that the reference could be offer for further study in DSSC and the techniques and technological parameters could be provided for practical application of DSSC.