Study Of Dye-sensitized Solar Cells Based On PVDF-HFP Gel Electrolytes

Dye-sensitized solar cells have the advantages of low cost,easy processing,no pollution etc.They can be used in building claddings,electronic products,and textiles as the generators.Gel electrolyte DSSCs,however,are more promising by virtue of their high stability and long life.DSSCs fabricated with poly?vinylidene fluoride-co-hexafluoropropylene??PVDF-HFP?gel electrolytes were studied in this paper.Glycerol,kaolin and montmorillonite were respectively added into PVDF-HFP polymer membranes?PMs?.The additives were contributed to the increase of porosity and decrease of crystallinity for PMs,the increase of ionic conductivity for gel electrolyte,and the improvement of photoelectric conversion efficiency for DSSC.The main studies and results are summarized as follows:1.Glycerol was added into polymer solution,which increased the diameter of PMs through delaying the time of phase separation of polymer in the process of immersion precipitation phase inversion.The morphology and porosity of PMs were characterized by scanning electron microscopy?SEM?and n-butanol uptake method,respectively.The ionic conductivity???and diffusion coefficient?I₃^-?(D_ss)of polymer gel electrolytes?PGEs?were measured by AC impedance?ACI?test and linear sweep voltammetry?LSV?test.The J-V curves and EIS measurement indicated that with the addition of 80 wt%glycerol,the lowest resistance and the highest short-circuit current density(J_sc)and efficiency???of DSSC were obtained.The optimum level of photoelectric conversion efficiency???reached 7.29%,increased 4.3%compared with the control group.2.The kaolin was modified with silane coupling agent KH550,and then it was added into PVDF-HFP solution at various ratios.The obtained modified kaolin?M-KL?was characterized by SEM and Fourier-transform infrared spectroscopy?FTIR?.The results of X-ray diffraction?XRD?and differential scanning calorimetry?DSC?indicated that the crystallinity of PMs decreased with the addition of M-KL nanoparticles.The?and D_ss of PGEs reached optimum values of 9.452×10^-3 S cm^-1and 10.37×10^-6 cm² s^-1 for 3 wt%M-KL,respectively,which contributed to higher J_scc and?of the corresponding DSSCs.The optimum level of?reached 7.48%,the increase of 16.3%compared with the DSSC without M-KL.3.The modified montmorillonite?M-MMT?was added into PVDF-HFP membranes.A series of measurement of PMs,PGEs and DSSC indicated that the optimum amount of M-MMT was 3 wt%,and at this point the?of DSSC reached7.57%,which achieved 12.2%performance improvement.The comparison between gel and liquid electrolyte DSSC showed that with the addition of appropriate amounts of additives the gel electrolytes DSSC presented higher stability and without loss of efficiency.