Application Of Quasi-solid-state Electrolyte In Dye-sensitized Solar Cell

Dye-sensitized solar cells(DSSCs)have attracted much attention and research due to their simple process,low cost and high photoelectric conversion efficiency.As the significant part of DSSC,electrolyte affects the process of electronic transmission and dye regeneration,those could ultimately affect the photoelectric performance and stability of the DSSC.At present,the photoelectric conversion efficiency(PCE)of DSSC based on liquid electrolyte has exceeded 14%.However,owing to the leakage and volatilization of solvents in liquid electrolyte,the fabrication of devices is difficult and the device life is shortened,which limits the industrialization process of DSSC.In order to solve these problems,a series of quasi-solid-state electrolytes are prepared.And the microstructure,mechanical properties,thermal stability,kinetics and photoelectric properties of DSSC are studied in detail.The main research contents are as follows:1.Two types of supramolecular gel electrolytes Gel 1 and Gel 2 by are prepared by mixing N,N?-1,3-propanediylbis-dodecanamide with hexamethylene diamine and adipic acid respectively.The microstructure and thermodynamic properties of two kinds of gel electrolytes are characterized.The effects of different microstructure on ionic diffusion and photoelectric performance of the DSSCs are analyzed.Meanwhile,the influence of acid/base in different quasi-solid electrolytes on electron transport and recombination kinetics in devices are studied in detail by IMVS/IMPS,CV and EIS.Due to the interaction between Li⁺ions in electrolyte and amide groups in Gel 1,the adsorption of Li⁺in the TiO₂ film surface is decreasing and the conduction band edge of TiO₂ in DSSC is negatively shifted,which leads to higher open-circuit voltage.In Gel 2,because adipic acid exists,H⁺will be ionized and adsorbed on the surface of TiO₂,which enhances the electron injection efficiency,making the short-circuit current of the quasi-solid-state DSSC larger than that of the liquid-state DSSC.Finally,the PCE of the quasi-solid-state DSSC based on Gel 2 is 5.89%,which is higher than that of the corresponding liquid-state DSSC.In addition,in the stability test,both quasi-solid-state DSSCs show excellent stability,which is greatly improved compared with the corresponding liquid-state DSSC.2.A novel Fe-TMA metallogel electrolyte is prepared by using the coordination bond between Fe³⁺and trimesic acid and applied to DSSC.The microstructure of the metallogel exhibits porous structure,which is conducive to the diffusion of ions in the electrolyte.In addition,it is found that the metallogel electrolytes prepared by different liquid electrolyte concentrations have an influence on the electrochemical and photoelectric properties of the cell,mainly due to the difference in the level of TiO₂conduction band edge and the electron recombination in the electrolyte/TiO₂ interface.With the concentration of absorbed liquid electrolyte increasing,the TiO₂ conduction band edge shifts negatively and then positively,and the electron recombination degree decreases first and then increases.Finally,by optimizing the concentration of electrolyte,a PCE of 5.31%is obtained for quasi-solid-state DSSC.3.A UV-cured polymer gel electrolyte with simple process,fast curing and high swelling rate is prepared by using PVCi as polymer monomer and 2-Hydroxy-2-methyl-1-phenyl-1-propanone as photoinitiator.The polymer exhibits a porous structure,which is conductive to the diffusion of ions in the electrolyte.Meanwhile,the thermal stability of the polymer is tested by TGA.The initial degradation temperature of the polymer is 130?,which is higher than the operating temperature of DSSC and inhibits the solvent evaporation.This thermostability of polymer gel electrolyte is bond to improve the long-term stability of DSSCs.Moreover,the dye regeneration ability and electrochemical performance of the DSSCs are studied by using transient PL spectrum and EIS.Finally,the mechanism of the effect of microstructure of the quasi-solid-state electrolyte on the electron transmission and the photoelectric conversion performance of the device is illuminated.