Preparation And Performance Study Of Flexible Photoanode For Dye-sensitized Solar Cell

Dye-sensitized solar cells（DSSC）have high photoelectric efficiency,low cost,and good development prospects.However,traditional DSSC with conductive glass base is expensive,heavy and unbendable,which restricts the large-scale production and application of DSSC.These problems can be solved by replacing traditional conductive glass base material with flexible conductive base materials.Textiles are foldable and wearable,and can be used as the base of DSSC to prepare textile-based DSSC,which can be used as the energy collector of self-powered wearable electronic textiles and applied to medical care,military and sports and fitness fields.However,the flexible material is hard to withstand the sintering temperature of the preparation process of semiconductor layer,meanwhile the connection between TiO₂ particles in the DSSC prepared by low temperature method is not close enough and easy to break away from the substrate,which affect the photoelectric conversion efficiency and life of the battery.Furthermore the DSSC low-temperature preparation process is complex and difficult to be used commercially.In addition,the combination of dye sensitizer and semiconductor material has great influence on the photoelectric conversion efficiency of DSSC,but the related research is not sufficient now.In view of the above problems,this paper mainly carried on the following two aspects of research:（1）The flexible DSSC photoanode was prepared by TiO₂/Polyvinylidene Fluoride（PVDF）as photoanode material.TiO₂/PVDF photoanodes with different TiO₂ content,drying temperature and coating thickness were prepared by coating process,and then textile-based DSSC were assembled.The prepared TiO₂/PVDF film surface was continuous and uniform,TiO₂ particles were evenly dispersed in PVDF films,and there was no obvious crack on the film surface.PVDF acted as a three-dimensional skeleton to support and connect TiO₂ particles,making them attached to the surface of the conductive fabric more firmly and evenly.However,when the TiO₂content increased to 70%,obvious cracks appeared in the TiO₂/PVDF films.When drying temperature rised to 90℃,TiO₂ particles aggregated clearly,and the micro gap and defects of TiO₂/PVDF film increased.The dye adsorption capacity increased with the increase of TiO₂ content.When drying temperature was raised,dye adsorption quantity was reduced.With the increase of TiO₂ content,the light absorption of TiO₂/PVDF film was enhanced,and when the TiO₂ content reached60%,the light absorption of TiO₂/PVDF film was close to saturation.When TiO₂content was 60%,drying temperature 30℃and coating thickness 6 layers,the DSSC had the highest photoelectric conversion efficiency of 0.4292%and J_SC,V_OC,and FF were 2.7852 m A/cm²,0.536 V and 0.2875,respectively.（2）TiO₂ semiconductor film was prepared by high temperature sintering on conductive glass substrate.The adsorption properties of TiO₂ film on N719 dye and the effect of the dye sensitization conditions on the photoelectric properties of the cell were investigated.Firstly,the adsorption curves of the dye at different concentrations（0.2 m M,0.5 m M,0.8 m M,sensitization temperature of 20℃）and different sensitization temperatures（10℃,20℃,30℃,dye concentration of 0.5 m M）were measured.The results showed that the adsorption process of N719 by TiO₂ film conformed to the quasi-second-order kinetic equation,the adsorption isotherm of N719 conformed to the Langmuir isotherm model.Accordingly the adsorption of N719 by TiO₂ film was a monomolecular layer adsorption and an endothermic process.Secondly,the photoanodes sensitized by N719 were assembled into the cells and their photoelectric performance was tested.It was found that J_SC and photoelectric conversion efficiency were improved with the increase of dye sensitization time,and tended to level off after a certain time.In addition,it was found that the increase of photoanode area led to the decrease of the photoelectric performance of DSSC.