Photoanode And Stability Study Of Dye-sensitized Solar Cells

As a novel green energy conversion device,dye-sensitized solar cells(DSSCs)have attracted increasing attention due to the low cost and facile manufacture.DSSCs mainly consist of three components:photoanode,electrolyte and counter electrode,and the kernel part is the photoanode,because it plays a significant role in electron transport and dye adsorption.And thus,its physico-chemical microstructures have significant influence on the photoelectric conversion efficiency of DSSCs.The most used photoanode is TiO2 film,in which the particle size,pore structure,thickness and the adsorption capacity of dye determine the photo electric conversion efficiency of DSSCs.In this thesis,in order to clarify the internal relationship between the structure of photoanode and the photoelectric conversion efficiency of DSSCs,the slurries composed of carbon and TiO2 nanoparticles were used to prepare TiO2 photoanode,aiming for high adsorption capacity of the dye.The pore structure of TiO2 film was regulated with the amount of carbon nanoparticles,and then a series of TiO2 film shave been easily prepared,and used to study the relationship among the pore structure,dye adsorption capacity and photoelectric conversion efficiency.These researches would provide technical support for the development of DSSCs.In the second part of this thesis,the influences of chemical composition and mass ratio of theco-sensitized dye systems on the photoelectric conversion efficiency of DSSCs were studied.These work provides a meaningful exploration for pure organic co-sensitized solar cell.Details are as the follows:1.Firstly,the effects of preparation parameters of Ti02 film on the photoelectric property of DSSCs were investigated.The results showed that the composition of TiO2(-20 nm)slurry and the subsequent drying process have remarkable influence on photoelectric property of DSSCs,which is mainly attributed to the changed pore structure of TiO2 film.Secondly,under optimized experimental conditions,a series of composite slurry containing carbon nanoparticles(100-200 nm)and TiO2(-20 nm)nanoparticle shave been prepared,to investigate the relationship among the adsorption capacity of dyes,the photoelectric property of DSSCs and the pore structure of TiO2 film,in which carbon nanoparticle shave been removed by calcination.The results indicated that,the surface area of TiO2 film,dye adsorption capacity and photoelectric property of DSSCs increased with increasing the carbon nanoparticles mass ratio in the composite slurry.In case of carbon nanoparticles mass ratio of 3%,the photoelectric conversion efficiency of DSSCs with dye(E)-3-(5'-(4-(bis(1,3-dihexyl-2-thioxo-2,3-dihydro-lH-benzo[d]imidazol-5-yl)amino)phenyl)-[2,2'-bithiophen]-5-yl)-2-cyanoacrylic acid(AZ6)increased to 7.34%from 6.61%.Finally,fixed the coating number of thin film at 3,the effect of the coating sequence and coating number of carbon/TiO2 composite slurry on the photoelectric property of DSSCs were studied.The results showed that,when the carbon/TiO2 composite slurry and TiO2slurry were used interchangeably to prepare the photoanode film,the location and layer number of carbon/TiO2 composite slurry have influences on the photoelectric property of DSSCs.On optimized experiment condition,the photoelectric conversion efficiency of DSSCs with dye AZ6 increased to 7.77%from 6.61%.A reasonable explanation is that,the location and number of the pore formed in photoanode film after removing carbon nanoparticles by calcination can enhance the dye adsorption capacity,resulting in an improved photoelectric conversion efficiency.2.The influence of three novel co-sensitizers(with pyridine group and liquid crystal characters)on the photoelectric property of DSSCs with dye AZ6 was investigated.The results showed that,the molecular structure,concentration and sensitization time of these co-sensitizers are important factors toregulate the property of DSSCs.Under the optimized condition,the co-sensitizer 4-(2-(4-(2-(4-propylcyclohexyl)ethyl)phenyl)ethynyl)pyridine(3N)is helpful to improve the photoelectric property,and specially benefit to the long-term stability of DSSCs,resulting in a very small drop of 8.56%for the photoelectric conversion efficiency of DSSCs over 1000 h,which suggests it is entirely feasible to control the property of DSSCs with suitable co-sensitizers.