Research On Modified PEDOT Counter Electrode Of Dye-sensitized Solar Cells

The dye sensitized solar cell（DSSC）is a type of solar cell with relatively high photoelectric conversion efficiency and no pollution.It belongs to mesoscopic solar cells like quantum dot sensitized solar cells and mesoscopic perovskite solar cells.Photoelectrons generation and carrier transfer are two separate processes in this kind of batteries.Thus,there is no need to use p-n junction to achieve photovoltaic effect.In DSSC,the roles of the counter electrode are transfer electrons after collecting them and catalyzing redox couple by adsorbing them.In many researches,Pt is generally used as the counter electrode material.However,due to the high price and limited reserves of Pt,many researchers have been devoted to the development of new materials.Conductive polymer poly（3,4-ethylenedioxythiophene）（PEDOT）with catalytic activity,conductivity and green environmental protection performance is an excellent substitute for Pt electrode.In this thesis,modified PEDOT thin films were used as counter electrodes to assemble DSSC and its application was discussed as well.There are some major works and results as following.1)1 to 9 layers of PEDOT thin film electrodes were prepared by screen printing.As the layer of films increased,the surface roughness increased,and the resistance along with the transmittance decreased.The average transmittance of 1-layer PEDOT thin film was about66.3%when the incident wavelength is between 400nm and 550nm,but the average transmittance of 9-layer PEDOT thin film was less than 20%.The efficiency of the battery reached its peak at 6.19%with 4-layer PEDOT thin film.2)The optimal combination of rotational speed was 500rpm（first 5s）and 3000rpm（next 25s）of PEDOT film fabricated by spin coating method.The efficiency of the battery with 1-layer PEDOT thin film was 6.12%,which is higher than that with 2-layer PEDOT thin film（5.47%）.The efficiency of battery with 1-layer spin coating PEDOT thin film coated with DMSO directly was higher than that of PEDOT thin film coated with DMSO after drying,but both of that batteries’efficiencies were not much higher than that of pristine battery.3)The efficiency of the battery with H₂PtCl₆（0.1mol/L）doped PEDOT thin film was13%higher than of pristine PEDOT thin film battery.The efficiency of single LiClO₄ doped PEDOT thin film was lower than that of pristine PEDOT thin film battery.However,the appropriate concentration of double dopers made the efficiency increase by 11.8%compared with that of the undoped battery.The best performance of 7.51%was obtained when the PEDOT thin film was doped with 5wt%dimethyl sulphoxide（DMSO）,the value was 18%higher than that of the non-doping battery.The convenient doping method and simple film preparing process can make PEDOT film widely used in industrial applications.4)Two types of flexible batteries assembled by DMSO doped PEDOT thin film electrodes reached the highest efficiency when the doping amount was 5wt%.The efficiencies were 1.76%and 4.62%,respectively,which was 35%and 39%higher than that of undoped batteries.It is simple and efficient to use spin coating to fabricate PEDOT thin film on ITO-PET flexible substrate.