Preparation And Application Of Counter Electrodes In Dye-sensitized Solar Cells

Dye-sensitized solar cells(DSSCs)have become one of the third-generation solar cells because of its low cost,simple process,large area printing and excellent performance characteristics.The counter electrode is an important part of dye-sensitized solar cells,usually composed of conductive substrate and catalytic material.Now the most common counter electrode is the FTO conductive glass coated with a layer of catalytic Pt film.The FTO substrate is used to collect the electrons in the external circuit.The catalytic material mainly catalyzes the regeneration of the redox couple in the electrolyte,and thus the reduction and regeneration of the dye is ensured.Therefore,it is very important to find a suitable method for the preparation of highly conductive polymer and low Pt loading counter electrode.In this paper,we used different types of counter electrode materials used as the research object and different preparation process to carry out the following innovative research.The photoelectrochemical performance of DSSCs assembled by different electrodes is the key research.The main conclusions are summarized as follows:(1)Firstly,the preparation conditions of in-house iFTO conductive glass were explored.It was found that the sheet resistance of the iFTO glass prepared at 450 ? wasthe smallest,so the optimum preparation temperature was 450 ?.Then,the Pt//iFTO electrode was prepared by spray-coating on the glass slide by spraying the precursor of F-doped SnO2 and the solution of chloroplatinic acid.The transparency of Pt//iFTO electrode was higher than traditional Pt electrode.(4,60)Pt//iFTO electrode with an Pt coating time of 4 s and an iFTO coating time of 60 s displayed an efficiency of 6.77%,comparable to the efficiency of the traditional Pt electrode.And the fill factor was 0.66,which was consistent with that of traditional Pt electrode.And the biggest bright spot of the method is to combine the formation of the Pt catalyst layer and the iFTO conductive layer into one body,with less energy consumption,simple operation,cost saving and less Pt loading.The method has the advantages of low cost and simple equipment,and provides a new synthesis method for the catalytic material which needs high temperature treatment.(2)A low-temperature immersion method was used to deposit a Ni conductive layer on the ground glass substrate.The sheet resistivity of Ni layer was about 2 ? sq-1 and was used as a conductive substrate.The Pt/Ni electrode was prepared by the low-temperature immersion method and high-temperature decomposition method,respectively.The Pt/Ni electrodes prepared by the two methods were compared with the surface morphology,Pt loading,photovoltaic properties and electrocatalytic activity.It was found that the Pt particles on Pt/Ni electrodes prepared by low-temperature impregnation were mono dispersed,uniform in particle size and uniform in Pt loading.However,the Pt/Ni electrodes prepared by high temperature decomposition method has a very serious agglomeration on the surface,and the Pt loading is much larger.The Pt/Ni electrodes prepared by the low temperature impregnation method has the optimized Pt content of only 15.4 ?g cm-2,but its photoelectric conversion efficiency is 7.88%,which is much higher than that of sputtered Pt with the loading of 53.6 ?g cm-2(7.55%),and the Pt loading efficiency was 6.59%for 91.2 ?g cm-2 Pt loading.(3)Polypyrrole(PPy)thin films were synthesized on FTO conductive glass by low temperature in-situ synthesis.The transparent PPy electrodes were obtained by using FeCl3 as oxidant(dopant),sodium dodecylbenzenesulfonate(SDBS)as surfactant and pyrrole as monomers.When the concentration of FeClh was 0.2 M,the cell efficiency was the highest(7.00%).The obtained PPy electrode was first subjected to hydrazine reduction treatment and then iodine vapor oxidation treatment.When the concentration of FeCl3 was 0.2 M,the highest 'cell efficiency was 7.45%.The low temperature in-situ synthesis method has the advantages of wide sources,simple operation steps,and no post-treatment such as high-temperature treatment or purification.It provides a new choice for the preparation of similar conductive polymer counter electrode.(4)The derivatives of three pyrrole monomers were synthesized and the polypyrrole derivative films were synthesized by chemical oxidation and used in DSSCs.It was found that only poly-3-ethylpyrrole was used in DSSCs to achieve good photoelectric conversion efficiency,and the efficiency was up to 6.44%.The necessary conditions for the application of materials in DSSCs are considered from a series of characterization,especially from the view point of UV-visible and electrochemical tests,and provide experimental and theoretical support for further research.