Preparation Of Inorganic Solid-state Electrolytes And Their Application In Dye-sensitized Solar Cells

Dye-sensitized solar cells?DSSCs?are a type of solar cells developed by imitating the principle of photosynthesis.As an important part of DSSCs,electrolytes directly affect the photoelectric properties and stability of DSSCs.Two widely used electrolytes are the redox couples Co³⁺/Co²⁺and I^-/I₃^-.State-of-the-art,DSSCs based on Co?II/III?tris?phenanthroline?liquid electrolytes and the co-sensitization of organic dyes obtained the highest power convert efficiency?PCE?of 14.30%.Although DSSCs based on liquid electrolytes can achieve a higher PCE,liquid electrolytes are expensive and prone to leaks,resulting in poor stability of DSSCs.In order to reduce costs and improve the long-term stability of DSSC,the development of cheap and more stable solid-state electrolytes has become an important topic in DSSC research and development.In order to reduce the production cost and improve the stability of DSSCs,this paper carried out the following research work:?1?The surface of the two-dimensional material Ti₃C₂ is loaded with a large number of functional groups such as hydroxyl groups and fluorine groups.After calculation,it is known that Ti₃C₂O₂ is a narrow-bandgap semiconductor,and the load functional group can be changed to determine the change of the bandgap.The adjustability of the energy band structure means that this material has the possibility of replacing the I^-/I₃^-redox pair as an electrolyte.Preparation conditions of Ti₃C₂O₂:?1?etch Al of Ti₃AlC₂ with HF acid to prepare Ti₃C₂,?2?intercalate Ti₃C₂ with tetrabutylammonium hydroxide?TBAOH?,?3?sinter under low temperature and oxygen atmosphere,generating Ti₃C₂O₂ and apply it as solid-state electrolyte in DSSCs.Then we used processed methods such as scraping,spraying and others to apply it onto the solid-state electrolyte in the DSSCs.However,the PCE is low.The main reason is that the conduction band position of Ti₃C₂O₂ is lower than the HOMO energy level of the dye,which cannot effectively prevent the electrons from being transferred to the counter electrode.At the same time,the connection between the Ti₃C₂O₂ sheets and between the Ti₃C₂O₂electrode and the dyed TiO₂ layer is not tight,resulting in increased resistance and lower efficiency.Although the PCE is low,it proves the feasibility of this method and provides a new idea for the future application of Mxene in DSSCs.?2?The valence band of CuI?about-5.1 eV?can match the HOMO energy level of most photosensitive materials.At the same time,the higher CuI conduction band?-2.0 eV?can prevent electrons from being transferred from the LUMO energy level of the photosensitive material to the counter electrode.The hole mobility of CuI material is 43.9 cm²/?V·s?.It is in a stable state at room temperature and exhibits the characteristics of a p-type semiconductor.Therefore,we selected CuI as the solid-state electrolyte for the preparation of DSSCs.First,we select a suitable solvent?acetonitrile?to dissolve CuI to prepare DSSCs.And then,we explore the effect of 4-tert-butylpyridine?TBP?and LITFSI on solar cell efficiency.We found that when 15 mg CuI was dissolved in 1 ml of acetonitrile and 75?L of TBP and 90?L of LITFSI were added to it,the efficiency of the solar cell was the highest at 7.3%.Then we prepared the quasi-solid-state dye-sensitized solar cell?qssDSSCs?and solid-state dye-sensitized solar cell?ssDSSCs?by solvent evaporation and other methods,and the PCE was 4.36%and 2.32%respectively.This research provides a new possibility for designing high-efficiency ssDSSCs.