Modification Of Heterogeneous Junction Interface In TiO₂/Polymer Hybrid Solar Cells

In this paper,a one-dimensional ordered array of TiO₂ nanorods was fabricated on the FTO conductive glass substrate by hydrothermal method,and three amphiphilic trianiline organic dye molecules M with different structures were adsorbed on the surface as heterojunction interface modifiers to form FTO/TiO₂/M nanometer array structure.FTO/TiO₂/M/P3HT composite structure was prepared by spin-coating a layer of semiconducting polymer P3HT on the above-mentioned structure,and then assembled into the cell and tested the performance.The FTO/TiO₂/M3/PCPDTBT composite structure was formed by spinning another PCPDTBT thin film on the FTO/TiO₂/M3 structure by selecting the dye molecule M3 with the best interface modification performance.Urchin-like type TiO₂ with large surface was prepared by a simple controlled one-step solvothermal method.P25 type TiO₂ and urchin-like TiO₂ were prepared into FTO/P25/P3HT,FTO/P25/urchin-like TiO₂/P3HT and FTO/urchin-like TiO₂/P3HT hybrid system by screen printing,and organic molecule M3 was used to modify the interface of the cell heterojunction.The morphology,structure and photoelectric properties of the samples were measured and analyzed by SEM,XRD,HRTEM,EDS,contact angle test,UV-visible diffuse reflectance spectroscopy,fluorescence spectroscopy and photoelectrochemical properties.The specific research contents are as follows:1)An ordered array of TiO₂ nanorods was grown on the FTO conductive glass substrate by hydrothermal method.The morphology,crystal structure and photoelectric properties of TiO₂ nanorod arrays were investigated.2)By immersing TiO₂ nanorods in three kinds of amphiphilic triphenylamine organic M solution,we prepared FTO/TiO₂/M composite nanorod arrays.The energy level of M dye molecules was determined by combining the absorption spectra and cyclic voltammetry curves.The effects of different dye molecules on the optical absorption and photoelectric properties of FTO/TiO₂/M composite nanorod arrays were investigated.3)FTO/TiO₂/M/P3HT composite nanorod array structure was prepared by spin coating method,and FTO/TiO₂/M/P3HT composite structure was assembled into hybrid solar cell.The effects of different dye molecules on the photoelectric conversion properties of the cells were studied,and the working mechanism of the hybrid solar cells was discussed.The results show that the energy conversion efficiency of solar cells based on FTO/TiO₂/M3/P3HT is the highest.The short-circuit current density is 8.22 m A·cm^-2,the open circuit voltage is 371 m V,the filling factor is 0.51,and finally the conversion efficiency is 1.56%.4)The structure of FTO/TiO₂/M3/PCPDTBT was fabricated by spin coating method.The FTO/TiO₂/M3/PCPDTBT composite structure was assembled into hybrid solar cells.The results show that the short-circuit current density of the solar cell based on FTO/TiO₂/M3/PCPDTBT is 5.40 m A·cm^-2,the open circuit voltage is 488 m V,the filling factor is 0.31,and the conversion efficiency is 0.82%.5)The urchin-like TiO₂ nanoparticles were prepared on the FTO conductive substrate by screen printing method,and the structure of FTO/urchin-like TiO₂ nanostructure was formed.The effects of TiO₂ on the morphology,light absorption and photoelectric properties of FTO/urchin-like TiO₂ nanostructures were studied by comparing with FTO/P25,FTO/P25/urchin-like TiO₂.6)FTO/P25,FTO/P25/urchin-like TiO₂ and FTO/urchin-like TiO₂ structures were immersed in amphiphilic triphenylamine organic molecule M3 solution to prepare FTO/P25/M3,FTO/P25/urchin-like TiO₂/M3 and FTO/urchin-like TiO₂/M3 composite nanometer array.The effects of M3 dye on the optical absorption and photoelectric properties of FTO/urchin-like TiO₂/M3 composite nanocrystals were studied.7)FTO/P25/P3HT,FTO/P25/urchin-like TiO₂/P3HT,FTO/urchin-like TiO₂/P3HT and FTO/urchin-like TiO₂/M3/P3HT nanocomposite structures were prepared by spin coating method.The specific surface area advantage of urchin-like TiO₂ is beneficial to the separation and transfer of charge.Finally,the energy conversion efficiency of hybrid solar cells assembled by FTO/urchin-like TiO₂/M3/P3HT was the highest,and the conversion efficiency was 0.46%.