Preparation、Properties And Photoelectric Conversion Mechanism Of Dye-Sensitized Solar Cell Photoanode

Dye-sensitized TiO₂solar cells with strong visible light response, highphotoelectric conversion efficiency, environment-friendly and low cost, and hasbroad prospects for development in the new energy development. However, in theprocess of the photoelectric conversion, photo-generated electrons will compositewith photo-generated holes of the valence band by the surface of the photoanode andinterface defects, such as surface oxygen vacancies energy levels, which wouldreducing the photoelectric conversion efficiency. In response to these problems, inthis paper we designed and prepared a series of new nano-titanium dioxide electrode,a detailed study of the physical and chemical properties of the thin-film electrode,photoelectric conversion efficiency of dye-sensitized solar cell and discuss itsphotoelectric conversion mechanism. The main points could be summarized asfollows:1、TiO₂-5, TiO₂-10and TiO₂-20samples prepared by modified TiCl4hydrolyzed,have different properties on surface. Then they were further surface-sensitized withthe Rup2P（Ru（phen）2（PIBH） complex）for surface sensitization film electrode ofRup2P/TiO₂-5/ITO, Rup2P/TiO₂-10/ITO and Rup2P/TiO₂-20/ITO. The measuredresults of photovoltaic properties of the three films revealed that Rup2P/TiO₂-10/ITOis best and the Rup2P/TiO₂-5/ITO is worst. We analyzed the energy band structures,properties on surface of Rup2P and the three TiO₂samples using DRS, SPS, PL andphotocurrent action spectrum; studied the photo-induced charge transfer process withcyclic voltammograms under irradiation and photocurrent action spectra. The resultsrevealed the oxygen vacancy at the TiO₂surface was very important for thephoto-induced charge transfer process of Rup2P/TiO₂-X/ITO, and further more wediscussed the photocurrent mechanism of Rup2P/TiO₂-X/ITO.2、We prepared surface-modified TiO₂nanoparticle （TiO₂-Inx%） by using sol-gelmethod. By using N719（[NaRu（4,40-bis-（5-（hexylthio）thiophen-2-yl）-2,20-bipyridine）（4-carboxylicacid-40-carboxylate-2,20-bipyridine）（NCS）2]） as thesensitizing agent, the N719/TiO₂/FTO and N719/TiO₂-Inx%/FTO film electrodes were prepared. Under the solar cell structure of the thin film electrodes, thephotoelectric conversion efficiency of all the N719/TiO₂-Inx%/FTO film electrodeswere higher than that of N719/TiO₂/FTO, and the photoelectric conversion efficiencyof the N719/TiO₂-In0.1%/FTO was enhanced by20%than that of N719/TiO₂/FTO.We analyzed the band structure and presence of In ion in TiO₂-Inx%samples usingXRD, XPS, DRS, PL spectra and surface photocurrent action spectra. Thephoto-induced charge transfer process of the N719/TiO₂-Inx%/FTO film electrodeswere studied by surface photocurrent action spectra. The results show that the speciesO-In-Cl（nn=1or2）are formed at the TiO₂surface, and the surface state energy levelsof the species locates at0.3eV below the conduction band of TiO₂. The surface stateenergy levels of the species can effectively inhibit the recombination ofphoto-generated carrier in the process of photocurrent generation, increase the anodicphotocurrent, and improve the photoelectric conversion efficiency ofN719/TiO₂-Inx%/FTO thin film electrode significantly. And the charge transfermechanism in the light-induced interfacial is further discussed.3、We prepared Sn ions doped TiO₂nanoparticle （TiO₂-Snx%） by using sol-gelmethod. By using N719as the sensitizing agent, the N719/TiO₂/FTO andN719/TiO₂-Snx%/FTO film electrodes were prepared. We analyzed the bandstructure and presence of Sn ion in TiO₂-Snx%samples using XRD, XPS, DRS, PLspectra and surface photocurrent action spectra. The results show that the Sn ionssubstituted the lattice titanium ions in TiO₂lattice. And thus, the doping energy levelwas located at0.1eV below the conduction band of TiO₂; The energy levels of thespecies can effectively inhibit the recombination of photo-generated carrier in theprocess of photocurrent generation, increase the anodic photocurrent. Under the solarcell structure of the thin film electrodes, the photoelectric conversion efficiency of allthe N719/TiO₂-Snx%/FTO film electrodes were higher than that of N719/TiO₂/FTO,and the photoelectric conversion efficiency of the N719/TiO₂-Sn0.2%/FTO wasenhanced by46%than that of N719/TiO₂/FTO. The photo-induced charge transferprocess of the N719/TiO₂-Snx%/FTO film electrodes were studied by surfacephotocurrent action spectra. And the charge transfer mechanism in the light-inducedinterfacial is further discussed. 4、We prepared B ions doped TiO₂nanoparticle （TiO₂-Bx%） by using sol-gelmethod. By using N719as the sensitizing agent, the N719/TiO₂/FTO andN719/TiO₂-Bx%/FTO film electrodes were prepared. We analyzed the band structureand presence of Sn ion in TiO₂-Bx%samples using XRD, XPS, DRS, PL spectra andsurface photocurrent action spectra. The results show that the B ions gap-type dopinginto the TiO₂lattice; the doping energy level was located at0.1eV on the valenceband of TiO₂. The B doped TiO₂can effectively inhibit the recombination ofphoto-generated carrier in the process of photocurrent generation, increase the anodicphotocurrent. Under the solar cell structure of the thin film electrodes, thephotoelectric conversion efficiency of the N719/TiO₂-Bx%/FTO film electrodes werehigher than that of N719/TiO₂/FTO, and the photoelectric conversion efficiency ofthe N719/TiO₂-B0.05%/FTO was enhanced by15.8%than that of N719/TiO₂/FTO.The photo-induced charge transfer process of the N719/TiO₂-Bx%/FTO filmelectrodes were studied by surface photocurrent action spectra., and the chargetransfer mechanism in the light-induced interfacial is further discussed.