Application Of Rare-earth Doped Ti-containing Oxides In Dye-sensitized Solar Cells

N3 and N719 dyes are usually used to sensitize electrodes of dye-sensitized solar cell(DSSC), and the sensitized electrodes mainly absorb visible light, but little ultraviolet and infrared light. However, rare-earth doped down/up-conversion luminescent materials can down/up-convert ultraviolet/infrared light which can’t be absorbed by DSSC to visible light that can be fully utilized by DSSC. It extends spectral response range to ultraviolet/infrared region, and leads to the improvement of photoelectric conversion efficiency. Sr Ti O3 with the typical perovskite structure has the characteristics of wide band gap width and good photocatalytic performance, and it is widely used in photocatalysis and photochemical battery fields. In the present work, SrTiO3, as the multiple semiconductor oxide, was used as matrix of rare-earth doped down-conversion luminescent material. Rare-earth doped SrTiO3 was applied as light conversion agent to DSSC, which provided a new efficient way to apply rare-earth doped luminescent materials to DSSC in order to improve the photoelectric conversion efficiency. The main obtained results are as follows:(1) SrTiO3:Ho3+ particles were synthesized through solid state interaction method, and the diameter and pore size were 40~400nm and 45 nm, respectively. Then the particles were used to prepare SrTiO3:Ho3+ down-conversion membrane anodes, and the effects of rare-earth doping content on the photoelectric performance of DSSC assembled with SrTiO3:Ho3+ anodes were studied. The as-prepared SrTiO3:Ho3+ anodes could convert ultraviolet light to visible light and thus improved the current density. Compared with the DSSC assembled with Sr Ti O3 anodes, the photoelectric conversion efficiency of the DSSC assembled with Sr Ti O3:Ho3+(the theory doping content of Ho2O3 was 1wt%) down-conversion anodes was enhanced by 60% and achieved significant increase of photoelectric performance.(2) SrTiO3:Sm3+ particles were prepared by hydrothermal method, and then Sr Ti O3:Sm3+@SiO2 core–shell particles were achieved by St?ber method. SrTiO3:Sm3+ and Sr Ti O3:Sm3+@SiO2 were doped in the nano TiO2 anode as down-conversion agent to study the effect of doping content on the photoelectric performance of DSSCs assembled with Sr Ti O3:Sm3+/TiO2 and SrTiO3:Sm3+@SiO2/TiO2 composite anodes. Compared with Sr Ti O3:Sm3+, SrTiO3:Sm3+@SiO2 particles possess weaker luminous intensity. But both of them have down-conversion function and can convert ultraviolet light to visible light, widen spectra response range. When the doping content of SrTiO3:Sm3+ was 10wt%, the photoelectric conversion efficiency of DSSC assembled with SrTiO3:Sm3+/TiO2 composite anodes reached 4.38% which was 27% higher than that of pure TiO2 anodes. With the doping content at 10wt%, compared with SrTiO3:Sm3+/TiO2 composite anodes, the photoelectric conversion efficiency of DSSC assembled with Sr Ti O3:Sm3+@SiO2/TiO2 composite anodes have certain enhancement and reached 5.07%. The significant improvement of photoelectric performance can be attributed to triple function of SrTiO3:Sm3+@SiO2 core-shell structure: inhibiting the recombination between electron and hole, scattering light and down-converting luminescence.(3) TiO2 nanowires/nanoparticles composite powders were successfully prepared by hydrothermal reaction for 16 h with P25 TiO2 as raw material. Combined nanowires’ promotion for electron transmission with nanoparticles’ larger relative surface area to absorb more dyes, the DSSC assembled with TiO2 nanowires/nanoparticles composite anodes achieved the photoelectric conversion efficiency of 2.75%. TiO2 nanowires were synthesized by hydrothermal reaction for 24 h and abtain TiO2:Ho3+ down-conversion nanowires after doped Ho3+ in it by dipping method. Then the effect of rare-earth doping content on their photoelectric properties of the DSSC assembled with TiO2:Ho3+ down-conversion nanowires were investigated. When the doping content of Ho2O3 was 4wt%, compared with TiO2 anodes, the photoelectric conversion efficiency of the DSSCs assembled with TiO2:Ho3+ down-conversion nanowires increased by double.