The Research Of The Dye-Sensitized Nanocrystalline TiO₂ Solar Cells

The dye-sensitized solar cell (DSSC) based on TiO₂ have been attracted much attention because of easily fabrication, low cost, and high theoretical conversion efficiency. In this thesis, TiO₂ nanoparicle films was synthesized by using sol-gel and hydrothermal methods, and the reactive conditions depended photoelectronic properties of the DSSC were investigated by adopted differential thermal analysis, scanning electron microscopy, atomic force microscope, X-ray diffraction and photoelectric detection, include:TiO₂ powder was synthesized by using sol-gel method, then it was deposited on ITO glass to form films, after that the films was annealed at certain temperatures and the crystal structure and photoelectric properties (of the DSSC) were investigated. It is found that the as-deposited film was amorphous and transformed to anatase structure at 300℃. And from anatase to rutile at 600℃. The average crystalline size was 17.58 nm at 300℃, and increased to 49.55 nm at 800℃. The DSSC made by anatase TiO₂ had the best photoelectric performance, with the open voltage 0.53 V, and short-circuit 5.11 mA/cm2, investigated by a self-constructed I-V measurement system. TiO₂ powder was synthesized by using hydrathermal method, and then was deposited, dye-sensitized and sealed to form DSSC. We have investigated the chemical reaction conditions have influences with the performance of the cells, and found: The photoelectric conversion efficiency will increase slightly with the increasing of the Ti4+ concentration; The conversion efficiency will increase and then decrease with the increasing of the thickness of the TiO₂ layer, the maximal efficiency 4.09% happens at the thickness of 9.3 um; If the TiO₂ nanoparticles were thermal-treated by NaOH solution after they were synthesized, the conversion efficiency increased to 4.16%.The results showed that, by increasing the Ti4+ content, and NaOH thermal treating, the crystal structure and surface morphology can be manipulated, and then the performance of the DSSC can be improved. In addition, we can improve the conversion efficiency of the dye-sensitized solar cells through controlling the thickness of the TiO₂ film.