| Since the report of highly efficient(~10%) dye-sensitized nanocrystalline solar cell(DSSC) by M Gr?tzel, DSSC has become the most promising alternative to conventional silicon solar cell. It is currently under great investigation for its low cost, simple processes, stability, extensive application and little weight. In this thesis, the preparation of the nanocrystalline TiO2 electrode and its sensitization by phthalocyanine complexes were the emphases to study.⒈Eighteen phthalocyanine (Pc) complexes of cobalt, nickel, copper and zinc had been prepared by a simple method in the solid state in the presence of ammonium molybdate catalyst and carboxyl-, nitro- or amino-groups were induced around the periphery. The processes were optimized and the purification of the complexes was simplified. The synthesized complexes were characterized by elemental analysis, IR and UV-vis spectroscopy. All of the complexes show tow absorption bands of the B-band (200-400nm) and the Q-band (600-800nm) and the maxima of the absorption bands change with the central metals. An absorption band appears due to the face-to-face molecular association of the 18 π-electron conjugated systems, which extend the absorption of the sunlight spectra, and this absorption band of phthalocyanine nickel is much stronger than the complexes of other three metals. Compared with the corresponding complexes with the electron-withdrawing nitro-groups (TNPcM), the maxima of aminophthalocyanines' (TAPcM) Q-bands red-shift by 50-100nm. ⒉The TiO2 sol solution, the paste for the electrode, was prepared by the sol-gel method and hydrolysis of alkoxide, and the influence of reaction time, temperature and acidity on the diameters of the particles in the sol were studied. The sizes of particles in the colloid solution obtained by hydrolysis of alkoxide were larger than the particles obtained by the sol-gel method, and they could cover a more extensive range. The gel and the materials heated at different temperature or stored for different time were characterized by XRD, and the results were analyzed in the presence of the TG-DTA curves. Sintered at 450℃, the usual temperature at which the electrodes were treated, mixture of rutile and anatase was attained. By layer-by-layer screen printing, TiO2 multilayered films were obtained. The layer-by-layer assembly of the TiO2 films proceeded linearly as shown by sequential UV-vis absorption and so were the sintered films. The morphology of TiO2 nanocrystylline electrode sintered was characterized using SEM and AFM. The morphology of representative field on TiO2 electrode surface magnified different times showed the uniformity of the total and the high surface roughness was apparent for the numerous pores in the film, so it was competent for the electrode of DSSC.⒊The dye-sensitized electrode was prepared as follows: after removing the water adsorbed, the TiO2 electrode was immersed in the the solution of phthalocyanine in DMSO for 36h, and then was dried in vacuum. The dye-sensitized electrode was gently squeezed together with a ITO glass electrode coated with metal or carbon, and the redox electrolyte was attracted into the cavities of the dye-sensitized electrode by capillary forces. Several series of phthalocyanine compounds were chosen as the sensitizing dye and their photovoltaic behavior was investigated measuring the I-V curves of the cells. The major contributions were listed as follows: ⑴Overall conversion efficiencies of the cells sensitized by tetracarboxymetalphthalocyanines (TCPcM) with different central metal ions (M= Co, Ni, Cu, Zn) were compared, and there was a rule of Co﹤Ni﹤Cu﹤Zn. In order to suppressed aggregation of the phthalocyanine molecule on the surface of electrode, the n-dodecanoic acid was coadsorbed with the TCPcMs, and the efficiencies of the cells sensitized by TCPcM (M= Co, Ni, Cu) were improved while the efficiency of the cell sensitized by TCPcZn reduced tinily, it still obeyed the rule.⑵The influence of the structure of phthalocyanine complexes on the efficiency w...
|
PDF Full Text Request