| Abstract:Modification of different metallic ions doped TiO2was used to solve the technical problem of wider band gap (3.2eV) and recobminaiton between electrons and holes for applications of nanometer titanium dioxide in dye sensitized solar cell. Metallic ions doped TiO2always introduced impurity energy levels and surface defect position, increased the electronic capture and reduced the probability of recombination between electron and hole, improving the photoelectric conversion efficiency.But so far, doping research have mostly focued on individual metallic ions doped TiO2to modify photoelectric performance without conducting a comprehensive comparison and systematical research on different types and concentration of metallic elements doped TiO2and two kinds of metallic elements co-doped TiO2.In this study,4kinds of the first transition metal elements (Manganese, Iron, Cobalt, Zinc), two kinds of IIA metal elements (Magnesium and Calcium) and1kind of IIIA Aluminum elements single doped TiO2and Calcium-Iron, Zinc-Magnesium co-doped TiO2were prepared by hydrothermal method for new film electrode.The microstructure, phase composition, element structure, the surface electron binding energy spectrum, ultraviolet visible light of TiO2thin films before and after doped TiO2was investigated by using XRD, SEM, EDX, TEM and XPS, UV-Vis analysis method. The flat band potential of TiO2film electrode was studied after various metallic ions doped by electrochemical Mott-Schottky test method; the kinetic parameters of the electrons in the film, including electronic transport speed and the recombination probability were analysed with light intensity modulation optical current/voltage spectrum measurement techniques; and the influence of uv-visible absorption spectrum, dynamic performance, the band structure of TiO2thin film on the photoelectric performance of dye sensitized solar cell (DSSC) were analyzed through theoretical analysis method. The above mentioned methods are beneficial to develop high performance semiconductor nano crystal film for work electrode of DSSC.The main conclusions of this paper are as follows:1、Doped TiO2crystal grains of seven kinds of metallic elements were prepared under the same condition.The grain size is about the10～15nm. Doping metallic ions were distributed evenly in the TiO2nano crystal phase.The morphology of doped thin films show groove; Zinc metal elements doping TiO2thin film electrode modification effect is ideal in the first transition series.The photoelectric conversion efficiency of electrode doped is7.68%, mainly due to the electronic transmission time increased and the recombination time is the lowest.Band potential shift positively, which leads to energy level spacing between the electrodes and dye the lowest empty orbital increases, the electron injection efficiency increased.2、TiO2crystal particles of different doping amounts of Iron, Zinc,Magnesium and Calcium were prepared. Ti2p3/2and Ti2p1/2binding energy decreased after doped TiO2mainly due to electronegativity difference between three types of titanium metal atoms and atomic caused.When Iron doping amount is2.0mol%, the open circuit photovoltage reached maximum value, its value is645mv, mainly because the flat band potential of doped iron film appeared negative shift, and energy level difference between the lowest empty orbital of dye and TiO2reduced, potential difference between the oxidation reduction and TiO2increased.2.0mol%calcium doped TiO2, absorption wavelength of the thin film electrode move to visible light wavelengths,the electron transfer rate increased by55.2%, the photoelectric conversion efficiency is8.35%.3、The crystal particles of different doping amounts of Calcium-Iron and Zinc-Magnesium co-doped TiO2were prepared.Photoelectric performance test results show that the ideal doping concentration is1.0mol%, the photoelectric conversion efficiency are6.07%and9.07%respectively, increased by17.6%and26.7%. IMPS data show that mainly because of the zinc and magnesium composite electronic transport speed increase after doping. And the photoelectric conversion properties of zinc-magnesium composites doped TiO2obviously better than that of the single Zinc or Iron doped TiO2.4、It was found that joint effect of band potential and the rate of electron transmission and recombination of TiO2thin film electrodes on photoelectric performance through metal ion doping TiO2thin film, the reasonable balance among them can be obtain by optimization of doped TiO2thin film electrode; Also it was found that there is inversely proportional relationship between the ration of electron transmission and recombination and photoelectric conversion efficiency of doped TiO2. |
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