Studying Of Titanium Dioxide Photoanode For Dye Sensitized Solar Cells

As a broad prospects for the development of wide band gap semiconductor materials, Anatase titanium dioxide has been received extensive attention, especially in dye-sensitized solar cell attract in-depth study of the majority of scholars. In the dye-sensitized solar cell, the urgent problem is the photoelectric conversion efficiency and the stability of the absorption of the dye.This paper proposes a method for verifying the first-principles model geometry convergence test, the main significance lies in the convergence test accuracy and repeatability of the results of far-reaching significance. According to this method, tests the convergence the cutoff and k-point of anatase titanium dioxide, calculates the energy structure and density of states and optical properties of anatase titanium dioxide, the result shows anatase titanium dioxide directly with intrinsically gap semiconductor; by the analysis of the conduction and valence bands near the Fermi level, clearly constitute the mechanism of the conduction band and valence band; by the analysis of the optical properties, the absorption coefficient in 5 11.0 10 cm-′ agnitude, demonstrates thin crystal structure can achieve strong absorption of light energy.Secondly, in order to further improve the utilization of energy, and improve the photoelectric conversion efficiency, the paper calculate the doped titania photoanode Depending on the doping concentration of doping atoms, single, double and three atoms dopant are calculated. The results show that with increasing concentration of doping, titania photoanode exhibits optical properties very satisfactory and the three-atom doping case is the best option. In this case, the band gap size 1.251 eV, although the band gap there is a clear size reduced, but the composition of the Fermi level near the conduction band and valence band do not change significantly. For the case of two-atom doping, discuss in detail the influence of the doping on the size of the bandgap, doping symmetrical structure due to the oxygen atom microstructure symmetrical force causes the bandgap more narrow level, indicating the position can affect the essential characteristics of the entire structure. Although symmetrical doping effect outstanding, but the effect is not as in the case of three-atom doping ideal.Finally, according to the calculation of reasonable dopant location and the dopant concentration, study the adsorption properties of the dye molecules on the anatase titanium dioxide(101) surface. This paper studies-COOH,-CN,-OH three kinds of dye molecules functional groups, analyzes the stability of three dye molecules on the(101) surface of pure anatase titanium dioxide adsorption. The results show that under the same calculation conditions, the functional group with –COOH is proven to be the greatest. In addition, calculate and analysis the stability of the dye molecules with the functional group with –COOH on different doping levels and different doping position on the(101) surface, the final results show that the double-doped symmetrical structure the maximum adsorption energy, this structure is ideal.This paper compromise between the structural characteristics of photoanode and the stability of the dye molecules on the(101) surface of the anatase titanium dioxide, we get the conclusion is :the ideal dye molecules dye molecules with-COOH functional groups, and the photoanode choose the symmetrical structure of double-atoms doped, not only meet with the reasonable photoelectric conversion efficiency, but also meet the stability of the dye molecules adsorbed.