Calculati̇on of electronic properties of doped dye-sensitized solar cells

Dye-sensitized solar cells are structures which consist of dye molecules are held to metal-oxides layer. The purpose of this study is to develop structures which will enhance the efficiency of solar cell by doping foreign atoms on metal-oxide layer in dye-sensitized solar cells.The main ones are these effecting efficiency of dye-sensitized solar cells: Wave lenght range that dye molecule absorb photon(Visible region 400-800nm), HOMO-LUMO levels of TiO2, dye molecule and electrolyte and forgive band gaps, holding energy to metal-oxide layer surface of dye molecule, electron injection times etc. In this study the metal oxide layer was taken as the TiO2 (Titania) material which is generally used in these cells. First of all, there-dimension bulk calculations of TiO2's anatase and rutile phases were performed. Bonding energies were calculated for anatase phase 2.0 eV and rutile phase 1.85 eV. Secondly, the surface geometries of these phases were optimized using ionic relaxation methods. We determined the most energetically favourable structure of the system by embedding the dye molecules to certain chemically active points on optimized anatase or rutile surfaces. We used a specific type of molecule in Boradiazaindacenes (BODIPY) dye family as a dye in our calculations. The final geometries are in good agreement with the literature. Finally, we discusssed the effect of doping of foreign atoms such as N, B, Al, Zn and Nb on the efficiency of dye-sensitized solar cells. Electron injection times were performed on the purpose of dopping's effects of these foreign atoms to dye-sensitized solar cell efficiency can be seen. (Electron injection times for anatase-dye molecules system bonding modes 4.7 fs, 5.1 fs, 5.9 fs ve 1.5 fs). The density of states figures were plotted for each doped structures. Electron injection times were examinated by way of these figures. We expect that the study will provide an important insight to the scientific groups and companies working experimentally on dye-sensitized solar cells before production level in our country. This thesis was supported by TUBITAK project number: 112T771.