Özet:

Due to its electronic properties, Zinc Oxide (ZnO) is one of the important materials used in new generation solar cells. However, it is necessary to increase the working efficiency of pure ZnO with the rays coming from the sun. Doping with foreign atoms is one of the important techniques in this sense. In this study, the doping of ZnO crystal with Se atom was investigated theoretically. Density functional theory (DFT) was used in the calculations. However, DFT+U correction was made in the calculations to correct the known errors of the theory. With this method, the band gap of pure ZnO was calculated at 3.27 eV. This value is close to the experimental value of 3.44 eV. The Se atom causes local distortions in the crystal structure. However, these deteriorations do not significantly change the characteristic properties of the ZnO crystal. Doping with Se mainly leads to a change in the electronic structure. When the Se and Zn atoms, which have more valence electrons, are replaced, two occupied energy levels are formed in the band gap, above the valence band maximum, due to impurity. These energy levels increase the light absorption activity of ZnO in the visible region. Another important data obtained is that the lack of oxygen in the Se-doped ZnO crystal positively affects the absorption activity in the visible region

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