The use of solar energy as a source of free, unlimited access, has led to the manufacture of solar cells. Conventional solar cells such as silicon or germanium semiconductor materials are made with good yields despite high costs. Thus, a new generation of solar cells as Dye-Sensitized Solar Cell have been studied. In this cell, light is absorbed by a colorful material and excite its electrons. Dyes have nano structure, so for increasing the amount of absorption, a slab is used. Among solar cells, Dye-Sensitized Solar Cell are cheaper, flexible, traarent and diversity in shape, color makes them important. The problem that these solar cells have and should be improved is lower efficiency. One of the ways for increasing efficiency is recovering dye as a light sensitive absorbent. In this article the optical spectrum of different groups of dyes such as Opv3, Nkx-2, Cyanine, D5, D7, Squaraine, C343, Alizarin have been studied. In these calculations Homo-Lumo gap and response charge density have been determined. Results have shown that with increase the size, Homo-Lumo gap decrease. We have used zinc oxide as a semi-conductor and studied electronical structure. For determination the number of layers, surface energy, calculations have shown of that the surface energy has not changed after six layer. Among dyes which have studied OPV3 trans-trans is chosen. It has lied on the ZnO. Calculated gap of this set has gotten lower compare to first dye. The calculation has done by turbo-TDDFT that is an implementation of the Liouville-Lanczos approach to linearized time-dependent density-functional theory on Quantum Espresso.
