In this work, the performance of several thieno [3, 2-b] thiophene based organic dye molecules as sensitizer in the dye-sensitized solar cell (DSSC) was investigated using the theoretical calculations. In this regard, the efficiency of electron transfer from the dye molecule to the conduction band of TiO2 was calculated in the gas phase and acetonitrile, separately. The calculation of the efficiency of electron transfer was performed based on the first and the most intense electronic transition, separately. It was observed that the dyes do not tend for the electron transfer in the gas phase while there is electron transfer in the solvent. Theoretical calculations showed that the dyes N1, N2 and, O1 have considerable negative free energy for the electron transfer to the conduction band of TiO2. Also, the effect of the increase of the length of conjugated carbonic chain between the bases of dye and their anchor groups on the electron transfer was investigated. It was found that the efficiency of electron transfer decreased by the increase of chain length. The adsorption of N1 molecule, as a good candidate for electron transfer, on the (001) and (101) TiO2 surfaces were investigated using periodic density functional theory calculations. Different initial geometries were selected for the adsorption of N1 molecule on the TiO2 surface and the adsorption energy for each configuration was determined. It was observed that the adsorption of N1 on the (101) surface is more suitable than that on the (001) surface.