In this research, we evaluated the photovoltaic properties of the some organic dyes based on triphenyamine, which are composed of triphenylamine as the electron donor, cyanoacrylic acid and benzoic acid as the electron acceptors and varying -conjugated systems (Figure 1). All calculations were performed by density functional theory (DFT) [1], time-dependent (TD-DFT) [2] computations and natural bond orbital (NBO) [3] analysis at the M06-2X/6-311++G(2d,2p) level of theory. The calculated Gibbs energy of the electron injection from the dye to TiO2 (Ginj) and Gibbs energy of dye regeneration (Greg) of the dyes show that TC601 has the lowest value of the Ginj and Greg, which makes the electron transfer and dye regeneration process favorable, respectively. The results related to the charge transfer properties showed that TC601 dye has the longer charge transfer distance (DCT) and lower overlap of electron-hole distribution (S) due to the presence of a triple bond in the vicinity of triphenylamine. Also, the voltage-current curve of these compounds was studied theoretically and showed that the highest values of the short circuit current density and open-circuit voltage are related to TC601 and P1B dyes, respectively (Figure 2). Finally, based on the Gibbs energies, charge transfer properties and short-circuit current density, TC601 is proposed as the best candidate to be used in the DSSC.

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