New Organic Dyes with Low Bandgap Based on Heterocyclic Compounds for Dye-sensitized Solar Cells Applications

In this paper, a theoretical study has been carried out. This study concerns four organic dyes with structure D–π–A on the base of triphenylamine; we choose thiophene and thieno [3, 4-b] pyrazine group as a donor and the group cyanoacrylic acid as an acceptor bridged by four conjugated spacers consisting of phenyl, pyrrole, thiophene, and furan. Our studied dyes' ground state geometric and electronic properties are calculated after optimization in their fundamental states with DFT / B3LYP / 6−311G (d, p). Using this method, EHOMO, ELUMO, bandgap energy, λmax, chemical reactivity indices, dipole moment, the Voc, molecular electrostatic potential (MEP), the LHE, the free injection energy (ΔGinj), the regeneration energy (ΔGreg), and the total reorganization energy (λtot) for all these dyes have been calculated and discussed. The optical properties such as Etr, the maximum wavelength (λmax), and the corresponding oscillator strengths have been carried out by the TD−DFT method at CAM–B3LYP/6–311G (d, p). The calculated results for all these dyes indicate that all these latters can be considered favorable candidates for an efficient DSSC sensitizer.