Tuning optical properties of triphenylamine-pyrrole by alkyl-substituted thiobarbituric acid for dye-sensitized solar cell

Nonfullerene acceptors (NFAs) have been recently explored to tune the organic dye-sensitized solar cells. We designed three alkyl derivatives of NFAs from thiobarbituric acid (TBT1) decorated the triphenylamine featuring pyrrole unit (TPAP) to yield TPAP-TBT1, TPAP-TBT2, and TPAP-TBT3 for the potential activity in solar cell applications. Density functional theory (DFT) calculations using B3LYP level of theory and b3lyp/6-311g(d) basis set was used for the structures optimization. The TD-DFT calculations were performed for the structures orbitals (HOMO and LUMO) calculations. The electronic structures of TPAP-TBT2 derivative show the transethyl group on the structure, which facilitates the binding (-15.6 kcal/mol) to the semiconductor surface (TiO2) rather than the steric-hindered N-benzyl derivative (-13.1 kcal/mol). TBT alkyl substituents facilitate the intramolecular charge transfer within the dyes and improved the D-pi-A electron mobility and the solar cell efficiency. The N-ethyl and N-benzyl derivatives showed better performance with respect to the calculated Delta G(inject) (-1.27) and (-1.22) and V-OC values (1.45) and (1.40), respectively.

Automated summary

Nonfullerene acceptors (NFAs) have been explored for organic dye-sensitized solar cells, with three alkyl derivatives designed from thiobarbituric acid and triphenylamine. Density functional theory (DFT) calculations and TD-DFT calculations showed that alkyl substituents facilitated intramolecular charge transfer, with N-ethyl and N-benzyl derivatives showing better performance in solar cell applications.