Theoretical investigation of the effect of different π-spacers on the performance of dye-sensitized solar cells based on quinoline

Herein we report a heterocyclic organic system to be used in dye-sensitized solar cells. We propose 9 D-p-A compounds in with N,N-diphenyl quinoline-6-amine as the electron donor, cyanoacrylic acid as the electron acceptor, and various conjugate systems of thiophene is used as a p-spacers. The studied substance systems are calculated by density functional theory (DFT) method with 6-311G(d) basis set. This study focuses on examining the effect of the p bridge on the properties of the molecule. The structural parameters of the molecular geometry were optimized, the HOMO and LUMO energies were calculated and analyzed in detail. In addition, the absorption wavelength, excitation energy, vibration intensity and electron transfer were calculated through the time-dependent density functional theory (TD-DFT) method. The result shows that replacing thiophene ring by 3,4-ethylenedioxythiophene (EDOT) significantly improved the properties of dye. Compounds B12 and B23 have not only small HOMO-LUMO gap but also good charge transfer (small reorganization energies) and optical properties (high LHE).