Theoretical study of an asymmetric A-π-D-π-D-π-A′ tribranched organic sensitizer for dye-sensitized solar cells

Abstract

An asymmetric A-{\pi}-D-{\pi}-D-{\pi}-A' tribranched organic dye (dye1) with a cyanoacrylic acid and an indolinum carboxyl acid as electron acceptors and a triphenylamine as an electron donor was designed and theoretically investigated for dye-sensitized solar cells (DSSCs). Dye1 was compared to reference well-known dyes with single electron acceptors (D5 and JYL-SQ6). Density functional theory and time-dependent density functional theory calculations were used to estimate the photovoltaic properties of the dyes. Due to the different lowest unoccupied molecular orbital levels of each acceptor and the energy antenna of the dual electron donor (D-{\pi}-D), the absorption spectrum of each branch displayed different shapes. Considering the overall properties, the asymmetric A-{\pi}-D-{\pi}-D-{\pi}-A' tribranched organic dye exhibited high conversion efficiency performance for DSSCs. The findings of this work suggest that optimizing the branch of electron donors and acceptors in dye sensitizers based on asymmetric A-{\pi}-D-{\pi}-D-{\pi}-A' tribranched organic dye produces good photovoltaic properties for DSSCs.