Density functional theory characterization and verification of high-performance indoline dyes with D–A–π–A architecture for dye-sensitized solar cells

Six indoline-based dyes 1–6 used in DSSCs with difference in π spacer were theoretically researched and verified using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) to shed light on how the additional (auxiliary) acceptor and π spacer order influence the performance of the dye. Key parameters associate with the short-circuit current density (Jsc) and open-circuit photovoltage (Voc), including light-harvesting efficiency LHE, electron injection driving force ΔGinject, total reorganization energy λtotal (λh and λe), the vertical dipole moment μnormal, the energy differences eVoc between ELUMO and ECB as well as the extent of electron recombination were characterized. The theoretical results reveal that compared with dye 1, dyes 2–6 improve the performance potentially due to their auxiliary acceptor. These enable us to determine these factors related to the Jsc and Voc can be significantly influenced by the incorporated electron-withdrawing subunit into molecular backbone.

► Electronic structure and photophysical properties of dyes 1–6 were studied.
► Quantum chemical calculations were performed to characterization the performance of DSSCs.
► D–A–π–A architecture is superior to traditional D–π–A system.
► π spacer sequence would influence the performance of dye largely.