Theoretical screening and design of SM315-based porphyrin dyes for highly efficient dye-sensitized solar cells with near-IR light harvesting

We screened five π-conjugated bridges and further designed four dyes FSQ101-FSQ104 with screened π-linker B1 as bridge, four electron-rich units D1-D4 as donors and electron-withdrawing cyanoacrylic acid as acceptor, based on experimentally synthesized dye SM315 for highly efficient dye-sensitized solar cells (DSSCs) using density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods. Our theoretical results reveal that designed dyes FSQ101-FSQ104 have not only remarkably better light harvesting abilities toward the near-infrared (NIR) region with broader light harvesting efficiency (LHE) curves and higher maximum short circuit current densities (Jscmax), but also obviously narrower band gaps, larger adsorption energies (Eads), lower exciton binding energies (EBEs), larger conduction band energy shifts (ΔECB) compared to dye SM315. Therefore, the designed dyes FSQ101-FSQ104 might have superior performances and could be promising sensitizer candidates for highly efficient DSSCs.