First-principles screening and design of C275-based organic dyes for highly efficient dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) are one of the most promising alternatives to traditional silicon-based photovoltaic cells. Herein, we have systematically investigated the optoelectronic properties of five dyes CD1-5 designed via the screened donor D1 and acceptors A4-8 based on experimentally synthesized dye C275 by using the density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. Compared to C275, the designed dyes exhibit the enhanced light-harvesting abilities where the absorption spectra are extended to the near-infrared region with the improvement of ~119 nm redshift maximum absorption wavelengths and widened light-harvesting efficiency (LHE) curves, ascribed to their more conjugated structures and narrower bandgaps. Mainly distributed by the obvious enhancement of ~42% for the theoretical short current densities (JscTheor.), the power conversion efficiency (PCE) of the designed dyes increases by more than 54% compared to C275. Consequently, dyes CD1-5 have the potentials to be the promising candidates with the overall efficiency beyond 18.8%. We believe that this work could provide theoretical guidance for designing potential organic sensitizers in high-efficiency DSSCs.