An automated quantum chemistry-driven, experimental characterization for high PCE donor--acceptor NIR molecular dyes

A readily accessible (less than four synthetic steps) dye molecule with potential properties well-beyond the current state-of-the-art for use in dye-sensitized solar cells (DSCs) is realized from extensive quantum chemical characterization of nearly 8000 stochastically-derived novel molecules. The synthesized molecule, 23ed_20b_1ea/WM3, possesses a julolidine electron donor group and promises to exhibit a 17.5% power conversion efficiency (PCE) if paired with a suitable redox shuttle based on practical performance analysis (and up to 26.8% in a tandem system). This represents a notable PCE increase for DSC technology. The stochastic quantum chemical analysis exploring molecular dyes is based on combinations of electron donors, pi-bridges, and electron acceptors to create the D-pi-A molecular dye design. The D-pi-A dye combinations are defined via SMILES strings and converted to Cartesian coordinates. The theoretical dyes then undergo density functional theory geometry optimizations, absorption computations, and molecular orbital analyses where a least squares fitting of two functionals minimizes the error with respect to benchmark experiment. While only a small percentage of the computed, novel molecular dyes have better properties than the current best performing benchmark molecular dyes, these still represent a notable increase in potential targets for subsequent experiment as evidenced by the experimental characterization of the synthesized 23ed_20b_1ea/WM3 molecular dye. A readily accessible dye molecule with potential properties well-beyond the state-of-the-art for dye-sensitized solar cells is realized from extensive quantum chemical characterization of nearly 8000 stochastically-derived novel molecules.