Design Principles and Top Non-Fullerene Acceptor Candidates for Organic Photovoltaics

Non-fullerene acceptors in organic photovoltaics (OPVs) continue to improve upon the shortcomings of many fullerene-based solar cells. We explored the chemical space of over 51,000 non-fullerene acceptors featuring 106 common moieties from the organic electronics literature, including naphthalene diimides, benzathiadiazoles, and fused fluoroanthenediimides. We identify top candidates featuring optimal energy level offsets, based on a well-studied electron-donor: poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)]. The Harvard Clean Energy Project infrastructure was employed through the IBM World Community Grid to carry out quantum mechanical calculations using density functional theory. Gaussian processes regression was utilized to correct the computed frontier molecular orbital energies. Additional time-dependent density functional theory calculations on a subset of the top candidates refined the narrow band-gap chromophores for OPVs. These results on electron-acceptor materials complement the electronic structure calculations of over one million electron-donor materials publicly available through our website.