Terminally Chlorinated and Thiophene-linked Acceptor-Donor-Acceptor Structured 3D Acceptors with Versatile Processability for High-efficiency Organic Solar Cells.

To exploit the potential of our newly developed three-dimensional (3D) dimerized acceptors, a series of chlorinated 3D acceptors (namely CH8-3/4/5) were reported by precisely tuning the position of chlorine (Cl) atom. The introduction of Cl atom in central unit affects the molecular conformation. Whereas, by replacing fluorinated terminal groups (CH8-3) with chlorinated terminal groups (CH8-4 and CH8-5), the red-shift absorption and enhanced crystallization are achieved. Benefiting from these, all devices received promising power conversion efficiency (PCEs) over 16% as well as decent thermal/photo-stabilities. Among them, PM6:CH8-4 based device yielded a best PCE of 17.58%. Besides, the 3D merits with multi alkyl chains enable their versatile processability during the device preparation. Impressive PCEs of 17.27% and 16.23% could be achieved for non-halogen solvent processable devices prepared in glovebox and ambient, respectively. 2.88 cm2 modules also obtained PCEs over 13% via spin-coating and blade-coating methods, respectively. These results are among the best performance of dimerized acceptors. The decent performance of CH8-4 on small-area devices, modules and non-halogen solvent-processed devices highlights the versatile processing capability of our 3D acceptors, as well as their potential applications in the future.