Electroactive ionenes combining caged‐shaped diazabicyclic cations and aromatic diimides were developed as interlayers in organic solar cells (OSCs). These ionenes reduce the work‐function of air‐stable metal electrodes (e.g., Ag, Cu and Au) by generating strong interfacial dipoles, and their optoelectronic and morphological characters can be modulated by aromatic diimides, leading to high conductivity and good compatibility with active layers. The optimal ionene exhibits superior charge‐transport, desirable crystallinity, and weak visible‐absorption, boosting the efficiency of benchmark PM6 : Y6‐based OSCs up to 17.44 %. The corresponding normal devices show excellent stability at maximum power point test under one sun illumination for 1000 h. Replacing Y6 with L8‐BO promotes the efficiency to 18.43 %, one of the highest in binary OSCs. Notably, high efficiencies >16 % are maintained as the interlayer thickness increasing to 105 nm, the best result with interlayer‐thickness over 100 nm.

Zwitterionic polymers or small molecules are a class of widely used interlayer materials in organic solar cells (OSCs). It is challenging to develop such materials that combine good film-forming property, high batch-to-batch reproducibility, and broad thickness processing window in device applications. Herein, we designed and synthesized two self-doped conjugated mesopolymer zwitterions (CMZs), namely, MT 2 PDIMz and MT 2 PDINz (PDI = perylenediimide, M = mesopolymer, T 2 = dithiophene, Mz = imidazolium zwitterion, Nz = ammonium zwitterion). Both show good processability and effectively reduce the work function of metal electrodes. The substitution of imidazolium cations with ammonium cations on the side-chains can further modulate the solution assembly and self-doping effect of CMZs, enabling improved interfacial compatibility with active layers and higher electron mobility in MT 2 PDIMz. The versatility of CMZs interlayers for OSCs is confirmed with several binary and ternary active layers, affording efficiencies up to 19.01%. Notably, over 98% of the optimal efficiency is maintained as the thickness of the interlayers increases to 40 nm with good reproducibility.

Electroactive ionenes combining caged-shaped diazabicyclic cations and aromatic diimides were developed as interlayers in organic solar cells (OSCs). These ionenes reduce the work-function of air-stable metal electrodes (e.g., Ag, Cu and Au) by generating strong interfacial dipoles, and their optoelectronic and morphological characters can be modulated by aromatic diimides, leading to high conductivity and good compatibility with active layers. The optimal ionene exhibits superior charge-transport, desirable crystallinity, and weak visible-absorption, boosting the efficiency of benchmark PM6 : Y6-based OSCs up to 17.44 %. The corresponding normal devices show excellent stability at maximum power point test under one sun illumination for 1000 h. Replacing Y6 with L8-BO promotes the efficiency to 18.43 %, one of the highest in binary OSCs. Notably, high efficiencies > 16 % are maintained as the interlayer thickness increasing to 105 nm, the best result with interlayer-thickness over 100 nm.