Multifunctional all‐polymer photovoltaic blend with simultaneously improved efficiency (18.04%), stability and mechanical durability

One of the most appealing material systems for solar energy conversion is all‐polymer blend. Presently, the three key merits (power conversion efficiency, operation stability and mechanical robustness) exhibited a trade‐off in a particular all‐polymer blend system, which greatly limit its commercial application. Diverting the classic ternary tactic of organic solar cells based on polymer, nonfullerene small molecule and fullerene, herein we demonstrate that the three merits of a benchmark all‐polymer blend PM6:PY‐IT can be simultaneously maximized via the introduction of a polymerized fullerene derivative PPCBMB. Importantly, the addition of the guest component promoted the power conversion efficiency of PM6:PY‐IT blend from 16.59% to 18.04%. Meanwhile, the device stability and film ductility are also improved due to the addition of this polymerized fullerene material. Morphology and device physics analyses reveal that optimal ternary system contains well‐maintained molecular packing and crystallinity, being beneficial to keeping favorable charge transport and the reduced domain size contributed to charge generation and ductility improvement. Furthermore, the ternary photovoltaic blend was successfully used as photocatalysts, and an excellent heavy metal removal from water was demonstrated. This study showcases the multi‐functions of all‐polymer blends via the use of polymerized fullerenes. A classic ternary strategy inspired blend for high‐efficiency (18.04%) all‐polymer solar cells processed by non‐halogenated solvent is successfully reported, thus polymerized fullerene comes back to the focus of the field. Large‐area and thick‐film devices reach record efficiencies too. Furthermore, the ternary all‐polymer blend film is found to be effective in water purification by removing heavy metal atoms.