Chlorinated polymerized small molecule acceptor enabling ternary all-polymer solar cells with over 16.6% efficiency

Recently, all-polymer solar cells (all-PSCs) based on polymerized small molecule acceptors (PSMAs) have achieved significant progress. Ternary blending has proven to be an effective strategy to further boost the power conversion efficiency (PCE) of the all-PSCs. Herein, a new A-DA’D-A small-molecule acceptor-based PSMA (named as PYCl-T) was designed and synthesized, which possesses similar polymer backbone with the widely used PY-IT, but with chlorine substitution on the A-end groups in the A-DA’D-A structure. PYCl-T was then employed as the third component into the PM6:PY-IT system and the ternary all-PSCs based on PM6:PY-IT:PYCl-T demonstrated a high PCE of 16.62% (certified value of 16.3%). Moreover, the PCE of 15.52% was realized in the enlarged ternary all-PSCs with effective area of 1 cm², indicating the great potential in large-scale applications. Moreover, the optimized ternary blend films of PM6:PY-IT:PYCl-T show excellent thermal stability at 150 °C. This work demonstrates that the utilization of a ternary blend system involving two well-compatible PSMA polymer acceptors is an effective strategy to boost the performance of the all-PSCs. [Figure not available: see fulltext.]