Enhanced εr/LD and improved acceptor crystal growth enable all-polymer solar cells with outstanding efficiency, stability, and processability from a chlorinated-dimer diluent additive

Abstract

Controlling morphological evolution during film formation is crucial for simultaneously achieving high power conversion efficiency (PCE) and solution processability in all-polymer solar cells (all-PSCs). However, the intrinsically strong intermolecular interactions and chain entanglements of polymeric materials present persistent challenges to achieving an ideal blend microstructure. Here, we introduce a chlorinated dimer acceptor, D-SeV-Cl, as a 5 wt% diluent additive in the PM6:PYT all-polymer system. Benefiting from favorable interactions with PYT, D-SeV-Cl induces a finely intermixed phase and promotes PYT crystallization, thereby enhancing the dielectric constant, extending exciton diffusion length, and suppressing trap-state density. Blade-coated devices deliver over 20% PCE for green solvent (toluene) with concurrent gains in charge management, alongside outstanding thermal- and photo-stability. The dimer-diluent strategy also broadens the processing window, sustaining PCEs above 19% across varied coating speeds (~1.0-30.0 m min-1) and achieving approximately 17% in large-area (15.40 cm2) modules. These results establish a scalable route to high-performance all-PSCs with excellent efficiency, stability, and processability.