Control of Phase Separation and Crystallization for <scp>High‐Efficiency</scp> and <scp>Mechanically Deformable</scp> Organic Solar Cells

Stretchable organic solar cells (OSCs) have great potential as power sources for the next-generation wearable electronics. Although blending rigid photovoltaic components with soft insulating materials can easily endow mechanical ductility of active layers, efficiencies usually drops in resulting OSCs. Herein, a high efficiency 15.03% and large crack-onset strain 15.70% is simultaneously achieved based on ternary blend consisting polymer donor poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo[1,2-b:4,5-b′]dithiophene))-alt-(5,5-(1′,3′-di-2-thienyl-5′,7′-bis(2-ethylhexyl)benzo[1′,2′-c:4′,5′-c']dithiophene-4,8-dione)] (PM6), non-fullerene accepter 2,2′-((2Z,2′Z)-((12,13-bis(2-ethylhexyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2′′,3′′:4′,5′]thieno[2′,3′:4,5]pyrrolo[3,2-g]thieno[2′,3′:4,5]thieno[3,2-b]indole-2,10-diyl)bis (methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (Y6), elastomer polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS) through control phase separation crystallization. By employing high-boiling point solvent additive 1-chloronaphthalene (CN) different solubilities PM6 Y6, aggregation dynamics Y6 well film solidification process are dramatically altered, allowing molecular rearrangement liquid–liquid evolution. Consequently, optimal CN content presents decreased SEBS domains moderately improved ordering enabling effective deformation charge generation/transport. The revealed corrections between film-formation process, microstructure, photovoltaic/mechanical characteristics provide deep understanding morphology toward high-performance stretchable