Acceptor-only oligomers with high coplanarity enable efficient and stable organic solar cells

Acceptor-only oligomers are developed as guest components to construct oligomer-assisted active layers for high performance organic solar cells. Due to the high planarity and structural similarity with the host polymer donor, BDD-based acceptor-only oligomers formed an alloy phase with PM6 and optimized the phase morphology effectively, achieving a stable device displaying 18% efficiency. Active layers assisted by highly planar acceptor-only oligomers enable the production of efficient and stable organic solar cells, due to the enhanced light absorption, deeper HOMO level, and especially the formed alloy phase and optimized phase morphology.