Amplifying High‐Performance Organic Solar Cells Through Differencing Interactions of Solid Additive with Donor/Acceptor Materials Processed from Non‐Halogenated Solvent

Abstract Developing non‐halogenated solvent‐processed organic solar cells (OSCs) demands precise control over the bulk‐heterojunction (BHJ) morphology of the photoactive layer. However, the limited solubility of halogen‐free solvents to photoactive materials hinders microstructure morphology fine‐tuning for boosting photovoltaic performance. This study not only examines the debated intermolecular interactions between the DBrDIB solid additive and photoactive materials but also analyzes the substantial influence of volatile solid additive on the BHJ morphological properties. The DBrDIB effectively restricts the excessive aggregation of Y6‐BO and regulates the phase separation, which is attributed to strong intermolecular interactions with Y6‐BO and rapid quenching during morphology formation. It then achieves a well‐mixed D/A phase with favorable domain size, resulting in a balanced aggregation and dispersion of D/A, ultimately leading to markedly enhanced charge transfer and transport as well as suppressed charge recombination. The transformative use of the o‐xylene/DBrDIB solvent system propels PM6:Y6‐BO and PM6:Y6‐HU OSCs to impressive efficiencies of 17.9% and 19.1%, respectively, outperforming those of the control devices. These findings provide crucial insights into theoretical and experimental areas, offering actionable guidelines for designing high‐performance OSCs processed from halogen‐free solvent.