Fine‐Tuning Electrostatic Interactions and Dispersion of a Guest Component Toward High‐Performance Polymer Solar Cells

ABSTRACT Ternary strategy represents a straightforward and effective approach for enhancing the power conversion efficiency (PCE) of polymer solar cells (PSCs). However, incorporating a third component, especially polymers, leads to additional complexity in the structure and morphology. Herein, the wide bandgap polymer donor PBQ10 with a larger total average molecular surface electrostatic potential distributions (ESP) relative to the host donor, is adopted into the PM6:L8‐BO system to elucidate the underlying mechanisms and enhance photovoltaic performance. Benefiting from complementary absorption spectra, excellent compatibility with host donors, weakened ESP‐induced intermolecular interactions and low binding energy between PBQ10 and L8‐BO, an optimized multi‐scale morphology of the ternary blend is constructed. Thus, the ternary device exhibits superior exciton generation, diffusion, and dissociation process, along with higher, and more balanced charge transport capabilities. Consequently, the ternary PSCs boost the PCE up to 20.02%, surpassing the reference binary system with 19.39%. This work not only presents a practical method toward high‐performance ternary PSCs but also provides valuable insights for molecular structure selection of the third component.