The Impact of Direct and Sequential Synthesis of Donor‐Acceptor Block Copolymers for Single‐Material Organic Solar Cells

ABSTRACT Significant progress has been made in advancing the photovoltaic performance of donor‐acceptor block copolymers (BCPs) for single‐material organic solar cells (SMOSCs). However, the influence of the synthetic protocol on material properties remains poorly understood. This work presents a comprehensive investigation of how synthetic methodologies affect the BCP performance using PBDB‐T‐ b ‐PNDIT as a model system. By employing direct synthesis (donor‐first and acceptor‐first) and sequential synthesis approaches, this study demonstrated that the synthetic pathway profoundly affects molecular ordering, charge transport, and morphology. The donor‐first direct synthesis ( d ‐BCP‐D) yields BCPs with optimized crystallinity, balanced hole/electron mobility, and favorable nanofibrillar networks, facilitating efficient exciton dissociation while suppressing trap‐assisted recombination. As a result, d ‐BCP‐D achieved a power conversion efficiency (PCE) of 5.71%, significantly outperforming other synthetic routes and its bulk heterojunction counterparts. These findings would provide insight into preparing enhanced conjugated BCPs for high‐performance SMOSCs.