• Dual-donor strategy with PTzBI-dF enhances crystallinity, achieving 19.23% efficiency in organic solar cells.
• PTzBI-dF suppresses trap-assisted recombination and current leakage, improving device stability (82% PCE retention after 800 h).
• The approach is versatile, boosting PCE by >1% across various Y6 derivatives.
• Donor phase engineering offers a practical route to optimize molecular packing for high-performance OSCs.