High-Crystallinity Polymer-Driven Fiber Network Morphology Optimization for Efficient Ternary All-Polymer Organic Solar Cells

Stability remains a critical bottleneck hindering the large-scale commercialization of organic solar cells (OSCs), while all-polymer solar cells have demonstrated significant potential in this regard. In this work, we focus on investigating the efficiency of all-polymer active layers and strategies to enhance stability by employing a ternary approach with the introduction of the highly crystalline polymer donor D18. The results indicate that the compatibility between the highly crystalline polymer donor and the all-polymer active layer is a crucial factor influencing both efficiency and stability. The controlled incorporation of D18 optimally diminishes the scale of phase-segregated domains within the all-polymer active layer while inducing the formation of an interpenetrating nanofibrillar network morphology. Compared to the binary all-polymer system, the ternary all-polymer system exhibits significantly improved crystallinity, further optimizing charge transport properties. The optimized PM6:D18:PY-IT ternary blend achieved a higher PCE (17.81%) compared to PM6:PY-IT system (16.18%). Moreover, the tricomponent has an efficiency of 89% after 1600 h of storage in the glovebox, showing excellent stability.