Organic solar cells (OSCs) based on poly(3-hexylthiophene) (P3HT) have achieved a significant enhancement of the power conversion efficiency (PCE), mainly driven by the development of non-fullerene small-molecule acceptors. However, their...
Nonfused ring acceptors (NFRAs) have attracted significant attention for nonfullerene organic solar cells (OSCs) owing to their chemical tunability and facile synthesis. In this study, a benzotriazole-based NFRA with chlorinated end groups (Triazole-4Cl) is developed to realize highly efficient and thermally stable NFRA-based OSCs; an analogous NFRA with nonchlorinated end groups (Triazole-H) is synthesized for comparison. Triazole-4Cl film exhibits the high-order packing structure and the near-infrared absorption capability, which are advantageous in charge transport and light harvesting of the resulting OSCs. In particular, the strong crystalline behavior of Triazole-4Cl results in enhanced self-aggregation, leading to high charge carrier mobility. Owing to these properties, a PBDB-T (polymer donor):Triazole-4Cl OSC demonstrates a high short-circuit current, fill factor, and power conversion efficiency (PCE = 10.46%), outperforming a PBDB-T:Triazole-H OSC (PCE = 7.65%). In addition, the thermal stability of a PBDB-T:Triazole-4Cl OSC at an elevated temperature of 120 °C exceeds that of a PBDB-T:Triazole-H OSC. This is mainly attributed to the significantly higher cold crystallization temperature of Triazole-4Cl (205.9 °C). This work provides useful guidelines for the design of NFRAs to achieve efficient and thermally stable NFRA-based OSCs.
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