Fluorine Positional Isomerism Enables H-Aggregation for High-Performance Semicrystalline Polymer Donors in Organic Solar Cells.

Authors

Shisong Sun, Zhenyu Wei, Wenhao Peng, Yuchen Yue, Han Shen, Bing Zheng, Jianling Ni, Meixiu Wan, Jingxia Wang, Jianqi Zhang, Lijun Huo

Published in

Small (Weinheim an der Bergstrasse, Germany). Pages e74571. Jul 16, 2026. Epub Jul 16, 2026.

Abstract

Constructing high-performance semicrystalline polymer donors is often hindered by the trade-off between crystalline order and donor-acceptor miscibility. Herein, we demonstrate that fluorine positional isomerism serves as a precise molecular handle to reconcile this conflict by modulating aggregation behaviors. Through regulating fluorine substitution from alkoxy ortho- (PFo) to meta- (PFm) and para- (PFp) positions, a distinct transition from J-aggregation to H-dominant aggregation is achieved. Contrary to the conventional preference for J-aggregates, the H-aggregated PFp achieves superior photovoltaic performance in this BDF-based polymer system, driven by the synergistic effects of HOMO stabilization, optimized packing, and matched interfacial energetics. Comprehensive dynamical studies, including vibronic analysis and transient absorption (TA) spectroscopy, reveal that H-aggregation maximizes π-π orbital overlap and optimizes phase separation, thereby suppressing non-radiative recombination and accelerating ultrafast charge transfer. Consequently, PFp-based binary devices deliver a champion efficiency of 18.54%. Furthermore, demonstrating the universality of this strategy, PFp acts as a potent morphology regulator in ternary blends, boosting the efficiency to an impressive 19.77%. This work establishes fluorine positional isomerism as a precise molecular handle to guide H-aggregation, synergistically optimizing energy levels and interfacial miscibility, offering an effective design strategy for high-performance semicrystalline polymer donors.

PMID:
42460519
Bibliographic data and abstract were imported from PubMed on 16 Jul 2026.

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