Insulator Polymer Matrix Construction on All-Small-Molecule Photoactive Blend Towards Extrapolated 15000 Hour T<sub>80</sub> Stable Devices.

Ma, Ruijie; Jiang, Xinyu; Dela Peña, Top Archie; Gao, Wei; Wu, Jiaying; Li, Mingjie; Roth, Stephan V; Müller-Buschbaum, Peter et al. · Adv Mater · 2024

basic_science · Level V

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Abstract

To boost the stability of all-small-molecule (ASM) organic photovoltaic (OPV) blends, an insulator polymer called styrene-ethylene-butylene-styrene (SEBS) as morphology stabilizer is applied into the host system of small molecules BM-ClEH:BO-4Cl. Minor addition of SEBS (1 mg/ml in host solution) provides a significantly enhanced T<sub>80</sub> value of 15000 hours (extrapolated), surpassing doping-free (0 mg/ml) and heavy doping (10 mg/ml) counterparts (900 hours, 30 hours). The material reproducibility and cost-effectiveness of the active layer will not be affected by this industrially available polymer, where the power conversion efficiency (PCE) can be well maintained at 15.02%, which is still a decent value for non-halogen solvent-treated ASM OPV. Morphological and photophysical characterizations clearly demonstrate SEBS's pivotal effect on suppressing the degradation of donor molecules and blend film's crystallization/aggregation reorganization, which protects the exciton dynamics effectively. This work pays meaningful attention to the ASM system stability, performs a smart strategy to suppress the film morphology degradation, and releases a comprehensive understanding of the mechanism of device performance reduction.