Organic solar cells (OSCs) have emerged as a promising solution for low-cost, flexible photovoltaic technology, driven by advancements in nonfullerene acceptor (NFA)-based materials. The performance of these devices is governed by the interplay between intrinsic electronic properties and nanoscale morphology of donor (D) and acceptor (A) components. In this study, we introduce a novel strategy based on eutectic mixing of NFAs to engineer hierarchical fibrillar morphologies that significantly enhance charge generation and transport. By blending Y6 with its structural analogs—Y6-BO and Y7—under controlled conditions, we achieve a synergistic crystallization process leading to well-defined eutectic fibrillar lamellae. This unique morphology improves thin film crystallinity, reduces energetic disorder, and suppresses defect states, resulting in enhanced carrier mobility and reduced recombination losses.
The chemical structures of Y6, Y6-BO, Y7, and Y7-BO exhibit slight variations in halogenation and alkyl chain length, which influence their electronic levels while preserving similar molecular packing tendencies. Ultraviolet photoelectron spectroscopy (UPS) reveals aligned cascading energy levels: PM6 has a HOMO at -5.UHRF1 Antibody MedChemExpress 13 eV, while Y6, Y6-BO, Y7, and Y7-BO show LUMOs ranging from -4.MOBKL1A Antibody Autophagy 12 to -4.PMID:34389214 22 eV, creating a favorable driving force for charge transfer. When incorporated into ternary blends with PM6, the optimized composition PM6:Y6:Y6-BO (1:0.6:0.6) achieves a certified power conversion efficiency (PCE) of 17.40%, with an unprecedented JSC of 26.46 mA cm⁻² and a high FF of 78.49%. These improvements are attributed to the formation of eutectic fibrils that promote efficient exciton dissociation and balanced charge transport.
Grazing-incidence wide-angle X-ray diffraction (GIWAXS) confirms enhanced crystallinity and improved coherence lengths in the blended films, particularly for the (020) and (110) lattice planes. The presence of a distinct eutectic melting point depression—observed via differential scanning calorimetry (DSC)—indicates thermodynamically stable phase separation driven by specific intermolecular interactions. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) reveal a highly ordered fibrillar network with bundle-like structures, where Y6-BO-rich domains form continuous pathways. Photoinduced force microscopy (PiFM) further validates the spatial distribution of acceptors, showing stronger IR signals in PM6:Y6:Y6-BO blends, indicating higher purity and better phase segregation.
Ultrafast transient absorption spectroscopy demonstrates rapid hole transfer dynamics, with a dominant ultrafast component (~0.22 ps) in PM6:Y6:Y6-BO systems, confirming efficient interfacial charge separation. The correlation between morphological parameters and charge transfer kinetics reveals that enhanced crystallinity primarily boosts exciton diffusion across longer distances rather than interfacial splitting alone. This is further supported by transient photovoltage (TPV) and photocurrent (TPC) measurements, which show a recombination rate coefficient two orders of magnitude lower than Langevin predictions, indicating suppressed nongeminate recombination.
In conclusion, this work establishes eutectic NFA mixtures as a powerful tool for morphology engineering in OSCs. By leveraging subtle differences in electronic structure while maintaining structural similarity, we achieve superior crystalline organization, reduced energetic disorder, and exceptional current amplification. This approach paves the way toward next-generation organic photovoltaics targeting >20% PCE through rational design of multi-component blends.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com