Supramolecular complexation of C₆₀ with branched polyethylene

Fullerene C₆₀ is a ubiquitous material for application in organic electronics and nanotechnology, due to its desirable optoelectronic properties including good molecular orbital alignment with electron-rich donor materials, as well as high and isotropic charge carrier mobility. However, C₆₀ possesses two limitations that hinder its integration into large-scale devices: (1) poor solubility in common organic solvents leading to expensive device processing, and (2) poor optical absorbance in the visible portion of the spectrum. Covalent functionalization has long been the standard for introducing structural tunability into molecular design, but non-covalent interactions have emerged as an alternative strategy to tailor C₆₀-based materials, offering a versatile and tuneable alternative to novel functional materials and applications. In this work, we report a straightforward non-covalent functionalization of C₆₀ with a branched polyethylene (BPE), which occurs spontaneously in dilute chloroform solution under ambient conditions. A detailed characterization strategy, based on UV-vis spectroscopy and size-exclusion chromatography was performed to verify and investigate the structure of the C₆₀+BPE complex. Among others, our work reveals that the supramolecular complex has an order of magnitude higher molecular weight than its C₆₀ and BPE constituents and points towards oxidation as the driving force behind complexation. The C₆₀+BPE complex also possesses significantly broadened optical absorbance compared to unfunctionalized C₆₀, extending further into the visible portion of the spectrum. This non-covalent approach presents an inexpensive route to address the shortcomings of C₆₀ for electronic applications, situating the C₆₀+BPE complex as a promising candidate for further investigation in organic electronic devices.