Preparation and stabilization of C₆₀-carbon nanotube exohedral hybrids with controlled nano-morphology

Abstract: Molecularly engineered non-covalent hybrids comprising carbon nanotubes (CNTs) and fullerenes may combine the electronic and mechanical properties of CNTs with the optical and excellent electron acceptor characteristics of the fullerenes. As was demonstrated by us in a previous study, a two-step process comprising solution processing of multi-wall nanotubes (MWNTs) followed by vacuum deposition of fullerenes can be used for the preparation of non-covalent C₆₀–MWNTs hybrids. Transmission electron microscopy measurements and Raman characterization indicate that the hybrids comprise random 3D scaffolds of individual MWNTs and fullerite nanocrystals. While surface migration of the fullerenes on the MWNTs surface leads to coarsening of the nanocrystals, we find that controlled induction of SP³ point defects on the MWNTs surface (via UV/O₃ treatment) traps the initial nano-morphology and preserves the nano-dimensions and structure of the fullerene crystals. The nano-morphology of the treated nanotubes is preserved also when the hybrid is coated by a polymer layer (poly(3-hexylthiophene-2,5-diyl), P3HT, and the polymer-hybrid films show significant quenching of the photoluminescence, indicating that these hybrids could be useful in photovoltaic applications where the typical size of the nano-domains and the degree of crystallinity of the fullerenes play an important role in light-matter interactions. Graphical abstract: [Figure not available: see fulltext.]