Synthesis of Nanoscale Fullerene C60 Filaments in the Volume of an Evaporating Drop of a Molecular Solution and Preparation of Thin Nanostructured Coatings on Their Basis

Abstract

The features of nucleation and the mechanisms of further growth of nano- and microsized filamentary crystals (so-called whiskers) of fullerene in the volume of an isolated evaporating drop of a C₆₀ molecular solution in ortho-xylene on a smooth surface of silicon and glass substrates have been studied for the first time. The morphological features and the exact dimensional characteristics of nanostructured mC₆₀ fullerene filamentary crystals (where m is the number of spherical C₆₀ macromolecules in the synthesized whisker) that are promising for the creation of nano- and micro-dimensional photoelectric converters in solar energy were determined by high-resolution scanning electron microscopy. When a drop of a molecular solution of C₆₀ in ortho-xylene is transferred onto the surface of an optically smooth glass substrate, filamentary crystalline structures (nanowhiskers) with sizes of ∼250–700 nm in length and ∼50 nm wide were synthesized in the process of natural thermal evaporation of an organic solvent at room temperature (T ≈ 25°С). In this case, the surface of the resulting mC₆₀ nanowhiskers is molecularly smooth, and the roughness does not exceed ∼5 nm. It has been found that at a temperature of silicon substrate T ≈ 35°С, not only the nucleation and growth of crystalline structures of filamentary nanocrystals in a volume of evaporating drop of C₆₀ solution are accelerated, but there is also a significant (more than two orders of magnitude) increase in the final geometric dimensions of the synthesized whiskers. The ratio of the length (L ≈ 80 μm) to width (D ≈ 7.0 μm) of the filamentary crystals is approximately 11 : 1. A nanostructured organic semiconductor coating with a thickness of 10 μm, consisting of closely spaced mC₆₀ filamentary crystals and a molecular layer of fullerene C₆₀ on the smooth surface of a plane silicon substrate has been obtained for the first time.