Study on the Size of Fullerene (C60) Aggregates in Solution by Photoluminescence and HRTEM Measurements

In the present paper, results on the polymerization Of C-60 in benzene-ethanol mixtures are reported. The photoluminescence (PL) of the C-60 aggregates prepared by using two different methods was investigated using PL spectroscopy. In the case of benzene-ethanol mixtures of different compositions with ethanol volume fractions less than 50% in the solvent mixture, the PL spectra showed the spectral shape of aggregates at 120 K. The change in the spectral shape of the PL emission due to the formation of C-60 aggregates at the liquid-solid transition temperature of the solvent mixture as in case of a single solvent (benzene, toluene, Or CS2) is reported. A shift in 0-0 transition energy to a high-energy compared with the C-60 crystal was noticed. The 0-0 transition energy for a high ethanol volume fraction (>70%) of the solvent mixture showed no shift and was located at almost the same region as that of the C-60 crystal PL spectrum. A significantly big size Of C-60 aggregates in a mixture of benzene-ethanol with a high ethanol volume fraction compared to that of C-60 aggregates in a single solvent (>2.3 nm in benzene) is reported. Furthermore, the high-resolution transmission electron microscopy (HRTEM) image of a C-60 cluster produced by irradiating C-60 aggregates with on UV pulse-laser reconfirmed these results.