Synthesis and photophysical properties of fullerene derivatives containing a C60-fluorene core

Abstract

Three novel fullerene derivatives containing a C₆₀-fluorene core and thiophenyl, terthiophenyl and tetrathiophenyl groups grafted at the 2-position of the fluorene ring, respectively, were synthesized and characterized. Their photophysical and electrochemical properties were investigated systematically. The results showed that their UV-vis absorption bands in the range of 350–500 nm were much wider and stronger than that of the traditional fullerene derivative PC₆₁BM, and the LUMO energy levels of the synthesized fullerene derivatives were gradually up-shifted by increasing of the number of thiophene rings in the oligothiophene units.