Ethynyl-bridged fullerene derivatives: effect of the secondary group on electronic properties

Abstract

Eight new ethynyl-bridged fullerene derivatives with different substituents (referred to as the “secondary group”) in the α-position relative to the alkyne have been prepared in order to study the ability of the secondary group to modulate their electrochemical properties, especially the LUMO energy level, of C60. These new materials have been characterized using cyclic voltammetry, and the results have been compared to those obtained using DFT calculations. Unexpectedly, the introduction of an electron-rich group induced a decrease of the LUMO energy level of the C60 cage, while an electron-poor group increased it. The newly prepared materials are electrochemically stable, opening the way to the use of these n-type materials in organic electronics.