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.