FeCl3-Mediated Synthesis of Fullerenyl Esters as Low-LUMO Acceptors for Organic Photovoltaic Devices

C60 reacted with aromatic and aliphatic carboxylic acids in the presence of inexpensive FeCl3 at room temperature to produce hydroxyfullerenyl esters C60(OCOR)(OH) in up to 68% isolated yield. The hydroxyl group was utilized in functional group transformations to obtain a diester derivative C60(OCOAr)(OCOPh) (Ar = 2,6-xylyl) and a siloxyl derivative C60(OCOAr)(OSiMe3). The diester and siloxyl derivatives were found to possess low-lying LUMO levels were utilized in organic photovoltaic devices showing 1.3% power conversion efficiency.