The invention relates to improved fullerene derivatives, to methods for their synthesis and any educts or intermediates used in such methods, to compositions and formulations containing fullerene derivatives, to the use of the fullerene derivatives, compositions and formulations in, or for the preparation of, organic electronic (OE) devices like for example organic photovoltaic (OPV) devices or organic photodetectors (OPD), and to OE, OPV and OPD devices comprising, or being prepared from, these fullerene derivatives, compositions or formulations.