What makes fullerene acceptors special as electron acceptors in organic solar cells and how to replace them.

Low lying excited states of the fullerene anion promote a faster charge separation in organic solar cells containing fullerene derivatives as electron acceptors. Alternative electron acceptors, not based on fullerenes but that share the same property, can be easily designed. On the other hand, it is unlikely for a generic electron acceptor to replicate this fullerene characteristic by chance.