fluoren (nahoře), thiofen (uprostřed), C60-N,N-dimethylpyrrolidinium, Sarah H. Tolbert et al., Long-lived photoinduced polaron formation in conjugated polyelectrolyte-fullerene assemblies, Science 19 June 2015: Vol. 348 no. 6241 pp. 1340-1343, DOI: 10.1126/science.aaa6850