Acceptor dependent polaron recombination dynamics in poly 3-hexyl thiophene: Fullerene composite films

► Recombination dynamics in P3HT:fullerene films is temperature and acceptor dependent. ► The acceptor dependence is due to the effective distance between the polymer and the core fullerene. ► More functionalized fullerenes yield slower recombination (bisPC62BM < PC61BM < C60). ► Smaller fullerenes yield slower recombination (PC61BM < PC71BM < PC81BM). ► The acceptor dependence is defeated by thermal motion at ambient temperature.