Influence of nanoscale phase separation on geminate versus bimolecular recombination in P3HT:fullerene blend filmsElectronic supplementary information (ESI) available: Synthesis and steady state absorption. See DOI: 10.1039/c003394d

• Main Authors: Shoaee, Safa, Eng, Mattias P, Espíldora, Eva, Delgado, Juan Luis, Campo, Bert, Martín, Nazario, Vanderzande, Dirk, Durrant, James R
• Format: Article
• Language: English
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/c003394d

In this paper, we compare the charge recombination dynamics observed in films comprising poly(3-hexylthiophene) blended with three fullerene derivatives: PCBM and two alternative pyrazolinofullerenes. Transient absorption data indicate that replacement of PCBM with either of the pyrazolinofullerene derivatives results in a transition from bimolecular to monomolecular (geminate) recombination dynamics. We show that this transition cannot be explained by a difference in interfacial energetics. However, this transition does correlate with nanomorphology data which indicate that both pyrazolinofullerenes yield a much finer phase segregation, with correspondingly smaller domain sizes, than observed with PCBM . Our results therefore provide clear evidence of the role of nanomorphology in determining the nature of recombination dynamics in such donor/acceptor blends. Transient absorption data indicate that replacement of PCBM with two pyrazolinofullerene derivatives results in a transition from bimolecular to monomolecular recombination dynamics.