Charge Separation Pathways in a Highly Efficient Polymer: Fullerene

Jan 8, 2014 - Very interestingly, all the charge separation pathways are highly efficient. .... A Close Look at Charge Generation in Polymer:Fullerene...
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Article pubs.acs.org/JACS

Charge Separation Pathways in a Highly Efficient Polymer: Fullerene Solar Cell Material Arun Aby Paraecattil and Natalie Banerji* Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), SB ISIC GR-MO, Station 6, CH-1015 Lausanne, Switzerland S Supporting Information *

ABSTRACT: PBDTTPD is one of the best conjugated polymers for solar cell applications (up to 8.5% efficiency). We have investigated the dynamics of charge generation in the blend with fullerene (PCBM) and addressed highly relevant topics such as the role of bulk heterojunction structure, fullerene excitation, and excess energy. We show that there are multiple charge separation pathways. These include electron transfer from photoexcited polymer, hole transfer from photoexcited PCBM, prompt (