title: Molecular-Scale Understanding of Cohesion and Fracture in P3HT:Fullerene Blends.
abstract: Quantifying cohesion and understanding fracture phenomena in thin-film electronic devices are necessary for improved materials design and processing criteria. For organic photovoltaics (OPVs), the cohesion of the photoactive layer portends its mechanical flexibility, reliability, and lifetime. Here, the molecular mechanism for the initiation of cohesive failure in bulk heterojunction (BHJ) OPV active layers derived from the semiconducting polymer poly(3-hexylthiophene) [P3HT] and two monosubstituted fullerenes is examined experimentally and through molecular-dynamics simulations. The results detail how, under identical conditions, cohesion significantly changes due to minor variations in the fullerene adduct functionality, an important materials consideration that needs to be taken into account across fields where soluble fullerene derivatives are used.
authors.forename: Naga Rajesh
authors.initials: NR
authors.lastname: Tummala
authors.affiliation: ‡Department of Materials Science and Engineering, Stanford University, Palo Alto, California 94305-4034, United States.
authors.forename: Christopher
authors.initials: C
authors.lastname: Bruner
authors.forename: Chad
authors.initials: C
authors.lastname: Risko
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Brédas
authors.affiliation: ‡Department of Materials Science and Engineering, Stanford University, Palo Alto, California 94305-4034, United States.
authors.forename: Reinhold H
authors.initials: RH
authors.lastname: Dauskardt
keywords: P3HT; cohesion and fracture; molecular dynamics; solar cells; substituted fullerenes; thin films