title: Functionalized squaraine donors for nanocrystalline organic photovoltaics.
abstract: We study a family of functionalized squaraine (fSQ) donors for absorbing in the near-infrared (NIR) and green spectral regions. The NIR-absorbing materials are the symmetric molecules 2,4-bis[4-(N-phenyl-1-naphthylamino)-2,6-dihydroxyphenyl]squaraine (1-NPSQ), 2,4-bis[4-(N,N-diphenylamino)-2,6 dihydroxyphenyl]squaraine, and 2,4-bis[4-(N,N-dipropylamino)-2,6-dihydroxyphenyl]squaraine. The green light absorbing donors are asymmetric squaraines, namely, 2,4-bis[4-(N,N-diphenylamino)-2,6-dihydroxyphenyl]squaraine and 2-[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl]-4-diphenylamino]squaraine. Substitution of the arylamine groups enhances intermolecular packing, thereby increasing hole transport and the possibility of forming extended nanocrystalline junctions when annealed. Nanocrystalline solar cells based on fSQ and a C(60) acceptor have V(oc) = 1.0 V and fill factors 0.73 ± 0.01. Solar cells incorporating annealed 1-NPSQ films result in a power conversion efficiency of 5.7 ± 0.6% at 1 sun, AM1.5G illumination.
authors.affiliation: Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Guodan
authors.initials: G
authors.lastname: Wei
authors.forename: Xin
authors.initials: X
authors.lastname: Xiao
authors.forename: Siyi
authors.initials: S
authors.lastname: Wang
authors.forename: Kai
authors.initials: K
authors.lastname: Sun
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Bergemann
authors.forename: Mark E
authors.initials: ME
authors.lastname: Thompson
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Forrest
mesh_terms: D011211:Electric Power Supplies; D004867:Equipment Design; D019544:Equipment Failure Analysis; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D009930:Organic Chemicals / Q000737:chemistry*; D010316:Particle Size; D012993:Solar Energy
chemical_list: D009930:Organic Chemicals