title: Understanding and controlling organic-inorganic interfaces in mesostructured hybrid photovoltaic materials.
abstract: The chemical compositions and structures of organic-inorganic interfaces in mesostructurally ordered conjugated polymer-titania nanocomposites are shown to have a predominant influence on their photovoltaic properties. Such interfaces can be controlled by using surfactant structure-directing agents (SDAs) with different architectures and molecular weights to promote contact between the highly hydrophobic electron-donating conjugated polymer species and hydrophilic electron-accepting titania frameworks. A combination of small-angle X-ray scattering (SAXS), scanning and transmission electron microscopy (SEM, TEM), and solid-state NMR spectroscopy yields insights on the compositions, structures, and distributions of inorganic and organic species within the materials over multiple length scales. Two-dimensional NMR analyses establish the molecular-level interactions between the different SDA blocks, the conjugated polymer, and the titania framework, which are correlated with steady-state and time-resolved photoluminescence measurements of the photoexcitation dynamics of the conjugated polymer and macroscopic photocurrent generation in photovoltaic devices. Molecular understanding of the compositions and chemical interactions at organic-inorganic interfaces are shown to enable the design, synthesis, and control of the photovoltaic properties of hybrid functional materials.
authors.affiliation: Department of Materials Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel.
authors.forename: S
authors.initials: S
authors.lastname: Neyshtadt
authors.forename: J P
authors.initials: JP
authors.lastname: Jahnke
authors.forename: R J
authors.initials: RJ
authors.lastname: Messinger
authors.forename: A
authors.initials: A
authors.lastname: Rawal
authors.forename: T
authors.initials: T
authors.lastname: Segal Peretz
authors.forename: D
authors.initials: D
authors.lastname: Huppert
authors.forename: B F
authors.initials: BF
authors.lastname: Chmelka
authors.forename: G L
authors.initials: GL
authors.lastname: Frey