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.

In situ syntheses of semiconducting nanoparticles in conjugated polymer matrices and their application in photovoltaics.

“…However, the interaction between the TiO 2 and the MEH-PPV chains strongly depends on the type of block copolymer as analyzed by TEM and 2-dimensional-NMR studies. In the case where a direct interaction between donor and acceptor was possible also the highest PCE value of 0.082% was observed [68].…”

Functionally Active Membrane Proteins Incorporated in Mesostructured Silica Films

“…Compared to lipid bilayers, mesostructured oxides are physically and chemically robust and can be synthesized with diverse mesoscopic (e.g., cubic, hexagonal, lamellar, or ‘worm-like’) structures and macroscopic morphologies that include films, fibers, powders, and monoliths. 46 Furthermore, their mesoscale channel dimensions (3-12 nm) and specific volumes (1-2 cm 3 /g) are suitable for macromolecular or colloidal guests, such as proteins, 5,8,47–51 conjugated polymers, 52,53 or nanoparticles. 54,55 For example, by adjusting the mesochannel diameters of mesoporous silica hosts to be within approximately 1 nm of the dimensions of a folded protein, such protein species could be stabilized within the host; 48,56 for the case of the water-soluble enzyme protein lipase, higher activities were observed for lipase molecules incorporated in mesoporous silica hosts with optimized mesochannel dimensions.…”

Universal Calibration of Computationally Predicted N 1s Binding Energies for Interpretation of XPS Experimental Measurements

“…3–6 Carbon and nitrogen core level energies are commonly used to assess the chemical environment of a variety of functional groups on surfaces of organic monolayers and multilayers. Given the rapidly widening range of heterogeneous hybrid surfaces, 7–9 multielement polymers, 10–12 and the increasing breadth of organic and bio-organic species specifically linked to a surface, 13,14 the analysis of the observed C 1s and N 1s binding energies becomes more and more significant, but also more complex.…”