The review highlights different approaches to template organic materials as well as hybrid materials that find or are expected to find application in optoelectronic devices. The first templating approach focuses on the use of preformed nanoporous membranes as templates for organic materials and polymeric materials. Such nanoporous templates can be track-etched membranes, anodic aluminum oxide membranes and other variants thereof, or block copolymer templates. Further, opals have been described as templates. In the second part, we have summarized developments that take advantage of self-assembly processes to pattern hybrid materials. Examples are sol-gel templating techniques using amphiphiles, evaporation-induced self-assembly, lyotropic templating as well as templating from block copolymers. Both routes are very promising templating approaches for optoelectronic materials and represent complementary rather than competing techniques.
We demonstrate an integrated approach to prepare a nanostructured, multifunctional material with mutually exclusive, orthogonal properties. The hybrid material was obtained within a single step via self-assembly in solution. It consists of TiO(2) as a functional metal oxide and an amphiphilic block copolymer, poly(ethylene oxide)-b-poly(triphenylamine) (PEO-PTPA). Within the materials' synthesis, the block copolymer not only acts as a templating agent but also adds an electronic functionality to the resulting hybrid material. During the synthesis, a variety of self-assembled morphologies, ranging from spheres to wires, can be created. The obtained morphology depends on the weight fraction of the polymer, solvent, TiO(2), and acid (HNO(3)). When films on silicon wafers are studied with scanning electron microscopy (SEM) and transmission electron microscopy (TEM), a ternary phase diagram could be mapped, whereas the crystallinity of TiO(2) could be proved by high-resolution TEM. Different morphologies of this self-assembled hybrid material were tested for solar cell application. Even for devices with layer thicknesses of the active material below 10 nm, power conversion efficiencies up to 0.15% at 1 sun and 1.5 AM were observed.
Abstract. In this article we discuss the applicability of global scattering functions for structure analysis of Grazing Incidence Small Angle X-ray Scattering (GISAXS) data. Contrary to rigorous analysis of the full 2-D detector image, which can be performed with complex simulation models, the global scattering functions described here will be used to model transverse detector scans in the q reciprocal scattering planes. In contrast to a full GISAXS analysis, this procedure cannot explain structural features perpendicular to the sample plane. The discussed method is useful for the analysis of weakly correlated films. These films are e.g. found in polymer inorganic composite materials based on commercially available nanoparticles. In hybrid material systems polydisperse structures, including particle aggregates without precisely defined shape are formed. The pictured approach, which models scattering in terms of structural levels, has been previously applied with success in conventional transmission SAXS geometry. It is based on conventional exponential and power laws. Hence, data analysis becomes less complex compared to simulation approaches. Here we examine if this unified fitting model can be used to model diffuse, non specular scattering resulting from GISAXS. In this context the applicability and limit of its application to diffuse scattering in the GISAXS geometry is discussed. Furthermore diffuse q scattering from different ideal particle types is simulated and compared with fitted results. To verify our approach, fit results from experimental GISAXS curves obtained for real samples are compared with results from Scanning Probe Microscopy and Scanning Electron Microscopy studies. The samples investigated range from evaporated Au films to hybrid TiO2/polymer films and demonstrate the usefulness in the structural analysis of complex films.
Optoelectronic devices usually consist of a transparent conductive oxide (TCO) as one electrode. Interfacial engineering between the TCO electrode and the overlying organic layers is an important method for tuning device performance. We introduce poly(methylsilsesquioxane)-poly(N,N-di-4-methylphenylamino styrene) (PMSSQ-PTPA) as a potential hole-injection layer forming material. Spin-coating and thermally induced crosslinking resulted in an effective planarization of the anode interface. HOMO level (-5.6 eV) and hole mobility (1 × 10(-6) cm(2) · Vs(-1) ) of the film on ITO substrates were measured by cyclovoltammetry and time-of-flight measurement demonstrating the hole injection capability of the layer. Adhesion and stability for further multilayer built-up could be demonstrated. Contact angle measurements and tape tests after several solvent treatments proved the outstanding film stability.
A series of segmented multiblock copolymers containing aramid hard segments and extended polycaprolactone soft segments (with an M n of 4,200 or 8,200 g mol -1 ) was prepared and tested for their shape-memory properties. Chain extenders were essential to raise the hard segment concentration so that an extended rubbery plateau could be observed. Dynamic mechanical thermal analysis provided a useful guide in identifying (i) the presence of a rubbery plateau, (ii) the flow temperature, and (iii) the temperature when samples started to deform irreversibly.
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