Facile and scalable fabrication methods are attractive to prepare materials for diverse applications. Herein, a method is presented to prepare cross-linked polymeric nanoparticles with graphene oxide (GO) nanosheets covalently attached to the surface. Alkene-modified GO serves as a surfactant in a miniemulsion polymerization, and the alkene functionalities of GO exposed to the oil-phase are incorporated into the polymer particle through thiol-ene reactions, leaving the unreacted alkene functional groups of the other face of GO available for further functionalization. The surface of GO-armored polymer particles is then modified with a small molecule fluorophore or carboxylic acid functional groups that bind to Fe2 O3 and TiO2 nanoparticles. This methodology provides a facile route to preparing complex hybrid composite materials.

For over a decade, a great amount of research effort has focused on controlling the size and shape of organic small molecule crystals, as these parameters impact physical and optoelectronic properties. A thorough understanding of how functionalization impacts assembly as well as guiding principles to control aggregation and self-assembly are vital to producing novel organic nanostructures for electronic applications such as organic photovoltaics (OPVs). Herein, we study the influence of unsymmetrical functionalization of perylene diimide (PDI) on self-assembly. The guiding hypothesis of this work is that the identity of the pendant functionalities will impact the size, aspect ratio, and surface properties of the resulting assemblies. Twelve asymmetrically functionalized PDI molecules are reported, in which the length of the alkyl substituents at the imide position is varied, and include alcohol and silylated alcohol functionalities at the end of the alky chain. Morphologies of these self-assembled structures were characterized by scanning and transmission electronic microscopy; crystallinity was verified by powder X-ray diffraction, and the optoelectronic and thermal properties are also reported. On the basis of the functionality of the PDI molecules, different shaped assemblies are prepared, including high aspect ratio structures with widths ranging from 0.1 to 2.5 μm and lengths 1–800 μm.

Aluminum-doped zinc oxide (AZO) is a low-temperature processed transparent conductive oxide (TCO) made of earth abundant elements; its applications are currently limited by instability to heat, moisture, and acidic conditions. We demonstrate that the application of an organofunctional silane modifier mitigates AZO degradation and explore the interplay between performance and material composition and morphology. Specifically, we evaluate degradation of bare AZO and APTES (3-aminopropyltriethoxysilane)-modified AZO in response to damp heat (DH, 85 °C, 85% relative humidity) exposure over 1000 h and then demonstrate how surface modification impacts changes in electrical and optical properties and chemical composition in one of the most thorough studies to date. Hall measurements show that the resistivity of AZO increases due to a decrease in electron mobility, with no commensurate change in carrier concentration. APTES decelerates this electrical degradation, without affecting AZO optical properties. Percent transmission and yellowness index of an ensemble of bare and modified AZO are stable upon DH exposure, but haze increases slightly for a discrete sample of modified AZO. Atomic force microscopy (AFM) and optical profilometer (OP) measurements do not show evidence of pitting or delamination after 1000 h DH exposure but indicate a slight increase in surface roughness on both the nanometer and micrometer length scales. X-ray photoelectron spectroscopy data (XPS) reveal that the surface composition of bare and silanized AZO is stable over this time frame; oxygen vacancies, as measured by XPS, are also stable with DH exposure, which, together with transmission and Hall measurements, indicate stable carrier concentrations. However, after 1500 h of DH exposure, only bare AZO shows signs of catastrophic destruction. Comparison of the data presented herein to previous reports indicates that the initial AZO composition and microstructure dictate the degradation profile. This work demonstrates that surface modification slows the bulk degradation of AZO and provides insight into how the material can be more widely used as a transparent electrode in the next generation of optoelectronic devices.

This study reports on time-of-flight (TOF) hole mobility measurements in aged 2,3,6,7,10,11-Hexakis(pentyloxy)triphenylene columnar liquid crystals. In contrast to the original samples reported in 2006, homeotropically aligned samples yielded TOF transients with an extended non-exponential rise. The experimental data were fit to a simple model that accurately reproduces the TOF transients assuming delayed charge release from traps near the optically excited electrode. While interfacial trapping appears only in the aged materials, the bulk mobility is similar to the pristine material. The model addresses dispersive transport in quasi-one-dimensional materials, determines the charge carrier mobility in systems with interfacial traps, and provides a method for characterizing the traps.

Silyl-substituted ketenes are attractive molecular building blocks due to their stability and ease of storage, as opposed to unstable alkyl and aryl ketenes. To better understand the reactivity of silyl ketenes and, in turn, their use in the preparation of highly functionalized small molecules, the reaction of silyl ketenes with different nucleophiles was studied. The addition of alcohol, amine, or thiol nucleophiles to the central carbon of silyl ketene, followed by proton transfer afforded α-silyl ester, amide, or thio-ester, respectively. Catalytic amounts of Lewis acid greatly increase the rate of the reaction, and the impact of nucleophile, Lewis acid, and silyl substituent are evaluated. The small molecules produced from these reactions give insight into the use of silyl ketenes as building blocks for complex molecular structures.