Nanoscale film morphology and property characteristics of dielectric polymers bearing monomeric and dimeric adamantane units

Adamantane-type clusters: compounds with a ubiquitous architecture but a wide variety of compositions and unexpected materials properties

The research into adamantane-type compounds has gained momentum in recent years, yielding remarkable new applications for this class of materials. In particular, organic adamantane derivatives (AdR4) or inorganic adamantane-type compounds of the general formula [(RT)4E6] (R: organic substituent; T: group 14 atom C, Si, Ge, Sn; E: chalcogenide atom S, Se, Te, or CH2) were shown to exhibit strong nonlinear optical (NLO) properties, either second-harmonic generation (SHG) or an unprecedented type of highly-directed white-light generation (WLG) - depending on their respective crystalline or amorphous nature. The (missing) crystallinity, as well as the maximum wavelengths of the optical transitions, are controlled by the clusters' elemental composition and by the nature of the organic groups R. Very recently, it has been additionally shown that cluster cores with increased inhomogeneity, like the one in compounds [RSi{CH2Sn(E)R'}3], not only affect the chemical properties, such as increased robustness and reversible melting behaviour, but that such 'cluster glasses' form a conceptually new basis for their use in light conversion devices. These findings are likely only the tip of the iceberg, as beside elemental combinations including group 14 and group 16 elements, many more adamantane-type clusters (on the one hand) and related architectures representing extensions of adamantane-type clusters (on the other hand) are known, but have not yet been addressed in terms of their opto-electronic properties. In this review, we therefore present a survey of all known classes of adanmantane-type compounds and their respective synthetic access as well as their optical properties, if reported.

Chemically Controlled Volatile and Nonvolatile Resistive Memory Characteristics of Novel Oxygen-Based Polymers

Recent advancements in modern microelectronics continuously increase the data storage capacity of modern devices, but they require delicate and costly fabrication processes. As alternatives to conventional inorganic based semiconductors, semiconducting polymers are of academic and industrial interest for their cost-efficiency, power efficiency, and flexible processability. Here, we have synthesized a series of novel oxygen-based polymers through the postmodification reactions of poly(ethylene-alt-maleate) with various oxybenzyl alcohol derivatives. The oxygen-based polymers are thermally stable up to 180 °C, and their nanoscale film devices exhibit reliable, power efficient p-type unipolar volatile and nonvolatile resistive memory characteristics with high ON/OFF current ratios. Additionally, when given a higher number of oxygen atoms in oxyphenyl side groups, the thin film polymer devices demonstrate a wide operational film thickness range. The memory characteristics depend on the oxyphenyl moieties functioning as charge trap sites, where a combination of Schottky emission and trap-limited space charge limited conductions in OFF-state and hopping conduction in ON-state are observed. This study demonstrates the chemical incorporation of oxyphenyl derivatives into polymer dielectrics as a powerful development tool for p-type resistive memory materials.

Cyclic topology effects on the morphology of biocompatible and environment-friendly poly(ε-caprolactone) under nanoscale film confinement

Quantitative grazing incidence X-ray scattering analysis combined with X-ray reflectivity using synchrotron radiation sources was explored for the first time cyclic topology effects on the nanoscale film morphology of poly(ε-caprolactone).