Time-resolved color-changed long-afterglow for security systems based on metal-organic hybrids

Organic solid-state materials with p-RTP (persistent room-temperature phosphorescence) properties have been made infusive achievements. However, researches on metal-organic hybrids with p-RTP are limited, in which dual phosphorescent ones are relatively...

From the Superatom to a Large Variety of Supermaterials: A Theoretical Study

<p>Metal clusters have been a subject of interdisciplinary research for many years as they act as a bridge between atoms and solid-state materials. In particular, clusters that show distinct thermodynamic stability and unusual atom like behavior, with an electronic shell structure that exhibits a superatomic nature, have attracted considerable attention. The concept of clusters behaving as individual atoms and furthermore mimicking the chemistry of specific elements directly leads to the idea of using those nanoparticles as building blocks for new functional materials. Furthermore, it is interesting that one can change the properties of cluster assembled materials by solely changing the properties of the individual clusters involved. In this work, various factors affecting superatomic assemblies are identified and critically analyzed within the means of first-principles computations. The icosahedral gold cluster Au₁₃[RS(AuSR)₂]₆ has been chosen as a model system to study the tunability of the electronic structure using single atomic impurities. In this context the doped clusters were found to be tunable such, that they reveal atomic properties, e.g. electron affinities similar to individual halogen atoms. In addition, the choice of ligands protecting the clusters is evaluated regarding the stability of the whole cluster and the involvement of the ligands in creating the superatomic structure. The latter was found to be important when thinking of orbital overlap in superatomic assemblies. In a next step the knowledge gained is used to investigate cluster-cluster interactions and detect pairs of clusters that are good candidates to create new superatomic materials. Furthermore basic principles regarding cluster assemblies are established and partially tested in an experimental collaboration studing the structure of an Au₉(PPh₃)₈-C₆₀ assembly. Beyond the investigation of individual gold clusters and gold cluster materials, the electronic structure of binary solid state materials consisting of ligand protected transition metal-chalcogen clusters and fullerenes, as synthesized by Roy et al., is presented. This study shows an intermediate case of non-tunable clusters and furthermore displays the partial loss of the superatomic character of the transition metal chalcogen clusters due to charge transfer. An experimental collaboration conducted in cooperation with the research group of Prof. Beate Paulus in Berlin proceeds even further and investigates the absorption of water on non-superatomic aluminumoxo fluoride clusters.</p>

From the Superatom to a Large Variety of Supermaterials: A Theoretical Study

<p>Metal clusters have been a subject of interdisciplinary research for many years as they act as a bridge between atoms and solid-state materials. In particular, clusters that show distinct thermodynamic stability and unusual atom like behavior, with an electronic shell structure that exhibits a superatomic nature, have attracted considerable attention. The concept of clusters behaving as individual atoms and furthermore mimicking the chemistry of specific elements directly leads to the idea of using those nanoparticles as building blocks for new functional materials. Furthermore, it is interesting that one can change the properties of cluster assembled materials by solely changing the properties of the individual clusters involved. In this work, various factors affecting superatomic assemblies are identified and critically analyzed within the means of first-principles computations. The icosahedral gold cluster Au₁₃[RS(AuSR)₂]₆ has been chosen as a model system to study the tunability of the electronic structure using single atomic impurities. In this context the doped clusters were found to be tunable such, that they reveal atomic properties, e.g. electron affinities similar to individual halogen atoms. In addition, the choice of ligands protecting the clusters is evaluated regarding the stability of the whole cluster and the involvement of the ligands in creating the superatomic structure. The latter was found to be important when thinking of orbital overlap in superatomic assemblies. In a next step the knowledge gained is used to investigate cluster-cluster interactions and detect pairs of clusters that are good candidates to create new superatomic materials. Furthermore basic principles regarding cluster assemblies are established and partially tested in an experimental collaboration studing the structure of an Au₉(PPh₃)₈-C₆₀ assembly. Beyond the investigation of individual gold clusters and gold cluster materials, the electronic structure of binary solid state materials consisting of ligand protected transition metal-chalcogen clusters and fullerenes, as synthesized by Roy et al., is presented. This study shows an intermediate case of non-tunable clusters and furthermore displays the partial loss of the superatomic character of the transition metal chalcogen clusters due to charge transfer. An experimental collaboration conducted in cooperation with the research group of Prof. Beate Paulus in Berlin proceeds even further and investigates the absorption of water on non-superatomic aluminumoxo fluoride clusters.</p>

Soft and flexible: core-shell ionic liquid resistive memory for electronic synapses

The human brain is the most efficient computational and intelligent system, and researchers are trying to mimic the human brain using solid-state materials. However, the use of solid-state materials has a limitation due to the movement of neurotransmitters. Hence, soft memory devices are receiving tremendous attention for smooth neurotransmission due to the ion concentration polarization mechanism. This paper proposes a core-shell soft ionic liquid (IL)-resistive memory device for electronic synapses using Cu/Ag@AgCl/Cu with multistate resistive behavior. The presence of the Ag@AgCl core shell in the liquid electrolyte significantly helps to control the movement of Cu2+ ions, which results in multistate resistive switching behavior. The core-shell IL soft memory device can open a gateway for electronic synapses.