Search

Limited stability of blue quantum dot light-emitting diodes (QLEDs) under current stress impedes commercialization. Multi-layer structures of the state-of-the-art blue QLEDs pose significant difficulty in the fundamental understanding of degradation mechanisms. Here, by applying transient electroluminescence measurements, we disentangle charge transport in both pristine and degraded blue QLEDs. By varying thicknesses of the charge transport layers and the emissive layer, respectively, we show that the charge transport in pristine QLEDs is primarily dominated by holes. Furthermore, the degradation of QLEDs under electrical stress is governed by the decrease of hole transport in the emissive quantum dot layer due to the formation of hole traps. [ABSTRACT FROM AUTHOR]

Biaxially oriented polypropylene (BOPP) film used in pulse film capacitors withstands high temperatures for a long time. This leads to frequent faults in pulse film capacitors, affecting the reliability of the pulse system. In this paper, the thermal aging tests of BOPP films at 100°C for 10–80 days are carried out in this paper, and the physicochemical and electrical properties of the aging materials are characterized. The results show that more deep and shallow traps to BOPP films are introduced during the thermal aging process. With the increase in aging time, the breakdown field strength gradually decreases, and the conductivity decreases first and then increases. Under the action of thermal aging for a long time, the recrystallization of materials and the destruction of molecular chains by thermal aging are the main reasons for the increase of traps and the decrease of breakdown field strength. The former is dominant in the early stage of aging, and the latter is dominant in the late stage of aging. Therefore, the conductivity shows the law of slow decrease first and then rapid increase. The relevant research provides a theoretical foundation for the process improvement and life prediction of BOPP films. [ABSTRACT FROM AUTHOR]

The nanointerfaces of ZnO-Cu and the size of active nanoparticles (NPs) play crucial roles in the development process of CO2 hydrogenation. Herein, Zn-PBC80 with an unsaturated coordination Zn2+ center was constructed from Zn-(NO3)2·6H2O and 3,5-bis-(4′-carboxyl-phenyl) pyridine (H2PBC), serving as an anchoring site for supporting Cu2+ and a platform for encapsulating NPs. The different loading concentrations of Cu2+ and pyrolysis of the MOFs-based precursor vary the chemical environments of the catalysts, resulting in different distributed states and average sizes of active sites. Specifically, the pyrolysis of Zn-PBC80-Cu-1 with a concentration ratio of 1:1 facilitates the construction of an interfacial ZnO-Cu nanocomposite and smaller NP size. Among a series of CO2 catalysts, the resultant ZnO-Cu-1-700 exhibits the best catalytic performance with a satisfying CO2 conversion rate (16.5%), outstanding CO selectivity (100%), and promoting catalytic stability over 30 h. The best catalytic performance could be attributed to the more stable electronic structure of metallic Cu NPs and the generation of oxygen vacancies resulting from the unique ZnO-Cu nanointerfaces among the catalysts. This discrepancy in catalytic performance indicates that the active nanointerfaces affects the electronic structure of active centers, providing valuable insight into the design of efficient catalysts for CO2 reduction. [ABSTRACT FROM AUTHOR]

Cable accessory has the interface formed by cross‐linked polyethylene (XLPE)/silicone rubber (SiR), which is prone to surface discharge and thus causes the failure of cable system. This article conducts the simulated experiment of thermal–mechanical aging on the interface of XLPE/SiR. The interfacial breakdown and dielectric properties under different aging states are analyzed. It is found the interfacial aging process of XLPE can be divided into the recrystallization stage and the oxidation reaction stage. The former contributes to the interfacial roughness and thus the better insulating performance, whereas the latter leads to degradation of interface, and thus the worse insulating performance. In addition, combined with the established electric field model for the interface, the differences between thermal–mechanical aging and individual thermal aging on the interface are discussed. The sample under thermal–mechanical aging reaches the maximum interfacial breakdown voltage later than that under individual thermal aging, but their performance tends to be consistent in the later stage of aging. [ABSTRACT FROM AUTHOR]

A novel metal–organic framework (MOF) Zn-PBC (H2PBC = pyridine-3,5-bis(phenyl-4-carboxylic acid)) was designed and synthesized via a solvothermal reaction with the H2PBC ligand, and produced a strong fluorescence. The material exhibited good stability and an ideal luminescent property in water. In addition, it was found that Zn-PBC displayed a different fluorescent response to different types of amino acids, and the mechanism was investigated. This research might give insight to the interaction between MOFs and amino acids, which would provide a strategy to fabricate MOF-based sensors for biomolecules in future. [ABSTRACT FROM AUTHOR]