ALBERT

Description: Charge generation in a typical intermediate connector, composed of “n-type doped layer/transition metal oxide (TMO)/hole transporting layer (HTL),” of a tandem organic light-emitting device (OLED) has recently been found to arise from charge transfer at the TMO/HTL interfaces. In this paper, we investigate the effect of hole injection barriers from intermediate connectors on the performance of tandem OLEDs. The hole injection barriers are caused by the offset of the highest occupied molecular orbital (HOMO) energy levels between HTLs contained in the intermediate connector and the top electroluminescence (EL) unit. We also find that although charge generation can occur at the interfaces between the TMO and a wide variety of HTLs of different HOMO values, an increase in the hole injection barrier however limits the electroluminescence efficiency of the top EL units. In the case of large hole injection barriers, significant charge accumulation in the HTLs makes the intermediate connector lose its functionality gradually over operating time, and limits device stability.

Description: The authors develop a facile and effective method to produce the chlorinated indium tin oxide (Cl-ITO) treated by InCl 3 aqueous solution and UV/ozone. The work function of the Cl-ITO achieved by this treatment is as high as 5.69 eV, which is increased by 1.09 eV compared with that of the regular ITO without any treatment. Further investigation proved that the enhancement of the work function is attributed to the formation of In-Cl bonds on the Cl-ITO surface. Green phosphorescent organic light-emitting devices based on the Cl-ITO electrodes exhibit excellent electroluminescence performance, elongating lifetime due to the improvement in hole injection.

Description: Tandem organic light-emitting devices (OLEDs), i.e., OLEDs containing multiple electroluminescence (EL) units that are vertically stacked, are attracting significant interest because of their ability to realize high current efficiency and long operational lifetime. However, stacking multiple EL units in tandem OLEDs increases driving voltage and complicates fabrication process relative to their standard single unit counterparts. In this paper, we demonstrate low driving voltage tandem OLEDs via utilizing exciplex-forming hosts in the EL units instead of conventional host materials. The use of exciplex-forming hosts reduces the charge injection barriers and the trapping of charges on guest molecules, resulting in the lower driving voltage. The use of exciplex-forming hosts also allows using fewer layers, hence simpler EL configuration which is beneficial for reducing the fabrication complexity of tandem OLEDs.

Description: We demonstrate an approach to enhance the energy storage density W of antiferroelectric film through simple altering a crystallographic orientation of the substrate. We reveal that the antiferroelectric phase stability of PbZrO 3 can be enhanced for the (110) or (111) SrTiO 3 substrate orientation, thus suppresses the antiferroelectric-ferroelectric phase transition to higher electric field with ∼120 kV/cm increment. In addition, the polarization values of these films are also favorably increased hence increases W by 5.3 J/cm 3 at 700 kV/cm. The observed enhancement is found to originate from a high sensitivity of phase transition to mechanical confinements due to the volume expansion at the transition.

Description: The discovery of novel antiviral materials is important because many infectious diseases are caused by viruses. Silver nanoparticles have demonstrated strong antiviral activity, and graphene is a potential antimicrobial material due to its large surface area, high carrier mobility, and biocompatibility. No studies on the antiviral activity of nanomaterials on non-enveloped viruses have been reported. To investigate the antiviral activity of graphene oxide (GO) sheets and GO sheets with silver particles (GO-Ag) against enveloped and non-enveloped viruses, feline coronavirus (FCoV) with an envelope and infectious bursal disease virus (IBDV) without an envelope were chosen. The morphology and sizes of GO and GO-Ag were characterized by transmission, scanning electron microscopy, and X-ray diffraction. A virus inhibition assay was used to identify the antiviral activity of GO and GO-Ag. Go-Ag inhibited 25% of infection by FCoV and 23% by IBDV, whereas GO only inhibited 16% of infection by FCoV but showed no antiviral activity against the infection by IBDV. Further application of GO and GO-Ag can be considered for personal protection equipment to decrease the transmission of viruses.

Description: Water, Vol. 10, Pages 616: A Non-Equilibrium Sediment Transport Model for Dam Break Flow over Moveable Bed Based on Non-Uniform Rectangular Mesh Water doi: 10.3390/w10050616 Authors: Gangfeng Wu Zhehao Yang Kefeng Zhang Ping Dong Ying-Tien Lin The use of multiple-level non-uniform rectangular mesh in coupled flow and sediment transport modeling is preferred to achieve high accuracy in important region without increasing computational cost greatly. Here, a robust coupled hydrodynamic and non-equilibrium sediment transport model is developed on non-uniform rectangular mesh to simulate dam break flow over movable beds. The enhanced shallow water and sediment transport equations are adopted to consider the mass and momentum exchange between the flow phase and sediment phase. The flux at the interface is calculated by the positivity preserving central upwind scheme, which belongs to Godunov-type Riemann-problem-solver-free central schemes and is less expensive than other popular Riemann solvers while still capable of tracking wet/dry fronts accurately. The nonnegative water depth reconstruction method is used to achieve second-order accuracy in space. The model was first verified against two laboratory experiments of dam break flow over irregular fixed bed. Then the quantitative performance of the model was further investigated by comparing the computational results with measurement data of dam break flow over movable bed. The good agreements between the measurements and the numerical simulations are found for the flow depth, velocity and bed changes.

Description: Organic light-emitting diodes (OLEDs) with a p-i-n-p structure were developed by inserting a p-doped layer, MoO 3 doped N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-benzidine (NPB), between an n-doped electron injection layer and the cathode. The device showed a 33.5% improvement in the power efficiency and 70.7% improvement in the half operational lifetime compared with the conventional p-i-n structure based device. The improved device performance is mainly ascribed to an improved conductivity, an enhanced thermal stability, and the protection of the electron injection layer by the NPB:MoO 3 p-doped layer. The finding indicates that the p-i-n-p structure is beneficial for improving the efficiency and the stability of OLEDs.

Description: Forests, Vol. 9, Pages 87: Transcriptome Analysis of the Biosynthesis of Anthocyanins in Begonia semperflorens under Low-Temperature and High-Light Conditions Forests doi: 10.3390/f9020087 Authors: Yanpeng Dong Ying Qu Rui Qi Xue Bai Geng Tian Yang Wang Jiawan Wang Kaiming Zhang Anthocyanins are considered a stress indicator due to their involvement in the response to many stresses including high light (HL) and low temperature (LT). With the development of transcriptomics, it is necessary to find the different and common points in the mechanisms of LT-induced and HL-induced anthocyanin biosynthesis. In the present study, we determined the transcriptomes of Begonia semperflorens leaves under three different conditions (normal growing conditions (CK), HL, and LT). To validate the differentially expressed genes (DEGs), we selected four core genes involved in anthocyanin biosynthesis to perform real-time reverse transcription-quantitative PCR (RT-qPCR), and then determined anthocyanin content. In total, 94,880 unigenes with a mean length of 635 bp were assembled. The N50 values of the transcripts and unigenes were 2286 bp and 1064 bp, respectively. The functional annotations of the unigenes were analysed against five protein databases. DEGs related to anthocyanin biosynthesis, transportation, and regulation were identified. We also analysed the enrichment pathway, and the differences in mechanisms of anthocyanin induced under low-temperature and high-light conditions are discussed in this paper. This study is the first to examine broad-scale gene expression in Begonia semperflorens. By identifying DEGs regulated by both LT and HL conditions, we found that anthocyanin accumulation was employed as a common strategy by Begonia seedlings in resisting LT and HL stress. By identifying DEGs regulated differently by LT and HL conditions, we found that Begonia seedlings also had some different strategies for resisting LT and HL stresses: anthocyanins were biosynthesized under HL condition, while lignin, proanthocyanidins, and anthocyanins were biosynthesized under LT condition.