Method for fabricating the compact layer in dye-sensitized solar cells by titanium sputter deposition and acid-treatments

Dye-sensitized solar cells (DSCs) have been put forward as a potential low-cost alternative to the widely used silicon solar cells, which are subject to cost limitations. However, some problems need to be solved in order to enhance the efficiency of DSCs. In particular, the electron recombination occurred by the contact between the transparent conductive oxide (TCO) and a redox electrolyte is one of the main limiting factors of efficiency. Accordingly, a compact layer plays an important role in realizing highly efficient DSCs because it improves the adhesion of the TiO₂ to the TCO and provides a larger contact area and more effective electron transfer by preventing electron recombination. In this work, the fabrication of a TiO₂ compact layer using Ti sputter deposition and acid-treatment was investigated rather than the conventional method, which uses a TiCl₄ aqueous solution. The acid-treatment of the sputtered Ti film actively oxidized the Ti particles. As a result, such a cell exhibited an additional 1.3% in total efficiency compared to the standard DSC without a compact layer. These improvements are not inferior to those obtained by the conventional fabrication method using a TiCl₄ aqueous solution.     

Grain dependence of ferroelectric domain switching on SrBi2Ta2O9 thin films observed by Kelvin probe force microscope

We have studied grain-shape dependence of Kelvin probe force microscopy of SrBi₂Ta₂O₉ thin films on epitaxial La_0.5Sr_0.5CoO₃/LaAlO₃ substrates. By changing the growth condition in pulsed laser deposition, we have grown the SrBi₂Ta₂O₉ thin films with various grain shapes. The shape and the orientation of SrBi₂Ta₂O₉ the thin films with various growth conditions have been analyzed by X-ray diffraction and scanning electron microscope. The large number of the long rectangular grains was observed accompanied with relatively larger (220) peaks than other peaks. From the Kelvin probe force microscope study, it has been observed that the long rectangular grains showed characteristics of easy ferroelectric domain switching at a low writing bias and weaker influence of surface charges.     

Synthesis and electrochemical characterization of Li2MnO3–LiNixCOyMnzO2 cathode for lithium battery using co-precipitation method

The Li_xNi_0.23Co_0.12Mn_0.65O₂ electrode system with various compositions (x = 1.19, 1.33, 1.46, 1.58) was synthesized from a metal oxide precursor synthesized by co-precipitation method. The XRD patterns of the prepared powders revealed a hexagonal α-NaFeO₂ structure (space group: R-3m, 166) and the existence of a Li₂MnO₃ phase in the composite structure. In particular, the low Li content sample shows a three integrated structure (spinel, Li₂MnO₃, LiMO₂) for a Li/Metal(Ni/Co/Mn) mol ratio of 1.2. Scanning electron microscopy showed that all the synthesized samples contained spherical agglomerates with a size of 8–10 μm. Among the samples tested, Li_1.46Ni_0.23Co_0.12Mn_0.65O₂ shows relatively high charge and discharge capacity for the first cycle is 287, 192.9 mA h g^?1, respectively. Also, charge transfer resistance was also significantly improved compare with other samples.     

BCGAN: A CGAN-based over-sampling model using the boundary class for data balancing

The Journal of Supercomputing - A class imbalance problem occurs when a dataset is decomposed into one majority class and one minority class. This problem is critical in the machine learning...     

Fuzzy kernel K-medoids clustering algorithm for uncertain data objects

Pattern Analysis and Applications - Most data mining algorithms are designed for traditional type of data objects which are referred to as certain data objects. Certain data objects contain no...     

Photosynthetic Cyanobacteria can Clearly Induce Efficient Muscle Tissue Regeneration of Bioprinted Cell-Constructs

Tissue engineering strategies using cell-laden constructs have shown promising results in the treatment of various types of damaged tissues. However, inadequate oxygen delivery to the macroscale 3D cell-constructs for regenerating skeletal muscle tissue has remained a multiplex issue owing to the pivotal factors including cell metabolism and several regulatory intercellular pathways that eventually influence various cellular activities and determines cell phenotype. To overcome this issue, a photosynthetic cyanobacterium (Synechococcus elongatus) is employed in a methacrylated gelatin bioink. Furthermore, to effectively induce cell alignment in the bioink, in situ electric field stimulation is used in a bioprinting system to fabricate cell-laden scaffolds for regenerating skeletal muscle tissue. Owing to the synergistic effects of the bioactive microenvironment that rescues cells from hypoxic conditions and activations of voltage-gated ion channels, highly aligned, multi-nucleated myofibers are obtained as well as significant upregulation (7–10-fold) of myogenic-related genes compared with conventionally prepared cell-constructs. In addition, in vivo studies using a mouse volumetric muscle loss model demonstrate considerable restoration of muscle functionality and regeneration.     

All-Impurities Scavenging,Safe Separators with Functional Metal-Organic-Frameworks for High-Energy-Density Li-Ion Battery

Li-ion batteries (LIBs) have wide applications owing to their high-energy density and stable cycle characteristics. Nevertheless, with the rapid expansion of electric vehicle market, issues such as explosion of LIBs and the need to secure a longer driving distance have emerged. In this work, functional metal–organic frameworks (MOFs) are introduced as a separator in LIBs, in which a highly heat-resistant polymer separator is fabricated through electrospinning. The MOFs can scavenge impurities (including gas, water, and hydrofluoric acid) that positively affect battery performance and safety. The multi-functional separator suppresses salt decomposition when a nickel-rich cathode is operated at high voltage and high temperature through it. This delays the deterioration of the cathode interface and results in a superb cycle stability with 75% retention even in the presence of 500 ppm of water in the electrolytes. In addition, the pouch cell is manufactured by enlarging the separator, and the degree of electrode swelling due to gas generation and interface degradation in the pouch state is alleviated to 50% or less. These findings highlight the necessity of scavenging impurities to maintain excellent performance and provides the development direction of functional separators in LIBs.     

Chemically Recyclable Conjugated Polymer and One-Shot Preparation of Thermally Stable and Efficient Bulk-Heterojunction from Recycled Monomer

Recyclable conjugated polymers are important for realizing eco-friendly electronics with advantages of solution processability and flexibility. A recyclable conjugated polymer, PY-TIP is developed, of which a key monomer is successfully extracted via a mild depolymerization process and is reused for the synthesis of novel conjugated polymers. One-shot preparation of polymer acceptor and its bulk-heterojunction (BHJ) is demonstrated from the recycled monomer, Y5-TA, for the first time and the resulting BHJ film shows optimal nanoscale morphology for efficient charge generation and transport. As a result, the solar cells prepared using the BHJ film show a higher efficiency of 13.08% and much improved thermal and mechanical stability compared with those based on the small molecular acceptor. These results are important in that the various polymers can be prepared from the recycled monomer in a solid state without organic solvents and purification step and this strategy is effective for improving the thermal and mechanical stability of the BHJ film as well as achieving high photovoltaic performance. PY-TIP is exemplary in that it can reproduce its monomer which can be used to synthesize conjugated polymers with novel chemical structures and physical properties. This work provides a design guideline for developing recyclable conjugated polymers with dynamic covalent bonds.