Influence of aromatic heterocycle of conjugated side chains on photovoltaic performance of benzodithiophene-based wide-bandgap polymers

Xue, X.,Fan, B.,Liu, T.,Sun, X.,Huo, L.,Ha, S.,Choi, H.,Kim, T.,Kim, J.,Wei, D. Royal Society of Chemistry 2016 Polymer chemistry Vol.7 No.24

<P>Extensive efforts have been focused on the study of wide-band gap (WBG) polymers due to their important applications in multiple junction and ternary blend organic solar cells. Herein, three WBG copolymers named PBDT(X)-T1 (X = O, S, Se) were synthesized based on the benzodithiophene (BDT) donor unit and 1,3-bis(5-bromothiophen-2-yl)-5,7-bis(2-ethylhexyl)-4H, 8H-benzo[1,2-c: 4,5-c']dithiophene-4,8-dione (T1) acceptor unit. Different aromatic heterocycle groups (furan, thiophene and selenophene) were introduced to modify the BDT unit to investigate the influence of conjugated side chains on the photovoltaic properties of conjugated polymers. Photophysical properties, electrochemistry, charge transport and crystalline properties of the polymers were studied to discuss the role of chalcogen atoms on the performance of conjugated polymers. Solar cells based on these three WBG copolymers were fabricated. Among them, the PBDT(Se)-T1-based solar cell shows the best photovoltaic performance with the highest power conversion efficiency (PCE) of 8.52%, an open-circuit voltage (V-oc) of 0.91 V, and a high fill factor (FF) of 72%. The high crystallinity and preferential face-on orientation in the blend film partially explain the superior photovoltaic performance achieved in PBDT(Se)-T1-based solar cells. The results indicate the important role of chalcogen atoms in conjugated side chains and that high photovoltaic performance can be realized through side chain engineering of BDT-based WBG conjugated polymers.</P>

Microstructure and Properties of the Cr–Si–N Coatings Deposited by Combining High-Power Impulse Magnetron Sputtering (HiPIMS) and Pulsed DC Magnetron Sputtering

Wang, T. G.,Dong, Y.,Gebrekidan, B. A.,Liu, Y. M.,Fan, Q. X.,Kim, K. H. Springer Science + Business Media 2017 Acta metallurgica sinica Vol.30 No.7

<P>The Cr-Si-N coatings were prepared by combining system of high-power impulse magnetron sputtering and pulsed DC magnetron sputtering. The Si content in the coating was adjusted by changing the sputtering power of the Si target. By virtue of electron-probe microanalysis, X-ray diffraction analysis and scanning electron microscopy, the influence of the Si content on the coating composition, phase constituents, deposition rate, surface morphology and microstructure was investigated systematically. In addition, the change rules of micro-hardness, internal stress, adhesion, friction coefficient and wear rate with increasing Si content were also obtained. In this work, the precipitation of silicon in the coating was found. With increasing Si content, the coating microstructure gradually evolved from continuous columnar to discontinuous columnar and quasi-equiaxed crystals; accordingly, the coating inner stress first declined sharply and then kept almost constant. Both the coating hardness and the friction coefficient have the same change tendency with the increase of the Si content, namely increasing at first and then decreasing. The Cr-Si-N coating presented the highest hardness and average friction coefficient for an Si content of about 9.7 at.%, but the wear resistance decreased slightly due to the high brittleness. The above phenomenon was attributed to a microstructural evolution of the Cr-Si-N coatings induced by the silicon addition.</P>

OPTIMIZATION RESEARCH FOR A HIGH PRESSURE COMMON RAIL DIESEL ENGINE BASED ON SIMULATION

Y. LIU,Y.-T. ZHANG,T. QIU,X. DING,Q. XIONG 한국자동차공학회 2010 International journal of automotive technology Vol.11 No.5

ABSTRACT−A TP (Temperature Phase) model is presented to carry out optimization calculation for a high-pressure common rail diesel engine. Temperature is the most important parameter in the TP model. For the lower branch (when temperature T < 850 K) of the S-shaped curve (auto-ignition phase), a 6-step ad-hoc model with adjusted rate constants of nheptane is used, referred to steady state assumption. Steady state assumption is based on the observation that, due to very fast chemical processes in combustion problems, many chemical species and reactions are in a quasi-steady state or partial equilibrium. When a species is assumed to be in the steady state, the corresponding differential equation can be replaced by an algebraic relation, which reduces the computational costs. For the middle branch (850 K ≤ T < 1100 K) of the S-shaped curve, a 4-step model is used to calculate the unstable phase. For the upper branch (T≥1100 K) of the S-shaped curve, onestep model is used because the one-step model has widely been used in descriptions of flame stability where it essentially serves as a model that produces a thin flame with strong temperature sensitivity. When zone temperature T<1500 K, only the soot precursors –PAHs (Polycyclic aromatic hydrocarbons) is created and there is no soot emission. When zone temperature T≥1500 K, PAHs and soot source terms (particle inception, surface growth, oxidation, coagulation) are calculated. The TP model is then applied in multidimensional simulations to carry out optimizing, which reduces experiment cost. The results of cylinder pressures, the corresponding heat release rates, NOx and soot with variation of injection time at constant rail pressure, variation of EGR-rate at constant rail pressure and variation of rail pressure at constant EGR-rate between simulation and experimental data are analyzed. The results indicate that the TP model can carry out optimization and CFD (computational fluid dynamics) and can be a tool to calculate for a high-pressure common rail diesel engine.

The enhanced phosphorescence from Alq₃ fluorescent materials by phosphor sensitization

Tsuboi, T.,Kwon, J.H.,Liu, X.,Huang, W. Elsevier Sequoia 2014 Journal of photochemistry and photobiology Chemist Vol.291 No.-

The green emission accompanied with intense red phosphorescence is observed from the tris(8-hydroxyquinoline) aluminum (Alq<SUB>3</SUB>) in the heavily doped tris(2-phenylpyridine) iridium [Ir(ppy)<SUB>3</SUB>] films. This photoluminescence (PL) emission mechanism is studied by the PL excitation (PLE) spectra for the red and green emissions. From the PLE spectrum for the red emission, the energy transfer from Ir(ppy)<SUB>3</SUB> to Alq<SUB>3</SUB> is confirmed. The increase of the green emission with increasing temperature from 12K is explained by the endothermic back Forster energy transfer from the triplet T<SUB>1</SUB> state of Ir(ppy)<SUB>3</SUB> to the singlet S<SUB>1</SUB> state of Alq<SUB>3</SUB>. It is suggested that this back transfer is partially responsible for the decrease of the red emission intensity corresponding to the increase of the green emission. Unlike the Forster energy transfer, the Dexter energy transfer from the T<SUB>1</SUB> state of Ir(ppy)<SUB>3</SUB> to the T<SUB>1</SUB> state of Alq<SUB>3</SUB> is highly efficient. The explanation for this process is presented here. The green emission is not attributed to Ir(ppy)<SUB>3</SUB> but to Alq<SUB>3</SUB>, because not only the green emission profile but also the red emission profile is quite similar to the δ-phase polycrystalline Alq<SUB>3</SUB>. From these results, it is concluded that the Alq<SUB>3</SUB> forms a δ-phase polycrystalline state to accept the phosphor sensitization. The unusual enhancement of the red phosphorescence from the Alq<SUB>3</SUB> is explained by the mixing of the T<SUB>1</SUB> state of Ir(ppy)<SUB>3</SUB> with the T<SUB>1</SUB> state of Alq<SUB>3</SUB> under the Dexter energy transfer of short range process, by taking into account that the T<SUB>1</SUB> state of Ir(ppy)<SUB>3</SUB> contains the singlet state by the strong spin-orbit coupling.

Synthesis, spectroscopic investigations, X-ray crystallographic studies and magnetic properties of heterobimetallic Fe(II)-Hg(II) polynuclear complexes

Jin, L. T.,Liu, X. T.,Wang, X. Q.,Wang, L. N.,Zhang, G. H.,Zhu, L. Y.,Xu, D. Informa UK (TaylorFrancis) 2014 Materials research innovations Vol.18 No.2

Strain-Engineered Magnetic Anisotropy of GaMnAs Ferromagnetic Semiconductors

T. Kim,이상훈,D.Y. Shin,I.S. Choi,J.K. Furdyna,정선재,X. Liu 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.3

A series of GaMnAs epilayers grown on GaInAs buffer layers have been investigated. The concentrations of Mn in the GaMnAs layer and In in the GaInAs layer were varied in the series, for which the tensile strain condition for the GaMnAs layer are systematically changed. The X-ray measurement provided the lattice constants of the layers, from which the stain of the GaMnAs layer was determined. The magneto-transport data revealed in-plane anisotropy in the GaMnAs sample grown on a GaInAs buffer with a low concentration of In. Such in-plan magnetic anisotropy of the GaMnAs layer continuously changed to a vertical magnetic anisotropy when the tensile strain was increased in the sample grown on the GaInAs buffer with a higher In concentration. This experiment clearly demonstrated that the magnetic anisotropy of GaMnAs could be continuously engineered by using the strain introduced by the GaInAs buffer layers.

Pulsed Laser Deposition and Characterization of InZnO Alloyed Thin Film

Shan, F.K.,Liu, G.X.,Shin, Byoung Chul,Lee, Won Jae,Oh, W.T. Trans Tech Publications, Ltd. 2008 Key Engineering Materials Vol.368 No.-

<P>High-quality In2O3 powder and ZnO powder had been used to make the ceramic target and the atomic ratio of 1 to 1 of indium and zinc had been prepared in this study. The alloyed thin films had been deposited on sapphire (001) substrates at different temperatures (100-600°C) by using pulsed laser deposition (PLD) technique. An x-ray diffractometer and an atomic force microscope were used to investigate the structural and morphological properties of the alloyed thin films. It was observed that the alloyed thin films deposited at the temperatures lower than 300°C were amorphous, and the alloyed thin films deposited at high temperatures were crystallized. A spectrophotometer was used to investigate the transmittances of the alloyed thin films. It was found that the alloyed thin films were of high quality. The band gap energies of the alloys were calculated by linear fitting the sharp absorption edges of the transmittance spectra. The Hall measurements were also carried out to identify the electrical properties of the thin films.</P>

Long-lived K isomer and enhanced γ vibration in the neutron-rich nucleus ¹⁷²Dy: Collectivity beyond double midshell

Watanabe, H.,Zhang, G.X.,Yoshida, K.,Walker, P.M.,Liu, J.J.,Wu, J.,Regan, P.H.,Soderstrom, P.A.,Kanaoka, H.,Korkulu, Z.,Lee, P.S.,Nishimura, S.,Yagi, A.,Ahn, D.S.,Alharbi, T.,Baba, H.,Browne, F.,Bruce North-Holland Pub. Co 2016 Physics letters. Section B Vol.760 No.-

The level structure of <SUP>172</SUP>Dy has been investigated for the first time by means of decay spectroscopy following in-flight fission of a <SUP>238</SUP>U beam. A long-lived isomeric state with T<SUB>½</SUB>=0.71(5) s and K<SUP>π</SUP>=8<SUP>-</SUP> has been identified at 1278 keV, which decays to the ground-state and γ-vibrational bands through hindered electromagnetic transitions, as well as to the daughter nucleus <SUP>172</SUP>Ho via allowed β decays. The robust nature of the K<SUP>π</SUP>=8<SUP>-</SUP> isomer and the ground-state rotational band reveals an axially-symmetric structure for this nucleus. Meanwhile, the γ-vibrational levels have been identified at unusually low excitation energy compared to the neighboring well-deformed nuclei, indicating the significance of the microscopic effect on the non-axial collectivity in this doubly mid-shell region. The underlying mechanism of enhanced γ vibration is discussed in comparison with the deformed Quasiparticle Random-Phase Approximation based on a Skyrme energy-density functional.

Surface segregation and oxidation of Pt₃Ni(111) alloys under oxygen environment

Lee, H.C.,Kim, B.M.,Jeong, C.K.,Toyoshima, R.,Kondoh, H.,Shimada, T.,Mase, K.,Mao, B.,Liu, Z.,Lee, H.,Huang, C.Q.,Li, W.X.,Ross, P.N.,Mun, B.S. Elsevier Science Publishers 2016 CATALYSIS TODAY - Vol.260 No.-

<P>Utilizing ambient pressure X-ray photoelectron spectroscopy (AP-XPS), the surface segregation and oxidation of Pt3Ni(1 1 1) alloys are investigated as a function of temperature and oxygen pressure. The in situ AP-XPS measurements of oxygen oxidation process show that the Pt 'skin' surface is not stable under the exposure of oxygen pressure of 100 mTorr at room temperature. As the temperature and pressure are elevated, the formations of Ni2O3, NiOx, and NiO are observed on surface while Pt atom starts to reduce its adsorbed oxygen, which is a clear sign of surface segregation of Ni to surface. Upon the evacuation of oxygen gas, i.e. ultrahigh vacuum condition, both of NiOx and NiO oxide get reduced and Ni2O3 remains on the surface. The DFT calculation is employed to explain the formation of surface oxides under oxidation condition. (C) 2015 Elsevier B.V. All rights reserved.</P>

β-Catenin Regulates Hepatic Mitochondrial Function and Energy Balance in Mice

Lehwald, Nadja,Tao, Guo&#x2013,Zhong,Jang, Kyu Yun,Papandreou, Ioanna,Liu, Bowen,Liu, Bo,Pysz, Marybeth A.,Willmann, Jü,rgen K.,Knoefel, Wolfram T.,Denko, Nicholas C.,Sylvester, Karl G. Elsevier 2012 Gastroenterology Vol.143 No.3

<P><B>Background & Aims</B></P> <P>Wnt signaling regulates hepatic function and nutrient homeostasis. However, little is known about the roles of β-catenin in cellular respiration or mitochondria of hepatocytes.</P> <P><B>Methods</B></P> <P>We investigated β-catenin's role in the metabolic function of hepatocytes under homeostatic conditions and in response to metabolic stress using mice with hepatocyte-specific deletion of β-catenin and their wild-type littermates, given either saline (sham) or ethanol (as a model of binge drinking and acute ethanol intoxication).</P> <P><B>Results</B></P> <P>Under homeostatic conditions, β-catenin-deficient hepatocytes demonstrated mitochondrial dysfunctions that included impairments to the tricarboxylic acid cycle and oxidative phosphorylation (OXPHOS) and decreased production of adenosine triphosphate (ATP). There was no evidence for redox imbalance or oxidative cellular injury in the absence of metabolic stress. In mice with β-catenin-deficient hepatocytes, ethanol intoxication led to significant redox imbalance in the hepatocytes and further deterioration in mitochondrial function that included reduced OXPHOS, fatty acid oxidation (FAO), and ATP production. Ethanol feeding significantly increased liver steatosis and oxidative damage, compared with wild-type mice, and disrupted the ratio of nicotinamide adenine dinucleotide. β-catenin-deficient hepatocytes also had showed disrupted signaling of Sirt1/peroxisome proliferator-activated receptor-α signaling.</P> <P><B>Conclusions</B></P> <P>β-catenin has an important role in the maintenance of mitochondrial homeostasis, regulating ATP production via the tricarboxylic acid cycle, OXPHOS, and fatty acid oxidation; β-catenin function in these systems is compromised under conditions of nutrient oxidative stress. Reagents that alter Wnt-β-catenin signaling might be developed as a useful new therapeutic strategy for treatment of liver disease.</P>