Theoretical investigations on the weak nonbonded CS···CH2 interactions: Chalcogen‐bonded complexes with singlet carbene as an electron donor

In this article, we explored the noncovalent bonding interactions between O?C?S, S?C?S, F₂C?S, Cl₂C?S, and singlet carbene. Six chalcogen‐bonded complexes were obtained. It is found that all the vibrational frequencies of C?S bond presented a red shift character. Interaction energy, topology property of the electron density and its Laplacian, and the donor–acceptor interaction have been investigated. All these results show that there exists a weak nonbonded interaction between the chalcogen bond donor and CH₂. An energy decomposition analysis was performed to disclose that the electrostatic interaction is the main stabilized factor in these nonbonded complexes. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Higher Dimensional Rotating Black Hole Solutions in Quadratic f(R) Gravitational Theory and the Conserved Quantities

We explore the quadratic form of the f(R)=R+bR2 gravitational theory to derive rotating N-dimensions black hole solutions with ai,i≥1 rotation parameters. Here, R is the Ricci scalar and b is the dimensional parameter. We assumed that the N-dimensional spacetime is static and it has flat horizons with a zero curvature boundary. We investigated the physics of black holes by calculating the relations of physical quantities such as the horizon radius and mass. We also demonstrate that, in the four-dimensional case, the higher-order curvature does not contribute to the black hole, i.e., black hole does not depend on the dimensional parameter b, whereas, in the case of N>4, it depends on parameter b, owing to the contribution of the correction R2 term. We analyze the conserved quantities, energy, and angular-momentum, of black hole solutions by applying the relocalization method. Additionally, we calculate the thermodynamic quantities, such as temperature and entropy, and examine the stability of black hole solutions locally and show that they have thermodynamic stability. Moreover, the calculations of entropy put a constraint on the parameter b to be b<116Λ to obtain a positive entropy.     

热轧优化剪切系统介绍

为了减少热轧带钢中间坯头部和尾部的切损，精轧机组前的飞剪采用了优化剪切系统来控制。优化剪切系统的使用不仅减低了带钢的切损，还有利于精轧机的咬钢，尤其是在薄系列热轧带钢生产中拥有着良好的应用效果。     

寒冷地区微模块数据中心能耗分析

从降低数据中心的能耗出发,对工作在自然冷源场景下的冷水机组能耗进行分析,并计算出全年的PUE值。提出了在寒冷地区新建数据中心,采用以微模块为核心,配合具有Free Cooling冷却技术的冷水机组为数据中心进行制冷的技术架构,根据系统仿真测试,结果表明,提高末端空调的供水温度,每当提高1℃的出水温度,冷水机组的制冷量将提高3%~4%,而功耗约增加1%。有效地降低了PUE值,从而节约了电能,降低了碳排量及成本。     

Low‐Power Cool Bypass Switch for Hot Spot Prevention in Photovoltaic Panels

With the introduction of high‐current 8‐inch solar cells, conventional Schottky bypass diodes, usually adopted in photovoltaic (PV) panels to prevent the hot spot phenomenon, are becoming ineffective as they cause relatively high voltage drops with associated undue power consumption. In this paper, we present the architecture of an active circuit that reduces the aforementioned power dissipation by profitably replacing the bypass diode through a power MOS switch with its embedded driving circuitry. Experimental prototypes were fabricated and tested, showing that the proposed solution allows a reduction of the power dissipation by more than 70% compared to conventional Schottky diodes. The whole circuit does not require a dedicated DC power and is fully compatible with standard CMOS technologies. This enables its integration, even directly on the panel, thereby opening new scenarios for next generation PV systems.     

Analysis of a transparent organic photoconductive sensor

The electro-optical performance of transparent photoconductive sensors based on stacks of organic layers is investigated. The photoconductive sensors are composed of interdigitated electrodes covered with a stack of two transparent organic compounds: a hole transport layer 1,3,5-tris[(3-methylphenyl)phenylamino]benzene (m-MTDAB) and an exciton generation layer 3,4,9,10-perylenetetracarboxylic bis-benzimidazole (PTCBI). The photocurrent through the device is measured as a function of the voltage across the electrodes for different illumination levels. Based on the measurements we can explain the working principle of the photoconductive sensor and compare the performance of four different stacks. In order to study the optical sensitivity in more detail, a photoconductive device with two parallel electrodes is manufactured and illuminated by a line-shaped laser beam that covers only a fraction of the gap between the electrodes. The current through the photoconductive sensor is measured as a function of the position of the local illumination for a set of voltages. The experimental results confirm that there is a high-field space charge region near the cathode.     

Synthesis and properties of 3,4-dioxythiophene and 1,4-dialkoxybenzene based copolymers via direct C?H arylation: Dopant-free hole transport material for perovskite solar cells

Direct C H arylation coupling reaction has gained significant importance in synthesis of conjugated polymers for organic electronic applications. We report here a facile and straightforward method called “direct C H arylation” reaction to synthesize conjugated 3,4-dioxythiophene and 1,4-dialkoxybenzene based copolymers as hole transport material (HTM) for perovskite solar cells. Two electron-rich conjugated polymers P1-2 were synthesized, in which 1,4-dibromo-2,5-bis(dodecyloxy)benzene and 3,4-dialkoxy-thiophene units were used for polymerization. The resulting polymers were characterized and exhibited high solubility in organic solvents. Electrochemical and optical characterizations were carried out by cyclic voltammetry and UV–Vis–NIR absorption spectroscopy and found that these polymers show higher-lying HOMO energy levels with wide band gap. Density functional theory calculation was performed on these polymers ( P1-2 ) and correlated with our experimental results. Finally, perovskite solar cells were fabricated by solution-processable deposition of P1-2 as dopant-free HTM with device geometry ITO/SnO₂/Perovskite/HTM( P1 / P2 )/Ag and achieved a maximum power conversion efficiency of 5.28%. This study provides information on designing and simple preparation by direct C H arylation reaction of higher-lying HOMO energy level polymer as HTM for perovskite solar cells.     

p-GaN/p-AlxGa1-xN异质结界面处二维空穴气的性质及其对欧姆接触的影响

通过自洽求解一维泊松方程和薛定谔方程,得到了p-GaN/p-Al_xGa_1-xN异质结界面处的价带结构和二维空穴气（2DHG）分布,研究了A1组分和压电极化效应对界面处2DHG性质的影响,给出了异质界面处2DHG的面密度、浓度分布以及价带结构.实验结果表明:随着Al组分的增加,异质结界面处势阱明显加深变窄,这使得2DHG的峰值密度加速上升,也使得面空穴密度近直线上升;压电极化效应也明显使界面处势阱加深变窄,并且使费米能级向势垒顶端移动,峰值浓度的位置向界面处移动;另外,价带带阶高度和受主杂质浓度对2DHG的影响较小.利用这层2DHG制作的p-Al_xGa_1-xN的欧姆接触,电流电压特性明显好于直接制作的电极,说明了2DHG可以显著改善p-Al_xGa_1-xN的欧姆接触性能.