Thiadiazoloquinoxaline and benzodithiophene bearing polymers for electrochromic and organic photovoltaic applications

Abstract

Two novel thiadiazoloquinoxaline and benzodithiophene (BDT) bearing copolymers were designed and synthesized. Different BDT units (alkoxy and thiophene substituted) were used as donor materials and the effect of alkoxy and thiophene substitution on the electrochemical, spectroelectrochemical and photovoltaic properties were investigated. Both polymers exhibited low oxidation potentials at around 0.90 V and low optical band gaps at around 1.00?eV due to the insertion of electron poor thiadiazoloquinoxaline unit into the polymer backbone. Both P1 (poly-6,7-bis(3,4-bis(decyloxy)phenyl)-4-(4,8-bis(nonan-3-yloxy)benzo[1,2-b:4,5-b']dithiophen-2-yl)-[1, 2, 5]thiadiazolo[3,4-g]quinoxaline) and P2 (poly- 4-(4,8-bis(5-(nonan-3-yl)thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophen-2-yl)-6,7-bis(3,4-bis(decyloxy)phenyl)-[1, 2, 5]thiadiazolo[3,4-g]quinoxaline) exhibited multichromic behavior with different tones of greenish yellow and gray in the neutral and fully oxidized states, respectively. In addition, both polymers revealed very high optical contrasts (～87%) in the NIR region which make these promising polymers good candidates for NIR applications. Finally, in order to explore the organic photovoltaic performances, P1 and P2 were mixed with PC₇₁BM in the active layer of organic solar cells (OSCs) by conventional device structure. As a result P1 and P2 based devices revealed power conversion efficiencies (PCEs) of 0.33% and 0.60% respectively. However, the additive treatment enhanced PCE from 0.49 to 0.73% for P2 based devices.     

含有非磁性气隙层叠层电感直流特性的研究

为了获得适合功率电感磁芯材料的磁导率及提升器件的直流特性,提出了在器件磁芯材料层中引入一定厚度的非磁性气隙层可有效调节磁芯材料的磁导率,以提升器件的直流偏置性能。设计仿真了尺寸为2.0mm×2.5mm×1.05mm,含有10匝线圈的叠层功率电感中引入非磁性气隙层的直流特性。研究了在磁芯中部引入5²0μm不同厚度气隙层的直流特性,结果表明直流电流从1.18A上升到2.34A;同时研究了引入不同层数及不同分布排列的气隙层的直流特性,表明气隙层数越多,分布在磁芯中越稀疏,可获得更好的直流性能。     

Adsorption of CO on the O2 pre-adsorbed LaFeO3 (0 1 0) surface: A density functional theory study

The adsorption of CO molecule on the O₂ pre-adsorbed LaFeO₃ (0 1 0) surface has been investigated using a density functional theory calculation. The calculated results show that the most appropriate reaction occurs between the CO and the pre-adsorbed O₂. After CO adsorption, the bonding mechanism between Fe site and the pre-adsorbed O₂ is not modified, and the HOMO–LUMO energy gap of the M1 mode is narrowed, which is caused by the redistribution of electron density in the surface.     

求解变分不等式问题的一类新算法

变分不等式问题(简称VIP)通过广义D-gap函数可以转化成无约束优化问题.在找到使优化问题目标函数达到最大的y值后,直接构造了一类下降方向,使算法避免了求解梯度问题.最后证明了这种算法具有全局收敛性.     

产业结构变动与城乡收入差距关系的协整分析

根据中国1952-2008年的数据,运用协整理论和Granger因果检验分析了中国产业结构变动与城乡收入差距的关系.协整检验及误差修正模型结果表明,二者之间在所研究期间内存在长期稳定的正向均衡关系,并且短期动态校正作用明显.同时,Granger因果关系检验结果说明中国的产业结构变动与城乡收入差距扩大之间存在双向因果关系.     

嵌套技术扩散模型估计与落后地区的技术追赶

技术差距带来的技术扩散效应决定了区域间可能存在着技术收敛.在限制指数模型中,所有国家和地区将获得相同的技术进步率,在逻辑斯蒂模型中,人力资本水平成为制约技术收敛的条件.将Benhabib和Speigel(2005)的跨国技术收敛的实证研究工作推广到国内地区研究之中,分析了中国30个省区1990-2008年技术进步率的影响因素及收敛情况.实证研究结果表明,中国30个省区的技术进步率趋异.人力资本是促进地区自主创新和技术扩散的积极因素.     

Convergence to equilibrium of biased plane Partitions

We study a single‐flip dynamics for the monotone surface in (2 + 1) dimensions obtained from a boxed plane partition. The surface is analyzed as a system of non‐intersecting simple paths. When the flips have a non‐zero bias we prove that there is a positive spectral gap uniformly in the boundary conditions and in the size of the system. Under the same assumptions, for a system of size M, the mixing time is shown to be of order M up to logarithmic corrections. © 2010 Wiley Periodicals, Inc. Random Struct. Alg., 39, 83–114, 2011     

Decay of a quantum dot in two-dimensional metallic photonic crystals

In this paper we have developed a theory for the decay of a quantum dot doped in a two-dimensional metallic photonic crystal consisting of two different metallic pillars in an air background medium. This crystal structure forms a full two-dimensional photonic band gap when the appropriate pillar sizes are chosen. The advantage of using two metals is that one can easily control the density of states and optical properties of these photonic crystals by changing the plasma energies of two metals rather than one. Using the Schrödinger equation method and the photonic density of states, we calculated the linewidth broadening and the spectral function of radiation due to spontaneous emission for two-level quantum dots doped in the system. Our results show that by changing the plasma energies one can control spontaneous emission of quantum dots doped in the metallic photonic crystal.     

Enlargement of absolute photonic band gap in modified 2D anisotropic annular photonic crystals

We analyze the absolute photonic band gap in two dimensional (2D) square, triangular and honeycomb lattices composed of air holes or rings with different geometrical shapes and orientations in anisotropic tellurium background. Using the numerical plane wave expansion method, we engineer the absolute photonic band gap in modified lattices, achieved by addition of circular, elliptical, rectangular, square and hexagonal air hole or ring into the center of each lattice unit cell. We discuss the maximization of absolute photonic band gap width as a function of main and additional air hole or ring parameters with different shapes and orientation.     

Abnormal behaviour of one-dimensional photonic crystal with defect

The effect of introduction a defect in a conventional one-dimensional photonic band gap (PBG) structure in respect of the dispersion relation, reflectivity, group velocity and effective group index of such a structure has been studied. In particular, the dependence of various properties of such a structure on the angle of incidence of the electromagnetic waves has been given more importance in the present study. The study shows that inside the conventional PBG structure as well as defect PBG structure, the group velocity and effective group index become negative for certain ranges of normalized frequency. In a defect PBG structure, it is possible to achieve desired values (negative or positive) of group velocity and effective group index by choosing appropriate angle of incidence, whereas in conventional PBG structures, the maximum (negative and positive) values of group velocities and effective group index are found to be almost independent of the angle of incidence. This is a unique property of defect PBG structure which is different from the properties of conventional PBG structures. Because of this unique property, defect PBG structure may be widely used for construction super lenses, lasing without inversion and other optical systems in photonics.