White organic light-emitting diodes based on a combined electromer and monomer emission in doubly-doped polymers

We report on white organic light-emitting diodes(WOLEDs) based on polyvinylcarbazole(PVK) doped with 1,1-bis((di-4-tolylamino)phenyl)cyclohexane(TAPC) and perylene,and investigate the luminescence mechanism of the devices.The chromaticity of light emission can be tuned by adjusting the concentration of the dopants.White light with the Commission Internationale de L’Eclairage(CIE) coordinates of(0.33,0.34) is achieved by mixing the yellow electromer emission of TAPC and the blue monomer emission of perylene from the device ITO/PVK:TAPC:perylene(100:9:1 in wt.)(100 nm)/tris-(8-hydroxyquinoline aluminum(Alq 3)(10 nm)/Al.The device exhibits a maximal luminance of 3727 cd/m2 and a current efficiency of 2cd/A.     

Solvent-vapour treatment induced performance enhancement of amplified spontaneous emission based on poly[2-methoxy-5-（2＇-ethyl-hexyloxy）-l, 4-phenylene vinylene]

In this work, performance enhancements of amplified spontaneous emission （ASE） from poly[2-methoxy-5-（2＇- ethyl-hexyloxy）-l,4-phenylene vinylene] （MEH-PPV） have been achieved via solvent vapour treatment. Correlations between the morphology of the film and the optical performance of polymer-based ASE are investigated. The active layers are characterised by atomic force microscopy and optical absorption. The results show that the solvent-vapour treatment can induce the MEH-PPV self-organisation into an ordered structure with a smooth surface, leading to enhanced optical gain. Thus the solvent-vapour treatment is a good method for improving the optical properties of the MEH-PPV.     

锥形微通道内液滴自输运特性及力学驱动机制研究

针对液体在微通道内的自输运特性,采用数值仿真与能量解析相结合的方法研究了液滴在锥形微通道内的自输运特性及力学驱动机制,得到微通道的锥形角、液滴与微通道内壁的接触角及微通道的润湿性对液滴自输运特性的影响关系.分析表明,微通道的锥形角、液滴与微通道内壁的接触角均能影响液滴的自输运方向及驱动力大小.对于亲水性微通道,微通道的锥形角、液滴与微通道内壁的接触角其作用效果呈现整体形态;对于疏水性微通道,微通道的锥形角、液滴与微通道内壁的接触角其作用效果呈现局域形态.这可为研究液体在微通道内的自输运机理及界面内液体细观流动机制奠定理论基础.     

考虑界面粗糙度动态变化的点接触弹流润滑特性研究

针对点接触弹流润滑的粗糙度效应,建立了考虑表面粗糙度动态变化的点接触弹流润滑模型,实现了油膜厚度和压力分布的快速求解. 对点接触弹流润滑下的粗糙表面弹性变形进行了定性和定量研究,同时分析了表面均方根粗糙度、载荷、相对运动速度和滑滚比对最小膜厚和最大压力的影响,以及表面形貌动态变化对膜厚比的影响. 结果表明:形貌变化改变了弹流油膜和压力分布特性,相对于光滑表面,表面粗糙度总体上提高了最大接触压力、降低了最小膜厚,在轻载工况下表面粗糙度对油膜厚度的削弱更加显著,而不同速度下粗糙度的影响程度基本相同,呈现线性变化趋势,膜厚比随载荷增大呈现先增后减的变化趋势,并在530 MPa左右达到峰值.      

微凹坑织构表面对脂润滑关节轴承摩擦特性的影响

为研究脂润滑下表面织构对关节轴承摩擦特性的影响,设计和制造了4组表面高度算术平均值相同、表面微凹坑面积占有率分别为7%、10%、15%和21%的关节轴承内圈表面形貌.使用Talysurf CCI Lite非接触式三维轮廓仪对试件表面进行测量,采用ISO25178定义的表面参数对试件表面形貌进行表征.在改造的HDM-20端面摩擦磨损试验机上,采用2#锂基脂润滑在不同载荷、转速条件下进行了一系列摩擦磨损试验,研究了表面形貌参数与摩擦系数的关系.在本试验中,选取表面高度算术平均值Sa和表面峰态Sku等表面高度参数、表面峰区平均材料体积Vmp、表面中心区平均空体体积Vvc和表面谷区平均空体体积Vvv等表面功能参数以及平均谷体积Sdv等表面特征参数对关节轴承表面形貌进行表征.结果表明:各表面参数对摩擦系数的影响不同,将表面高度参数、功能参数和特征参数这几种表面形貌参数结合对关节轴承表面形貌进行表征,更有利于脂润滑下关节轴承表面形貌的摩擦学设计.     

Polymer solar cells based on a PEDOT:PSS layer spin-coated under the action of an electric field

In the process of fabrication of polymer photovoltaic(PV) devices,poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS) thin film,acting as an anode buffer layer,is spin-coated under the action of an electric field.The PV devices with a PEDOT:PSS layer spin-coated under the action of a static electric field exhibit improved short-circuit current density(J sc) and power conversion efficiency(PCE).The investigation of morphology shows that the appropriate intensity of the electric field can increase the roughness of the surface of the PEDOT:PSS layer,which results in improved contact between the anode and hole transport layer and thus enhances the J sc of the devices.Chemical analysis is also provided by x-ray photoelectron spectroscopy(XPS) spectra.     

Effect of slow-solvent-vapour treatment on performance of polymer photovoltaic devices

In this work, enhanced poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) bulkheterojunction photovoltaic devices are achieved via slow-solvent-vapour treatment. The correlations between the morphology of the active layer and the photovoltaic performance of polymer-based solar cell are investigated. The active layers are characterized by atomic force microscopy and optical absorption. The results show that slow-solventvapour treatment can induce P3HT self-organization into an ordered structure, leading to the enhanced absorption and efficient charge transport.     

固体表面液滴铺展与润湿接触线的移动分析

液滴在固体表面上的铺展行为与润湿特性对许多工业生产过程的研究具有重要意义.根据液滴在光滑表面上的受力情况,建立了液滴平壁铺展的动力学模型.应用润滑近似方法和二维Navier-Stokes方程,建立了液滴沿理想表面铺展的动量和连续性方程.根据建立的方程,应用数值解法求解并详细分析了液滴在铺展过程中膜厚、接触线铺展半径以及铺展速度随时间的变化关系.研究结果表明:液滴的铺展过程可分为扩展和收缩两个阶段,铺展过程伴随着表面能、动能以及各种势能的相互转化,液滴最终的铺展半径大小由固体基面固有的润湿特性所决定;液滴在铺展过程中出现的"坍塌效应"与弯曲液面处的Laplace压力差有关;铺展半径随时间变化的标定律近似满足"1/7"次方标度律.     

弹流润滑条件下表面形貌对摩擦噪声的影响

研究了弹流润滑状态下表面形貌对摩擦噪声的影响.通过激光微加工方法在金属圆盘试件表面上制造了两种沟槽型织构表面形貌,在双盘摩擦磨损试验机上对不同表面形貌进行了摩擦噪声和摩擦特性试验,分析了线接触弹流润滑条件下不同工况和表面形貌影响摩擦噪声的机理,并结合有限元分析对结论加以验证.结果表明:载荷和转速的变化对线接触摩擦噪声有明显影响,由于线接触副工作在部分膜弹流润滑状态下,所以摩擦噪声的特性与干摩擦时类似,摩擦因数较大的表面会辐射出更强的摩擦噪声;特定结构的表面形貌能改善表面润滑特性,有效降低摩擦噪声声压级,沟槽型织构的存在可以打断接触区域应力分布,减轻接触面微凸体碰撞作用,从而降低了表面自激振动,同时合适的表面形貌结构也有利于润滑油膜的形成,减小了系统的摩擦能量,达到降低摩擦噪声的效果.     

Amplified spontaneous emission from metal-backed poly[2-methoxy-5-(2’-ethylhexyloxy)-1,4-phenylenevinylene] film

We investigate the amplified spontaneous emission (ASE) from an Ag-backed poly[2-methoxy-5-(2’-ethylhexyloxy)1,4-phenylenevinylene] (MEH-PPV) film with different film thicknesses.The ASE characteristics of Ag-backed MEHPPV films with different thicknesses show that increasing the film thickness can reduce the influence of the Ag cladding.The threshold,the gain,and the loss of the device with a thickness of 170 nm are comparable to those of a metal-free device.The lasing threshold of this device is about 7.5 times that of a metal-free device.Our findings demonstrate that Ag-backed MEH-PPV film with an appropriate thickness can still be a good polymer gain material for the fabrication of solid-state lasers.