Improved performance of organic light-emitting diodes with dual electron transporting layers

In this study the performance of organic light-emitting diodes(OLEDs) are enhanced significantly,which is based on dual electron transporting layers(Bphen/CuPc).By adjusting the thicknesses of Bphen and CuPc,the maximal luminescence,the maximal current efficiency,and the maximal power efficiency of the device reach 17570 cd/m2 at 11 V,and 5.39 cd/A and 3.39 lm/W at 3.37 mA/cm2 respectively,which are enhanced approximately by 33.4%,39.3%,and 68.9%,respectively,compared with those of the device using Bphen only for an electron transporting layer.These results may provide some valuable references for improving the electron injection and the transportation of OLED.     

Improving efficiency of organic light-emitting devices by optimizing the LiF interlayer in the hole transport layer

The efficiency of organic light-emitting devices (OLEDs) based on N,N'-bis(1-naphthyl)-N,N'-diphenyl-N,1'-biphenyl-4,4'-diamine (NPB) (the hole transport layer) and tris(8-hydroxyquinoline) aluminum (Alq₃) (both emission and electron transport layers) is improved remarkably by inserting a LiF interlayer into the hole transport layer. This thin LiF interlayer can effectively influence electrical performance and significantly improve the current efficiency of the device. A device with an optimum LiF layer thickness at the optimum position in NPB exhibits a maximum current efficiency of 5.96 cd/A at 215.79 mA/cm², which is about 86% higher than that of an ordinary device (without a LiF interlayer, 3.2 cd/A). An explanation can be put forward that LiF in the NPB layer can block holes and balance the recombination of holes and electrons. The results may provide some valuable references for improving OLED current efficiency.     

对电力体制改革与电力企业财务风险的认识

改革开放以来,我国的电力行业进行了三轮重大改革。第一轮是从上世纪80年代中期开始,实行了集资办电、多渠道筹资办电等政策,极大地调动了社会办电的积极性,迅速扭转了全国性严重缺电的局面。第二轮是从上世纪90年代后期开始,电力行业实现政企分开,     

浅谈财务舞弊和内部控制

随着市场经济体制的建立和不断完善,企业经营方式和企业信息使用者的多元化,会计信息的质量日益受到社会各界的高度重视。但近几年来,利用伪造变造会计记录或会计凭证、隐瞒或删除交易或事项、记录虚假的交易或事项、蓄意使用不正当的会计政策等舞弊手段谋取个人或小集团利益的现象普遍存在,这种弄虚作假、真账假做、假     

Efficiency of a blue organic light-emitting diode enhanced by inserting charge control layers into the emission region

We demonstrate high current efficiency of a blue fluorescent organic light-emitting diode (OLED) by using the charge control layers (CCLs) based on Alq3 . The CCLs that are inserted into the emitting layers (EMLs) could impede the hole injection and facilitate the electron transport, which can improve the carrier balance and further expand the exciton generation region. The maximal current efficiency of the optimal device is 5.89 cd/A at 1.81 mA/cm2 , which is about 2.19 times higher than that of the control device (CD) without the CCL, and the maximal luminance is 19.660 cd/m2 at 12V. The device shows a good color stability though the green light emitting material Alq3 is introduced as the CCL in the EML, but it has a poor lifetime due to the formation of cationic Alq3 species.     

微腔效应对顶发射串联蓝光有机电致发光器件性能的影响

相比于传统有机电致发光器件,串联有机电致发光器件的发光效率与寿命均得到明显提升.因此,深入研究微腔效应对顶发射串联有机电致发光器件性能的影响具有重要意义.本文以蓝光器件为例,通过光学仿真模拟与实际实验相结合的方法,研究了顶发射串联蓝光器件的光学性能与电学性能变化规律.具体实验为:分别制备了顶发射串联蓝光器件,使其两个发光层位置分别位于器件光学结构中的第一与第二反节点、第二与第三反节点、第三与第四反节点.分析并确定了顶发射串联蓝光器件的两个发光层位置分别位于第二反节点与第三反节点处时,器件性能较佳.即:当器件电流密度为15 mA/cm^2时,器件电流效率为10.68 cd/A(色坐标CIEx,y=0.14,0.05),其亮度衰减到95%所需时间为1091.55 h.可能原因是:器件腔长较长时,既可以改善第一发光单元的空穴与电子平衡度、削弱表面等离激元效应,降低膜厚波动性对器件腔长的影响性;又可以在一定程度内起到包裹Partical的作用,提高效率,延长寿命.这一研究成果为设计高效率、长寿命的顶发射串联器件提供了重要依据.     

Low driving voltage in an organic light-emitting diode using MoO3/NPB multiple quantum well structure in a hole transport layer

The driving voltage of an organic light-emitting diode(OLED) is lowered by employing molybdenum trioxide(MoO3)/N,N’-bis(naphthalene-1-yl)-N,N’-bis(phe-nyl)-benzidine(NPB) multiple quantum well(MQW) structure in the hole transport layer.For the device with double quantum well(DQW) structure of ITO/[MoO3(2.5 nm)/NPB(20 nm)]2/Alq3(50 nm)/LiF(0.8 nm)/Al(120 nm)],the turn-on voltage is reduced to 2.8 V,which is lowered by 0.4 V compared with that of the control device(without MQW structures),and the driving voltage is 5.6 V,which is reduced by 1 V compared with that of the control device at the 1000 cd/m2.In this work,the enhancement of the injection and transport ability for holes could reduce the driving voltage for the device with MQW structure,which is attributed not only to the reduced energy barrier between ITO and NPB,but also to the forming charge transfer complex between MoO3 and NPB induced by the interfacial doping effect of MoO3.     

双材料界面裂纹断裂参数的实验测定

首先推导了双材料界面裂纹尖端的位移场和应力强度因子之间的关系式。利用云纹干涉法实测了应力强度因子,并将实验结果与理论结果进行了比较。     

木质纤维素高效降解菌株的筛选及其对小麦秸秆的强化降解

为有效加速废弃生物质的转化速度,以林下土壤为菌种来源进行木质纤维素高效降解菌株的筛选和鉴定,利用BBD(Box-Behnken-Design)二阶模型优化其对木质纤维素的降解条件,并探究预处理对细菌菌株降解小麦秸秆的影响.结果显示,初筛共计筛选出5株对木质纤维素具有降解能力的细菌菌株,经复筛后获得1株对木质纤维素具有较强降解能力的细菌菌株(RS22),经16S rRNA基因鉴定为Klebsiella oxytoca.RS22的滤纸酶、羧甲基纤维素酶和半纤维素酶活性分别为1.01、0.82和5.87 U·mL^-1,其对木质纤维素的最佳降解条件为pH:6.8、温度：30.9℃和转速56.8 r·min^-1.小麦秸秆降解实验表明,经化学预处理后的小麦秸秆木质纤维素总量降低最为明显,达到了54.30%,各处理中滤纸酶、羧甲基纤维素酶和半纤维素酶活性均呈现随时间缓慢增加的趋势,而对照组中各种酶活性变化呈“M”型.结晶度分析显示,除粉碎预处理外,其他处理组的小麦秸秆生物降解后木质纤维素的结晶度均有一定的提高,说明RS22可以有效加速非晶态木质纤维素的降解...     

基于岛–桥结构的拉伸AMOLED显示技术

LTPS–AMOLED技术已经广泛应用在柔性显示领域,但是由于脆性膜层材料限制无法直接应用于拉伸显示领域.本文以LTPS–AMOLED技术为基础结合镂空技术制备了具有岛桥结构的拉伸显示器件.为确保拉伸显示具有良好的拉伸性能,本文研究了影响拉伸性能的影响因素.首先通过研究拉伸变形机理发现拉伸结构设计时减小桥宽度、增加桥的长度、减小夹角角度和适当增大夹角半径可以更好的释放应力应变.其次研究表明拉伸过程中连接桥会产生拉应变、压应变和中性位置,金属引线位于中性位置或者压应变位置会有效减小断裂风险.连接桥的无机层裂纹产生的诱导断裂会随着其膜厚的增加而增强,而有机层可以阻隔诱导断裂并且阻隔性随着有机层厚度增加而增强,因此通过减小连接桥的无机层厚度、增加有机层厚度可有效减小无机层断裂产生的影响.最后制备了2.3 inch的OLED可伸缩显示屏,水平方向的拉伸量可达到5%以上.