【作者】 张妍斐；

【导师】 徐叙瑢； 赵谡玲；

【作者基本信息】 北京交通大学 ， 光学， 2013， 博士

【摘要】 摘要：本文针对不同结构的有机电致发光器件,研究了提高其电学性能和发光效率的机制并加以利用。1.针对多层结构器件：a)利用有机无机复合发光,选用电子传输能力优的材料硫化锌做电子传输层和空穴阻挡层,提高了以MEH-PPV为发光层的器件的电子注入效率,使启亮电压与具有同样能级结构的有机器件相比降低了3V;b)针对有机无机界面处相容性差的缺点,对阳极一侧的氧化钼进行紫外臭氧处理,提高了器件ITO/MoO3(5nm)/MEH-PPV/Al的载流子注入效率；c)通过在阳极一侧的Mo03与TPD之间插入5nm金属层Au,形成一个小的空穴陷阱,降低了器件中的电流密度,提高了器件ITO/MoO3(5nm)/TPD/AlQ/LiF/Al的发光效率；d)以NPB:TphNI的激基复合物发光作为指示器,将三层器件ITO/NPB/NPB:TPhNI(1:1)/TPhNI/LiQ/Al发光复合区控制在器件中间远离电极处,电致发光光谱不随电压的改变而移动。提高了发光色度在改变正向偏压时的稳定性。并相对于同发光材料的双层和单层器件获得了更高的发光效率。2.针对叠层结构器件：a)加入半透明Au/Al层做阳极,讨论了由Au薄膜特有的光的“选择”透过率造成的器件EL光谱在长波一侧窄化的现象；b)通过插入半透明的双金属中间电极,得到结构为ITO/TPD/AlQ:DCJTB(5%)/LiF/Al/Au/TPD/AlQ/LiF/Al的由三个电极和两个独立的发光单元串联组成的叠层器件,其发光色度可以经由向两个发光单元施加不同电压改变光强的配比来精确调制。且由于Al/Au连接层的电荷产生特性,器件整体的发光效率大于两个单元在相同电流密度下的发光效率之和若干倍。3.针对单层器件：a)对MEH-PPV薄膜热退火的同时施加电场,提高了器件的发光效率；b)在掺杂系统PVK:TPB, PVK:C545T, PVK:Rubrene和PVK:DCJTB中,发现延迟荧光的衰减时间长短与主体和客体能级之间的差值ΔEHOMO、 ΔELUMO的大小有关,进而影响了发光效率。ΔEHOMO或ΔELUMO越小时,器件的延迟荧光寿命越短,器件的发光效率越高。本文中共有图78幅,表4个,参考文献128篇。更多还原

【Abstract】 ABSTRACT:In this paper, OLEDs of all kinds of structures are researched to improve their electrical properties and current efficiency.1. for devices of multi-layer structure:a) Organic-inorganic composite devices ITO/MEHPPV(-70nm)/ZnS(20nm)/Al was prepared. Compared with the monolayer device ITO/MEHPPV(-70nm)/Al, the spectral red shift and broadening towards the long-wavelength direction in the EL of bilayer devices are observed, due to the exciplex emission in bilayer devices. The current efficiency of organic-inorganic composite device is not higher than that of device ITO/MEHPPV(-70nm)/BCP (20nm)/Al, but the turn-on voltage has been lower3V;b) For the poor compatibility of interface of organic and inorganic, using the UV ozone treatment onto molybdenum oxide near to anode, the carrier injection efficiency of the device ITO/MoO3(5nm)/MEH-PPV/A1has been improved;c) By inserting5nm of Au layer between MoO3and TPD near to anode, forming a small trap for holes, reducing the current density in the device, the current efficiency of device ITO/MoO3(5nm)/TPD/Alq/LiF/Al has been improved;d) Taking exciplex luminous of NPB:TphNI as an indicator, prepared the three-layer device ITO/NPB/NPB:TPhNI (1:1)/TPhNI./LiQ/Al, keep the luminescence area away from two electrodes and are controlled at the middle position of the device, EL spectra does not change with the voltage. Stability of the chromaticity has been improved, and so the current efficiency, compare to the double and single devices with the same luminescent layer.2. for devices of tandem structure:a) By adding semi-transparent Au/Al layer as anode, the narrowing of EL spectra was discussed, and the reason is the "selected pass" of light-transmissivity in Au thin layer;b) By cautiously designing an evaporation mask, tandem OLED consisting of three electrodes and two independent light-emitting units was successfully prepared(ITO/TPD/AlQ:DCJTB(5%)/LiF/Al/Au/TPD/AlQ/LiF/Al). The translucent Al/Au intermediate electrode can be drawn forth and act as cathode and anode. The emission color of this OLED can be controlled by the applied bias. The voltage of the entire device is approximately equals to the sum of units R and G when the current densities are the same. The current efficiency of the entire device is several folds larger than the sum of two components at the same current density. The source of higher current efficiency can be attributed to the charge-generating of the Al/Au intermediate electrode. Besides connecting light-emitting units in series, this kind of intermediate electrode can also generate charge and improve the current efficiency of the tandem OLED, provides an experimental basis for preparation of controllable emission color and high-efficiency OLED.3. for devices of single-layer structure:a) The efficiency of the single-layer device was improved by thermal annealing while applying an electric field to MEH-PPV thin film;b) Prepared doping system of PVK:TPB, PVK:C545T, PVK:Rubrene and PVK: DCJTB, found that the lifetime of delayed fluorescence depends on the gap between the HOMO of host and dopant materials, so as the gap between the LUMO of host and dopant materials, the smaller the ΔELUMO and ΔELUMO are, the shorter the lifetime of delayed fluorescence are, the higher the current efficiency are.更多还原