有机电致发光器件光取出效率增强研究进展

有机电致发光器件(OLED)经过近三十年的发展,已经在照明和显示上得到一定程度的应用。OLED具有全固态、响应速度快、易于实现柔性显示等优点。由于磷光材料的应用,其内量子效率几乎达到了理论的极限值100%,但其外量子效率却只有20%左右,制约外量子效率进一步提高的主要因素是器件的光取出效率。本文从提高OLED光取出效率的方法入手,综述了国内外关于顶发射和底发射有机发光器件光取出效率增强的研究现状、最新进展及以后的研究方向。

不同结构储热水箱分层特性的实验研究

在太阳能集热系统中,储热水箱内的温度分层效果受不同水箱结构的影响巨大。为研究这一特性,搭建了一套储热水箱分层特性测试实验台,对直接进口式、三层孔板式和盒状结构水箱进行了测试实验。水箱内初始水温为70℃,在相同的进水温度和不同的流量条件下,根据实验数据绘制了不同结构水箱内的各层温度变化曲线。结果显示,进水流量越大,水箱内混合效应越大,各层温度趋于一致的时间越短。在热力学定律的基础上,计算并分析了3种结构水箱的取出效率、?和Str数等分层特性指标。结果表明,3种结构中,盒状结构水箱内的温度分层效果最好,对热量的利用率最高,盒装结构有效地抑制了冷热水混合效应,其次为三层孔板式水箱,而直接进口式水箱的温度分层效果最差。

单层热激活延迟荧光有机发光器件及其激子分布特性

单层结构对简化有机电致发光器件(OLED)的制备工艺及降低其制造成本具有重要意义。本文采用非掺杂热激活延迟荧光(TADF)发光层,结合C_(60)(2 nm)/MoO_(3)(3 nm)/C_(60)(2 nm)修饰的ITO阳极及4,7-二苯基-1,10-菲啰啉(Bphen,3 nm)修饰的Ag阴极,制备了单层TADF器件(TADF-OLED)。该单层TADF-OLED具有良好的空穴和电子注入能力,开启电压为3 V,最大电流、功率及外量子效率分别可达到37.7 cd/A、47.4 lm/W和13.24%。然后,我们利用“探针法”研究了该单层TADF-OLED的激子分布情况,发现大部分激子在发光层靠近阳极侧形成。最后,我们利用经典电磁学理论对器件的光取出效率进行模拟分析,证实了这种激子分布特性有助于实现较高的光取出效率,进而改善器件的外量子效率。

Extraction of nickel from molybdenum leaching residue of metalliferous black shale by segregation roasting and acid leaching

The recovery of nickel from molybdenum leach residue by the process of segregation roasting-sulfuric acid leaching-solvent extraction was investigated. The residue was characterized by microscopic investigations, using X-ray fluorescence spectrometry （XRF） and X-ray diffractometry （XRD） techniques and the residue after segregation roasting was characterized by chemical phase analysis method. A series of experiments were conducted to examine the mass ratio of activated carbon （AC） to the residue, segregation roasting time and temperature, sulfuric acid concentration, liquid-to-solid ratio, leaching time, leaching temperature, addition amount of 30% H2O2, stirring speed （a constant） on the leaching efficiency of nickel. A maximum nickel leaching efficiency of 90.5% is achieved with the mass ratio of AC to the residue of 1：2.5, segregation roasting time of 2 h, segregation roasting temperature of 850 ℃, sulfuric acid concentration of 4.5 mol/L, liquid-to-solid ratio of 6：1, leaching time of 5 h, leaching temperature of 80 ℃, addition of 30% H202 of 0.6 mL for 1 g dry residue. Under these optimized conditions, the average leaching efficiency of nickel is 89.3%. The nickel extraction efficiency in the examined conditions is about 99.6%, and the nickel stripping efficiency in the examined conditions is about 99.2%.

Manganese extraction from high-iron-content manganese oxide ores by selective reduction roasting-acid leaching process using black charcoal as reductant

Reduction roasting-acid leaching process was utilized to process high-iron-content manganese oxide ore using black charcoal as reductant. The results indicate that, compared with the traditional reductant of anthracite, higher manganese extraction efficiency is achieved at lower roasting temperature and shorter residence time. The effects of roasting parameters on the leaching efficiency of Mn and Fe were studied, and the optimal parameters are determined as follows: roasting temperature is 650 °C, residence time is 40 min, and black charcoal dosage is 10%(mass fraction). Under these conditions, the leaching efficiency of Mn reaches 82.37% while that of Fe is controlled below 7%. XRD results show that a majority of MnO2 and Fe2O3 in the raw ore are reduced to MnO and Fe3O4, respectively.

Efficiency Improvement of 590 nm AIGalnP Light Emitting Diode with a Reflective Top Electrode

In this work, enhancement of the light extraction efficiency of a 590 nm AIGaInP light-emitting diodes （LED） with a reflective top electrode （RTE） was investigated. A distributed Bragg reflector （DBR）, consisting of AIAs/AIGaAs pairs, grown on an AlGaInP structure was used as a reflector for a reflective top electrode. It was found that a higher output power was observed from the AIGalnP LED with a RTE than from a conventional one. In addition, it was noted that the improvement in the output power depends strongly on the reflectivity of the reflector and that it exhibits a more effective performance with low injection currents. The increase in the optical output power was attributed to the enhanced extraction efficiency caused by a reduction of light absorbed from the emission region to top electrode through the RTE.

Rational design of perfectly oriented thermally activated delayed fluorescence emitter for efficient red electroluminescence

How to control the dipole orientation of organic emitters is a challenge in the field of organic light-emitting diodes(OLEDs).Herein,a linear thermally activated delayed fluorescence(TADF)molecule,PhNAI-PMSBA,bearing a 1,8-naphthalimide-acridine framework was designed by a doublesite long-axis extension strategy to actively control the dipole orientation.The horizontal ratio of emitting dipole orientation of PhNAI-PMSBA reaches 95%,substantially higher than that of isotropic emitters(67%).This unique feature is associated with the intrinsically horizontal molecular orientation of PhNAI-PMSBA and the good agreement between its transition dipole moment direction and molecular long axis.The PhNAI-PMSBA-based OLED achieves an ultrahigh optical outcoupling efficiency of 43.2%and thus affords one of the highest red electroluminescence with an external quantum efficiency of 22.3%and the Commission International de l’Eclairage 1931 coordinates at around(0.60,0.40).