【作者】 王宇；

【导师】 钱磊；

【作者基本信息】 河南大学 ， 物理化学， 2016， 硕士

【摘要】 在目前的聚合物太阳能电池和量子点发光二极管中,ITO通常用来作为透明电极。而PEDOT:PSS通常用来修饰ITO表面被做为阳极缓冲层。但是由于PEDOT:PSS本身的酸性会导致聚合物太阳能电池和量子点发光二管的性能衰减。为了解决这个问题,有人开始研发新的阳极缓冲层去替代PEDOT:PSS。其中过渡金属氧化物(WO3,MoO3,NiO,Cu2O,ReO3和V2O5)在很多聚合物太阳能电池中被用作阳极缓冲层,并取得不错的性能。尤其是氧化钼具有一个很深的电子能级态和有效的空穴注入。然而这些具有独特电子特性的薄膜,其获得大多都是通过昂贵的真空设备沉积所制备,这明显表现出了设备高昂的缺点和与大规模的卷对卷制备不相符。本论文主要采用一种简答的溶液法制备氧化钼。本论文主要围绕溶液法制备氧化钼在P3HT:PC60BM聚合物太阳能电池中的应用,以及在量子点发光二管中的应用展开研究。通过对氧化钼薄膜的厚度优化和通过不同的后处理优化,来改变该层的电荷传输能力,进而改善和提升聚合物太阳能电池器件的效率。同样在增加电荷的传输能力外,也平衡了电子和空穴在量子点发光二极管中的复合。本论文的创新工作可以总结为以下三部分:(1)在基于溶液法制备的MoO_x空穴注入层的P3HT:PCBM器件中,通过优化氧化钼的浓度和后处理方式等使得器件的光电转换效率得到优化,并取得了和基于PEDOT:PSS的标准器件相当的效率甚至超过了标准器件的效率,这归因于使用真空退火后氧化钼产生了带隙态更有利于空穴的传输以及其具有较高的光透过率、优良的成膜和较小的表面粗糙度。基于氧化钼制备的聚合物太阳能电池获得了比标准器件更优异的稳定性,其中器件性能的衰减主要是由于电流密度的衰减导致,取得这些性能的原因源于:无机氧化物具有稳定的性能,而PEOT:PSS具有易吸水和酸性导致器件效率的衰退。(2)首先对量子点发光二极管的标准器件进行优化,然后对基于氧化钼空穴传传输层的器件进行了浓度和退火条件的探索和优化。最终使得基于s-MoO_x空穴注入层的绿光和红光QLED器件的电流效率都要优于基于PEDOT:PSS空穴注入层的QLED器件的效率和EQE。更是使得绿光的电流效率和EQE分别从11.9 cd/A和2.9%提高到了16.1 cd/A和4.11%。亦使得红光的电流效率在整个发光的过程中都高于标准器件效率。发现这一影响源于我们制备的s-MoO_x空穴注入层,具有更优异的空穴和电子平衡复合的性能;s-MoO_x薄膜比PEDOT:PSS薄膜更致密和均一,薄膜的表面缺陷态更少,进而使得器件中的电荷被缺陷态俘获的更少,提高器件的性能。(3)本论文制备了全无机QLED器件,其器件结构为:ITO/s-MoO_x/QDs/ZnO/Al,最后器件的亮度达到800cd/m2,电流效率达到了2.94cd/A。这也是目前全溶液法和全无机法制备的QLED器件中较好的器件性能。这主要归因于氧化钼具有较好的载流子平衡复合能力。更多还原

【Abstract】 ITO is the most commonly used transparent electrode for polymer solar cells(PSCs) and quantum dot light emitting diodes(QLEDs). PEDOT:PSS is the most commonly used anode buffer layer on ITO in PSCs and QLEDs, but the acidic nature of PEDOT:PSS could result in degradation of the performance of the PSCs and QLEDs. To solve this problem, there is graet interest in developing new anode buffer layers to replace PEDOT:PSS. Transition metal oxide(WO3, MoO3, NiO, Cu2 O, ReO3, or V2O5) have been successfully used as anode buffer layers in high performance PSCs. In particular, MoO3 exhibiting remarkably deep lying electronic states and efficient hole-injection into organic materials have been demonstrated. However, their unique electronic properties have so far been primarily achieved using thin films made by high-cost thermal evaporation under vacuum, which presents disadvantages due to the cost issues and incompatibility with roll-to-roll scalable manufacturing.This paper focused on the application of solution-processed molybdenum oxide in polymer solar cell and quantum dot light emitting diodes. The carrier transport efficiency was improved by optimizating the thickness and post processes of Molybdenum Oxide thin films, leading to improved efficiency of PCEs. In the meanwhile, Molybdenum Oxide thin film can effectively balance the recombation of hole and electron in QLEDs. The work in this thesis can be summarized as follows:(1) In the P3HT:PCBM devices based on solution processed MoO_x hole injectiong layer, thickness and post processing of Mo Ox films were optimized to improve the performance of the devices. Performance of the device based on MoO_x is compatible with or even higher than the standard devices based on PEDOT:PSS layers. It could be attributed to the generated gat stetes by vaccum annealing, higher light transmittance and smaller surface roughness. Moreover, the PSCs based on solution processed MoO_x show better stability than standard device. The major degredation came from the decrease of the current devsity of the devices, and the slower degedation could be attribute to the stability of inorganic oxide and the acid and hygroscopicity of PEDOT:PSS.(2)We also optimized the quantum dot light emitting diodes. Then device based on MoO_x hole transport layer were optimized and explored by changing the concentration and annealing condition. We demonstrated that the current efficiency and external quantum efficiency(EQE) of green and red QLEDs based on MoO_x were better than the standard device based on PEDOT:PSS. The current efficiency and EQE of green QLEDs were increased from 11.9 cd/A and 2.9% to 16.1 cd/A and 4.11%. At the same time, the current efficiency of red QLEDs was higher than that of the standard QLEDs in the entire luminous process. We found that the higher performance is mainly due to the more balanced carrier recombination and smoother surface of the the MoO_x hole transport layer compared to that of the PEDOT:PSS layer.(3)All inorganic QLEDs were also demonstrated in this thesis. The device structure is ITO/s-MoO_x/QDs/ZnO/Al, which shows the luminance of 800cd/m2 and current efficiency of 2.94cd/A. Such great device performance could also be attributed to the excellent balance carrier recombination based on MoO_x layer.更多还原