高性能蓝光量子点发光二极管电子注入特性的研究
发布时间：2018-08-31 13:59
【摘要】：因其诸多优越的性质,胶体量子点(QDs)技术在过去30年里迅猛发展,逐渐应用于生产、科研中的各个领域。而II-VI族半导体量子点材料具有优越的量子产率、色纯度与光色可调性,是制备LED器件的理想材料。从1994年加州大学的Alivisatos等首次研制出胶体量子点LED(QLED)以来,量子点电致发光器件在材料、器件结构、制备工艺等方面都有了长足的进步。这些技术进步还伴随着人们对量子点电致发光效应背后的相关物理过程愈加深入的理解。然而,由于QD层的大带隙引起的电荷注入困难,蓝色QLED的性能目前显然劣于绿色和红色的性能。本文中,我们引入了一种部分自然氧化铝阴极(Al:Al2O3),利用ZnCdS/ZnS核壳结构量子点作为发光材料,制备了性能优良的蓝光量子点LED器件。器件的亮度达13000 cd/m2,最高电流效率1.1 cd/A,并且有着457 nm的电致发光峰与20.8 nm的半峰宽,展现出纯净的深蓝发射光。我们还对自然氧化制备的Al:Al2O3进行了一系列表征分析,证实了其对电子注入与激子有效复合的促进作用。这种自然氧化方法工艺简单价格低廉,为QLED中电子注入层/阴极的制备提供了新的思路。在Al:Al2O3阴极的基础上,本文还将Zn O纳米颗粒作为电子传输层插入量子点层与阴极之间制备LED器件,并调节ZnO层制备的条件,进一步提高了器件的性能。通过调控ZnO层退火的条件控制载流子注入的平衡,我们最终制备出了亮度高达37000 cd/m2,电流效率4.5 cd/A的高性能蓝光量子点LED器件。据我们所知,该器件的亮度是目前为止蓝光QLED的纪录。比较不同退火条件的ZnO层结合不同的阴极制备器件的性能,我们确定了ZnO的制备条件对于其中缺陷态密度以及电子迁移率的调整。这种调控载流子注入的平衡的方法不必改变器件原有结构,可以通过简单的退火手段使不同器件结构的载流子注入平衡达到最优,对量子点LED器件的相关后续研究具有启发意义。
[Abstract]:Because of its many superior properties, colloidal quantum dot (QDs) technology has developed rapidly in the past 30 years, and has been gradually applied in various fields of production and scientific research. However, II-VI semiconductor quantum dot materials have excellent quantum yield, color purity and photochromatic tunability, so they are ideal materials for the preparation of LED devices. Since the first development of colloidal quantum dot (LED (QLED) by Alivisatos of the University of California in 1994, quantum dot electroluminescent devices have made great progress in material, device structure and fabrication process. These advances have been accompanied by a deeper understanding of the physical processes behind the quantum dot electroluminescence. However, due to the difficulty of charge injection due to the large band gap in QD layer, the performance of blue QLED is obviously inferior to that of green and red at present. In this paper, we introduce a partial natural alumina cathode (Al:Al2O3) and use ZnCdS/ZnS core-shell structure quantum dots as luminescent materials to fabricate blue quantum dot LED devices with excellent performance. The luminance of the device is up to 13000 cd/m2, the maximum current efficiency is 1.1 cd/A, and the luminescence peak of 457 nm is half width of 20.8 nm, showing pure dark blue emission. A series of characterization and analysis of Al:Al2O3 prepared by natural oxidation have also been carried out, and it has been proved that it can promote the effective recombination of electron injection and exciton. This natural oxidation process is simple and cheap, which provides a new idea for the preparation of electron injection layer / cathode in QLED. On the basis of Al:Al2O3 cathode, the Zn O nanoparticles were inserted into the quantum dot layer and cathode as the electron transport layer to fabricate the LED device, and the preparation conditions of the ZnO layer were adjusted to further improve the performance of the device. By adjusting the condition of annealing in ZnO layer to control the equilibrium of carrier injection, we have finally fabricated a high performance blue quantum dot LED device with a luminance up to 37000 cd/m2, current efficiency of 4.5 cd/A. As far as we know, the brightness of the device is so far the record of Blu-ray QLED. Comparing the properties of ZnO layers with different cathodic fabrication devices under different annealing conditions, we determine the adjustment of the defect density of states and electron mobility for the preparation conditions of ZnO. This method of adjusting the equilibrium of carrier injection does not need to change the original structure of the device, and the carrier injection equilibrium of different device structures can be optimized by simple annealing method. It has enlightening significance for further research on quantum dot LED devices.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN312.8
本文编号：2215205
[Abstract]:Because of its many superior properties, colloidal quantum dot (QDs) technology has developed rapidly in the past 30 years, and has been gradually applied in various fields of production and scientific research. However, II-VI semiconductor quantum dot materials have excellent quantum yield, color purity and photochromatic tunability, so they are ideal materials for the preparation of LED devices. Since the first development of colloidal quantum dot (LED (QLED) by Alivisatos of the University of California in 1994, quantum dot electroluminescent devices have made great progress in material, device structure and fabrication process. These advances have been accompanied by a deeper understanding of the physical processes behind the quantum dot electroluminescence. However, due to the difficulty of charge injection due to the large band gap in QD layer, the performance of blue QLED is obviously inferior to that of green and red at present. In this paper, we introduce a partial natural alumina cathode (Al:Al2O3) and use ZnCdS/ZnS core-shell structure quantum dots as luminescent materials to fabricate blue quantum dot LED devices with excellent performance. The luminance of the device is up to 13000 cd/m2, the maximum current efficiency is 1.1 cd/A, and the luminescence peak of 457 nm is half width of 20.8 nm, showing pure dark blue emission. A series of characterization and analysis of Al:Al2O3 prepared by natural oxidation have also been carried out, and it has been proved that it can promote the effective recombination of electron injection and exciton. This natural oxidation process is simple and cheap, which provides a new idea for the preparation of electron injection layer / cathode in QLED. On the basis of Al:Al2O3 cathode, the Zn O nanoparticles were inserted into the quantum dot layer and cathode as the electron transport layer to fabricate the LED device, and the preparation conditions of the ZnO layer were adjusted to further improve the performance of the device. By adjusting the condition of annealing in ZnO layer to control the equilibrium of carrier injection, we have finally fabricated a high performance blue quantum dot LED device with a luminance up to 37000 cd/m2, current efficiency of 4.5 cd/A. As far as we know, the brightness of the device is so far the record of Blu-ray QLED. Comparing the properties of ZnO layers with different cathodic fabrication devices under different annealing conditions, we determine the adjustment of the defect density of states and electron mobility for the preparation conditions of ZnO. This method of adjusting the equilibrium of carrier injection does not need to change the original structure of the device, and the carrier injection equilibrium of different device structures can be optimized by simple annealing method. It has enlightening significance for further research on quantum dot LED devices.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN312.8
【参考文献】
相关期刊论文 前1条
1 柳杨;刘志伟;卞祖强;黄春辉;;高效、稳定Ⅱ-Ⅵ族量子点发光二极管(LED)的研究进展[J];无机化学学报;2015年09期
，本文编号：2215205
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