有机及有机无机杂化电致发光器件研究
发布时间：2018-11-26 07:20
【摘要】：自从OLED及QD-LED提出以来,因其在能源消耗、显示质量、低成本以及轻便等特点,所以已经成为显示领域研究的热点。本文以研究OLED及QD-LED中的工作机制为目的,从器件的结构及材料特性出发,基于载流子注入及能量传递理论,对基于FIrpic的蓝光OLED中的激子淬灭机制进行了深入的研究,并对QD-LED的工作机制及界面处激子的淬灭进行了调控,最终改善了器件性能。针对于OLED,我们着重于磷光器件的研究。我们知道,小分子磷光材料的发明及其成功的在OLED的引入,使得器件效率得到了大幅度的提高,理论上其可实现100%的内量子效率。但是,其一个显著的缺点是高电流密度下的载流子淬灭过程。这一淬灭过程发生的几率与载流子密度的平方成正比。其极大的限制了器件的性能,使得器件具有高的效率滚降。而且,磷光材料在OLED中需要利用合适的材料作为母体,其本身作为掺杂剂。这一掺杂过程增加了器件的制备成本,降低了器件的良率,限制了OLED的商业化进程。这里,我们针对于蓝光磷光FIrpic材料进行了详细研究。通过改变FIrpic在CBP母体中的掺杂浓度,研究了器件效率及效率滚降随掺杂浓度变化的关系。我们惊奇的发现,基于FIrpic的蓝光器件的效率对掺杂浓度有着很低的依赖特性。即使利用纯的FIrpic作为发光层,其发光效率也达到了7.76cd/A。在量子点电致发光器件方面,我们研究了QD-LED器件的发光机制。我们知道对于倒置类型的有机/无机杂化的QD-LED的发光机制为电荷的直接注入方式。基于这一结论,我们着重对器件的空穴传输特性进行了研究与设计。首先设计出了既有利于空穴传输与注入,又有效的降低了空穴载流子对量子点中激子的淬灭几率的阶梯式结构的空穴传输层,大大的提高了器件的电流效率。我们制备了结构为ITO/Zn O/QDs/m CP/CBP/Mo O3/Al的QD-LED。由于CBP与m CP的HOMO能级存在势垒,使得由Mo O3注入的空穴在CBP/m CP界面有一定的积累。这就在很大程度上避免了空穴在m CP/QDs界面的聚集,减少了空穴载流子对量子点中激子的淬灭。大大的提高了器件的发光效率。同时,由于激子淬灭过程的抑制,使得器件的效率滚降也有很大的降低。另外,通过利用乙醇对PEDOT:PSS空穴注入层的处理,使得该层的导电性能得到改善,增加了空穴的注入效率,提高了器件的光电性能。最后,由于高反射金属电极的存在,使得从量子点发出的光在金属电极处发生反射,反射的光场在器件之中形成驻波场,这一光场对量子点中的激子动力学过程有着很大的影响。通过对倒置器件中的光场分布分析,我们研究了光场对激子动力学过程的影响,并通过合理设计器件结构,有效的提高了器件效率,降低了器件效率滚降。
[Abstract]:Since OLED and QD-LED were proposed, they have become the focus of research in the field of display because of their characteristics of energy consumption, display quality, low cost and portability. In order to study the working mechanism of OLED and QD-LED, based on the theory of carrier injection and energy transfer, the exciton quenching mechanism in blue-light OLED based on FIrpic is studied in this paper, based on the structure and material characteristics of the device, and based on the theory of carrier injection and energy transfer, the mechanism of exciton quenching in blue-light OLED based on FIrpic is studied. The working mechanism of QD-LED and the quenching of excitons at the interface are regulated and the performance of the device is improved. We focus on phosphorescence devices for OLED,. We know that the invention of small molecule phosphorescent material and its successful introduction into OLED have greatly improved the device efficiency and theoretically it can achieve 100% internal quantum efficiency. However, a significant drawback is the carrier quenching process at high current density. The probability of this quenching process is proportional to the square of carrier density. It greatly limits the performance of the device and makes the device roll down with high efficiency. Moreover, phosphorescence materials need to be used as parent materials and dopants in OLED. This doping process increases the fabrication cost of the device, reduces the yield of the device, and limits the commercialization process of OLED. Here, we study the blue phosphorescence FIrpic materials in detail. By changing the doping concentration of FIrpic in the CBP matrix, the relationship between the device efficiency and the efficiency roll down with the doping concentration is studied. We are surprised to find that the efficiency of blue light devices based on FIrpic is very low dependent on doping concentration. Even if the pure FIrpic is used as the luminescent layer, the luminescence efficiency is up to 7.76 cdr / A. In the aspect of quantum dot electroluminescent devices, we study the luminescence mechanism of QD-LED devices. We know that the photoluminescence mechanism of the inverted organic / inorganic hybrid QD-LED is a direct charge injection. Based on this conclusion, we focus on the hole transmission characteristics of the device. At first, the hole transport layer with step structure is designed, which is not only favorable for hole transmission and injection, but also effectively reduces the probability of quenching excitons in quantum dots, which greatly improves the current efficiency of the device. We have prepared QD-LED. with ITO/Zn O/QDs/m CP/CBP/Mo O3/Al structure. Due to the existence of potential barriers in the HOMO energy levels of CBP and m CP, the holes implanted by Mo O 3 have a certain accumulation at the interface of CBP/m CP. This greatly avoids the accumulation of holes at the m CP/QDs interface and reduces the quenching of excitons in quantum dots by hole carriers. The luminous efficiency of the device is greatly improved. At the same time, due to the suppression of exciton quenching process, the efficiency roll drop of the device is also greatly reduced. In addition, by using ethanol to treat the PEDOT:PSS hole injection layer, the conductivity of the layer is improved, the hole injection efficiency is increased, and the photoelectric performance of the device is improved. Finally, due to the existence of high reflective metal electrode, the light emitted from quantum dots is reflected at the metal electrode, and the reflected light field forms a standing wave field in the device. This field has a great influence on the exciton dynamics in quantum dots. Through the analysis of the optical field distribution in the inverted device, we study the effect of the light field on the exciton dynamics process, and through the reasonable design of the device structure, the device efficiency is effectively improved and the device efficiency roll down is reduced.
【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN383.1
本文编号：2357763
[Abstract]:Since OLED and QD-LED were proposed, they have become the focus of research in the field of display because of their characteristics of energy consumption, display quality, low cost and portability. In order to study the working mechanism of OLED and QD-LED, based on the theory of carrier injection and energy transfer, the exciton quenching mechanism in blue-light OLED based on FIrpic is studied in this paper, based on the structure and material characteristics of the device, and based on the theory of carrier injection and energy transfer, the mechanism of exciton quenching in blue-light OLED based on FIrpic is studied. The working mechanism of QD-LED and the quenching of excitons at the interface are regulated and the performance of the device is improved. We focus on phosphorescence devices for OLED,. We know that the invention of small molecule phosphorescent material and its successful introduction into OLED have greatly improved the device efficiency and theoretically it can achieve 100% internal quantum efficiency. However, a significant drawback is the carrier quenching process at high current density. The probability of this quenching process is proportional to the square of carrier density. It greatly limits the performance of the device and makes the device roll down with high efficiency. Moreover, phosphorescence materials need to be used as parent materials and dopants in OLED. This doping process increases the fabrication cost of the device, reduces the yield of the device, and limits the commercialization process of OLED. Here, we study the blue phosphorescence FIrpic materials in detail. By changing the doping concentration of FIrpic in the CBP matrix, the relationship between the device efficiency and the efficiency roll down with the doping concentration is studied. We are surprised to find that the efficiency of blue light devices based on FIrpic is very low dependent on doping concentration. Even if the pure FIrpic is used as the luminescent layer, the luminescence efficiency is up to 7.76 cdr / A. In the aspect of quantum dot electroluminescent devices, we study the luminescence mechanism of QD-LED devices. We know that the photoluminescence mechanism of the inverted organic / inorganic hybrid QD-LED is a direct charge injection. Based on this conclusion, we focus on the hole transmission characteristics of the device. At first, the hole transport layer with step structure is designed, which is not only favorable for hole transmission and injection, but also effectively reduces the probability of quenching excitons in quantum dots, which greatly improves the current efficiency of the device. We have prepared QD-LED. with ITO/Zn O/QDs/m CP/CBP/Mo O3/Al structure. Due to the existence of potential barriers in the HOMO energy levels of CBP and m CP, the holes implanted by Mo O 3 have a certain accumulation at the interface of CBP/m CP. This greatly avoids the accumulation of holes at the m CP/QDs interface and reduces the quenching of excitons in quantum dots by hole carriers. The luminous efficiency of the device is greatly improved. At the same time, due to the suppression of exciton quenching process, the efficiency roll drop of the device is also greatly reduced. In addition, by using ethanol to treat the PEDOT:PSS hole injection layer, the conductivity of the layer is improved, the hole injection efficiency is increased, and the photoelectric performance of the device is improved. Finally, due to the existence of high reflective metal electrode, the light emitted from quantum dots is reflected at the metal electrode, and the reflected light field forms a standing wave field in the device. This field has a great influence on the exciton dynamics in quantum dots. Through the analysis of the optical field distribution in the inverted device, we study the effect of the light field on the exciton dynamics process, and through the reasonable design of the device structure, the device efficiency is effectively improved and the device efficiency roll down is reduced.
【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN383.1
【参考文献】
相关期刊论文 前1条
1 曹进;刘向;张晓波;委福祥;朱文清;蒋雪茵;张志林;许少鸿;;微腔结构顶发射有机发光器件[J];物理学报;2007年02期
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