高效激基复合物体系有机白光二极管及其动态特性和延迟发光

Organic light emitting devices (OLEDs) are considered as the next main technology for displays and solid-state light sources. Despite the enormous progress the OLED technology has made over the past two decades, further improvements are still required: for instance in efficiency, stability, fabrication cost, and the efficiency roll-off. Therefore, one goal of this project is to prepare exciplex based OLEDs and exciplex-phosphor hybrid white OLEDs. The energy splitting of formed exciplex single exciton and triplet exciton will be smaller to realize the thermal relaxation delay fluorescence (TADF) in these exciplex systems by choosing suitable organic semiconductors. The photoluminescence and the emission delay will be measured at different temperature in order to get the value of the energy splitting. The electroluminescence and efficiency of such exciplex based system OLEDs should be investigated. In order to further improve the properties of exciplex based OLEDs, the electron transporting layer and the hole transporting layer will be used to modify these OLEDs. Then these exciplex systems should be used as co-host materials doped with phosphors to prepare exciplex- phosphor hybrid white OLEDs. The influence of the doped materials, the concentration, the device structure, the thickness of the function layers, and other parameters on the electroluminescence properties of prepared white OLEDs should be investigated. The transient and delayed electroluminescence will be detected by the system established by our group. During the measurement, the current density through the OLEDs and the environment temperature will be varied to explore the electroluminescence mechanisms. The process of the carrier transporting, the formation of excitons, and the effect of triplet excitons and trapped charges will be analyzed via the measurements. The mechanism of the efficiency roll-off of prepared OLEDs will be discussed according to all measured results.

有机电致发光器件（OLEDs）作为下一代显示器和固态照明的主要技术，必须进一步提高其效率和降低高亮度下的效率衰退。本课题目标之一是制备激基复合物发光OLEDs和激基复合物发光-磷光混合白光OLEDs，研究激基复合物体系在不同温度下的光致发光和衰减特性。通过材料的选择，减小激基复合物的单线态激子和三线态激子的能差，通过热弛豫延迟发光利用三线态激子，提高器件效率。并对器件进行功能层修饰，摸索优化条件，提高器件的性能。目标之二是利用课题组搭建的电致延迟发光和瞬态发光测试系统，研究所制备的激基复合物体系OLEDs在不同温度、不同电流密度下的动态特性和发光机制中所涉及的基本物理过程，阐明载流子的传输、三线态激子的贡献、陷阱载流子的作用，解释器件效率roll-off的原因，并为器件的优化提供参数。通过本项目的研究，我们将为提高白光OLEDs的性能提供强有力的技术基础，促进白光OLEDs的实用化。

有机电致发光器件（OLEDs）作为下一代显示器和固态照明的主要技术，必须进一步提高其效率和降低高亮度下的效率衰退。本课题目标之一是制备激基复合物发光OLEDs和激基复合物发光-磷光混合白光OLEDs，研究激基复合物体系在不同温度下的光致发光和衰减特性。目标之二是利用课题组搭建的电致延迟发光和瞬态发光测试系统，研究所制备的激基复合物体系OLEDs在不同温度、不同电流密度下的动态特性和发光机制中所涉及的基本物理过程。.1、我们选择了m-MTDATA与3TPYMB、CBP与B4PYMPM等材料形成激基复合物，制备了OLEDs器件，通过测试不同材料的PL和EL，证明了激基复合物发光的存在，测试了不同激发密度下器件的IVL特性，验证了发光层浓度、功能层的厚度对发光性能的影响。获得了最大亮度为17100 cd/m2，电流效率为41.07cd/A的高效绿色荧光OLEDs器件。进一步优化了溶液法TADF材料掺杂激基复合物器件的发光性能，通过浓度的优化，结合瞬态发光的测试，证明了器件的发光来源于TADF材料的载流子直接复合。利用磷光材料掺杂激基复合物体系，实现了红光发射。利用溶液法并通过器件优化，获得了电流效率为15.1cd/A的蓝光发射。在此基础上，我们进一步制备了白光OLEDs，并进一步优化了其性能。.2、利用课题组搭建的电致延迟发光和瞬态发光测试系统，研究了激基复合物体系OLEDs在不同电流密度下、不同序列脉冲下的动态特性。通过薄膜的稳态光致发光光谱以及瞬态光致发光衰减寿命等测试手段，证明了激基复合物体系能实现稳定的激基复合物发光，并利用电致瞬态测试研究电场对双分子激子衰减过程的影响：反向电压对即时发光强度明显减小的作用说明了外加电场使激基复合物激子中的电子和空穴距离增加而导致单线态激子不可逆的解离；高电流驱动时，存在大量的三线态激子、单线态激子以及极化子它们之间的相互作用、相互碰撞大大增加，三线态激子大量被猝灭；并利用延迟发光的方法研究了OLEDs中的存储电荷，通过交流激发，进一步利用了存储电荷，这为后期提高OLEDs性能提供了一种新的思路。.3、完成了本课题的全部指标：发表 SCI文章 20篇，专利 4项，培养博士 4人，硕士10人。