有机电致发光器件界面电荷存储对电老化的影响及其应用

Organic light-emitting diode (OLED) is the next generation technique of display and lighting, confronted with the bottle-neck chanllenge of electrical degradation. The nature of light emission and electrical degradation of OLED are processes of electrons and energy. Charge storage and dielectric loss play important roles in the electrical degradation of OLED. Aiming at the charge storage and dielectric loss, the project is to study charge storage under electric field, dielectric loss at excited state and electroluminescence properties of three types of polymers with various conjugate degree and permittivity through vacuum electroluminescence, transient and delayed electroluminescence testing systems. One of the objective is to reveal their working mechanisms on electrical degradation in order to uncover the initial processes and initial area of electrical degradation. The second objective of the project is to provide new pathways to apply the stored charges and meanwhile to decrease the dielectric loss, to control and use stored charges at the interface based on insulating polymer with various permittivity, so as to solve the problems of unbalance of electrons and holes and overheat due to charge storage, indicating new solutions to improve the stability of OLED. The project will uncover the initial mechanisms of electrical degradation of OLED based on charge storage at the interfaces and provide new solutions for stability improvement, promoting to solve the problem of electrical degradation of OLED.

有机电致发光器件（OLED）作为下一代显示和照明技术，电老化问题是制约其发展的瓶颈之一。OLED发光和电老化本质是电子和能量过程，界面处电荷存储和介电损耗对电老化起着至关重要的作用。针对界面处电荷存储和介电损耗，本课题通过搭建的真空发光、瞬态发光和延迟发光测试系统，研究由共轭程度和介电性能不同的聚合物材料制备的发光器件在电场下的电荷存储特性、激发态下的介电损耗和电致发光特性。目标之一是挖掘界面电荷存储对电老化的影响机制，揭示OLED电老化初始阶段发生机理和初始区域；目标之二是提出减少OLED中介电损耗和应用存储电荷的新方式，通过介电性能可调绝缘材料实现界面处电荷的可控利用，解决电子空穴不匹配和累积电荷导致的器件过热问题，为提高器件稳定性提供新的解决方案。本项目从界面电荷存储入手，揭示OLED电老化发生初始物理机制，并提出改进方案，促进解决OLED电老化难题。

有机发光二极管（OLED）是显示和照明的下一代技术，面临着OLED效率下降的瓶颈问题。OLED的发光性质和效率下降是电子和能量的过程，在此过程中，电荷注入和存储起着重要作用。随着电流密度的增加，OLED效率下降明显。通过瞬时电致发光测量分析了界面电荷的存储。发光峰值出现在正向和反向关断电压上，分别由电子扩散和陷阱载流子释放引起。时间分辨发射光谱证明了界面电荷与激子猝灭的关系。OLED效率下降与界面电荷存储呈正相关，尤其是在低电流密度下。这是由于界面电荷累积的影响，尤其是在OLED的不平衡电荷注入下，这对于提高OLED的性能并减少OLED在工业中的效率下降非常重要。