Modeling of organic light-emitting diodes: from molecule to device (MODEOLED)

MODEOLED项目涉及活跃在白色有机发光二极管(OLED)研究的两个荷兰和两个德国小组之间的跨国学术和工业合作。目前用于高效照明的白色OLED由不同有机分子的堆叠层组成，每一层都有特定的功能。与电极接触的高度正负掺杂的注入层注入空穴和电子，空穴和电子进入堆栈并相遇形成激子。在用于三原色的特殊发射有机层中，通常掺杂磷光染料，激子在光子的发射下辐射衰减，理想情况下应该具有广泛和平衡的发射光谱。目前，白光OLED的设计是通过反复试验进行的。MODEOLED的目标是开发和应用预测模型，仅根据特定材料和加工方法的分子结构来预测白色OLED的性能。这将导致白光OLED和OLED材料的合理设计策略，从而提高开发人员的理解并显著降低研发成本。将遵循多尺度建模方法，每个小组引入特定的专业知识。该方法首先使用蒙特卡罗建模(KIT的专业知识)确定材料的微观形态。接下来，将用量子化学方法(巴斯夫的专业知识)计算与电荷和激子激发分子有关的重组能和这些激发的分子间转移积分。这些信息将用于大规模蒙特卡罗模拟与应用相关的白色多层OLED中电荷和激子的运动和相互作用(EUT的专业知识)。OLED电池组中的预测电流-电压特性和发光特性将得到实验验证(飞利浦的专业知识)。这种比较将导致对建模预测能力的关键评估和改进。科学问题将集中在掺杂发射层中的激子过程(激子的运动，激子-激子以及激子-电荷的相互作用)和掺杂注入层的工作，即有机发光二极管中最复杂的材料中的关键过程。

The project MODEOLED involves a transnational academic-industrial collaboration between two Dutch and two German groups active in research on white organic light-emitting diodes (OLEDs). Present-day white OLEDs for high-efficiency lighting applications consist of stacked layers of different organic molecules, where each layer has a specific function. Highly positively and negatively doped injection layers contacted by electrodes inject holes and electrons, which move into the stack and meet to form excitons. In special emissive organic layers for the three primary colors, often doped with phosphorescent dyes, the excitons decay radiatively under emission of a photon which ideally should have a broad and balanced emission spectrum. Presently, the design of white OLEDs proceeds by trial and error. The goal of MODEOLED is to develop and apply predictive modeling to predict the properties of white OLEDs solely on the basis of the molecular structure of the specific materials and processing methods. This will lead to rational design strategies of white OLEDs and OLED materials leading to improved understanding and significant reduction in R&D cost for developers.A multi-scale modeling approach will be followed, where each group brings in a specific expertise. The approach starts with determining the microscopic morphology of the materials with Monte-Carlo modeling (expertise of KIT). Next, the reorganization energies related to the excitation of molecules by charges and excitons and the inter-molecular transfer integrals of these excitations will be calculated by Quantum-Chemistry methods (expertise of BASF). This information will be used in large-scale Monte-Carlo simulations of the motion and interaction of charges and excitons in application-relevant white multilayer OLEDs (expertise of EUT). The predicted current-voltage characteristics and light-emission profiles within the OLED stack will be verified experimentally (expertise of Philips). The comparison will lead to a critical evaluation and improvement of the predictive power of the modeling. The scientific questions will focus on the excitonic processes in the doped emissive layers (motion of excitons, and exciton-exciton as well as exciton-charge interactions) and on the working of the doped injection layers, i.e. on key processes in the most complex materials included in OLEDs.