Engmann Sebastian, Bittle Emily G, Richter Lee J, Hallani Rawad K, Anthony John E, Gundlach David J
Theiss Research, La Jolla, California 92037, United States.
Nanoscale Device Characterization Division, National Institute of Standards and Technology, 101 Bureau Drive, Gaithersburg, Maryland, 20899, United States.
J Mater Chem C Mater. 2021;9(31). doi: 10.1039/d1tc00314c.
Magneto electroluminescence (MEL) is emerging as a powerful tool to study spin dynamics in organic light emitting diodes (OLEDs). The shape of the MEL response is typically used to draw qualitative inference on the dominant process (singlet fission or triplet fusion) in the device. In this study, we develop a quantitative model for MEL and apply it to devices based on Rubrene, and three solution processable anthradithiophene emitters. The four emitters allow us to systematically vary the film structure between highly textured, poly-crystalline to amorphous. We find significant diversity in the MEL, with the textured films giving highly structured responses. We find that the additional structure does not coincide with energy anti-crossings, but intersections in the singlet character between adjacent states. In all cases the MEL can be adequately described by an extended Merrifield model. Via the inclusion of charge injection, we are able to draw additional information on underlying physics in OLED devices.
磁电致发光（MEL）正逐渐成为研究有机发光二极管（OLED）中自旋动力学的有力工具。MEL响应的形状通常用于对器件中的主导过程（单线态裂变或三线态融合）进行定性推断。在本研究中，我们开发了一种MEL定量模型，并将其应用于基于红荧烯以及三种可溶液加工的蒽二噻吩发射体的器件。这四种发射体使我们能够系统地改变薄膜结构，从高度纹理化的多晶结构到非晶结构。我们发现MEL存在显著差异，纹理化薄膜给出高度结构化的响应。我们发现额外的结构与能量反交叉不重合，而是相邻态之间单线态特征的交叉。在所有情况下，MEL都可以通过扩展的梅里菲尔德模型得到充分描述。通过纳入电荷注入，我们能够获取有关OLED器件基础物理的更多信息。
