The role of orientation in the MEL response of OLEDs. Issue 31 (22nd July 2021)

• Record Type: Journal Article
• Authors: Engmann, Sebastian; Bittle, Emily G.; Richter, Lee J.; Hallani, Rawad K.; Anthony, John E.; Gundlach, David J.
• Is Part Of: Journal of materials chemistry. Volume 9:Issue 31(2021)
• Page Start: 10052
• Page End: 10064
• Publication Date: 2021-07-22
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d1tc00314c
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : The magneto-electroluminescence response (MEL) of OLEDs strongly depends on the degree of order within the emitting film, with textured films exhibiting highly structured responses. The MEL is reproduced by a model that includes Zero-field splitting. Abstract : 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.