The role of orientation in the MEL response of OLEDs
Sebastian Engmann, Emily Bittle, Lee J. Richter, Rawad Hallani, John Anthony, David J. Gundlach
Magneto electroluminescence (MEL) is emerging as a powerful tool for the study of spin dynamics in emitting devices. 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 crossings in the singlet character between adjacent states. The zero-field-splitting parameter D and E, responsible for the anti-crossings in energy and crossings in the singlet character, can be determined from the OLED emission and yield D = 6.29 μeV and E = 0.19 μeV for 2,8-Difluoro-5,12-bis(triethylsilylethynyl)anthra[2,3-b;6,7- b']dithiophene, which are in good agreement with literature reports.
, Bittle, E.
, Richter, L.
, Hallani, R.
, Anthony, J.
and Gundlach, D.
The role of orientation in the MEL response of OLEDs, Journal of Materials Chemistry C, [online], https://doi.org/10.1039/D1TC00314C, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=930822
(Accessed December 11, 2023)