Magnetic Field Effects on Electroplex-Based Organic Light-Emitting Diodes

Abstract

An electroplex is an excited state charge transfer complex formed between a donor molecule and an acceptor molecule upon electrical excitation. Since the spatial overlap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of electroplex is small likewise exciplex, the energy difference between the singlet and the triplet charge transfer (1CT and3CT) states can be very small, which facilitate the conversion of triplet excitons into singlet excitons by the assistance of thermal energy and the emission as delayed fluorescence. However, in contrast to exciplex, the detailed analysis of the reverse intersystem crossing (RISC) from3CT to1CT and the exciton-related annihilation processes in electroplex OLEDs have been rarely reported. In this talk, the magnetic field effects (MFEs) on the electroplex host using 2,2′-di(9H-carbazol-9-yl)-1,1′-biphenyl (oCBP) and 9-(4,6-bis(3-(triphenylsilyl)phenyl)-1,3,5-triazin-2-yl)-9H-carbazole (DSiCzTrz) were investigated. Temperature-dependent MFE measurements revealed that RISC channel co-exists with the intersystem crossing (ISC) channel and triplet-polaron quenching process prevails in the electroplex EML. It was also found that3CT excitons behave as charge scattering sites. © 2022. John Wiley and Sons Inc. AIAA. All rights reserved.