ScholarWorks@성균관대학교

초록

In this study, we developed new p-type host materials based on a 9,9'-diphenyl-9H,9'H-3,3'-bicarbazole (BPCz) core by introducing bulky blocking groups at the 2-position of the BPCz core to control the intermolecular distance between host molecules. This structural modification induces steric hindrance, which suppresses intermolecular interactions and enables the material to maintain a high triplet energy. Two blocking groups, tetraphenylsilane and 9-phenyl-9H-carbazole (phenylcarbazole), are introduced into the BPCz backbone structure. The bulky blocking groups enable a high triplet energy of 2.74 eV in a solid film for triplet exciton harvesting of blue emitters. The device using a host with an ortho-connected phenylcarbazole on the BPCz core exhibits excellent device performance in blue thermally activated delayed fluorescence organic light-emitting diodes, achieving a low driving voltage of 5.0 V, a maximum external quantum efficiency of 28.6%, and minimized efficiency roll-off. This work first demonstrates that the BPCz can be used as a core structure of a high triplet energy host for blue thermally activated delayed fluorescence organic light-emitting diodes.

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