Control of the molecular orientation in a glassy film is a crucial issue, not only for an understanding of the fundamental processes of organic amorphous film formation but also for enhancement of the performance of organic light-emitting diodes (OLEDs) by increasing their light-outcoupling efficiency. In this study, the molecular orientation in codeposited films composed of a host molecule and a disk-shaped emitter that exhibits thermally activated delayed fluorescence is investigated systematically. It is found that the orientation of the transition dipole moment (TDM) of the disk-shaped emitters is strongly dependent on the glass transition temperature and the polarization of the host molecules, and almost perfectly horizontal orientation of the TDM of the disk-shaped emitters can be realized. Our findings clarify the role of the host-guest dipole-dipole interaction in the molecular orientation, and it will enable the expansion of both the molecular design and the material combination rules for high-performance OLEDs.
|ジャーナル||Applied Physics Letters|
|出版ステータス||出版済み - 1月 13 2020|
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