Prof. Daisuke Yokoyama from the Yamagata University in Japan published an interesting research paper about molecular orientation in small-molecule OLEDs. Daisuke says that orienting the molecules horizontally has two positive effects: the light outcoupling efficiency is increased (by around 50% compared to randomly oriented emitters) and the charge transport between molecules becomes more efficient (which can lead to a lower driving voltage).

Daisuke tells us that some materials in commercial OLEDs are already horizontally oriented - but not all. He claims that most phosphorescent emitters are not horizontally oriented yet. If so, we can expect good performance increases once these materials are oriented.

The 4th International TADF Workshop 2019The 4th International TADF Workshop 2019