Phosphorescent dye doped electron transport layer for yellow thermally activated delayed fluorescent electroluminescence device

In this work, we use iridium (III)bis[4-(tert-butyl)-2,6-diuoro-2,3-bipyridine]acetylacetonate (FK306) doped layer as an electron-transport layer to optimize the electron density on emitters with suitable device design strategy. Because of the specific electron trapping and transporting abilities of FK306, electrons can progressively inject into emitter molecules, yellow thermally activated delayed fluorescence (TADF) devices showed significant improvement in electroluminescent performance with reduced efficiency roll-off. Finally, the optimal device obtained the maximum brightness of 22474 cd/m2, maximum current efficiency, power efficiency and external quantum efficiency (EQE) up to 73.06 cd/A, 69.52 lm/W and 20.7%, respectively. At 1000 cd/ m2, the current efficiency and EQE of the same device can still remain as 42.22 cd/A and 11.9%, respectively.

Automated summary

In this study, the iridium (III)bis[4-(tert-butyl)-2,6-diuoro-2,3-bipyridine]acetylacetonate (FK306) doped layer was utilized as an electron-transport layer to optimize the electron density and improve the electroluminescent performance of yellow TADF devices. With a suitable device design strategy, significant improvements in efficiency were achieved while reducing efficiency roll-off.