Invention Grant
US09209415B2 Light-emitting element with multiple light-emitting layers having controlled carrier mobility and lighting device and electronic device using the same 有权
具有多个具有受控载波移动性的发光层和照明装置的发光元件以及使用该发光元件的电子装置

Light-emitting element with multiple light-emitting layers having controlled carrier mobility and lighting device and electronic device using the same
Abstract:
Disclosed is a light-emitting element which includes a first light-emitting layer over and in contact with a hole-transport layer and a second light-emitting layer over and in contact with the first light-emitting layer. The first and the second light-emitting layers contain a bipolar host material and an emissive guest material. The guest material in the first light-emitting layer has a lower ability for capturing a hole than a guest material in the second light-emitting layer; therefore, the hole-transport property of the first light-emitting layer can be controlled to be higher than that of the second light-emitting layer. The difference in hole-transport property between the first and second light-emitting layers allows a recombination region to be widely spread in the light-emitting layers. An anti-reducing material may be provided in the hole-transport layer, which prevents the hole-transport layer from being reduced by electrons which fail to undergo recombination in the light-emitting layers.
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