| 摘要 |
PROBLEM TO BE SOLVED: To obtain a light emitting element employing an organometallic complex for changing a pumped triplet state into luminescence in which a red light emitting element exhibiting high emission efficiency and excellent in color purity can be attained. SOLUTION: Since hosts contained in a hole transport layer and a light emitting layer, and a material employed in an electron transport layer have triplet pumping energy higher than that of a light emitting substance, i. e. an organometallic complex, the current efficiency and external quantum efficiency of a light emitting element are enhanced. A current efficiency of 2.0 cd/A or above or an external quantum efficiency of 5% or above can thereby be attained. Color purity is also good and an NTSC regulation can be cleared because following relations are satisfied; CIE chromaticity coordinate X≥0.7, Y≤0.3. COPYRIGHT: (C)2007,JPO&INPIT
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