Tandem organic electroluminescent apparatuses are fabricated by stacking several individual organic light emitting units vertically. Each organic light emitting unit includes an organic light emitting layer and organic layers on both sides of the organic light emitting layer. Emission efficiency of the tandem organic electroluminescent apparatus increases in proportion to the number of vertically stacked organic light emitting units. As compared to the conventional organic electroluminescent apparatuses, the tandem organic electroluminescent apparatuses have an improved current efficiency, an increased device lifetime, and an enhanced luminous intensity.
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