Organic light emitting device

Abstract

Provided is an organic light emitting device which, in a case where a donor dopant having excellent electron injecting property is used, prevents a change in light emitting efficiency caused by passage of time and gives high light emitting efficiency at low voltage. An organic light emitting device includes at least an emission layer, a first organic compound layer containing an aromatic compound which is free of a partial structure represented by the following general formula (1): where Ar represents a ring structure having a benzene ring, a second organic compound layer containing an aromatic compound which has the partial structure represented by the general formula (1), and an electron injection layer containing an organic compound forming a third organic compound layer and at least one of an alkali metal, an alkaline earth metal, an alkali metal compound, and an alkaline earth metal compound.

Description

technical field The present invention relates to organic light emitting devices. Background technique Recently, research on organic light emitting devices (organic electroluminescence (EL) devices) has been actively conducted. Meanwhile, various proposals have been made to improve the electron injection efficiency of organic light emitting devices. In Japanese Patent Application Laid-Open No. H10-270171, there is disclosed an organic light-emitting device in which an electron injection layer containing a metal functioning as a donor (electron-donating) dopant is provided. Furthermore, in Japanese Patent Application Laid-Open No. H10-270172, for the same purpose as in Japanese Patent Application Laid-Open No. H10-270171, there is disclosed an organic light-emitting device in which an electron injection layer containing Metal oxides or metal salts of bulk dopants. On the other hand, in Japanese Patent Application Laid-Open Nos. 2005-063910 and 2005-332690, both describe th...

AI Technical Summary

Problems solved by technology

However, when the dopant concentration is lowered, there is a problem that the driving voltage increases due to electron velocity determination and the carrier balance is disrupted, thereby deteriorating the luminous efficiency

In addition, even if the light emitting layer and the electron injection layer are spatially separated from each other, the same problem as in the case of lowering the dopant concentration arises because the thickness of the entire device increases due to the separation.

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