Organic electroluminescent element

Abstract

[Problem] The purpose of the present invention is to provide an organic EL element in which various materials for an organic EL element, which excel in hole injection / transport performance, electron injection / transport performance, electron blocking performance, stability in a thin film state, and durability, are combined so that properties of each of the materials can be effectively demonstrated,thereby achieving (1) high luminous efficiency and power efficiency, (2) low luminescence starting voltage, (3) low practical driving voltage, and (4) particularly long service life. [Solution] An organic EL element having at least a positive electrode, a hole transportation layer, a light emission layer, an electron transportation layer, and a negative electrode in the stated order, wherein theorganic EL element is characterized in that the hole transportation layer includes an arylamine compound represented by general formula (1), and the electron transportation layer includes a compound having a benzoazole ring structure represented by general formula (2). (1) (In the formula, Ar1-Ar5 may be identical to each other or different from each other, and represent a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted fused polycyclic aromatic group. Ar6-Ar8 may be identical to each other or different from each other, and represent a hydrogen atom, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted fused polycyclic aromatic group. n1 represents 0, 1, or 2. Ar3 and Ar4 may form a ring with a single bond or may form a ring so as to be bonded via a substituted or unsubstituted methylene group, an oxygen atom, or a sulfur atom. Ar3 or Ar4 may form a ring with a single bond with a benzene ring to which an Ar3Ar4-N group is bonded, and may form a ring so as to be bonded to each othervia a substituted or unsubstituted methylene group, an oxygen atom, or a sulfur atom.) (2) (In the formula, Ar9 and Ar10 may be identical to each other or different from each other, and represent a hydrogen atom, a deuterium atom, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, a substituted or unsubstituted fused polycyclic aromatic group, or a substituted or unsubstituted alkyl group. Y1 represents a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, a substituted or unsubstituted fused polycyclic aromatic group, or a substituted or unsubstituted alkyl group. X represents an oxygen atom or a sulfur atom. Z1 and Z2 may be identical to each other or different from each other, and represent a carbon atom or a nitrogen atom).

Description

technical field [0001] The present invention relates to an organic electroluminescence element, which is a self-luminous element suitable for various display devices, and relates in detail to an organic electroluminescence element using a specific arylamine compound and a compound having a specific benzoxazole ring structure (hereinafter , sometimes called organic EL elements). Background technique [0002] Since the organic EL element is a self-luminous element, it is brighter than a liquid crystal element, has excellent visibility, and can realize a clear display, so it has been actively studied. [0003] In 1987, C.W.Tang of Eastman Kodak Company developed a laminated structural element in which each material shared various functions, thus making the organic EL element using organic materials a practical element. They laminated a phosphor capable of transporting electrons and an organic substance capable of transporting holes, injected the charges of the two into the pho...

AI Technical Summary

Problems solved by technology

Although NPD has a good hole transport ability, its glass transition temperature (Tg), which is an index of heat resistance, is lower than 96°C, and it crystallizes at a high temperature, resulting in degradation of device characteristics (see, for example, Non-Patent Document 4).

In addition, among the aromatic amine derivatives described in the above-mentioned patent documents, it is known that the hole mobility is 10 -3 cm 2 Compounds having excellent mobility above / Vs (for example, refer to Patent Document 1 and Patent Document 2), but due to insufficient electron blocking properties, a part of electrons pass through the light-emitting layer, and improvement in luminous efficiency cannot be expected. Therefore, in order to further Higher efficiency requires materials with higher electron barrier properties, more stable thin films, and high heat resistance

In addition, although aromatic amine derivatives with high durability are disclosed (for example, refer to Patent Document 3), as a substance used as a charge transport material in an electrophotographic photoreceptor, there is no example of a substance used as an organic EL element.

[0010] As compounds with improved properties such as heat resistance and hole injection properties, arylamine compounds having a substituted carbazole structure have been proposed (for example, refer to Patent Document 4 and Patent Document 5). Although the heat resistance and luminous efficiency have been improved in the element used in the layer or hole transport layer, it is still not sufficient, and further lower driving voltage and higher luminous efficiency are required.

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