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Organic electroluminescent element

An electroluminescence element and luminescence technology, which is applied in the direction of electroluminescence light sources, electrical components, organic semiconductor devices, etc., can solve the problems of short life of blue phosphorescence, short life, insufficient luminous efficiency, etc.

Inactive Publication Date: 2012-04-25
IDEMITSU KOSAN CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, although the red phosphorescent element has reached the field of practical use, the life of the green and blue phosphorescent elements is shorter than that of the fluorescent element. In particular, the blue phosphorescence not only has a short life, but also has insufficient color purity and luminous efficiency. Not yet practical

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  • Organic electroluminescent element
  • Organic electroluminescent element
  • Organic electroluminescent element

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Experimental program
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no. 1 Embodiment approach

[0061] The present invention utilizes the TTF phenomenon. First, the following explains the TTF phenomenon.

[0062] Holes and electrons injected from the anode and cathode are recombined in the light-emitting layer to generate excitons. As known in the past, the rotation state is 25% singlet excitons and 75% triplet excitons. In the previously known fluorescent element, 25% of singlet excitons emit light when they relax to the ground state, but the remaining 75% of triplet excitons do not emit light but return to the ground state through a thermal inactivation process. Therefore, the theoretical limit value of the internal quantum efficiency of the conventional fluorescent element can be said to be 25%.

[0063] On the other hand, the behavior of triplet excitons generated inside organic matter has been theoretically studied. According to S.M.Bachilo et al. (J.Phys.Cem.A, 104, 7711 (2000)), if it is assumed that the quintet and other high-order excitons immediately return to th...

no. 2 Embodiment approach

[0224] The device of the present invention may have a tandem device structure having at least two organic layer units including a light-emitting layer. An intermediate layer (also referred to as an intermediate conductive layer, an electrochemical generating layer, or CGL) exists between the two light-emitting layers. Each unit can be equipped with an electron transport area. At least one light-emitting layer is a fluorescent light-emitting layer, and the unit containing the light-emitting layer satisfies the aforementioned requirements. An example of a specific stacking order is shown below. In addition, the light-emitting layer described below may be a laminate of a plurality of light-emitting layers, or may be one organic layer unit including the charge blocking layer of the third embodiment described later.

[0225] Anode / fluorescent light-emitting layer / intermediate layer / fluorescent light-emitting layer / barrier layer / cathode

[0226] Anode / fluorescent light-emitting layer / ...

no. 3 Embodiment approach

[0234] In this embodiment, an anode, a plurality of light-emitting layers, an electron transport region, and a cathode are sequentially provided. A charge blocking layer is provided between any two light-emitting layers among the plurality of light-emitting layers. The light-emitting layer close to the charge blocking layer is fluorescent The light-emitting layer satisfies the above requirements.

[0235] As the structure of a suitable organic EL element according to the present embodiment, as described in Japanese Patent No. 4134280, U.S. Patent Publication US2007 / 0273270A1, and International Publication WO2008 / 023623A1, anodes, In the structure of the first light-emitting layer, the charge blocking layer, the second light-emitting layer, and the cathode, there is an electron transport region between the second light-emitting layer and the cathode, and the electron transport region has a structure for preventing the diffusion of triplet excitons. Barrier layer. Here, the charge...

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Abstract

Disclosed is an organic electroluminescent element provided with an anode, a light-emitting layer, a barrier layer, an electron-injection layer, and a cathode, in that order. The light-emitting layer includes a host and a dopant that exhibits fluorescence having a main peak wavelength no greater than 550 nm. The affinity Ad of the dopant is less than the affinity Ah of the host, and the triplet energy E T d of the dopantis higher than the triplet energy E T h of the host. The triplet energy E T b of the barrier layer is higher than E T h , and the barrier layer comprises a hydrocarbon aromatic compound.

Description

Technical field [0001] The present invention relates to organic electroluminescence (EL) devices, and more particularly to high-efficiency organic EL devices. Background technique [0002] If organic EL elements are classified according to their light-emitting principles, they can be divided into two types: fluorescent type and phosphorescent type. After voltage is applied to the organic EL element, holes are injected from the anode and electrons are injected from the cathode, and they recombine in the light-emitting layer to form excitons. According to the statistical rules of electron spin, singlet excitons and triplet excitons are generated at a ratio of 25%:75%. Since it is a fluorescent type and utilizes light emission based on singlet excitons, the limit of internal quantum efficiency is considered to be 25%. With regard to fluorescent elements using fluorescent materials, the technology for increasing the lifespan has recently been developed, and although it has graduall...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01L51/50H05B33/12H10K99/00
CPCH05B33/10H01L51/005C09B57/008C09B57/00H05B33/14C09B57/001H01L51/006H01L51/0054C09B69/008H01L51/0058H01L51/5016H01L2251/552H10K85/60H10K85/622H10K85/626H10K85/633H10K50/11H10K2101/10H10K2101/30H10K85/615
Inventor 熊均河村祐一郎甚出行俊荻原俊成细川地潮
Owner IDEMITSU KOSAN CO LTD
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