Organic electroluminescent device

Patent metadata

Field	Value
Publication number	US-2016190478-A1
Application number	US-201414911761-A
Country	US
Kind code	A1
Filing date	Aug 13, 2014
Priority date	Aug 14, 2013
Publication date	Jun 30, 2016
Grant date	—

Abstract

An organic electroluminescent device having an anode, a cathode, and a light emitting layer between the anode and the cathode, in which the light emitting layer contains a first organic compound, a second organic compound, and a third organic compound that satisfy the following expression (A), the second organic compound is a delayed fluorescent material, and the third organic compound is a light emitting material, is capable of enhancing the light emission efficiency. E S1 (A), E S1 (B) and E S1 (C) represent a lowest singlet excitation energy level of the first, second and third organic compound, respectively.
E S1 (A)>E S1 (B)>E S1 (C)  (A)

First claim

1 . An organic electroluminescent device comprising an anode, a cathode, and at least one organic layer including a light emitting layer between the anode and the cathode,
the light emitting layer containing a first organic compound, a second organic compound, and a third organic compound that satisfy the following expressions (A) and (B), the second organic compound being a delayed fluorescent material, the second organic compound having an energy difference ΔE st between a lowest singlet excited state and a lowest triplet excited state at 77 K of 0.3 eV or less, and the third organic compound being a light emitting material:
E S1 (A)>E S1 (B)>E S1 (C)  (A)

wherein E S1 (A) represents a lowest singlet excitation energy level of the first organic compound; E S1 (B) represents a lowest singlet excitation energy level of the second organic compound; and E S1 (C) represents a lowest singlet excitation energy level of the third organic compound;
E T1 (A)>E T1 (B)  (B)

wherein E T1 (A) represents a lowest triplet excitation energy level at 77 K of the first organic compound; and E T1 (B) represents a lowest triplet excitation energy level at 77 K of the second organic compound.

2 . (canceled)

3 . The organic electroluminescent device according to claim 1 , wherein the second organic compound has an energy difference ΔE st between a lowest singlet excited state and a lowest triplet excited state at 77 K of 0.08 eV or less.

4 . (canceled)

5 . The organic electroluminescent device according to claim 1 , wherein the third organic compound emits fluorescent light on returning from the lowest singlet excitation energy level to a ground energy level.

6 . The organic electroluminescent device according to claim 1 , wherein in the light emitting layer, a content of the second organic compound is smaller than a content of the first organic compound.

7 . The organic electroluminescent device according to claim 1 , wherein the light emitting layer contains two or more kinds of compounds as the third compound.

8 . The organic electroluminescent device according to claim 1 , wherein the light emitting layer contains one kind or two or more kinds of organic compounds, in addition to the first organic compound, the second organic compound, and the third organic compound.

Assignees

• Univ Kyushu Nat Univ Corp

Inventors

• Nakanotani Hajime
• Adachi Chihaya
• Higuchi Takahiro
• Furukawa Taro

Classifications

• C09K2211/1033

  with oxygen · CPC title

• C09K2211/1077

  with oxygen · CPC title

• C09K2211/1011

  Condensed systems · CPC title

• C09K2211/186

  of the light metals other than alkali metals and alkaline earth metals, i.e. Be, Al or Mg · CPC title

• C09K2211/1044

  containing two nitrogen atoms as heteroatoms · CPC title