Organic electroluminescent element

Patent metadata

Field	Value
Publication number	US-9780322-B2
Application number	US-201214352472-A
Country	US
Kind code	B2
Filing date	Oct 2, 2012
Priority date	Oct 21, 2011
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

An organic electroluminescent element includes a hole injection layer (HI), a first hole transport layer (HT1), a second hole transport layer (HT2), and a light-emitting layer containing a host compound (H) and a phosphorescence emitting dopant compound (D), which are laminated in this order, between and an anode and a cathode. The phosphorescence emitting dopant compound has a partial structure represented by Formula (1):

The “highest occupied molecular orbital” HOMO of the second hole transport layer satisfies the expression: −5.4<HOMO (HT2)<−4.8; and the relationship of triplet excitation energies (T1) between the phosphorescence emitting dopant compound and a hole transport material contained in the second hole transport layer satisfies the expression: T1 (HT2)−T1 (D)>0.1.

First claim

The invention claimed is:

1. An organic electroluminescent element comprising a hole injection layer containing a hole injection material (HI), a first hole transport layer containing a first hole transport material (HT1), a second hole transport layer containing a second hole transport material (HT2), and a light-emitting layer containing a host compound (H) and a phosphorescence emitting dopant compound (D), which are laminated in this order, between an anode and a cathode,
wherein the phosphorescence emitting dopant compound has a partial structure represented by Formula (1),
the “highest occupied molecular orbital” HOMO of the second hole transport material satisfies the expression: −5.40<HOMO (HT2)<−4.80, and
the relationship of triplet excitation energies (T1) between the phosphorescence emitting dopant compound and the second hole transport material satisfies the expression: T1 (HT2)−T1 (D)>0.1:

where Ring A and Ring B each represent a five- or six-membered aromatic cyclic hydrocarbon or aromatic heterocycle; Ar represents an aromatic cyclic hydrocarbon, an aromatic heterocycle, a non-aromatic cyclic hydrocarbon, or a non-aromatic heterocycle; R 1 and R 2 each independently represent a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an amino group, a silyl group, an arylalkyl group, an aryl group, a heteroaryl group, a non-aromatic cyclic hydrocarbon group, or a non-aromatic heterocycle group; the groups may each have a substituent; at least one of R 1 and R 2 is an alkyl group having 2 or more carbon atoms or a cycloalkyl group;
Ra, Rb and Rc each independently represent a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an amino group, a silyl group, an arylalkyl group, an aryl group, a heteroaryl group, a non-aromatic cyclic hydrocarbon group, or a non-aromatic heterocycle group; the groups may each have a substituent; na and nc each represent 1 or 2; and nb represents an integer of 1 to 4.

2. The organic electroluminescent element of claim 1 , wherein the relationship of the HOMOs between the first hole transport material (HT1) and the second hole transport material (HT2)satisfies the expression: −0.50<HOMO (HT2)−HOMO (HT1)<−0.10.

3. The organic electroluminescent element of claim 1 , wherein the second hole transport material is represented by Formula (2):

where X and Y each represent O, S, or N—R (R represents a hydrogen atom or a substituent), A 1 and A 2 each represent a hydrogen atom or a substituent, L 1 and L 2 each represent a divalent linking group, n represents an integer of 1 or more, n1 and n2 represent an integer 0 or more, and n3 and n4 each represent 0 or 1 (where n1+n2≧2).

4. The organic electroluminescent element of claim 1 , further comprising an electron transport layer containing an electron transport material (ET) provided at least between the light-emitting layer and the cathode,
wherein the relationship of the “lowest unoccupied molecular orbit” LUMOs between the host compound and the electron transport material satisfies the expression: −0.40<LUMO (H)−LUMO (ET)<0.80.

5. The organic electroluminescent element of claim 4 , wherein the electron transport material is represented by Formula (3):

where R 61 represents a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group, and X 1 to X 8 each represent N or —CR 62 , and R 62 represents a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group.

6. The organic electroluminescent element of claim 4 , wherein the electron transport material is represented by Formula (4):

where A represents Li, Be or Al.

7. The organic electroluminescent element of claim 1 , wherein R 1 and R 2 in Formula (1) each represent an alkyl group having 2 or more carbon atoms or a cycloalkyl group.

8. The organic electroluminescent element of claim 1 , wherein at least one of R 1 and R 2 in Formula (1) is a branched alkyl group having 3 or more carbon atoms.

9. The organic electroluminescent element of claim 1 , wherein R 1 and R 2 each in Formula (1) represent a branched alkyl group having 3 or more carbon atoms.

10. The organic electroluminescent element of claim 1 , wherein Ring B in Formula (1) is a benzene ring.

11. The organic electroluminescent element of claim 1 , wherein Ar in Formula (1) is a benzene ring.

12. The organic electroluminescent element of claim 1 , wherein Formula (1) is represented by Formula (1-1):

where Ar represents an aromatic cyclic hydrocarbon, aromatic heterocycle, non-aromatic cyclic hydrocarbon or non-aromatic heterocycle; R 1 and R 2 each independently represent a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an amino group, a silyl group, an arylalkyl group, an aryl group, a heteroaryl group, a non-aromatic cyclic hydrocarbon group or a non-aromatic heterocycle group; the groups may each have a substituent; at least one of R 1 and R 2 is an alkyl group having 2 or more carbon atoms or a cycloalkyl group;
Ra, Rb and Rc each independently represent independently a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an amino group, a silyl group, an arylalkyl group, an aryl group, a heteroaryl group, a non-aromatic cyclic hydrocarbon group or a non-aromatic heterocycle group, the groups may each have a substituent; na and nc represent 1 or 2, and nb represents an integer of 1 to 4;
L′ represents one or more monoanionic bidentate ligands which are coordinated with M; M represents a transition metal atom having an atomic number of 40 or more and belonging to groups 8 to 10 in the periodic table; m′ represents an integer of 0 to 2, n′ represents at least 1, and m′+n′ is equal to 2 or 3.

13. The organic electroluminescent element of claim 1 , wherein the organic electroluminescent element emits white light.

Assignees

• Konica Minolta Inc

Inventors

• Tani Kunio
• Katoh Eisaku
• Ito Hiroto
• Hiyama Kunimasa

Classifications

• H01L51/5072

  Electricity · mapped topic

• H01L2251/55

  Electricity · mapped topic

• H01L51/0073

  Electricity · mapped topic

• H01L51/5088

  Electricity · mapped topic

• H01L51/5016

  Electricity · mapped topic