Coating liquid for forming light emitting layer, organic electroluminescent element, method for manufacturing organic electroluminescent element, and lighting/display device

Patent metadata

Field	Value
Publication number	US-10141520-B2
Application number	US-201414782110-A
Country	US
Kind code	B2
Filing date	Apr 1, 2014
Priority date	Apr 5, 2013
Publication date	Nov 27, 2018
Grant date	Nov 27, 2018

Abstract

One objective of the present invention is to provide a coating liquid for forming a light emitting layer, which improves quantum efficiency. Another objective of the present invention is to provide: an organic electroluminescent element which is formed by means of this coating liquid for forming a light emitting layer; a lighting device, a display device and a white electroluminescent device, each of which is provided with this organic electroluminescent element; and a method for manufacturing an organic electroluminescent element. A coating liquid for forming a light emitting layer according to the present invention is used for the purpose of forming a light emitting layer, which is one of one or more organic layers held between a positive electrode and a negative electrode, and this coating liquid for forming a light emitting layer is characterized by containing a thermally activated delayed fluorescent compound.

First claim

The invention claimed is:

1. A coating solution for forming a luminous layer included in one or more organic layers disposed between an anode and a cathode, the coating solution comprising:
a thermally-activated delayed fluorescent, compound, and
a heavy atom compound having an external heavy-atom effect to promote intersystem crossing of the thermally-activated delayed fluorescent compound from a triplet excited state to a singlet excited state to increase a fluorescent intensity,
wherein the heavy atom compound is a phosphorescent metal complex,
a lowest excited triplet energy level (T 1 (TADF)) of the thermally-activated delayed fluorescent compound and a lowest excited triplet energy level (T 1 (P)) of the phosphorescent metal complex are within ranges allowing transfer of energy electrons therebetween,
a difference in energy between a lowest excited singlet energy level (S 1 (TADF)) of the thermally-activated delayed fluorescent compound and the lowest excited triplet energy level (T 1 (P)) of the phosphorescent metal complex is within a range represented by Expression (1):
−0.2 eV≤[ S 1 (TADF)- T 1 ( P )]≤1.0 eV  (1), and

a difference in energy between the lowest excited triplet energy level (T 1 (TADF)) of the thermally-activated delayed fluorescent compound and the lowest excited triplet energy level (T 1 (P)) of the phosphorescent metal complex is within a range represented by Expression (3):
−0.2 eV≤[ T 1 (TADF)− T 1 ( P )]≤0.5 eV  (3)

2. The coating solution for forming the luminous layer according to claim 1 , wherein the difference in energy between the lowest excited singlet energy level (S 1 (TADF)) of the thermally-activated delayed fluorescent compound and the lowest excited triplet energy level (T 1 (P)) of the phosphorescent metal complex is within a range represented by Expression (2)
0 eV≤[ S 1 (TADF)− T 1 ( P )]≤0.2 eV  (2).

3. The coating solution for forming the luminous layer according to claim 1 , wherein the difference in energy between the lowest excited triplet energy level (T 1 (TADF)) the thermally-activated delayed fluorescent compound and the lowest excited triplet energy level (T 1 (P)) of the phosphorescent metal complex is within a range represented by Expression (4):
0 eV≤[ T 1 (TADF)− T 1 ( P )]≤0.1 eV  (4).

4. The coating solution for forming the luminous layer according to claim 1 , wherein the lowest excited triplet energy level (T 1 (TADF)) of the thermally-activated delayed fluorescent compound is within a range of 2.4 to 3.5 eV.

5. The coating solution for forming the luminous layer according to claim 1 , wherein the phosphorescent metal complex has a structure represented by Formula (I)

where M represents Ir, Pt, Rh, Ru, Ag, Cu p or Qs, A 1 and A 2 each represent a carbon or nitrogen atom; ring Z 1 represents a membered aromatic aromatic hydrocarbon ring group or 5- or 6-membered aromatic heterocyclic ring group containing A 1 and A 2 ; B 1 to B 5 each represent a carbon or nitrogen atom so that B 1 to B 5 form a 5-membered aromatic heterocyclic ring group, and B 1 to B 5 each optionally have a substituent; the ring Z 1 optionally has a substituent, or optionally has a condensed ring structure formed through bonding of substituents; substituents of ligands are optionally bonded to each other to bond the ligands to each other; L represents a monoanionic bidentate ligand coordinated with M; m represents an integer of 0 to 2; n represents an integer of 1 to 3; m+n is 2 or 3; when m is 2, two Ls are same or different, and when n is 2 or 3, two or three ligands each having the ring Z 1 and the aromatic heterocyclic ring group represented by B 1 to B 5 are same or different.

6. The coating solution for forming the luminous layer according to claim 1 , further comprising a host compound.

7. An organic electroluminescent element comprising a luminous layer included in one or more organic layers disposed between an anode and a cathode, wherein the luminous layer is made from the coating solution for forming the luminous layer according to claim 1 .

8. A lighting device comprising the organic electroluminescent element according to claim 7 .

9. A display device comprising the organic electroluminescent element according to claim 7 .

10. A white electroluminescent device which has a single luminous layer disposed between an anode and a cathode, the white electroluminescent device comprising:
the organic electroluminescent element according to claim 7 .

11. A method of producing an organic electroluminescent element including one or more organic layers disposed between an anode and a cathode, the method comprising:
forming a luminous layer with the coating solution for forming the luminous layer according to claim 1 , the luminous layer being one of the organic layers.

Assignees

• Konica Minolta Inc

Inventors

• Oikawa Kazuhiro
• Taka Hideo
• Ikemizu Dai

Classifications

• H01L51/0064

  Electricity · mapped topic

• H01L51/0003

  Electricity · mapped topic

• H01L51/5016

  Electricity · mapped topic

• C09K2211/1044

  containing two nitrogen atoms as heteroatoms · CPC title

• C09K2211/185

  of the platinum group, i.e. Os, Ir, Pt, Ru, Rh or Pd · CPC title