Organic electroluminescence device and method for fabricating the same
Disclosed herein are an organic electroluminescent (EL) device comprising a hole transport layer (HTL) and a method for fabricating the same. The organic electroluminescent (EL) device comprises a stack in which a light-emitting layer and a hole transport layer are interposed between an anode and a cathode, wherein the hole transport layer is made of a mixture of at least two materials, and wherein the mixture is selected from a mixture of an organic compound and one or more other organic compounds, a mixture of a metal or inorganic compound and one or more other metal or inorganic compounds, and a mixture of one or more organic compounds and one or more metal or inorganic compounds.
1 . An organic electroluminescent (EL) device comprising a stack in which a light-emitting layer and a hole transport layer are interposed between an anode and a cathode,
wherein the hole transport layer is made of a mixture of at least two materials, and
wherein the mixture is selected from: a mixture of an organic compound and one or more other organic compounds; a mixture of a metal or inorganic compound and one or more other metal or inorganic compounds; and a mixture of one or more organic compounds and one or more metal or inorganic compounds.
2 . The organic electroluminescent (EL) device according to claim 1 , wherein the hole transport layer has a thickness of 0.1 to 500 nm.
3 . The organic electroluminescent (EL) device according to claim 1 , wherein the hole transport layer is made of a mixture of a first material X and a second material Y, and
wherein the first material X and the second material Y are used in a ratio of 1:1 to 100:1 or 1:1 to 1:100.
4 . The organic electroluminescent (EL) device according to claim 1 , wherein the hole transport layer is made of a mixture of a first material X and a plurality of other materials Y, and
wherein the first material X and the plurality of other materials Y are used in a ratio of 1:1 to 100:1 or 1:1 to 1:100.
5 . The organic electroluminescent (EL) device according to claim 1 , wherein the hole transport layer includes at least one material having hole-blocking capability and at least one material having hole-transporting capability.
6 . The organic electroluminescent (EL) device according to claim 1 , wherein the hole-blocking material has an oxidation potential greater than 0.4 V and an absolute value of a highest occupied molecular orbital (HOMO) greater than or equal to 5.2 eV.
7 . The organic electroluminescent (EL) device according to claim 5 , wherein the hole-blocking material is a metal complex containing a substituted or unsubstituted 8-hydroxyquinoline, and
wherein the metal of the metal complex is selected from aluminum (Al), zinc (Zn), magnesium (Mg) and lithium (Li).
8 . The organic electroluminescent (EL) device according to claim 5 , wherein the hole-blocking material is a substituted or unsubstituted 1,10-phenanthroline derivative, or a substituted or unsubstituted carbazole derivative.
9 . The organic electroluminescent (EL) device according to claim 5 , wherein the hole-blocking material is selected from Balq (aluminum(III) bis(2-methyl-8-quinolinato)4-phenylphenolate), BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), CBP [4,48-N,N8-dicarbazole-1,18-biphenyl], CF-X and CF-Y.
10 . The organic electroluminescent (EL) device according to claim 5 , wherein the hole-transporting material has a hole mobility of 1.0×10 −5 cm 2 /Vs or more.
11 . The organic electroluminescent (EL) device according to claim 5 , wherein the hole-transporting material has an oxidation potential lower than 1.7 V and an absolute value of a highest occupied molecular orbital (HOMO) greater than or equal to 6.5 eV.
12 . The organic electroluminescent (EL) device according to claim 5 , wherein the hole-transporting material is aromatic amine.
13 . The organic electroluminescent (EL) device according to claim 5 , wherein the aromatic amine is a compound represented by Formula below:
wherein n is an integer of 1 to 4; and Ar 1 , Ar 2 and Ar 3 are independently a substituted or unsubstituted aromatic group.
14 . The organic electroluminescent (EL) device according to claim 13 , wherein Ar 1 , Ar 2 , and Ar 3 are independently selected from phenyl, naphthyl, biphenyl, biphenylelnyl, phenanthrenyl, fluorenyl, terphenylyl, and anthracenyl groups, and the substituent is selected from methyl, ethyl, propyl, t-buthyl, methoxy, ethoxy, propoxy, dimethylamine, diethylamine, phenyl, fluorine, chlorine, and bromine.
15 . The organic electroluminescent (EL) device according to claim 12 , wherein the aromatic amine is one selected from compounds represented by formulas below:
16 . The organic electroluminescent (EL) device according to claim 5 , wherein the hole-transporting material is a pyrazine derivative.
17 . The organic electroluminescent (EL) device according to claim 16 , wherein the pyrazine derivative is a compound represented by Formula below:
wherein each R is independently selected from a hydrogen atom, and C 1 -C 12 halogenated hydrocarbon, alkoxy, arylamine, ester, amide, aromatic hydrocarbon, heterocyclic, nitro, and nitryl groups.
18 . The organic electroluminescent (EL) device according to claim 1 , wherein the hole transport layer serves as an exciton diffusion barrier preventing excitons from being diffused from the light-emitting layer to the hole transport layer.
19 . The organic electroluminescent (EL) device according to claim 1 , wherein at least one of an electron transport layer and an electron injection layer is interposed between the anode and the light-emitting layer.
20 . The organic electroluminescent (EL) device according to claim 1 , wherein a hole injection layer is interposed between the anode and the hole transport layer.
21 . The organic electroluminescent (EL) device according to claim 1 , wherein the light-emitting layer consists of one or more layers.
22 . The organic electroluminescent (EL) device according to claim 1 , wherein the light-emitting layer includes a phosphorescent material.
23 . The organic electroluminescent (EL) device according to claim 1 , wherein at least one of the anode and the cathode is made of a transparent material.
24 . An organic electroluminescent (EL) device comprising a stack in which a light-emitting layer and a hole transport layer are interposed between an anode and a cathode,
wherein the light-emitting layer includes at least one phosphorescent material, and the hole transport layer is made of at least one material having hole-blocking capability, and at least one material having hole-transporting capability.
25 . An organic electroluminescent (EL) device comprising a plurality of light-emitting units in which a light-emitting layer and a hole transport layer are interposed between an anode and a cathode,
wherein adjacent light-emitting units are separated to each other by an associated interlayer, and the hole transport layer is made of a mixture of at least one material having hole-blocking capability and at least one material having hole-transporting capability.
26 . The organic electroluminescent (EL) device according to claim 25 , wherein the light-emitting units are same or different stacks.
27 . A method for fabricating an organic electroluminescent (EL) device comprising:
forming a first electrode on a substrate;
forming a hole transport layer made of a mixture of at least one hole-blocking material and at least one hole-transporting material on the first electrode;
forming a light-emitting layer including at least one phosphorescent material on the hole transport layer; and
forming a second electrode on the light-emitting layer.
28 . The method according to claim 27 , wherein the first electrode is an anode and the second electrode is a cathode.
29 . The method according to claim 27 , further comprising forming at least one of an electron injection layer and an electron transport layer between the second electrode and the light-emitting layer.
30 . The method according to claim 27 , further comprising forming a hole injection layer between the first electrode and the hole transport layer.