Oled Having Stacked Organic Light-Emitting Units

• US 20090009101A1
• Filed: 01/17/2007
• Published: 01/08/2009
• Est. Priority Date: 01/18/2006
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Chem Limited (LG Corporation)
• Inventors: Lee, Jung-Hyoung, Kang, Min-Soo, Noh, Jeoung-Kwen
• Granted Patent: US 8,680,693 B2
• Time in Patent Office: Days
• US Class Current: 315/250
• CPC Class Codes: H10K 50/19 Tandem OLEDs
• CPC Class Codes: H10K 59/32 Stacked devices having two or more layers, each emitting at different wavelengths
• CPC Class Codes: H10K 71/841 Applying alternating current [AC] during manufacturing or treatment

Abstract

The present invention provides a stacked organic light emitting device, comprising a first conductive layer, at least one intermediate conductive layer and a second conductive layer, and light emitting units disposed between the conductive layers, wherein at least two non-neighboring conductive layers among the conductive layers are conductive layers belonging to Group 1 such that they are electrically connected with each other to a common potential; at least one non-neighboring conductive layer among the conductive layers which are not electrically connected with the conductive layers belonging to Group 1 to a common potential are conductive layers belonging to Group 2 such that they are electrically connected with each other to a common potential; and the conductive layers belonging to Group 1 and the conductive layers belonging to Group 2 are connected with each other via a voltage regulator for alternately applying a positive voltage and a negative voltage.

Claims

1. A stacked organic light emitting device, comprising a first conductive layer, at least one intermediate conductive layer and a second conductive layer, and light emitting units disposed between the conductive layers,

wherein at least two non-neighboring conductive layers among the conductive layers are conductive layers belonging to Group 1 such that they are electrically connected with each other to a common potential;

at least one non-neighboring conductive layer among the conductive layers which are not electrically connected with the conductive layers belonging to Group 1 to a common potential are conductive layers belonging to Group 2 such that they are electrically connected with each other to a common potential; and

the conductive layers belonging to Group 1 and the conductive layers belonging to Group 2 are connected with each other via a voltage regulator for alternately applying a positive voltage and a negative voltage.

2. The stacked organic light emitting device according to claim 1, wherein the first conductive layer and at least one intermediate conductive layer are conductive layers belonging to Group 1 such that they are electrically connected with each other to a common potential;

the second conductive layer, and at least one intermediate conductive layer not belonging to Group 1 are conductive layers belonging to Group 2 such that they are electrically connected with each other to a common potential;

the conductive layers belonging to Group 1 are not neighboring to each other, the conductive layers belonging to Group 2 are not neighboring to each other, and the conductive layers belonging to Group 1 and the conductive layers belonging to Group 2 are connected with each other via a voltage regulator for alternately applying a positive voltage and a negative voltage.

3. The stacked organic light emitting device according to claim 1, wherein the first conductive layer and the second conductive layer are conductive layers belonging to Group 1 such that they are electrically connected with each other to a common potential;

at least one non-neighboring conductive layer among the intermediate conductive layers are conductive layers belonging to Group 2 such that they are electrically connected with each other to a common potential; and

the conductive layers belonging to Group 1 and the conductive layers belonging to Group 2 are connected with each other via a voltage regulator for alternately applying a positive voltage and a negative voltage.

4. The stacked organic light emitting device according to claim 1, wherein the first conductive layer, the second conductive layer, and at least one intermediate conductive layer which is not adjacent to the first and second conductive layers are conductive layers belonging to Group 1 such that they are electrically connected with each other to a common potential;

at least one non-neighboring conductive layer among the conductive layers which are not electrically connected with the conductive layers belonging to Group 1 to a common potential are conductive layers belonging to Group 2 such that they are electrically connected with each other to a common potential; and

the conductive layers belonging to Group 1 and the conductive layers belonging to Group 2 are connected with each other via a voltage regulator for alternately applying a positive voltage and a negative voltage.

5. The stacked organic light emitting device according to claim 1, comprising a first conductive layer, a first light emitting unit, an intermediate conductive layer, a second first light emitting unit, and a second conductive layer, wherein the first conductive layer and the second conductive layer are conductive layers belonging to Group 1 such that they are electrically connected with each other to a common potential;

and the intermediate conductive layer and the conductive layers belonging to Group 1 are connected with each other via a voltage regulator for alternately applying a positive voltage and a negative voltage.

6. The stacked organic light emitting device according to claim 1, comprising a first conductive layer, a first light emitting unit, a first intermediate conductive layer, a second light emitting unit, a second intermediate conductive layer, a third light emitting unit and a second conductive layer, wherein the first conductive layer and the second intermediate conductive layer are conductive layers belonging to Group 1 such that they are electrically connected with each other to a common potential;

the first intermediate conductive layer and the second conductive layer are conductive layers belonging to Group 2 such that they are electrically connected with each other to a common potential; and

the conductive layers belonging to Group 1 and the conductive layers belonging to Group 2 are connected with each other via a voltage regulator for alternately applying a positive voltage and a negative voltage.

7. The stacked organic light emitting device according to claim 1, comprising a first conductive layer, a first light emitting unit, a first intermediate conductive layer, a second light emitting unit, a second intermediate conductive layer, a third light emitting unit and a second conductive layer, wherein the first conductive layer and the second conductive layer are conductive layers belonging to Group 1 such that they are electrically connected with each other to a common potential;

and any one of the first intermediate conductive layer and the second intermediate conductive layer, and the conductive layers belonging to Group 1 are connected with each other via a voltage regulator for alternately applying a positive voltage and a negative voltage.

8. The stacked organic light emitting device according to claim 1, comprising a first conductive layer, a first light emitting unit, a first intermediate conductive layer, a second light emitting unit, a second intermediate conductive layer, a third light emitting unit, a third intermediate conductive layer, a fourth light emitting unit and a second conductive layer, wherein the first conductive layer and the second intermediate conductive layer are conductive layers belonging to Group 1 such that they are electrically connected with each other to a common potential;

the second conductive layer and the first intermediate conductive layer are conductive layers belonging to Group 2 such that they are electrically connected with each other to a common potential; and

the conductive layers belonging to Group 1 and the conductive layers belonging to Group 2 are connected with each other via a voltage regulator for alternately applying a positive voltage and a negative voltage.

9. The stacked organic light emitting device according to claim 1, comprising a first conductive layer, a first light emitting unit, a first intermediate conductive layer, a second light emitting unit, a second intermediate conductive layer, a third light emitting unit, a third intermediate conductive layer, a fourth light emitting unit and a second conductive layer, wherein the first conductive layer and second conductive layer are conductive layers belonging to Group 1 such that they are electrically connected with each other to a common potential;

and at least one of the first intermediate conductive layer, the second intermediate conductive layer and the third intermediate conductive layer, and the conductive layers belonging to Group 1 are connected with each other via a voltage regulator for alternately applying a positive voltage and a negative voltage.

10. The stacked organic light emitting device according to claim 1, comprising a first conductive layer, a first light emitting unit, a first intermediate conductive layer, a second light emitting unit, a second intermediate conductive layer, a third light emitting unit, a third intermediate conductive layer, a fourth light emitting unit and a second conductive layer, wherein the first conductive layer, the second intermediate conductive layer and the second conductive layer are conductive layers belonging to Group 1 such that they are electrically connected with each other to a common potential;

the first intermediate conductive layer and the third intermediate conductive layer are conductive layers belonging to Group 2 such that they are electrically connected with each other to a common potential; and

the conductive layers belonging to Group 1 and the conductive layers belonging to Group 2 are connected with each other via a voltage regulator for alternately applying a positive voltage and a negative voltage.

11. The stacked organic light emitting device according to claim 1, wherein the voltage regulator is used for applying a positive voltage and a negative voltage alternately by a sine wave alternating current voltage, a direct current voltage or a pulse voltage.

12. The stacked organic light emitting device according to claim 11, wherein the voltage regulator is provided with a means of modulating the width or height of the sine wave or the pulse.

13. The stacked organic light emitting device according to claim 1, wherein it is a bottom emission device, a top emission device, or a top-and-bottom emission device.

14. The stacked organic light emitting device according to claim 1, wherein the first conductive layer is an anode electrode, and the second conductive layer is a cathode electrode.

15. The stacked organic light emitting device according to claim 1, wherein the first conductive layer is a cathode electrode, and the second conductive layer is an anode electrode.

16. The stacked organic light emitting device according to claim 1, wherein the intermediate conductive layer is formed of transparent materials, or formed as a thin film to be transparent.

17. The stacked organic light emitting device according to claim 1, wherein the intermediate conductive layer is in a stacked form comprising an intermediate cathode electrode layer and an intermediate anode electrode layer.

18. The stacked organic light emitting device according to claim 1, wherein the intermediate conductive layer is in a form comprising a single conductive layer.

19. The stacked organic light emitting device according to claim 1, wherein the light emitting units are the same as or different from each other.

20. The stacked organic light emitting device according to claim 19, wherein the light emitting units each independently comprises at least one layer selected from a light emitting layer, a hole injecting layer, a hole transporting layer, an electron transporting layer, and an electron injecting layer.

21. The stacked organic light emitting device according to claim 19, wherein the light emitting units comprise light emitting layers formed of different materials.

22. The stacked organic light emitting device according to claim 19, wherein the light emitting units have a forward structure comprising a hole injecting layer, a hole transporting layer, a light emitting layer and an electron transporting layer, which are stacked in this order.

23. The stacked organic light emitting device according to claim 19, wherein the light emitting units have a reverse structure comprising an electron transporting layer, a light emitting layer, a hole transporting layer, and a hole injecting layer, which are stacked in this order.

24. The stacked organic light emitting device according to claim 19, wherein the light emitting units have both of a forward structure comprising a hole injecting layer, a hole transporting layer, a light emitting layer and an electron transporting layer, which are stacked in this order, and a reverse structure comprising an electron transporting layer, a light emitting layer, a hole transporting layer and a hole injecting layer, which are stacked in this order.

25. The stacked organic light emitting device according to claim 1, wherein at least one of the light emitting units comprises an n-type organic material layer adjacent to any one of the conductive layers, and a p-type organic material layer to form an NP junction with the n-type organic material layer, and their energy levels satisfy the following equations:

E_nL−

E_F≦

4 eV 

 

(1)

E_pH−

E_nL≦

1 eV 

 

(2)

(in the above equations (1) and (2), E_F is a Fermi energy level of the conductive layer adjacent to the n-type organic material layer, E_nL is a LUMO (lowest unoccupied molecular orbital) energy level of the n-type organic material layer, and E_pH is HOMO (highest occupied molecular orbital) energy level of the p-type organic material layer).

26. The stacked organic light emitting device according to claim 25, wherein the (n+1)th light emitting unit from the first conductive layer comprises an n-type organic material layer adjacent to the (n)th intermediate conductive layer from the first conductive layer, wherein n is an integer of 1 or more, and a p-type organic material layer to form an NP junction with the n-type organic material layer, and their energy levels satisfy the above-described equations (1) and (2).

27. The stacked organic light emitting device according to claim 25, wherein the light emitting unit adjacent to the first conductive layer comprises an n-type organic material layer adjacent to the first conductive layer, and a p-type organic material layer to form an NP junction with the n-type organic material layer, and their energy levels satisfy the above-described equations (1) and (2).

28. The stacked organic light emitting device according to claim 25, wherein the (n)th light emitting unit from the first conductive layer comprises an n-type organic material layer adjacent to the (n)th intermediate conductive layer from the first conductive layer, wherein n is an integer of 1 or more, and a p-type organic material layer to form an NP junction with the n-type organic material layer, and their energy levels satisfy the above-described equations (1) and (2).

29. The stacked organic light emitting device according to claim 25, wherein the light emitting unit adjacent to the second conductive layer comprises an n-type organic material layer adjacent to the second conductive layer, and a p-type organic material layer to form an NP junction with the n-type organic material layer, and their energy levels satisfy the above-described equations (1) and (2).

30. The stacked organic light emitting device according to claim 25, wherein the n-type organic material layer is a hole injecting layer in the each light emitting unit.

31. The stacked organic light emitting device according to claim 25, wherein the n-type organic material layer comprises a compound of the following formula 1:

wherein R¹ to R⁶ are each independently selected from the group consisting of hydrogen, a halogen atom, nitrile (—

CN), nitro (—

NO₂), sulfonyl (—

SO₂R¹¹), sulfoxide (—

SOR¹¹), sulfonamide (—

SO₂NR¹¹R¹²), sulfonate (—

SO₂R¹¹), trifluoromethyl (—

CF₃), ester (—

COOR¹¹), amide (—

CONHR¹¹ or —

CONR¹¹R¹²), substituted or unsubstituted linear or branched C₁-C₁₂ alkoxy, substituted or un-substituted linear or branched C₁-C₁₂ alkyl, substituted or unsubstituted aromatic or non-aromatic heterocycle, substituted or unsubstituted aryl, substituted or un-substituted mono-arylamine or di-arylamine, and substituted or unsubstituted aralkylamine, and R¹¹ and R¹² are selected from the group consisting of substituted or unsubstituted C₁-C₆₀ alkyl, substituted or unsubstituted aryl, and substituted or unsubstituted 5- to 7-membered heterocycle.

32. The stacked organic light emitting device according to claim 31, wherein the compound of the formula 1 is selected from the compounds represented by the following formulae 1-1 to 1-6:

33. The stacked organic light emitting device according to claim 25, wherein the n-type organic material layer comprises a compound selected from 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), fluorine-substituted 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA), cyano-substituted 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA), naphthalenetetracarboxylicdianhydride (NTCDA), fluorine-substituted naphthalenetetracarboxylicdianhydride (NTCDA), and cyano-substituted naphthalenetetracarboxylicdianhydride (NTCDA).

34. The stacked organic light emitting device according to claim 25, wherein at least two conductive layers of the first conductive layer, at least one intermediate conductive layer and the second conductive layer are formed of the same materials.

35. The stacked organic light emitting device according to claim 34, wherein at least two conductive layers of the first conductive layer, at least one intermediate conductive layer and the second conductive layer are formed of Ca, Ca—

Ag, Ag-IZO or Mg—

Ag.

36. The stacked organic light emitting device according to claim 1, wherein at least one of the light emitting units comprises an organic material layer containing the compound with a functional group selected from an imidazole group, an oxazole group and a thiazole group.

37. The stacked organic light emitting device according to claim 36, wherein the organic material layer comprising the compound containing a functional group selected from an imidazole group, an oxazole group and a thiazole group include the compounds represented by the following formula 2 or 3:

wherein R⁷ and R⁸ may be the same as or different from each other, and are each independently hydrogen, a C₁-C₂₀ aliphatic hydrocarbon, or an aromatic ring or aromatic heterocycle;

Ar is an aromatic ring or aromatic heterocycle;

R⁹ is hydrogen, a C₁-C₆ aliphatic hydrocarbon, or an aromatic ring or aromatic heterocycle;

X is O, S or NR¹³;

R¹³ is hydrogen, a C₁-C₇ aliphatic hydrocarbon, or an aromatic ring or aromatic heterocycle, provided that R⁷ and R⁸ are not hydrogen at the same time;

wherein Z is O, S or NR¹⁴;

R¹⁰ and R¹⁴ may be the same as or different from each other, and are each independently hydrogen, a C₁-C₂₄ alkyl, a C₅-C₂₀ aryl or heteroatom-containing substituted aryl, halogen or alkylene capable of forming a fused ring with a benzazole ring, or a heteroatom-containing alkylene;

B, as a linking unit, is alkylene, arylene, substituted alkylene, or substituted arylene to link the multiple benzazoles to be conjugated or non-conjugated; and

n is an integer of 3 to 8.

38. The stacked organic light emitting device according to claim 25, wherein at least one of the light emitting units comprises an organic material layer containing the compound with a functional group selected from an imidazole group, an oxazole group and a thiazole group.

39. The stacked organic light emitting device according to claim 38, wherein the organic material layer comprising the compound containing a functional group selected from an imidazole group, an oxazole group and a thiazole group include the compounds represented by the following formula 2 or 3:

wherein R⁷ and R⁸ may be the same as or different from each other, and are each independently hydrogen, a C₁-C₂₀ aliphatic hydrocarbon, or an aromatic ring or aromatic heterocycle;

Ar is an aromatic ring or aromatic heterocycle;

R⁹ is hydrogen, a C₁-C₆ aliphatic hydrocarbon, or an aromatic ring or aromatic heterocycle;

X is O, S or NR¹³;

R¹³ is hydrogen, a C₁-C₇ aliphatic hydrocarbon, or an aromatic ring or aromatic heterocycle, provided that R⁷ and R⁸ are not hydrogen at the same time;

wherein Z is O, S or NR¹¹;

R¹⁰ and R¹⁴ may be the same as or different from each other, and are each independently hydrogen, a C₁-C₂₄ alkyl, a C₅-C₂₀ aryl or heteroatom-containing substituted aryl, halogen or alkylene capable of forming a fused ring with a benzazole ring, or a heteroatom-containing alkylene;

B, as a linking unit, is alkylene, arylene, substituted alkylene, or substituted arylene to link the multiple benzazoles to be conjugated or non-conjugated; and

n is an integer of 3 to 8.

40. The stacked organic light emitting device according to claim 38, wherein the light emitting units containing an organic material layer comprising the compound containing a functional group selected from an imidazole group, an oxazole group and a thiazole group includes an n-type organic material layer adjacent to the conductive layer, and a p-type organic material layer to form an NP junction with the n-type organic material layer.