JP4736336B2 - Organic electroluminescence element, lighting device and display device - Google Patents

Description

  The present invention relates to an organic electroluminescence element, an illuminating device, and a display device, and particularly relates to an organic electroluminescent element, an illuminating device, and a display device having the same that are excellent in light emission luminance, luminous efficiency, and durability.

  Conventionally, there is an electroluminescence display (ELD) as a light-emitting electronic display device. Examples of the constituent elements of ELD include inorganic electroluminescent elements and organic electroluminescent elements (hereinafter also referred to as organic EL elements).

  Inorganic electroluminescent elements have been used as planar light sources, but an alternating high voltage is required to drive the light emitting elements.

  On the other hand, an organic EL element has a structure in which a light emitting layer containing a compound that emits light is sandwiched between a cathode and an anode. By injecting electrons and holes into the light emitting layer and recombining them, excitons (exciton) are obtained. And emits light using the emission of light (fluorescence / phosphorescence) when the exciton is deactivated, and can emit light at a voltage of several volts to several tens of volts. Since it is a light-emitting type, it has a wide viewing angle, high visibility, and since it is a thin-film type complete solid-state device, it has attracted attention from the viewpoints of space saving and portability.

  For the development of organic EL elements for practical use in the future, organic EL elements that emit light efficiently and with high brightness with lower power consumption are desired. For example, stilbene derivatives, distyrylarylene derivatives, or tris A technique for doping a styrylarylene derivative with a small amount of a phosphor to improve emission luminance and extend the lifetime of the device (see, for example, Patent Document 1), and 8-hydroxyquinoline aluminum complex as a host compound. A device having an organic light-emitting layer doped with a trace amount of phosphor (for example, see Patent Document 2), a device having an organic light-emitting layer doped with a quinacridone dye as a host compound using 8-hydroxyquinoline aluminum complex (for example, , See Patent Document 3).

  In the technique disclosed in the above-mentioned patent document, when the emission from the excited singlet is used, the generation ratio of the singlet exciton and the triplet exciton is 1: 3, so the generation probability of the luminescent excited species is 25%. Since the light extraction efficiency is about 20%, the limit of the external extraction quantum efficiency (ηext) is set to 5%.

  However, since Princeton University has reported on organic EL devices that use phosphorescence emission from excited triplets (see, for example, Non-Patent Document 1), research on materials that exhibit phosphorescence at room temperature has become active. (For example, see Non-Patent Document 2 and Patent Document 4.)

  When excited triplets are used, the upper limit of internal quantum efficiency is 100%, so in principle the luminous efficiency is four times that of excited singlets, and the performance is almost the same as that of cold cathode tubes. It can be applied to and attracts attention.

  For example, many compounds have been studied focusing on heavy metal complexes such as iridium complexes (see, for example, Non-Patent Document 3).

  Further, studies using tris (2-phenylpyridine) iridium as a dopant have been made (for example, see Non-Patent Document 2).

In addition, L ₂ Ir (acac), for example, (ppy) ₂ Ir (acac) (see, for example, Non-Patent Document 4) as a dopant, and tris (2- (p-tolyl) pyridine) iridium (as a dopant) Studies using Ir (ptpy) ₃ ), tris (benzo [h] quinoline) iridium (Ir (bzq) ₃ ), Ir (bzq) ₂ ClP (Bu) _3, etc. (for example, see Non-Patent Document 5). Has been done.

  In order to obtain high luminous efficiency, a hole transporting compound is used as a host of the phosphorescent compound (see, for example, Non-Patent Document 6).

  Further, various electron transporting materials are used as phosphorescent compound hosts by doping them with a novel iridium complex (for example, see Non-Patent Document 4). Furthermore, high luminous efficiency is obtained by introducing a hole blocking layer (see, for example, Non-Patent Document 5).

  Currently, further improvement in light emission efficiency and life of organic EL elements using phosphorescence emission are being studied.

  However, although the external extraction efficiency of 20%, which is the theoretical limit for green light emission, has been achieved, it is only in the low current region (low luminance region), and the theoretical limit is still in the high current region (high luminance region). Not achieved. Furthermore, sufficient efficiency has not yet been obtained for other luminescent colors, and improvements are required. In addition, organic EL devices for practical application in the future will emit light efficiently and with high brightness. Development of the organic EL element which does is desired. In particular, there is a demand for an element that emits light with high efficiency in an organic EL element that emits blue phosphorescence.

  As a hole transport material of an organic EL element using conventional phosphorescence, α-NPD, m-MTDATA, TPD, hm-TPD, PEDOT and PVK used in a polymer system are used.

  Α-NPD, which is the most common, easily injects holes into the light-emitting layer, but has low excitation triplet energy and has sufficient performance as a hole transport material for green phosphorescent organic EL devices. Of course, it does not have sufficient performance as a hole transport material for blue phosphorescent organic EL devices.

  m-MTDATA easily injects holes and has a relatively large excitation triplet energy, but does not have sufficient performance as a blue phosphorescent organic EL device. Similarly, TPD and hm-TPD (reference) are also unsuitable for blue phosphorescent elements, and further have a problem in terms of lifetime.

  PEDOT has a very small excited triplet energy, and does not have sufficient performance as a hole transport material for phosphorescent organic EL devices. PVK is very good because it has a very large excited triplet energy, but it has a very large ionization potential and a problem in terms of hole transportability (high driving voltage).

Naturally, even if these compounds are used, by devising the layer structure (adjustment of film thickness and injection balance of both charges), devising that triplet excitons are not deactivated by the hole transport layer. Although it is possible, it is very difficult, especially in the high current region (high luminance region).
Japanese Patent No. 3093796 Japanese Unexamined Patent Publication No. 63-264692 JP-A-3-255190 US Pat. No. 6,097,147 M.M. A. Baldo et al. , Nature, 395, 151-154 (1998) M.M. A. Baldo et al. , Nature, 403, 17, 750-753 (2000) S. Lamansky et al. , J .; Am. Chem. Soc. , 123, 4304 (2001) M.M. E. Thompson et al. , The 10th International Works on Organic and Organic Electroluminescence (EL'00, Hamamatsu) Moon-Jae Youn. Og, Tetsuo Tsutsui et al. , The 10th International Works on Organic and Organic Electroluminescence (EL'00, Hamamatsu) Ikai et al. , The 10th International Works on Organic and Organic Electroluminescence (EL'00, Hamamatsu)

  This invention is made | formed in view of the subject which concerns, and the objective of this invention is providing an organic EL element, an illuminating device, and a display apparatus with high luminous efficiency.

  The above object of the present invention has been achieved by the following constitutions 1 to 56.

(Claim 1)
In a light emitting device having at least a light emitting layer containing a phosphorescent compound and a hole transport layer containing a hole transport material adjacent to the light emitting layer,
The hole transport material has an 0-0 band of phosphorescence spectrum of 300 nm to 450 nm and a molecular weight of 550 or more, and is an organic electroluminescent device.

(Claim 2)
The organic electroluminescence device according to claim 1, wherein the hole transport material has an ionization potential Ip1 (eV) of 5.00 to 5.70 eV.

(Claim 3)
The organic electroluminescence device according to claim 1 or 2, wherein the ionization potential Ip1 (eV) of the hole transport material and the ionization potential Ip3 (eV) of the phosphorescent compound satisfy the following formula.

−0.1 eV ≦ Ip3−Ip1 ≦ 0.5 eV
(Claim 4)
The electron affinity Ea1 (eV) of the hole transport material and the excited triplet level T3 (eV) of the phosphorescent compound satisfy the following formulas: The organic electroluminescent element of description.

0.5eV <T3-Ea1 <1.3eV
(Claim 5)
The organic electroluminescent element according to any one of claims 1 to 4, wherein the phosphorescent compound has a phosphorescent maximum wavelength at 380 nm to 480 nm.

(Claim 6)
There is a hole transport layer adjacent to the hole transport layer and on the opposite side of the light emitting layer, and the ionization potential Ip4 (eV) of the hole transport material contained in the hole transport layer and the hole The organic electroluminescence device according to claim 1, wherein an ionization potential Ip1 (eV) of the transport material satisfies the following formula.

0.1 eV <Ip1-Ip4 <0.7 eV
(Claim 7)
The organic electroluminescence device according to claim 6, wherein the thickness of the hole transport layer adjacent to the light emitting layer is 5 nm to 20 nm.

(Claim 8)
The organic electroluminescence device according to claim 1, further comprising a host compound in the light emitting layer.

(Claim 9)
The organic electroluminescence device according to claim 8, wherein an ionization potential Ip1 (eV) of the hole transport material and an ionization potential Ip2 (eV) of the host compound satisfy the following formula.

0.3 eV <Ip2-Ip1 <1.0 eV
(Claim 10)
The organic electroluminescence device according to claim 8 or 9, wherein the electron affinity Ea1 (eV) of the hole transport material and the electron affinity Ea2 (eV) of the host compound satisfy the following formula.

0.1 eV <Ea2-Ea1 <0.8 eV
(Claim 11)
The organic electroluminescence device according to any one of claims 8 to 10, wherein a 0-0 band of a phosphorescence spectrum of the host compound is 300 nm to 450 nm.

(Claim 12)
The organic host device according to any one of claims 8 to 11, wherein the host compound is a carbazole derivative.

(Claim 13)
13. The organic electroluminescence device according to claim 12, wherein the carbazole derivative is a compound represented by the following general formula 11.

(In the formula, R _{1001 to} R ₁₀₁₃ each independently represents a hydrogen atom or a substituent, but at least one represents a substituent.)
(Claim 14)
13. The organic electroluminescence device according to claim 12, wherein the carbazole derivative is a compound represented by the following general formula 12.

(Wherein R ₁₀₂₁ represents an alkyl group, a cycloalkyl group, or a fluorinated alkyl group, and R _{1022 to} R ₁₀₂₉ each independently represents a hydrogen atom or a substituent, at least one of which represents a substituent. Represents.)
(Claim 15)
13. The organic electroluminescence device according to claim 12, wherein the carbazole derivative is a compound represented by the following general formula 13.

(Wherein R _{1031 to} R ₁₀₄₆ each independently represents a hydrogen atom or a substituent, and L ₃ represents a divalent linking group or a direct bond, but in the case of a direct bond, R ₁₀₃₇ and R ₁₀₃₈ Any one of R ₁₀₄₅ and R ₁₀₄₆ represents a substituent.)
(Claim 16)
The organic luminescence device according to claim 12, wherein the carbazole derivative is a compound represented by the following general formula 14.

(In the formula, R _{1051 to} R ₁₀₆₃ each independently represent a hydrogen atom or a substituent, and any of R ₁₀₅₇ , R ₁₀₅₈ , R ₁₀₆₂ , and R ₁₀₆₃ represents a substituent.)
(Claim 17)
The organic luminescence device according to claim 12, wherein the carbazole derivative is a compound represented by the following general formula 15.

(In the formula, each of R _{1071 to} R ₁₀₇₉ independently represents a hydrogen atom or a substituent, and one of R ₁₀₇₂ and R ₁₀₇₃ represents a substituent. N represents an integer of 1 to 8.) )
(Claim 18)
The organic electroluminescence device according to claim 1, wherein the hole transport material is a triarylamine compound.

(Claim 19)
The organic electroluminescence device according to claim 18, wherein the triarylamine compound is a compound represented by the following general formula 1.

(In the formula, Ar _{11 to} Ar ₁₃ each represent an arylene group or a heteroarylene group. R _{11 to} R ₁₃ each independently represents a hydrogen atom or a substituent, but at least one represents a substituent. .)
(Claim 20)
The organic electroluminescence device according to claim 18, wherein the triarylamine compound is a compound represented by the following general formula 2.

(In the formula, Ar ₃₀₁ represents an aryl group or heteroaryl group which may have a substituent, B represents the following general formula 3, and n represents an integer of 1 to 3.)

(Wherein Z ₁ and Z ₂ each independently represents an atomic group necessary to form an aromatic carbocycle or an aromatic heterocycle, and X _{1 to} X ₄ each independently represents C represents -R _301, N, O, S, a, R ₃₀₁ represents a hydrogen atom, or represents a substituent, at least one of X ₁ to X ₄ represents a C-R _301, R ₃₀₁ at that time Represents a substituent.)
(Claim 21)
The organic electroluminescence device according to claim 18, wherein the triarylamine compound is at least one of compounds represented by the following general formulas 4-1 and 4-2.

(In the formula, Ar _{801 to} Ar ₈₀₃ each represents an aryl group or a heteroaryl group which may have a substituent. R _{801 to} R ₈₂₇ each represents a hydrogen atom or a substituent, provided that R ₈₀₁ , R ₈₀₂ Any of R ₈₀₃ and R ₈₀₄ is a substituent, any of R ₈₀₅ and R ₈₀₆ is a substituent, any of R _{807 to} R ₈₁₀ is a substituent, and R _{811 to} R ₈₁₄ one of the substituents, any of R ₈₁₅ to R ₈₁₈ represents a substituent.)
(Claim 22)
The organic electroluminescence device according to claim 18, wherein the triarylamine compound is at least one of compounds represented by the following general formula 5.

(In the formula, R _{960 to} R ₉₇₆ each independently represents a hydrogen atom or a substituent. However, either R ₉₆₀ or R ₉₆₁ represents a substituent, and any of R ₉₆₃ and R ₉₆₄ represents a substituent. L ₁ represents a divalent linking group or a direct bond)
(Claim 23)
The organic electroluminescence device according to claim 18, wherein the triarylamine compound is at least one of compounds represented by the following general formula 6.

(In the formula, R _{960 to} R ₉₇₆ each independently represents a hydrogen atom or a substituent. L ₂ represents a divalent alkylene group, a cycloalkylene group, or a fluorinated alkylene group.)
(Claim 24)
The organic electroluminescence device according to claim 18, wherein the triarylamine compound is at least one of compounds represented by the following general formula 7.

(In the formula, B ₂ represents the following general formula 8, and Ar _{501 to} Ar ₅₀₃ each independently represents an aryl group or a heteroaryl group which may have a substituent. N represents an integer of 1 to 3. To express)

(In the formula, X _{5 to} X ₈ each independently represent N or C—R ₅₀₁ , and R ₅₀₁ represents a hydrogen atom or a substituent. At least one of X ₅ and X ₆ represents C— R ₅₀₁ , at least one of R ₅₀₁ represents a substituent, and at least one of X ₇ and X ₈ represents C—R ₅₀₁ , and at least one of R ₅₀₁ represents a substituent.
(Claim 25)
The organic electroluminescence device according to claim 18, wherein the triarylamine compound is at least one of compounds represented by the following general formula 9.

(In the formula, R _{833 to} R ₈₇₄ each independently represents a hydrogen atom or a substituent. However, one of R ₈₃₃ and R ₈₃₄ represents a substituent, and one of R ₈₃₅ and R ₈₃₆ . _Represents a substituent, one of R ₈₃₇ and R ₈₃₈ represents a substituent, one of R ₈₃₉ and R ₈₄₀ represents a substituent, and one of R ₈₄₁ and R ₈₄₂ represents a substituent. , R ₈₄₃ or R ₈₄₄ represents a substituent.)
(Claim 26)
The organic electroluminescence according to claim 18, wherein the triarylamine compound has at least one of terminal groups represented by the following general formulas 10-1, 10-2, 10-3, and 10-4. element.

(Wherein X ₉ and X ₁₀ each independently represent N, O, S, or C—R ₆₁₁ , and R ₆₁₁ represents a hydrogen atom or a substituent, but at least X ₉ and X ₁₀ One is C—R ₆₁₁ , where R ₆₁₁ is a substituent, and Z ₆₀₁ represents an atomic group necessary to form an aromatic carbocyclic ring or aromatic heterocyclic ring together with X ₉ and X _10. R _{601 to} R ₆₀₅ each independently represents a hydrogen atom or a substituent, and at least one of R ₆₀₁ and R ₆₀₅ is a substituent, and R _{606 to} R ₆₁₀ each independently represents a substituent. .)
(Claim 27)
In a light emitting device having at least a light emitting layer containing a phosphorescent compound and a hole transport layer containing a hole transport material adjacent to the light emitting layer,
The organic electroluminescence device, wherein the hole transport material is a triarylamine compound represented by the following general formula 1.

(In the formula, Ar _{11 to} Ar ₁₃ each represent an arylene group or a heteroarylene group. R _{11 to} R ₁₃ each independently represents a hydrogen atom or a substituent, but at least one represents a substituent. .)
(Claim 28)
In a light emitting device having at least a light emitting layer containing a phosphorescent compound and a hole transport layer containing a hole transport material adjacent to the light emitting layer,
The organic electroluminescence device, wherein the hole transport material is a triarylamine compound represented by the following general formula 2.

(In the formula, Ar ₃₀₁ represents an aryl group or heteroaryl group which may have a substituent, B represents the following general formula 3, and n represents an integer of 1 to 3.)

(Wherein Z ₁ and Z ₂ each independently represents an atomic group necessary to form an aromatic carbocycle or an aromatic heterocycle, and X _{1 to} X ₄ each independently represents C represents -R _301, N, O, S, a, R ₃₀₁ represents a hydrogen atom, or represents a substituent, at least one of X ₁ to X ₄ represents a C-R _301, R ₃₀₁ at that time Represents a substituent.)
(Claim 29)
In a light emitting device having at least a light emitting layer containing a phosphorescent compound and a hole transport layer containing a hole transport material adjacent to the light emitting layer,
The organic electroluminescence device, wherein the hole transport material is at least one of triarylamine compounds represented by the following general formulas 4-1 and 4-2.

(In the formula, Ar _{801 to} Ar ₈₀₃ each represents an aryl group or a heteroaryl group which may have a substituent. R _{801 to} R ₈₂₇ each represents a hydrogen atom or a substituent, provided that R ₈₀₁ , R ₈₀₂ Any of R ₈₀₃ and R ₈₀₄ is a substituent, any of R ₈₀₅ and R ₈₀₆ is a substituent, any of R _{807 to} R ₈₁₀ is a substituent, and R _{811 to} R ₈₁₄ one of the substituents, any of R ₈₁₅ to R ₈₁₈ represents a substituent.)
(Claim 30)
In a light emitting device having at least a light emitting layer containing a phosphorescent compound and a hole transport layer containing a hole transport material adjacent to the light emitting layer,
The hole transport material is a triarylamine compound represented by the following general formula 5;

(In the formula, R _{960 to} R ₉₇₆ each independently represents a hydrogen atom or a substituent. However, either R ₉₆₀ or R ₉₆₁ represents a substituent, and any of R ₉₆₃ and R ₉₆₄ represents a substituent. L ₁ represents a divalent linking group or a direct bond)
(Claim 31)
In a light emitting device having at least a light emitting layer containing a phosphorescent compound and a hole transport layer containing a hole transport material adjacent to the light emitting layer,
The hole transport material is a triarylamine compound represented by the following general formula 6;

(In the formula, R _{960 to} R ₉₇₆ each independently represents a hydrogen atom or a substituent. L ₂ represents a divalent alkylene group, a cycloalkylene group, or a fluorinated alkylene group.)
(Claim 32)
In a light emitting device having at least a light emitting layer containing a phosphorescent compound and a hole transport layer containing a hole transport material adjacent to the light emitting layer,
The organic electroluminescent device, wherein the hole transport material is a triarylamine compound represented by the following general formula 7.

(In the formula, B ₂ represents the following general formula 8, and Ar _{501 to} Ar ₅₀₃ each independently represents an aryl group or a heteroaryl group which may have a substituent. N represents an integer of 1 to 3. To express)

(In the formula, X _{5 to} X ₈ each independently represent N or C—R ₅₀₁ , and R ₅₀₁ represents a hydrogen atom or a substituent. At least one of X ₅ and X ₆ represents C— R ₅₀₁ , at least one of R ₅₀₁ represents a substituent, and at least one of X ₇ and X ₈ represents C—R ₅₀₁ , and at least one of R ₅₀₁ represents a substituent.
(Claim 33)
In a light emitting device having at least a light emitting layer containing a phosphorescent compound and a hole transport layer containing a hole transport material adjacent to the light emitting layer,
The organic electroluminescence device, wherein the hole transport material is a triarylamine compound represented by the following general formula 9.

(In the formula, R _{833 to} R ₈₇₄ each independently represents a hydrogen atom or a substituent. However, one of R ₈₃₃ and R ₈₃₄ represents a substituent, and one of R ₈₃₅ and R ₈₃₆ . _Represents a substituent, one of R ₈₃₇ and R ₈₃₈ represents a substituent, one of R ₈₃₉ and R ₈₄₀ represents a substituent, and one of R ₈₄₁ and R ₈₄₂ represents a substituent. , R ₈₄₃ or R ₈₄₄ represents a substituent.)
(Claim 34)
In a light emitting device having at least a light emitting layer containing a phosphorescent compound and a hole transport layer containing a hole transport material adjacent to the light emitting layer,
The hole transport material is a triarylamine compound having at least one of terminal groups represented by the following general formulas 10-1, 10-2, 10-3, and 10-4. Organic electroluminescence element.

(Wherein X ₉ and X ₁₀ each independently represent N, O, S, or C—R ₆₁₁ , and R ₆₁₁ represents a hydrogen atom or a substituent, but at least X ₉ and X ₁₀ One is C—R ₆₁₁ , where R ₆₁₁ is a substituent, and Z ₆₀₁ represents an atomic group necessary to form an aromatic carbocyclic ring or aromatic heterocyclic ring together with X ₉ and X _10. R _{601 to} R ₆₀₅ each independently represents a hydrogen atom or a substituent, and at least one of R ₆₀₁ and R ₆₀₅ is a substituent, and R _{606 to} R ₆₁₀ each independently represents a substituent. .)
(Claim 35)
35. The organic electroluminescence element according to claim 27, wherein the hole transport material has a molecular weight of 550 or more.

(Claim 36)
36. The organic electroluminescence device according to any one of claims 27 to 35, wherein an ionization potential Ip1 (eV) of the hole transport material is 5.00 to 5.70 eV.

(Claim 37)
37. The organic electro of claim 27, wherein an ionization potential Ip1 (eV) of the hole transport material and an ionization potential Ip3 (eV) of the phosphorescent compound satisfy the following formula. Luminescence element.

−0.1 eV ≦ Ip3−Ip1 ≦ 0.5 eV
(Claim 38)
38. The electron affinity Ea1 (eV) of the hole transport material and the excited triplet level T3 (eV) of the phosphorescent compound satisfy the following formula: The organic electroluminescent element of description.

0.5eV <T3-Ea1 <1.3eV
(Claim 39)
The organic electroluminescent element according to any one of claims 27 to 38, wherein the phosphorescent compound has a phosphorescent maximum wavelength at 380 to 480 nm.

(Claim 40)
There is a hole transport layer adjacent to the hole transport layer and on the opposite side of the light emitting layer, and the ionization potential Ip4 (eV) of the hole transport material contained in the hole transport layer and the hole The organic electroluminescence device according to any one of claims 27 to 39, wherein an ionization potential Ip1 (eV) of the transport material satisfies the following formula.

0.1 eV <Ip1-Ip4 <0.7 eV
(Claim 41)
41. The organic electroluminescent device according to claim 40, wherein the hole transport layer adjacent to the light emitting layer has a thickness of 5 nm to 20 nm.

(Claim 42)
The organic electroluminescence device according to any one of claims 27 to 41, wherein the light emitting layer further contains a host compound.

(Claim 43)
43. The organic electroluminescence according to claim 27, wherein an ionization potential Ip1 (eV) of the hole transport material and an ionization potential Ip2 (eV) of the host compound satisfy the following formula. element.

0.3 eV <Ip2-Ip1 <1.0 eV
(Claim 44)
44. The organic electroluminescence according to claim 27, wherein an electron affinity Ea1 (eV) of the hole transport material and an electron affinity Ea2 (eV) of the host compound satisfy the following formula. element.

0.1 eV <Ea2-Ea1 <0.8 eV
(Claim 45)
45. The organic electroluminescence device according to claim 27, wherein the 0-0 band of the phosphorescence spectrum of the host compound is 300 nm to 450 nm.

(Claim 46)
46. The organic electroluminescence device according to claim 27, wherein the host compound is a carbazole derivative.

(Claim 47)
47. The organic electroluminescence device according to claim 46, wherein the carbazole derivative is a compound represented by the following general formula 11.

(In the formula, R _{1001 to} R ₁₀₁₃ each independently represents a hydrogen atom or a substituent, but at least one represents a substituent.)
(Claim 48)
47. The organic electroluminescence device according to claim 46, wherein the carbazole derivative is a compound represented by the following general formula 12.

(Wherein R ₁₀₂₁ represents an alkyl group, a cycloalkyl group, or a fluorinated alkyl group, and R _{1022 to} R ₁₀₂₉ each independently represents a hydrogen atom or a substituent, at least one of which represents a substituent. Represents.)
(Claim 49)
47. The organic electroluminescence device according to claim 46, wherein the carbazole derivative is a compound represented by the following general formula 13.

(Wherein R _{1031 to} R ₁₀₄₆ each independently represents a hydrogen atom or a substituent, and L ₃ represents a divalent linking group or a direct bond, but in the case of a direct bond, R ₁₀₃₇ and R ₁₀₃₈ Any one of R ₁₀₄₅ and R ₁₀₄₆ represents a substituent.)
(Claim 50)
The organic luminescence device according to claim 46, wherein the carbazole derivative is a compound represented by the following general formula 14.

(In the formula, R _{1051 to} R ₁₀₆₃ each independently represent a hydrogen atom or a substituent, and any of R ₁₀₅₇ , R ₁₀₅₈ , R ₁₀₆₂ , and R ₁₀₆₃ represents a substituent.)
(Claim 51)
47. The organic electroluminescence device according to claim 46, wherein the carbazole derivative is a compound represented by the following general formula 15.

(In the formula, each of R _{1071 to} R ₁₀₇₉ independently represents a hydrogen atom or a substituent, and one of R ₁₀₇₂ and R ₁₀₇₃ represents a substituent. N represents an integer of 1 to 8.) )
(Claim 52)
The organic electroluminescence device according to any one of claims 1 to 51, wherein the hole transport layer is formed by vapor deposition.

(Claim 53)
The organic electroluminescence device according to any one of claims 1 to 51, wherein the hole transport layer is formed by a wet process.

(Claim 54)
54. A display device comprising the organic electroluminescence element element according to any one of claims 1 to 53.

(Claim 55)
An illuminating device comprising the organic electroluminescence element according to any one of claims 1 to 53.

(Claim 56)
56. A display device comprising: the lighting device according to claim 55; and a liquid crystal element as display means.

  According to the present invention, an organic EL element, a lighting device, and a display device with high luminous efficiency can be provided.

  In the organic electroluminescence device of the present invention, an organic EL device having high luminous efficiency can be obtained by adopting the configuration defined in any one of claims 1 to 13. In addition, using the organic EL element, it was possible to obtain a display device according to claim 54 or 56, a lighting device according to claim 55, or the like having high luminance.

  Hereinafter, details of each component according to the present invention will be sequentially described.

  As a result of intensive studies, the present inventors have found that in a light emitting element having at least a light emitting layer containing a phosphorescent compound and a hole transport layer containing a hole transport material adjacent to the light emitting layer, It has been found that when the 0-0 band of the phosphorescence spectrum of the transport material is 300 nm to 450 nm and the molecular weight is 550 or more, the thermal stability can be improved and the luminous efficiency can be increased. That is, the inventors of the present invention have not only re-combined electron-holes (holes) on the cathode side in the light emitting layer, but also actually transport holes in the light emitting layer. The light-emitting layer is found by using a hole transport material having a 0-0 band of phosphorescence spectrum of 300 nm to 450 nm and a molecular weight of 550 or more in the hole transport layer. It has been found that electron-hole (hole) recombination on the hole transport layer side can be efficiently performed, luminous efficiency can be increased, and thermal stability can be improved.

  Thus, the excitation triplet energy is increased by using a hole transporting material having a 0-0 band of phosphorescence spectrum of 300 nm to 450 nm and a molecular weight of 550 or more in the hole transporting layer adjacent to the light emitting layer. Thus, the triplet excitons can be confined, so that the luminous efficiency can be increased and the thermal stability can be further improved. In particular, a remarkable effect can be obtained in phosphorescence light emission in a high current region, blue phosphorescence light emitting element, and the like.

  The 0-0 band of the phosphorescence spectrum can be obtained by the following measurement method.

  The compound to be measured is dissolved in a well-deoxygenated mixed solvent of ethanol / methanol = 4/1 (vol / vol), put into a phosphorescence measurement cell, and then irradiated with excitation light at a liquid nitrogen temperature of 77K. The emission spectrum at 100 ms after irradiation is measured. Since phosphorescence has a longer emission lifetime than fluorescence, it can be considered that light remaining after 100 ms is almost phosphorescence. For compounds with a phosphorescence lifetime shorter than 100 ms, measurement may be performed with a shorter delay time, but phosphorescence and fluorescence cannot be separated if the delay time is shortened so that it cannot be distinguished from fluorescence. Since this is a problem, it is necessary to select a delay time that can be separated.

  In addition, for a compound that cannot be dissolved in the solvent system, any solvent that can dissolve the compound may be used (substantially, the solvent effect of the phosphorescence wavelength is negligible in the above measurement method).

  Next, the 0-0 band is determined. In the present invention, the emission maximum wavelength that appears on the shortest wavelength side in the phosphorescence spectrum chart obtained by the above-described measurement method is defined as the 0-0 band.

  Since the phosphorescence spectrum usually has a low intensity, when it is enlarged, it may be difficult to distinguish between noise and peak. In such a case, the stationary light spectrum is enlarged, and the peak wavelength is read from the portion of the stationary light spectrum derived from the phosphorescence spectrum by superimposing it with the emission spectrum 100 ms after irradiation with the excitation light (for convenience, this is called the phosphorescence spectrum). Can be determined. Further, by performing a smoothing process on the phosphorescence spectrum, it is possible to separate the noise and the peak and read the peak wavelength. As the smoothing process, a smoothing method of Savitzky & Golay can be applied.

In the present invention, the 0-0 band of this phosphorescence spectrum is 300 nm to 450 nm, more preferably 350 nm to 430 nm. Thereby, the luminous efficiency can be further increased. As such a hole transport material, a triarylamine compound is preferable.

  In the triaryl compound, the following triarylamine compounds are preferable, and thereby the luminous efficiency can be further improved.

  First, the triaryl compound represented by the general formula 1 is mentioned.

In the general formula 1, as the substituent represented by R _{11 to} R ₁₃ , an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, octyl group, Dodecyl group, tridecyl group, tetradecyl group, pentadecyl group etc.), cycloalkyl group (eg cyclopentyl group, cyclohexyl group etc.), alkenyl group (eg vinyl group, allyl group etc.), alkynyl group (eg ethynyl group, propargyl etc.) Group), aryl group (for example, phenyl group, biphenylyl group, etc.), heteroaryl group (for example, furyl group, thienyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, triazinyl group, imidazolyl group, pyrazolyl group, Thiazolyl group, carbazolyl group, etc.), heterocyclic group (for example, Loridyl group, imidazolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxy group (for example, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxy group (Eg, cyclopentyloxy group, cyclohexyloxy group, etc.), aryloxy group (eg, phenoxy group, naphthyloxy group, etc.), alkylthio group (eg, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group) , Dodecylthio group etc.), cycloalkylthio group (eg cyclopentylthio group, cyclohexylthio group etc.), arylthio group (eg phenylthio group, naphthylthio group etc.), alkoxycarbonyl group (eg methyloxy Rubonyl, ethyloxycarbonyl, butyloxycarbonyl, octyloxycarbonyl, dodecyloxycarbonyl, etc.), aryloxycarbonyl (eg, phenyloxycarbonyl, naphthyloxycarbonyl, etc.), sulfamoyl (eg, amino) Sulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2- Pyridylaminosulfonyl group, etc.), acyl groups (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexyl) Rubonyl group, octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (for example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, Octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino) Group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonyl Carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group) , Dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecyl group) Ureido group, phenylureido group, naphthylureido group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group, ethylsulfini group) Group, butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, Butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group (phenylsulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (for example, amino group, ethylamino) Group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pyridylamino group ), Halogen atoms (for example, fluorine atom, chlorine atom, bromine atom, etc.), fluorinated hydrocarbon groups (for example, fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl group, etc.), cyano group, Examples thereof include a nitro group, a hydroxy group, a mercapto group, and a silyl group (for example, a trimethylsilyl group, a triisopropylsilyl group, a triphenylsilyl group, and a phenyldiethylsilyl group).

  These substituents may be further substituted with the above substituents. In addition, as for these substituents, a plurality of substituents which may be bonded to each other to form a ring can be mentioned, but the only thing that is important is that the 0-0 band of the phosphorescence spectrum is 450 nm or less. Some groups with low excited triplet energy are preferred.

  For example, a phenyl group has a 0-0 band of phosphorescence spectrum of 400 nm or less and is preferably used as a substituent.

Among the substituents represented by R _{11 to} R ₁₃ , alkyl groups, cycloalkyl groups, fluorinated hydrocarbon groups, aryl groups, and heteroaryl groups are preferably used.

When R _{11 to} R ₁₃ represent an aryl group or a heteroaryl group, the aryl group is preferably, for example, a phenyl group, and the heteroaryl group is a furyl group, a thienyl group, a pyridyl group, a pyridazinyl group, a pyrimidinyl group, Pyrazinyl group, triazinyl group, imidazolyl group, pyrazolyl group, thiazolyl group, carbazolyl group and the like are preferable.

  Similarly, a group having a large excited triplet energy such that only the aryl group and the heteroaryl group have a 0-0 band of phosphorescence spectrum of 450 nm or less is preferable.

In the general formula 1, as the arylene group represented by Ar _{11 to} Ar ₁₃ , for example, a phenylene group (for example, o-phenylene group, m-phenylene group, p-phenylene group, etc.), a biphenyldiyl group (for example, [1,1′-biphenyl] -4,4′-diyl group, 3,3′-biphenyldiyl group, 3,6-biphenyldiyl group, etc.). The arylene group may have a substituent represented by each of R _{11 to} R ₁₃ .

In the general formula 1, as the heteroarylene group represented by each of Ar _{11 to} Ar ₁₃ , for example, a furan ring, a carbazole ring, a triazole ring, a pyrrole ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a triazine ring, an imidazole ring, Bivalent groups derived from the group consisting of a pyrazole ring, a thiazole ring, a thiophene ring, an oxadiazole ring, a dibenzofuran ring, a dibenzothiophene ring, an indole ring, and the like can be mentioned. You may have a substituent represented by R < ₁₁ > -R < ₁₃ >.

In the general formula 1, as for the arylene group and heteroarylene group represented by Ar _{11 to} Ar ₁₃ , similarly to the substituent represented by R _{11 to} R ₁₃ , the arylene group and the heteroarylene group alone, The 0-0 band of the spectrum of the phosphorescence spectrum is preferably 450 nm or less.

Further, the aryl group of R ₁₁ to R _13, the dihedral angle of the Ar ₁₁ to Ar ₁₃ which connects with the heteroaryl group is preferably at least 50 degrees. This can be sterically controlled by introducing a substituent into Ar _{11 to} Ar ₁₃ or R _{11 to} R ₁₃ . When a substituent is not introduced and steric control is not performed, the dihedral angle is generally 50 degrees or less. In such a state, when the conjugate length is extended, the 0-0 band of the phosphorescence spectrum tends to have a longer wavelength and the excited triplet energy tends to decrease.

  The dihedral angle refers to the angle between the aromatic ring plane directly connected and the aromatic ring plane on the side directly connected by optimizing the structure in the ground state by molecular orbital calculation (for example, MOPAC, Gaussian) of this compound.

  Next, the compound represented by the said General formula 2 is mentioned.

In the general formula 2, Ar ₃₀₁ represents an aryl group or a heteroaryl group which may have a substituent, B represents the general formula 3, and n represents an integer of 1 to 3.

In the general formula 3, Z ₁ and Z ₂ each independently represent an atomic group necessary for forming an aromatic carbocycle or an aromatic heterocycle, and X _{1 to} X ₄ are each independently , C-R ₃₀₁ , N, O, S, and R ₃₀₁ represents a hydrogen atom or a substituent, and at least one of X _{1 to} X ₄ represents C-R ₃₀₁ , R ₃₀₁ represents a substituent. At least one of X _{1 to} X ₄ represents C—R ₃₀₁ , and R ₃₀₁ is a substituent, so that steric repulsion occurs and a dihedral angle of 50 degrees or more is achieved.

  Next, the compound represented by the said general formula 4-1 and 4-2 is mentioned.

In the general formulas 4-1 and 4-2, R _{801 to} R ₈₂₇ each represents a hydrogen atom or a substituent. However, any of R ₈₀₁ and R ₈₀₂ represents a substituent, any of R ₈₀₃ and R ₈₀₄ represents a substituent, any of R ₈₀₅ and R ₈₀₆ represents a substituent, and any of R _{807 to} R ₈₁₀ represents a substituent. Any one of the groups, R _{811 to} R ₈₁₄ represents a substituent, and any of R _{815 to} R ₈₁₈ represents a substituent. By having a substituent in this way, a dihedral angle of 50 degrees or more can be achieved. In particular, the central skeleton is preferably triphenylamine, and more preferably a phenyl group which may have a substituent as an aryl group to be linked. Here, it is preferable that each phenyl group has a substituent at the m-position and the P-position. By having a substituent in this part, a larger excited triplet energy can be obtained, and the stability of the compound is also improved.

  Next, the compound represented by the said General formula 5 is mentioned.

In General Formula 5, R _{960 to} R ₉₇₆ each independently represent a hydrogen atom or a substituent. However, one of R ₉₆₀ and R ₉₆₁ represents a substituent, and one of R ₉₆₃ and R ₉₆₄ represents a substituent. L ₁ represents a divalent linking group or a direct bond, and is preferably an alkylene group, a cycloalkylene group, a fluorinated alkylene group, an arylene group, or a heteroarylene group.

Examples of the alkylene group represented by L ₁ include ethylene, trimethylene, tetramethylene, propylene, ethylethylene, pentamethylene, hexamethylene, 2,2,4-trimethylhexamethylene, hepta. Examples include a methylene group, octamethylene group, nonamethylene group, decamethylene group, undecamethylene group, dodecamethylene group and the like.

Examples of the cycloalkylene group represented by L ₁ include a cyclohexylene group (eg, 1,6-cyclohexanediyl group), a cyclopentylene group (eg, 1,5-cyclopentanediyl group), and the like. It is done.

Examples of the arylene group represented by L ₁ include an o-phenylene group, m-phenylene group, p-phenylene group, and biphenyldiyl group (for example, 3,3′-biphenyldiyl group, 3,6-biphenyldiyl group, etc.) Etc. The arylene group may further have a substituent represented by each of R _{1 to} R ₄ .

Examples of the heteroarylene group represented by L ₁ include a furan ring, a carbazole ring, a triazole ring, a pyrrole ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a triazine ring, an imidazole ring, a pyrazole ring, a thiazole ring, a quinoxaline ring, And divalent groups derived from the group consisting of a thiophene ring, an oxadiazole ring, a dibenzofuran ring, a dibenzothiophene ring, and an indole ring.

Each group represented by the above L ₁ may have a substituent represented by the above R _{11 to} R ₁₃ .

Also here, similarly, no substituent is required at the o-position of triphenylamine, and when L _{1 to} be further linked is arylene or heteroarylene, conjugation is connected, so that R _{960 to} R ₉₆₄ are sterically controlled. In order to achieve this, it is preferable to have a substituent.

  Next, the compound represented by the said General formula 6 is mentioned.

In the general formula 6, R _{960 to} R ₉₇₆ each independently represent a hydrogen atom or a substituent. L ₂ represents a linking group such as a divalent alkylene group, a cycloalkylene group, or a fluorinated alkylene group. By using a non-conjugated linking group as a linking group, a substituent for steric control is do not need. In the present invention, the same effect can be obtained by using a non-conjugated linking group. However, it is not necessary to introduce a substituent at the 2,6-position of triphenylamine for the same reason as described above.

  Next, the compound represented by the said General formula 7 is mentioned.

In the general formula 7, B ₂ represents the general formula 8, and Ar _{501 to} Ar ₅₀₃ each independently represents an aryl group or a heteroaryl group which may have a substituent. n represents an integer of 1 to 3.

In the general formula 8, X _{5 to} X ₈ each independently represent N or C—R ₅₀₁ , and R ₅₀₁ represents a hydrogen atom or a substituent. At least one of X _5, X ₆ is C-R _501, at least one of R ₅₀₁ represents a substituent. At least one of X ₇ and X ₈ is C—R ₅₀₁ , and at least one of R ₅₀₁ represents a substituent. Such a triarylamine compound improves the stability and improves the durability of the device.

  Next, the compound represented by the said General formula 9 is mentioned.

In the general formula 9, R _{833 to} R ₈₇₄ each independently represent a hydrogen atom or a substituent. However, one of R ₈₃₃ and R ₈₃₄ represents a substituent, one of R ₈₃₅ and R ₈₃₆ represents a substituent, and one of R ₈₃₇ and R ₈₃₈ represents a substituent, R ₈₃₉ , One of R ₈₄₀ represents a substituent, one of R ₈₄₁ and R ₈₄₂ represents a substituent, and one of R ₈₄₃ and R ₈₄₄ represents a substituent.

  In the phenylenediamine skeleton, by introducing a sterically hindered substituent into the phenylene moiety of phenylenediamine, the 0-0 band of the phosphorescence spectrum can be shortened (excitation triplet energy can be increased). Although it has been explained that it is preferable to introduce a substituent other than the 2,6 position in triphenylamine, instability of the compound is also reduced in the phenylenediamine skeleton.

  Examples of the triarylamine compound include triarylamine compounds having a terminal group represented by the general formulas 10-1, 10-2, 10-3, and 10-4.

In the general formulas 10-1, 10-2, 10-3, and 10-4, X ₉ and X ₁₀ each independently represent N, O, S, or C—R ₆₁₁ , and R ₆₁₁ represents hydrogen. Although it represents an atom or a substituent, at least one of X ₉ and X ₁₀ is C—R ₆₁₁ , and at this time, R ₆₁₁ is a substituent. Z ₆₀₁ represents an atomic group necessary for forming an aromatic carbocyclic ring or an aromatic heterocyclic ring together with X ₉ and X ₁₀ . R _{601 to} R ₆₀₅ each independently represent a hydrogen atom or a substituent, and at least one of R ₆₀₁ and R ₆₀₅ is a substituent. R ₆₀₆ to R ₆₁₀ each independently represents a substituent.

  The ortho and para orientations of the end groups of the compound are sites that are prone to degradation, particularly in triphenylamine derivatives and phenylenediamine derivatives. By introducing a substituent at this position, it is possible to effectively improve the stability of the compound. In particular, the present invention is characterized by a hole transport compound having a large excited triplet energy, and such a compound naturally has a wide band gap, and it cannot be said that the stability of the compound is good. Therefore, introduction of such a group is very effective in terms of durability of the element. Although it seems to be possible to use unsubstituted triphenylamine, since it crystallizes in practice, good results cannot be obtained.

  Next, the compounds represented by the following general formulas 16-1 and 16-2 are listed.

In General Formulas 16-1 and 16-2, R _{875 to} R ₉₅₃ each represents a hydrogen atom or a substituent. However, at least one of R _{875 to} R ₈₇₈ represents a substituent, at least one of R _{879 to} R ₈₈₂ represents a substituent, and at least one of R _{883 to} R ₈₈₆ represents a substituent. R _{910 to} R ₉₅₃ represent a hydrogen atom or a substituent. Provided that at least one of R _{910 to} R ₉₁₃ represents a substituent, at least one of R _{914 to} R ₉₁₇ represents a substituent, and at least one of R _{918 to} R ₉₂₁ represents a substituent; At least one of R _{922 to} R ₉₂₅ represents a substituent, and at least one of R _{926 to} R ₉₂₉ represents a substituent.

  Although the compound example of a triarylamine compound is shown below, it is not limited to these.

In the triarylamine compound, the 0-0 band of the phosphorescence spectrum is preferably 300 nm to 450 nm, more preferably 350 to 430 nm. Thereby, luminous efficiency can be further improved. The molecular weight of the triarylamine compound is preferably 550 to 2,000. When the molecular weight is 550 to 2000, Tg (glass transition temperature) is increased, thermal stability is improved, and device life is improved. A more preferred molecular weight is 800-2000.

  In the present invention, as described above, the hole transport material is preferably a triarylamine compound, but in addition to this, a phosphorescent spectrum can also be obtained by introducing a sterically hindered group in a compound having a phenylenediamine skeleton. The 0-0 band can satisfy 300 nm to 450 nm. The hole transport material is not limited thereto as long as the 0-0 band of the phosphorescence spectrum satisfies 300 nm to 450 nm.

<< Constituent layers of organic EL elements >>
The constituent layers of the organic EL element of the present invention will be described.

In this invention, although the preferable specific example of the layer structure of an organic EL element is shown below, this invention is not limited to these.
(I) Anode / light emitting layer / electron transport layer / cathode (ii) Anode / hole transport layer / light emitting layer / electron transport layer / cathode (iii) Anode / hole transport layer / light emitting layer / hole blocking layer / electron Transport layer / cathode (iv) anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode (v) anode / anode buffer layer / hole transport layer / light emitting layer / hole Blocking layer / electron transport layer / cathode buffer layer / cathode << Anode >>
As the anode in the organic EL element, an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function (4 eV or more) is preferably used. Specific examples of such electrode materials include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO ₂ and ZnO. Alternatively, an amorphous material such as IDIXO (In ₂ O ₃ —ZnO) capable of forming a transparent conductive film may be used. For the anode, a thin film may be formed by depositing these electrode materials by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by a photolithography method. Degree), a pattern may be formed through a mask having a desired shape when the electrode material is deposited or sputtered. When light emission is extracted from the anode, it is desirable that the transmittance is greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although the film thickness depends on the material, it is usually selected in the range of 10 to 1000 nm, preferably 10 to 200 nm.

"cathode"
On the other hand, as the cathode, a material having a low work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function value than this, such as a magnesium / silver mixture, magnesium, from the viewpoint of electron injectability and durability against oxidation, etc. / Aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm. In order to transmit the emitted light, if either one of the anode or the cathode of the organic EL element is transparent or translucent, the emission luminance is advantageously improved.

  Moreover, after producing the said metal with a film thickness of 1-20 nm on a cathode, a transparent or semi-transparent cathode can be produced by producing the electroconductive transparent material quoted by description of the anode on it, By applying this, an element in which both the anode and the cathode are transmissive can be manufactured.

  Next, an injection layer, a blocking layer, an electron transport layer, and the like used as a constituent layer of the organic EL element of the present invention will be described.

<< Injection layer >>: Electron injection layer, hole injection layer The injection layer is provided as necessary, and there are an electron injection layer and a hole injection layer, and as described above, between the anode and the light emitting layer or the hole transport layer, and You may exist between a cathode, a light emitting layer, or an electron carrying layer.

  An injection layer is a layer provided between an electrode and an organic layer in order to reduce drive voltage and improve light emission luminance. “Organic EL element and its forefront of industrialization (issued by NTT Corporation on November 30, 1998) 2), Chapter 2, “Electrode Materials” (pages 123 to 166) in detail, and includes a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer).

  The details of the anode buffer layer (hole injection layer) are described in JP-A Nos. 9-45479, 9-260062, and 8-288069, and a specific example is represented by copper phthalocyanine. Examples thereof include a phthalocyanine buffer layer, an oxide buffer layer typified by vanadium oxide, an amorphous carbon buffer layer, and a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene.

  The details of the cathode buffer layer (electron injection layer) are described in JP-A-6-325871, 9-17574, 10-74586, and the like, and specifically, strontium, aluminum, and the like are representative. A metal buffer layer, an alkali metal compound buffer layer typified by lithium fluoride, an alkaline earth metal compound buffer layer typified by magnesium fluoride, and an oxide buffer layer typified by aluminum oxide. The buffer layer (injection layer) is desirably a very thin film, and although it depends on the material, the film thickness is preferably in the range of 0.1 nm to 5 μm.

<< Blocking Layer >>: Hole Blocking Layer, Electron Blocking Layer As described above, the blocking layer is provided as necessary in addition to the basic constituent layer of the organic compound thin film. For example, JP-A Nos. 11-204258 and 11-204359, and “Organic EL devices and their forefront of industrialization” (published by NTS Corporation on November 30, 1998), etc. There is a hole blocking layer.

  The hole blocking layer is an electron transport layer in a broad sense, and is made of a material that has a function of transporting electrons and has a very small ability to transport holes. By blocking holes while transporting electrons, And the recombination probability of holes can be improved.

  On the other hand, the electron blocking layer is a hole transport layer in a broad sense, made of a material that has a function of transporting holes and has a very small ability to transport electrons, and blocks electrons while transporting holes. Thus, the probability of recombination of electrons and holes can be improved.

<Light emitting layer>
The light emitting layer according to the present invention is a layer that emits light by recombination of electrons and holes injected from the electrode, the electron transport layer, or the hole transport layer, and the light emitting portion is in the layer of the light emitting layer. May be the interface between the light emitting layer and the adjacent layer.

  A material used for the light emitting layer (hereinafter referred to as a light emitting material) is a phosphorescent compound. In the present invention, a phosphorescent compound is a compound in which light emission from an excited triplet is observed, and is at room temperature (25 ° C. ) And a phosphorescent quantum yield of 0.01 or more at 25 ° C. The phosphorescence quantum yield is preferably 0.1 or more.

  The phosphorescence quantum yield can be measured by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of Experimental Chemistry Course 4 of the 4th edition. Although the phosphorescence quantum yield in a solution can be measured using various solvents, the phosphorescence quantum yield used in the present invention only needs to achieve the above phosphorescence quantum yield in any solvent.

  There are two types of light emission of phosphorescent compounds in principle. One is the recombination of carriers on the host compound to which carriers are transported to generate an excited state of the host compound, and this energy is phosphorescent. Energy transfer type to obtain light emission from the phosphorescent compound by transferring to the compound, the other is that the phosphorescent compound becomes a carrier trap, carrier recombination occurs on the phosphorescent compound, and from the phosphorescent compound In any case, the excited state energy of the phosphorescent compound is lower than the excited state energy of the host compound.

  The phosphorescent compound can be appropriately selected from known compounds used for the light emitting layer of the organic EL device.

  The phosphorescent compound used in the present invention is preferably a complex compound containing a group 8 metal in the periodic table of elements, more preferably an iridium compound, an osmium compound, or a platinum compound (platinum complex system). Compound) and rare earth complexes, and most preferred is an iridium compound.

  Specific examples of the phosphorescent compound used in the present invention are shown below, but are not limited thereto. These compounds are described, for example, in Inorg. Chem. 40, 1704-1711, and the like.

  In the present invention, the phosphorescent maximum wavelength of the phosphorescent compound is not particularly limited. In principle, the phosphorescent compound can be obtained by selecting a central metal, a ligand, a ligand substituent, and the like. However, it is preferable that the phosphorescent compound has a phosphorescent maximum wavelength of 380 to 480 nm. With such a blue phosphorescent organic EL element and a white phosphorescent organic EL element, the luminous efficiency can be further increased.

  The light emitting layer may contain a host compound in addition to the phosphorescent compound.

  In the present invention, the host compound is a compound having a phosphorescence quantum yield of phosphorescence emission of less than 0.01 at room temperature (25 ° C.) among compounds contained in the light emitting layer.

  The host compound is preferably an organic compound or a complex, and in the present invention, the excited triplet energy of the host compound is preferably larger than the excited triplet energy of the phosphorescent compound.

  In the present invention, it is preferable that the 0-0 band of the phosphorescence spectrum of the host compound is 300 nm to 450 nm. This further enhances the light emission efficiency, and particularly enables BGR light emission.

  That is, by making the excited triplet energy of the host compound larger than the excited triplet energy of the phosphorescent compound, energy transfer type phosphorescence emission from the host compound to the phosphorescent compound is possible. A compound having a 0-0 band wavelength of 450 nm or less in the phosphorescence spectrum of the host compound has a very wide band gap (ionization potential-electron affinity, HOMO-LUMO), and thus works advantageously for a carrier trap type.

  As such a host compound, an arbitrary one can be selected and used from known materials used in organic EL elements, and most of the hole transport materials and electron transport materials described below are the host of the light emitting layer. It can also be used as a compound.

  A polymer material such as polyvinyl carbazole or polyfluorene may be used, and a polymer material in which the host compound is introduced into a polymer chain or the host compound as a polymer main chain may be used.

  Further, a plurality of host compounds and phosphorescent compounds may be used. By using a plurality of types of host compounds, it is possible to adjust the movement of charges, and the organic EL element can be made highly efficient. In addition, by using a plurality of phosphorescent compounds, it is possible to mix different light emission, thereby obtaining an arbitrary emission color. White light emission is possible by adjusting the kind of phosphorescent compound and the amount of doping, and can also be applied to illumination and backlight.

  As the host compound, a compound that has a hole transporting ability and an electron transporting ability, prevents the emission of light from being increased in wavelength, and has a high Tg (glass transition temperature) is preferable.

  As the host compound, a carbazole derivative is preferable, and a compound having the performance of a carbazole ring alone, more preferably N-phenylcarbazole alone or N-alkylcarbazole alone is effective. A carbazole ring alone, N-phenylcarbazole alone, or N-alkylcarbazole alone has a low glass transition point, which is undesired from the viewpoint of device lifetime, and therefore has a high molecular weight to ensure thermal stability. At this time, sufficient consideration is required for the linking group so that the performance of the carbazole ring alone, N-phenylcarbazole alone, or N-alkylcarbazole alone can be maintained.

  When it is connected with a simple phenyl group or naphthalene group as used in organic EL materials so far, conjugation extends and excitation triplet energy decreases. Therefore, the performance can be maintained by twisting the dihedral angle of the aromatic ring to 50 degrees or more with a substituent or using an alkyl group.

  In the present invention, carbazole derivatives having the following general formula are preferred.

  First, the compound represented by the said General formula 11 is mentioned.

In the general formula 11, R _{1001 to} R ₁₀₁₃ each independently represent a hydrogen atom or a substituent, but at least one represents a substituent.

When R _{1001 to} R ₁₀₁₃ are an aryl group or a heteroaryl group, the dihedral angle connecting to the aryl group, heteroaryl group and phenylcarbazole is preferably 50 degrees or more. This can be sterically controlled by introducing a substituent.

  Note that, as described in the hole transport material used in the present invention described above, a group having a phosphorescence 0-0 band of 450 nm or more with only a substituent, an aryl group, and a heteroaryl group is not appropriate.

When a substituent is not introduced and steric control is not performed, the dihedral angle is generally 50 degrees or less. In such a state, the excitation triplet energy may be reduced by extending the conjugate length (the 0-0 band of phosphorescence becomes longer in wavelength).
Next, the compound represented by the said General formula 12 is mentioned.

In the general formula 12, R ₁₀₂₁ represents an alkyl group, a cycloalkyl group, or a fluorinated alkyl group, and R _{1022 to} R ₁₀₂₉ each independently represents a hydrogen atom or a substituent, Represents a substituent.

When R _{1022 to} R ₁₀₂₉ are an aryl group or a heteroaryl group, the dihedral angle connecting to the aryl group, heteroaryl group and phenylcarbazole is preferably 50 degrees or more.

  Next, the compound represented by the said General formula 13 is mentioned.

In the general formula 13, R _{1031 to} R ₁₀₄₆ each independently represents a hydrogen atom or a substituent, and L ₃ represents a divalent linking group or a direct bond, and in the case of a direct bond, R ₁₀₃₇ , Any of R ₁₀₃₈ , R ₁₀₄₅ and R ₁₀₄₆ represents a substituent.

  Next, the compound represented by the said General formula 14 is mentioned.

In the general formula 14, R _{1051 to} R ₁₀₆₃ each independently represent a hydrogen atom or a substituent, and any of R ₁₀₅₇ , R ₁₀₅₈ , R ₁₀₆₂ , and R ₁₀₆₃ represents a substituent.

  Next, the compound represented by the said General formula 15 is mentioned.

In the general formula 15, R _{1071 to} R ₁₀₇₉ each independently represent a hydrogen atom or a substituent, and any of R ₁₀₇₂ and R ₁₀₇₃ represents a substituent. n represents an integer of 1 to 8.

  Although the compound example of a carbazole derivative is shown below, it is not limited to these.

  In the present invention, by combining the hole transport material of the present invention and the above-described host compound, a great effect can be obtained particularly in luminous efficiency.

  Moreover, the light emitting layer may contain the host compound which has a fluorescence maximum wavelength further as a host compound. In this case, the energy transfer from the other host compound and the phosphorescent compound to the fluorescent compound allows electroluminescence as an organic EL element to be emitted from the other host compound having a fluorescence maximum wavelength. A host compound having a fluorescence maximum wavelength is preferably a compound having a high fluorescence quantum yield in a solution state. Here, the fluorescence quantum yield is preferably 10% or more, particularly preferably 30% or more. Specific host compounds having a maximum fluorescence wavelength include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, and pyrylium dyes. Perylene dyes, stilbene dyes, polythiophene dyes, and the like. The fluorescence quantum yield can be measured by the method described in 362 (1992, Maruzen) of Spectroscopic II of the Fourth Edition Experimental Chemistry Course 7.

  The color emitted in this specification is the spectral radiance meter CS-1000 (Minolta) in FIG. 4.16 on page 108 of “New Color Science Handbook” (Edited by the Japan Society for Color Science, University of Tokyo Press, 1985). It is determined by the color when the measured result is applied to the CIE chromaticity coordinates.

  The light emitting layer can be formed by forming the above compound by a known thinning method such as a vacuum deposition method, a spin coating method, a casting method, an LB method, or an ink jet method. Although the film thickness as a light emitting layer does not have a restriction | limiting in particular, Usually, 5 nm-5 micrometers, Preferably it is chosen in the range of 5-200 nm. The light emitting layer may have a single layer structure in which these phosphorescent compounds and host compounds are composed of one or more kinds, or may have a laminated structure composed of a plurality of layers having the same composition or different compositions. Good.

《Hole transport layer》
The hole transport layer is made of a hole transport material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. The hole transport layer can be provided as a single layer or a plurality of layers.

  In the present invention, as the hole transport material adjacent to the light emitting layer, one or more of the above-described hole transport materials can be used.

  In the organic EL device of the present invention, the ionization potential of the hole transport material of the hole transport layer adjacent to the light emitting layer is preferably 5.00 to 5.70 eV. More preferably, it is 5.00-5.45 eV. Thereby, the light emission efficiency can be further increased and the drive voltage can be lowered.

  In the present invention, the ionization potential is defined as the energy required to emit electrons at the HOMO (highest occupied molecular orbital) level of a compound to the vacuum level, and specifically, in the film state (layer state). This is the energy required to extract electrons from the compound, and these can be measured directly by photoelectron spectroscopy. In the present invention, a value measured with an ESCA 5600 UPS (ultraviolet photoemission spectroscopy) manufactured by ULVAC-PHI Co., Ltd. is used.

  In the present invention, it is preferable that the ionization potential Ip1 (eV) of the hole transport material of the hole transport layer adjacent to the light emitting layer and the ionization potential Ip3 (eV) of the phosphorescent compound of the light emitting layer satisfy the following formula: Thereby, energy efficiency can be improved and luminous efficiency can be improved further.

−0.1 eV ≦ Ip3−Ip1 ≦ 0.5 eV
In the present invention, the ionization potential Ip1 (eV) of the hole transport material of the hole transport layer adjacent to the light emitting layer and the ionization potential Ip2 (eV) of the host compound of the light emitting layer preferably satisfy the following formula. , Energy efficiency can be improved and luminous efficiency can be further increased.

0.3 eV <Ip2-Ip1 <1.0 eV
In the present invention, the electron affinity Ea1 (eV) of the hole transport material of the hole transport layer adjacent to the light emitting layer and the excited triplet level T3 (eV) of the phosphorescent compound of the light emitting layer satisfy the following equation: Is preferred.

0.5eV <T3-Ea1 <1.3eV
T3 (eV) can be obtained by subtracting the excited triplet energy from Ip3 (eV) of the phosphorescent compound.

  The excited triplet state phosphorescent compound is more active and more easily oxidized than the ground state. Therefore, in some cases, it is deactivated by the transfer of electrons with the hole transport material existing around the phosphorescent compound, but the electron affinity Ea1 (eV) of the hole transport material and the excited triplet of the phosphorescent compound. When the level T3 (eV) satisfies the above relationship, transfer of electrons is restricted to prevent deactivation, thereby further improving the light emission efficiency.

In the present invention, the electron affinity is defined as the energy at which an electron in a vacuum level falls to the LUMO (lowest unoccupied molecular orbital) level of the material and stabilizes,
Electron affinity (eV) = ionization potential Ip (eV) + band gap (eV)
Can be obtained.

  In the present invention, the band gap represents energy between molecules HOMO-LUMO, specifically, a film is formed on a quartz substrate, an absorption spectrum is measured, and the band gap is obtained from the absorption edge.

  In the present invention, the electron affinity Ea1 (eV) of the hole transport material of the hole transport layer adjacent to the light emitting layer and the electron affinity Ea2 (eV) of the host compound of the light emitting layer are 0.1 eV <Ea2-Ea1 <0. It is preferable to satisfy 8 eV, and most preferable to satisfy 0.3 eV <Ea2−Ea1 <0.5 eV. When the electron affinity Ea1 (eV) of the hole transport material and the electron affinity Ea2 (eV) of the host compound satisfy the above-mentioned relationship, the electron is sent from the hole transport material to the host compound. Recombination of holes and electrons can be increased, and luminous efficiency can be further increased.

  In the present invention, there is a hole transport layer adjacent to the hole transport layer and on the opposite side of the light emitting layer, and the ion transport potential Ip4 (eV) of the hole transport layer and the hole transport material adjacent to the light emitting layer. It is preferable that the ionization potential Ip1 (eV) of the above satisfies 0.1 eV <Ip1-Ip4 <0.7 eV. By further providing a hole transport layer that satisfies the above relationship, the injection of holes into the hole transport layer was not smoothly performed due to the energy gap difference between the anode and the hole transport layer. Hole injection can be performed efficiently, whereby the luminous efficiency can be further increased and the drive voltage can be lowered. Furthermore, at this time, it is preferable that the film thickness of the hole transport layer adjacent to the light emitting layer is 5 to 20 nm, whereby the hole injection into the hole transport layer is more effectively performed, and the light emission efficiency is further increased. Can be increased. In particular, the drive voltage can be lowered.

  The hole transport material contained in the hole transport layer adjacent to the hole transport layer and located on the opposite side of the light emitting layer has either hole injection or transport or electron barrier properties. Yes, it may be organic or inorganic. For example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbenes Derivatives, silazane derivatives, aniline copolymers, conductive polymer oligomers, particularly thiophene oligomers, and the like can be given.

  As the hole transporting material contained in the hole transporting layer adjacent to the hole transporting layer and located on the opposite side of the light emitting layer, the above materials can be used. It is preferable to use a tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound.

  Representative examples of aromatic tertiary amine compounds and styrylamine compounds include N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl; N, N′-diphenyl-N, N′— Bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di-p-tolyl) Aminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N'-diphenyl-N, N ' − (4-methoxyphenyl) -4,4'-diaminobiphenyl; N, N, N ', N'-tetraphenyl-4,4'-diaminodiphenyl ether; 4,4'-bis (diphenylamino) quadriphenyl; N, N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 '-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenylamino- (2-diphenylvinyl) benzene; 3-methoxy-4'-N, N-diphenylaminostilbene; N-phenylcarbazole, as well as two of those described in US Pat. No. 5,061,569 Having a condensed aromatic ring in the molecule, for example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-30868 4,4 ', 4 "-tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine (MTDATA) in which three triphenylamine units described in No. 1 are linked in a starburst type Etc.

  Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used. In addition, inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole injection material and the hole transport material.

  The hole transport layer can be formed by thinning the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. it can. Although there is no restriction | limiting in particular about the film thickness of a positive hole transport layer, Usually, 5 nm-about 5 micrometers, Preferably it is 5-200 nm. This hole transport layer may have a single layer structure composed of one or more of the above materials.

《Electron transport layer》
The electron transport layer is made of a material having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. The electron transport layer can be provided as a single layer or a plurality of layers.

  Conventionally, in the case of a single-layer electron transport layer and a plurality of layers, the following materials are used as the electron transport material (also serving as a hole blocking material) used for the electron transport layer adjacent to the cathode side with respect to the light emitting layer. Are known.

  Further, the electron transport layer only needs to have a function of transmitting electrons injected from the cathode to the light emitting layer, and any material can be selected from conventionally known compounds. .

  Examples of materials used for this electron transport layer (hereinafter referred to as electron transport materials) include nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone. Derivatives, oxadiazole derivatives and the like. Furthermore, in the above oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and a quinoxaline derivative having a quinoxaline ring known as an electron withdrawing group can also be used as an electron transport material.

  Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

  In addition, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) aluminum, Tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), etc., and the central metals of these metal complexes are In, Mg, Cu , Ca, Sn, Ga, or Pb can also be used as an electron transport material. In addition, metal-free or metal phthalocyanine, or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transporting material. In addition, the distyrylpyrazine derivative exemplified as the material of the light emitting layer can also be used as an electron transport material, and similarly to the hole injection layer and the hole transport layer, inorganic such as n-type-Si and n-type-SiC A semiconductor can also be used as an electron transport material.

  The electron transport layer can be formed by thinning the electron transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. Although there is no restriction | limiting in particular about the film thickness of an electron carrying layer, Usually, 5 nm-about 5 micrometers, Preferably it is 5-200 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.

<< Substrate (also referred to as substrate, substrate, support, etc.) >>
The organic EL device of the present invention is preferably formed on a substrate.

  The substrate of the organic EL device of the present invention is not particularly limited to the type of glass, plastic, etc., and is not particularly limited as long as it is transparent. Examples of substrates that are preferably used include glass, quartz, A light transmissive resin film can be mentioned. A particularly preferable substrate is a resin film that can give flexibility to the organic EL element.

  Examples of the resin film include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate (PC), and cellulose triacetate. Examples thereof include films made of (TAC), cellulose acetate propionate (CAP) and the like. An inorganic or organic film or a hybrid film of both may be formed on the surface of the resin film.

  The external extraction efficiency at room temperature for light emission of the organic electroluminescence device of the present invention is preferably 1% or more, more preferably 5% or more. Here, the external extraction quantum efficiency (%) = the number of photons emitted to the outside of the organic EL element / the number of electrons sent to the organic EL element × 100.

  In addition, a hue improvement filter such as a color filter may be used in combination, or a color conversion filter that converts the emission color from the organic EL element into multiple colors using a phosphor. In the case of using a color conversion filter, the λmax of light emission of the organic EL element is preferably 480 nm or less.

<< Method for producing organic EL element >>
As an example of the method for producing the organic EL device of the present invention, a method for producing an organic EL device comprising an anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode will be described.

  First, a thin film made of a desired electrode material, for example, an anode material is formed on a suitable substrate by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably 10 to 200 nm, thereby producing an anode. To do. Next, an organic compound thin film of a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and a hole blocking layer, which are organic EL element materials, is formed thereon.

As a method for thinning the organic compound thin film, there are a vapor deposition method and a wet process (spin coating method, casting method, ink jet method, printing method) as described above, but it is easy to obtain a uniform film and a pinhole. From the point of being difficult to form, a vacuum deposition method, a spin coating method, an ink jet method, and a printing method are particularly preferable. Further, different film forming methods may be applied for each layer. When employing a vapor deposition method for film formation, the vapor deposition conditions vary depending on the type of compound used, but generally a boat heating temperature of 50 to 450 ° C., a vacuum degree of 10 ⁻⁶ to 10 ⁻² Pa, and a vapor deposition rate of 0.01 It is desirable to select appropriately within the range of ˜50 nm / second, substrate temperature −50 to 300 ° C., film thickness 0.1 nm to 5 μm, preferably 5 to 200 nm.

  After these layers are formed, a thin film made of a cathode material is formed thereon by a method such as vapor deposition or sputtering so as to have a thickness of 1 μm or less, preferably in the range of 50 to 200 nm, and a cathode is provided. Thus, a desired organic EL element can be obtained. The organic EL element is preferably produced from the hole injection layer to the cathode consistently by a single evacuation, but may be taken out halfway and subjected to different film forming methods. At that time, it is necessary to consider that the work is performed in a dry inert gas atmosphere.

  The multicolor display device of the present invention is provided with a shadow mask only when the light emitting layer is formed, and the other layers are common, so that patterning of the shadow mask or the like is not necessary. A film can be formed by a method or a printing method.

  When patterning is performed only on the light emitting layer, the method is not limited. However, a vapor deposition method, an inkjet method, and a printing method are preferable. In the case of using a vapor deposition method, patterning using a shadow mask is preferable.

  In addition, it is also possible to reverse the production order and produce the cathode, the electron injection layer, the electron transport layer, the light emitting layer, the hole transport layer, the hole injection layer, and the anode in this order. When a DC voltage is applied to the multicolor display device thus obtained, light emission can be observed by applying a voltage of about 2 to 40 V with the positive polarity of the anode and the negative polarity of the cathode. An alternating voltage may be applied. The alternating current waveform to be applied may be arbitrary.

  The multicolor display device of the present invention can be used as a display device, a display, or various light sources. In a display device or a display, full-color display is possible by using three types of organic EL elements of blue, red, and green light emission.

  Examples of the display device and display include a television, a personal computer, a mobile device, an AV device, a character broadcast display, and an information display in an automobile. In particular, it may be used as a display device for reproducing still images and moving images, and the driving method when used as a display device for reproducing moving images may be either a simple matrix (passive matrix) method or an active matrix method.

  Light sources include home lighting, interior lighting, clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, light sources for optical sensors, etc. For example, but not limited to.

  Further, the organic EL element according to the present invention may be used as an organic EL element having a resonator structure.

  Examples of the purpose of use of the organic EL element having such a resonator structure include a light source of an optical storage medium, a light source of an electrophotographic copying machine, a light source of an optical communication processing machine, and a light source of an optical sensor. It is not limited. Moreover, you may use for the said use by making a laser oscillation.

<Display device>
The organic EL element of the present invention may be used as one kind of lamp for illumination or exposure light source, a projection device for projecting an image, or a display for directly viewing a still image or a moving image. It may be used as a device (display). When used as a display device for reproducing moving images, the driving method may be either a simple matrix (passive matrix) method or an active matrix method. Alternatively, a full-color display device can be manufactured by using three or more organic EL elements of the present invention having different emission colors. Alternatively, it is possible to make a single color emission color, for example, white emission, into BGR using a color filter to achieve full color. Furthermore, it is possible to convert the emission color of the organic EL to another color by using a color conversion filter, and in this case, λmax of the organic EL emission is preferably 480 nm or less.

  An example of a display device composed of the organic EL element of the present invention will be described below based on the drawings.

  FIG. 1 is a schematic diagram illustrating an example of a display device including organic EL elements. It is a schematic diagram of a display such as a mobile phone that displays image information by light emission of an organic EL element.

  The display 1 includes a display unit A having a plurality of pixels, a control unit B that performs image scanning of the display unit A based on image information, and the like.

  The control unit B is electrically connected to the display unit A, and sends a scanning signal and an image data signal to each of the plurality of pixels based on image information from the outside. The pixels for each scanning line are converted into image data signals by the scanning signal. In response to this, light is sequentially emitted and image scanning is performed to display image information on the display unit A.

  FIG. 2 is a schematic diagram of the display unit A.

  The display unit A includes a wiring unit including a plurality of scanning lines 5 and data lines 6, a plurality of pixels 3 and the like on a substrate. The main members of the display unit A will be described below. FIG. 2 shows a case where the light emitted from the pixel 3 is extracted in the direction of the white arrow (downward).

  The scanning lines 5 and the plurality of data lines 6 in the wiring portion are each made of a conductive material, and the scanning lines 5 and the data lines 6 are orthogonal to each other in a grid pattern and are connected to the pixels 3 at orthogonal positions (details are shown in FIG. Not shown).

  When a scanning signal is applied from the scanning line 5, the pixel 3 receives an image data signal from the data line 6 and emits light according to the received image data. Full color display is possible by appropriately arranging pixels in the red region, the green region, and the blue region that emit light on the same substrate.

  Next, the light emission process of the pixel will be described.

  FIG. 3 is a schematic diagram of a pixel.

  The pixel includes an organic EL element 10, a switching transistor 11, a driving transistor 12, a capacitor 13, and the like. A full color display can be performed by using red, green, and blue light emitting organic EL elements as the organic EL elements 10 in a plurality of pixels, and juxtaposing them on the same substrate.

  In FIG. 3, an image data signal is applied from the control unit B to the drain of the switching transistor 11 through the data line 6. When a scanning signal is applied from the control unit B to the gate of the switching transistor 11 via the scanning line 5, the driving of the switching transistor 11 is turned on, and the image data signal applied to the drain is supplied to the capacitor 13 and the driving transistor 12. Is transmitted to the gate.

  By transmitting the image data signal, the capacitor 13 is charged according to the potential of the image data signal, and the drive of the drive transistor 12 is turned on. The drive transistor 12 has a drain connected to the power supply line 7 and a source connected to the electrode of the organic EL element 10, and the power supply line 7 connects to the organic EL element 10 according to the potential of the image data signal applied to the gate. Current is supplied.

  When the scanning signal is moved to the next scanning line 5 by the sequential scanning of the control unit B, the driving of the switching transistor 11 is turned off. However, even if the driving of the switching transistor 11 is turned off, the capacitor 13 maintains the potential of the charged image data signal, so that the driving of the driving transistor 12 is kept on and the next scanning signal is applied. Until then, the light emission of the organic EL element 10 continues. When the scanning signal is next applied by sequential scanning, the driving transistor 12 is driven according to the potential of the next image data signal synchronized with the scanning signal, and the organic EL element 10 emits light.

  That is, the organic EL element 10 emits light by the switching transistor 11 and the driving transistor 12 that are active elements for the organic EL elements 10 of the plurality of pixels, and the organic EL elements 10 of the plurality of pixels 3 emit light. It is carried out. Such a light emitting method is called an active matrix method.

  Here, the light emission of the organic EL element 10 may be light emission of a plurality of gradations by a multi-value image data signal having a plurality of gradation potentials, or on / off of a predetermined light emission amount by a binary image data signal. But you can.

  The potential of the capacitor 13 may be held continuously until the next scanning signal is applied, or may be discharged immediately before the next scanning signal is applied.

  In the present invention, not only the active matrix method described above, but also a passive matrix light emission drive in which the organic EL element emits light according to the data signal only when the scanning signal is scanned.

  FIG. 4 is a schematic view of a passive matrix display device. In FIG. 4, a plurality of scanning lines 5 and a plurality of image data lines 6 are provided in a lattice shape so as to face each other with the pixel 3 interposed therebetween.

  When the scanning signal of the scanning line 5 is applied by sequential scanning, the pixels 3 connected to the applied scanning line 5 emit light according to the image data signal. In the passive matrix system, the pixel 3 has no active element, and the manufacturing cost can be reduced.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, the embodiment of this invention is not limited to these.

Example 1
<Preparation of organic EL elements 1-1 to 1-19>
Transparent support provided with this ITO transparent electrode after patterning on a substrate (NH45 manufactured by NH Techno Glass) made of ITO (indium tin oxide) with a thickness of 100 nm on a glass substrate of 100 mm × 100 mm × 1.1 mm as an anode The substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes. This transparent support substrate is fixed to a substrate holder of a commercially available vacuum evaporation apparatus. Meanwhile, 200 mg of α-NPD is put into a molybdenum resistance heating boat, 200 mg of CBP is put into another resistance heating boat made of molybdenum, and another resistance made of molybdenum. 200 mg of bathocuproin (BCP) was put in a heating boat, 100 mg of Ir-1 was put in another resistance heating boat made of molybdenum, and 200 mg of Alq ₃ was put in another resistance heating boat made of molybdenum, and attached to a vacuum deposition apparatus.

Next, after reducing the vacuum chamber to 4 × 10 ⁻⁴ Pa, the heating boat containing α-NPD was heated by heating, and deposited on the transparent support substrate at a deposition rate of 0.1 nm / sec. A transport layer was provided. Further, the heating boat containing CBP and Ir-1 is energized and heated, and a light emitting layer is provided by co-deposition on the hole transport layer at a deposition rate of 0.2 nm / sec and 0.012 nm / sec, respectively. It was. In addition, the substrate temperature at the time of vapor deposition was room temperature. In addition, an electron transport layer that also serves as a hole blocking function with a film thickness of 10 nm is provided by energizing and heating the heating boat containing BCP and depositing on the light emitting layer at a deposition rate of 0.1 nm / sec. It was. Furthermore, the heating boat containing Alq ₃ was further energized and heated, and was deposited on the electron transport layer at a deposition rate of 0.1 nm / sec to provide an electron injection layer having a thickness of 40 nm. . In addition, the substrate temperature at the time of vapor deposition was room temperature.

  Then, 0.5 nm of lithium fluoride and 110 nm of aluminum were vapor-deposited, the cathode was formed, and the organic EL element 1-1 was produced. Other organic EL elements shown in Table 1 were also produced in the same manner as the organic EL element 1-1 except that the compounds of the hole transport layer and the light emitting layer were replaced with the compounds shown in Table 1. The structure of the compound used above is shown below.

<Evaluation of Organic EL Elements 1-1 to 1-19>
The organic EL elements 1-1 to 1-19 produced as described below were evaluated, and the results are shown in Table 2.

(External extraction quantum efficiency)
About the produced organic EL element, the external extraction quantum efficiency (%) when a ^2.5 mA / cm ² constant current was applied in a dry nitrogen gas atmosphere at 23 ° C. was measured.

(Lm / W)
Using the luminance measured with a spectral radiance meter CS-1000 (manufactured by Minolta), lm / W was obtained from the following equation.
lm / W = (luminance (cd / m ² ) × π) / (current density (A / m ² ) × voltage (V))
(Aging over time)
After the organic EL device was stored at 50 ° C. for 7 days, the external extraction quantum efficiency was measured by the above-described external extraction quantum efficiency measurement method.

  The measurement results of luminous efficiency, lm / W, and deterioration with time are expressed as relative values when the measured value of the organic EL element 1-1 is set to 100 for the organic EL elements 1-1 to 1-12. About 1-13 to 1-19, it represented with the relative value when the organic EL element 1-13 is set to 100.

  From Table 2, it was found that the organic EL device of the present invention was excellent in the external extraction quantum efficiency, lm / W, and further the deterioration with time of the external extraction quantum efficiency was suppressed. Moreover, compared with the comparative organic EL element 1-1, the organic EL elements 1-6, 1-10, and 1-18 of the present invention have less suppression of deterioration over time, but the external quantum efficiency and 1 m / It can be seen that W is greatly improved.

Example 2
<Preparation of organic EL elements 2-1 to 2-4>
Transparent support provided with this ITO transparent electrode after patterning on a substrate (NH45 manufactured by NH Techno Glass) made of ITO (indium tin oxide) with a thickness of 100 nm on a glass substrate of 100 mm × 100 mm × 1.1 mm as an anode The substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes. This transparent support substrate is fixed to a substrate holder of a commercially available vacuum evaporation apparatus, while 200 mg of CuPc is put in a molybdenum resistance heating boat, and 200 mg of 1-56 is put in another resistance heating boat made of molybdenum, and another molybdenum resistance is added. Put 200 mg of CBP in a heating boat, put 200 mg of bathocuproin (BCP) in another molybdenum resistance heating boat, put 100 mg of Ir-1 in another resistance heating boat made of molybdenum, and add Alq ₃ to another resistance heating boat made of molybdenum. 200 mg was added and attached to a vacuum deposition apparatus.

Next, the pressure in the vacuum chamber is reduced to 4 × 10 ⁻⁴ Pa, and then the heating boat containing CuPc is energized and heated, vapor-deposited on the transparent support substrate at a vapor deposition rate of 0.1 nm / sec, and the second hole transport A layer was provided. Furthermore, it supplied with electricity to the said heating boat containing 1-56, it heated, and it vapor-deposited on the said 2nd positive hole transport layer with the vapor deposition rate of 0.1 nm / sec, and provided the 1st positive hole transport layer. Further, the heating boat containing CBP and Ir-1 was energized and heated, and co-evaporated on the first hole transport layer at a deposition rate of 0.2 nm / sec and 0.012 nm / sec, respectively, to form a light emitting layer Was provided. In addition, the substrate temperature at the time of vapor deposition was room temperature. In addition, an electron transport layer that also serves as a hole blocking function with a film thickness of 10 nm is provided by energizing and heating the heating boat containing BCP and depositing on the light emitting layer at a deposition rate of 0.1 nm / sec. It was. Furthermore, the heating boat containing Alq ₃ was further energized and heated, and was deposited on the electron transport layer at a deposition rate of 0.1 nm / sec to provide an electron injection layer having a thickness of 40 nm. . In addition, the substrate temperature at the time of vapor deposition was room temperature.

  Subsequently, 0.5 nm of lithium fluoride and 110 nm of aluminum were vapor-deposited to form a cathode, and an organic EL element 2-1 was produced. Other organic EL elements shown in Table 3 were also produced in the same manner as the organic EL element 2-1, except that the compounds in the hole transport layer and the light emitting layer were replaced with the compounds shown in Table 3. The structure of the compound used above is shown below.

<Evaluation of organic EL elements 2-1 to 2-4>
The organic EL element was evaluated in the same manner as in Example 1.

  The measurement results of external extraction quantum efficiency, lm / W, and deterioration with time are as follows. For organic EL elements 2-1, 2-2, 2-3, 2-4, organic EL elements 1-2, 1-8, It was expressed as a relative value when 1-15 and 1-10 were taken as 100. The results are shown in Table 4.

  From Table 4, by providing the second hole transport layer satisfying 0.1 eV <Ip1-Ip4 <0.7 eV, the organic EL device of the present invention is further excellent in luminous efficiency and lm / W, and further It was found that deterioration with time was suppressed.

Example 3
The green and blue light emitting organic EL devices of the present invention prepared in the above examples, and the red light emitting organic EL device prepared in the same manner except that the phosphorescent compound of the green light emitting organic EL device of the present invention was replaced with Btp2Ir (acac). Were juxtaposed on the same substrate to produce an active matrix type full-color display device shown in FIG. FIG. 2 shows only a schematic diagram of the display portion A of the produced full-color display device. That is, a wiring portion including a plurality of scanning lines 5 and data lines 6 and a plurality of juxtaposed pixels 3 (light emission color is a red region pixel, a green region pixel, a blue region pixel, etc.) on the same substrate. Each of the scanning lines 5 and the plurality of data lines 6 in the wiring portion is made of a conductive material, and the scanning lines 5 and the data lines 6 are orthogonal to each other in a lattice shape and are connected to the pixels 3 at the orthogonal positions (details). Is not shown). The plurality of pixels 3 are driven by an active matrix system provided with an organic EL element corresponding to each emission color, a switching transistor as an active element, and a driving transistor, and a scanning signal is applied from a scanning line 5. Then, an image data signal is received from the data line 6 and light is emitted according to the received image data. In this way, full-color display is possible by appropriately juxtaposing the red, green, and blue pixels.

  By driving the full-color display device, a clear full-color moving image display with high luminance and good durability was obtained.

It is the schematic diagram which showed an example of the display apparatus comprised from an organic EL element. It is a schematic diagram of a display part. It is a schematic diagram of a pixel. It is a schematic diagram of a passive matrix type full-color display device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Display 3 Pixel 5 Scan line 6 Data line 7 Power supply line 10 Organic EL element 11 Switching transistor 12 Drive transistor 13 Capacitor A Display part B Control part

Claims (7)

In a light emitting device having at least a light emitting layer containing a phosphorescent compound and a hole transport layer containing a hole transport material adjacent to the light emitting layer,
The hole transport material is at least one compound represented by the following formula 5, and, the light emitting layer contains further host compound, a carbazole derivative which the host compound is represented by the following general formula 13 An organic electroluminescence device characterized by being at least one .

(In the formula, R _{960 to} R ₉₇₆ each independently represents a hydrogen atom or a substituent. However, any of R ₉₆₀ and R ₉₆₁ represents a substituent, and any of R ₉₆₃ and R ₉₆₄ is a substituted group. L ₁ represents a divalent linking group or a direct bond)

(In the formula, R _{1031 to} R ₁₀₄₆ each independently represents a hydrogen atom or a substituent, and L ₃ represents a divalent linking group or a direct bond, but in the case of a direct bond, R ₁₀₃₇ and R _1038. Any one of R ₁₀₄₅ and R ₁₀₄₆ represents a substituent.) The organic electroluminescence device according to claim 1, wherein the thickness of the hole transport layer adjacent to the light emitting layer is 5 nm to 20 nm. The organic electroluminescence device according to claim 1, wherein the hole transport layer is formed by vapor deposition. The organic electroluminescent element according to claim 1, wherein the hole transport layer is formed by a wet process. A display device comprising the organic electroluminescence element according to claim 1. An illuminating device comprising the organic electroluminescence element according to claim 1. A display device comprising the illumination device according to claim 6 and a liquid crystal element as a display means.

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