JP2010263065A - Organic light-emitting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic light-emitting element which is superior in durability. <P>SOLUTION: A condensed-polycyclic compound formed by condensation of two benzo terphenyls to perylene, and a condensed-polycyclic compound formed by condensation of two benzo terphenyls to naphthalene are included in a light-emitting layer of the organic light-emitting element composed of an organic compound layer which is sandwiched between an anode and a cathode, and has at least the light-emitting layer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an organic light emitting device.

  An organic light emitting device is an electronic device in which a thin film containing a fluorescent organic compound is sandwiched between an anode and a cathode. Further, by injecting electrons and holes from each electrode, excitons of the fluorescent organic compound are generated, and the organic light emitting element emits light when the excitons return to the ground state.

  2. Description of the Related Art In recent years, organic light-emitting devices have made remarkable progress, and their features include low voltage, high brightness, a variety of emission wavelengths, high-speed response, and light-emitting devices that can be made thinner and lighter.

  However, when considering application to a full-color display or the like, the light emission efficiency and stability of the organic light-emitting element are still insufficient, and further improvement is necessary.

  Therefore, various studies have been conducted for the purpose of further improving device characteristics. For example, Patent Document 1 discloses an organic light-emitting device using an organic compound having a perfluoranthene skeleton as a constituent material of the light-emitting layer, more specifically, as a dopant of the light-emitting layer. Patent Document 2 discloses an organic light-emitting device in which a light-emitting layer is composed of a mixture of a naphthacene derivative and an indenoperylene derivative.

JP-A-11-233261 JP 2003-338377 A

  The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to provide an organic light emitting device having excellent durability.

The organic light-emitting device of the present invention comprises an anode, a cathode,
An organic compound layer sandwiched between the anode and the cathode and having at least a light emitting layer,
The light emitting layer contains a condensed polycyclic compound represented by the following general formula [1] and a condensed polycyclic compound represented by the following general formula [2].

（式［１］において、Ｒ₁乃至Ｒ₃₆は、それぞれ水素原子、置換あるいは無置換のアルキル基、置換あるいは無置換のアルコキシ基、置換あるいは無置換のアリール基、置換あるいは無置換の複素環基、置換あるいは無置換のアリールオキシ基、置換アミノ基、ハロゲン原子、スルフィド基及びシリル基からなる群より選ばれる置換基であり、同じであっても異なっていてもよい。）

(In the formula [1], R ₁ to R ₃₆ are each a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group A substituent selected from the group consisting of a substituted or unsubstituted aryloxy group, a substituted amino group, a halogen atom, a sulfide group and a silyl group, which may be the same or different.

（式［２］において、Ｒ₁乃至Ｒ₃₂は、それぞれ水素原子、置換あるいは無置換のアルキル基、置換あるいは無置換のアルコキシ基、置換あるいは無置換のアリール基、置換あるいは無置換の複素環基、置換あるいは無置換のアリールオキシ基、置換アミノ基、ハロゲン原子、スルフィド基及びシリル基からなる群より選ばれる置換基であり、同じであっても異なっていてもよい。）

(In the formula [2], R _{1 to} R ₃₂ are each a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, respectively. A substituent selected from the group consisting of a substituted or unsubstituted aryloxy group, a substituted amino group, a halogen atom, a sulfide group and a silyl group, which may be the same or different.

  ADVANTAGE OF THE INVENTION According to this invention, the organic light emitting element excellent in durability can be provided.

1 is a schematic cross-sectional view illustrating an example of an embodiment of an organic light-emitting device of the present invention.

  Hereinafter, the present invention will be described in detail.

  The organic light emitting device of the present invention comprises an anode, a cathode, and an organic compound layer sandwiched between the anode and the cathode and having at least a light emitting layer.

  Hereinafter, the organic light emitting device of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view illustrating an example of an embodiment of the organic light-emitting device of the present invention. In the organic light emitting device 10 of FIG. 1, an anode 2, a hole transport layer 3, a light emitting layer 4, an electron transport layer 5 and a cathode 6 are laminated on a substrate 1 in this order.

  However, FIG. 1 is a very basic element structure, and the structure of the organic light-emitting element of the present invention is not limited to this. For example, various layer configurations such as providing an insulating layer, an adhesive layer, or an interference layer at the interface between the electrode and the organic compound layer, and a hole transport layer including two layers having different ionization potentials can be employed.

  In the organic light emitting device of the present invention, the light emitting layer 4 contains a condensed polycyclic compound represented by the following general formula [1] and a condensed polycyclic compound represented by the following general formula [2].

  First, the condensed polycyclic compound represented by the general formula [1] will be described.

In the formula [1], R _{1 to} R ₃₆ are each a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, It is a substituent selected from the group consisting of a substituted or unsubstituted aryloxy group, a substituted amino group, a halogen atom, a sulfide group and a silyl group.

Examples of the alkyl group represented by R _{1 to} R ₃₆ include methyl group, methyl-d1 group, methyl-d3 group, ethyl group, ethyl-d5 group, n-propyl group, n-butyl group, n-pentyl group, n -Hexyl group, n-heptyl group, n-octyl group, n-decyl group, iso-propyl group, iso-propyl-d7 group, iso-butyl group, sec-butyl group, tert-butyl group, tert-butyl- d9 group, iso-pentyl group, neopentyl group, tert-octyl group, fluoromethyl group, difluoromethyl group, trifluoromethyl group, 2-fluoroethyl group, 2,2,2-trifluoromethyl group, perfluoroethyl group 3-fluoropropyl group, perfluoropropyl group, 4-fluorobutyl group, perfluorobutyl group, 5-fluoropentyl group, 6-fluoro Hexyl group, chloromethyl group, trichloromethyl group, 2-chloroethyl group, 2,2,2-trichloroethyl group, 4-chlorobutyl group, 5-chloropentyl group, 6-chlorohexyl group, bromomethyl group, 2-bromoethyl group , Iodomethyl group, 2-iodoethyl group, hydroxymethyl group, hydroxyethyl group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cyclopentylmethyl group, cyclohexylmethyl group, cyclohexylethyl group, 4-fluorocyclohexyl group, norbornyl group And adamantyl group and the like, but are not limited thereto.

Examples of the alkoxy group represented by R _{1 to} R ₃₆ include the above-described alkyloxy groups having an alkyl group and aralkyloxy groups. Specific examples include a methoxy group, an ethoxy group, a propoxy group, a 2-ethyl-octyloxy group, a benzyloxy group, and the like, but of course not limited thereto.

Examples of the aryl group represented by R ₁ to R _36, a phenyl group, a phenyl -d5 group, 4-methylphenyl group, a 4-methoxyphenyl group, 4-ethylphenyl group, a 4-fluorophenyl group, 4-trifluoromethyl Phenyl group, 3,5-dimethylphenyl group, 2,6-diethylphenyl group, mesityl group, 4-tert-butylphenyl group, ditolylaminophenyl group, biphenyl group, terphenyl group, naphthyl group, naphthyl-d7 group Acenaphthylenyl group, anthryl group, anthryl-d9 group, phenanthryl group, phenanthryl-d9 group, pyrenyl group, pyrenyl-d9 group, acephenanthrenyl group, aceanthrylenyl group, chrysenyl group, dibenzochrysenyl group, benzo Anthryl, benzoanthryl-d11, dibenzoanthryl, naphth Seniru group, picenyl group, a pentacenyl group, a fluorenyl group, a triphenylenyl group, a perylenyl group, but perylenyl -d11 groups and the like, but the present invention is of course not limited thereto.

Examples of the heterocyclic group represented by R _{1 to} R ₃₆ include pyrrolyl, pyridyl, pyridyl-d5, bipyridyl, methylpyridyl, pyrimidinyl, pyrazinyl, pyridazinyl, terpyrrolyl, thienyl, and thienyl-d4. Group, tertenyl group, propylthienyl group, benzothienyl group, dibenzothienyl group, dibenzothienyl-d7 group, furyl group, furyl-d4 group, benzofuryl group, isobenzofuryl group, dibenzofuryl group, dibenzofuryl-d7 group, quinolyl Group, quinolyl-d6 group, isoquinolyl group, quinoxalinyl group, naphthyridinyl group, quinazolinyl group, phenanthridinyl group, indolizinyl group, phenazinyl group, carbazolyl group, oxazolyl group, oxadiazolyl group, thiazolyl group, thiadiazolyl group, acridinyl group, Jiniru group, and the like, but the invention is of course not limited thereto.

Examples of the aryloxy group represented by R _{1 to} R ₃₆ include the aryloxy group having the aryl group or heterocyclic group described above. Specific examples include a phenoxy group, a 4-tert-butylphenoxy group, a thienyloxy group, and the like, but are not limited thereto.

Examples of the substituted amino group represented by R _{1 to} R ₃₆ include a dimethylamino group, a diethylamino group, a dibenzylamino group, a diphenylamino group, a ditolylamino group, a dianisolylamino group, and the like. It is not a thing.

As the halogen atom represented by R ₁ to R _36, fluorine, chlorine, bromine, and iodine and the like, but the present invention is of course not limited thereto.

Examples of the silyl group represented by R _{1 to} R ₃₆ include, but are not limited to, a trimethylsilyl group, a triethylsilyl group, and a triisopropylsilyl group.

  As the substituent that the alkyl group, alkoxy group, aryl group, heterocyclic group and aryloxy group may further have, an alkyl group such as a methyl group, an ethyl group or a propyl group, an aryl group such as a phenyl group or a biphenyl group , Heterocyclic groups such as thienyl group, pyrrolyl group and pyridyl group, substituted amino groups such as dimethylamino group, diethylamino group, dibenzylamino group, diphenylamino group, ditolylamino group and dianisolylamino group, methoxy group and ethoxy group And alkoxy groups such as fluorine, chlorine, bromine, iodine and the like, hydroxyl groups, cyano groups, nitro groups, and the like, but are not limited thereto.

In the formula [1], R _{1 to} R ₃₆ may be the same or different. In the formula [1], adjacent substituents may be bonded to each other to form a ring structure such as a benzene ring.

  Specific examples of the condensed polycyclic compound represented by the formula [1] are shown below. However, these compounds are only specific examples, and the present invention is not limited to these.

  Next, the condensed polycyclic compound represented by the general formula [2] will be described.

In the formula [2], R _{1 to} R ₃₂ are each a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, It is a substituent selected from the group consisting of a substituted amino group, a halogen atom, a sulfide group and a silyl group.

Examples of the alkyl group represented by R _{1 to} R ₃₂ include methyl group, methyl-d1 group, methyl-d3 group, ethyl group, ethyl-d5 group, n-propyl group, n-butyl group, n-pentyl group, n -Hexyl group, n-heptyl group, n-octyl group, n-decyl group, iso-propyl group, iso-propyl-d7 group, iso-butyl group, sec-butyl group, tert-butyl group, tert-butyl- d9 group, iso-pentyl group, neopentyl group, tert-octyl group, fluoromethyl group, difluoromethyl group, trifluoromethyl group, 2-fluoroethyl group, 2,2,2-trifluoromethyl group, perfluoroethyl group 3-fluoropropyl group, perfluoropropyl group, 4-fluorobutyl group, perfluorobutyl group, 5-fluoropentyl group, 6-fluoro Hexyl group, chloromethyl group, trichloromethyl group, 2-chloroethyl group, 2,2,2-trichloroethyl group, 4-chlorobutyl group, 5-chloropentyl group, 6-chlorohexyl group, bromomethyl group, 2-bromoethyl group , Iodomethyl group, 2-iodoethyl group, hydroxymethyl group, hydroxyethyl group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cyclopentylmethyl group, cyclohexylmethyl group, cyclohexylethyl group, 4-fluorocyclohexyl group, norbornyl group And adamantyl group and the like, but are not limited thereto.

Examples of the alkoxy group represented by R _{1 to} R ₃₂ include the above-described alkyloxy groups having an alkyl group and aralkyloxy groups. Specific examples include a methoxy group, an ethoxy group, a propoxy group, a 2-ethyl-octyloxy group, a benzyloxy group, and the like, but of course not limited thereto.

As the aryl group represented by R _{1 to} R ₃₂ , phenyl group, phenyl-d5 group, 4-methylphenyl group, 4-methoxyphenyl group, 4-ethylphenyl group, 4-fluorophenyl group, 4-trifluoromethyl Phenyl group, 3,5-dimethylphenyl group, 2,6-diethylphenyl group, mesityl group, 4-tert-butylphenyl group, ditolylaminophenyl group, biphenyl group, terphenyl group, naphthyl group, naphthyl-d7 group Acenaphthylenyl group, anthryl group, anthryl-d9 group, phenanthryl group, phenanthryl-d9 group, pyrenyl group, pyrenyl-d9 group, acephenanthrenyl group, aceanthrylenyl group, chrysenyl group, dibenzochrysenyl group, benzo Anthryl, benzoanthryl-d11, dibenzoanthryl, naphth Seniru group, picenyl group, a pentacenyl group, a fluorenyl group, a triphenylenyl group, a perylenyl group, but perylenyl -d11 groups and the like, but the present invention is of course not limited thereto.

As the heterocyclic group represented by R _{1 to} R ₃₂ , pyrrolyl group, pyridyl group, pyridyl-d5 group, bipyridyl group, methylpyridyl group, pyrimidinyl group, pyrazinyl group, pyridazinyl group, terpyrrolyl group, thienyl group, thienyl-d4 Group, tertenyl group, propylthienyl group, benzothienyl group, dibenzothienyl group, dibenzothienyl-d7 group, furyl group, furyl-d4 group, benzofuryl group, isobenzofuryl group, dibenzofuryl group, dibenzofuryl-d7 group, quinolyl Group, quinolyl-d6 group, isoquinolyl group, quinoxalinyl group, naphthyridinyl group, quinazolinyl group, phenanthridinyl group, indolizinyl group, phenazinyl group, carbazolyl group, oxazolyl group, oxadiazolyl group, thiazolyl group, thiadiazolyl group, acridinyl group, Jiniru group, and the like, but the invention is of course not limited thereto.

Examples of the aryloxy group represented by R _{1 to} R ₃₆ include the aryloxy group having the aryl group or heterocyclic group described above. Specific examples include a phenoxy group, a 4-tert-butylphenoxy group, a thienyloxy group, and the like, but are not limited thereto.

As the substituted amino group represented by R ₁ to R _32, dimethylamino group, diethylamino group, dibenzylamino group, diphenylamino group, ditolylamino group, dianisolylamino an amino group and the like are of course limited to It is not a thing.

Examples of the halogen atom represented by R _{1 to} R ₃₂ include, but are not limited to, fluorine, chlorine, bromine, iodine and the like.

Examples of the silyl group represented by R _{1 to} R ₃₂ include, but are not limited to, a trimethylsilyl group, a triethylsilyl group, and a triisopropylsilyl group.

  As the substituent that the alkyl group, alkoxy group, aryl group, heterocyclic group and aryloxy group may further have, an alkyl group such as a methyl group, an ethyl group or a propyl group, an aryl group such as a phenyl group or a biphenyl group , Heterocyclic groups such as thienyl group, pyrrolyl group and pyridyl group, substituted amino groups such as dimethylamino group, diethylamino group, dibenzylamino group, diphenylamino group, ditolylamino group and dianisolylamino group, methoxy group and ethoxy group And alkoxy groups such as fluorine, chlorine, bromine, iodine and the like, hydroxyl groups, cyano groups, nitro groups, and the like, but are not limited thereto.

In the formula [2], R ₁ to R ₃₂ may be different even in respectively the same.

  Specific examples of the condensed polycyclic compound represented by the formula [2] are shown below. However, these compounds are only specific examples, and the present invention is not limited to these.

  In the organic light emitting device of the present invention, the light emitting layer 4 preferably further includes a condensed polycyclic compound having a pyrene skeleton. Here, examples of the condensed polycyclic compound having a pyrene skeleton include the following compounds. However, the compounds shown below are only specific examples, and the present invention is not limited thereto.

  In the organic light emitting device of the present invention, the light emitting layer 4 may be composed of only the condensed polycyclic compound of the formula [1] and the formula [2], but is preferably composed of a host and a guest (dopant). The When the light emitting layer 4 is comprised with a host and a guest, the condensed polycyclic compound of Formula [1] and Formula [2] may be used as a host, and may be used as a guest.

When the light-emitting layer is composed of a carrier transporting host and guest, the main process leading to light emission includes the following several processes.
1. Transport of electrons and holes in the light emitting layer.
2. Host exciton generation.
3. Excitation energy transfer between host molecules.
4). Excitation energy transfer from host to guest.

  Desired energy transfer and light emission in each process occur by various deactivation processes and competition.

  Here, in order to increase the light emission efficiency of the organic light emitting device, it is preferable that the emission center material itself has a higher emission quantum yield. However, whether or not energy transfer between the host and the host or between the host and the guest can be efficiently performed is also a big problem. In addition, although the cause of luminescence degradation due to energization is not clear at present, it is assumed that it is related to the environmental change of the luminescent center material due to at least the luminescent center material itself or molecules existing around the luminescent center material. The

  On the other hand, the condensed polycyclic compounds of the formulas [1] and [2] both have a common skeleton called a diphenylbenzofluoranthene skeleton in the molecule, so that both compounds have good compatibility. Therefore, when the condensed polycyclic compound of the formula [1] and the formula [2] is used as a host or guest of the light emitting layer, the condensed polycyclic compound of the formula [1] and the formula [2] is a thin film that becomes the light emitting layer 4 respectively. Uniformly distributed within. This makes it difficult for the guests to associate with each other in the light emitting layer.

  Further, the HOMO energy of the condensed polycyclic compound of the formula [1] is shallower than the HOMO energy of the condensed polycyclic compound of the formula [2]. For this reason, when the condensed polycyclic compound of the formula [1] is used as a guest in the light emitting layer, the condensed polycyclic compound of the formula [1] tends to trap holes, so that the light emitting region tends to be biased toward the anode side. . Therefore, it is considered that the element is deteriorated when the element is continuously driven.

  In order to prevent the above-described hole trapping, for example, it is conceivable to form not only holes but also electrons in the light emitting layer. By doing so, the light emitting region in the light emitting layer can be expanded without being biased to a specific location.

  Here, in order to sufficiently trap holes and electrons, preferably, the host HOMO is set to be deeper than the guest HOMO by 0.3 eV, and the host LUMO is more than 0.3 eV than the guest LUMO. Set shallow. On the other hand, since the energy gap of the condensed polycyclic compound of the formula [1] is about 2.1 eV, the host preferably has an energy gap of about 2.7 eV in order to realize the above-described relationship between HOMO and LUMO. .

  Thus, when the host is made of a material having a wide energy gap, the emission wavelength of the host exists in a short wavelength region. On the other hand, since the absorption band of the condensed polycyclic compound of the formula [1] hardly exists in the short wavelength region, when only the condensed polycyclic compound of the formula [1] is used as a guest, In this case, the energy transfer efficiency is lowered and the color purity is lowered.

  Therefore, the condensed polycyclic compound of the formula [2] is used as a constituent material of the light emitting layer together with the condensed polycyclic compound of the formula [1] as an auxiliary dopant (assist dopant), for example. At this time, the condensed polycyclic compound of the formula [2] has good compatibility with the condensed polycyclic compound of the formula [1] and has an absorption band in the light emitting region of the host. Energy transfer to the ring compound can be performed smoothly and efficiently. Therefore, the light emitted from the guest can be extracted and the life of the device can be extended. Further, when the condensed polycyclic compound of the formula [1] is used as a guest, the same effect appears even if the condensed polycyclic compound of the formula [2] is used as a host corresponding to the guest.

  On the other hand, the above-mentioned condensed polycyclic compound having a pyrene skeleton is excellent in amorphous properties and has a high glass transition temperature, and thus has high heat resistance. For this reason, when the condensed polycyclic compound having the pyrene skeleton is used as a host of the light emitting layer, a stable and good thin film can be formed, and uniform light emission without unevenness can be obtained.

  As described above, the combined use of the condensed polycyclic compound of the formula [1] and the condensed polycyclic compound of the formula [2] as the constituent material of the light emitting layer 4 can maintain the luminance for a long period of time and Deterioration can be reduced. Further, in addition to the condensed polycyclic compound of the formula [1] and the condensed polycyclic compound of the formula [2], the use of a condensed polycyclic compound having a pyrene skeleton as a constituent material of the light emitting layer 4 further reduces the deterioration of energization. be able to.

  When the condensed polycyclic compound of the formula [1] or the condensed polycyclic compound of the formulas [1] and [2] is used as the guest of the light emitting layer 4, the concentration of the guest with respect to the host is 0.01 wt% to 50 wt%. %, Preferably 1% to 20% by weight. The guest may be uniformly contained in the entire layer composed of the host, or may be contained with a concentration gradient. In addition, a region of a layer made of a host that does not include the guest material may be provided by being partially included in a certain region.

  The organic light emitting device of the present invention uses the condensed polycyclic compound of the formula [1] and the formula [2] as a constituent material of the light emitting layer 4. In addition to these compounds, if necessary, low molecular weight and polymer hole transporting materials, light emitting materials, electron transporting materials and the like may be used together.

  Examples of these compounds are given below.

  The hole injecting and transporting material preferably has excellent mobility for facilitating the injection of holes from the anode and transporting the injected holes to the light emitting layer. Low molecular and high molecular weight materials having hole injection and transport performance include triarylamine derivatives, phenylenediamine derivatives, triazole derivatives, oxadiazole derivatives, imidazole derivatives, pyrazoline derivatives, pyrazolone derivatives, oxazole derivatives, fluorenone derivatives, hydrazones. Examples include, but are not limited to, derivatives, stilbene derivatives, phthalocyanine derivatives, porphyrin derivatives, poly (vinyl carbazole), poly (silylene), poly (thiophene), and other conductive polymers.

  The electron injection / transport material can be arbitrarily selected from those having a function of facilitating injection of electrons from the cathode and transporting the injected electrons to the light emitting layer. Further, it is selected in consideration of the balance with the carrier mobility of the hole transport material. Materials having electron injection and transport performance include oxadiazole derivatives, oxazole derivatives, thiazole derivatives, thiadiazole derivatives, pyrazine derivatives, triazole derivatives, triazine derivatives, perylene derivatives, quinoline derivatives, quinoxaline derivatives, fluorenone derivatives, anthrone derivatives, phenanthroline derivatives. , Organometallic complexes and the like, but are not limited thereto.

  Next, other members constituting the organic light emitting device of the present invention will be described.

  As a constituent material of the anode, a material having a work function as large as possible is preferable. For example, simple metals such as gold, platinum, silver, copper, nickel, palladium, cobalt, selenium, vanadium, tungsten, or alloys thereof, tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide, etc. The metal oxide can be used. In addition, conductive polymers such as polyaniline, polypyrrole, polythiophene, and polyphenylene sulfide can also be used. These electrode materials may be used alone or in combination of two or more. Moreover, the anode may be composed of a single layer or a plurality of layers.

  On the other hand, the material constituting the cathode is preferably a material having a small work function. Examples thereof include simple metals such as lithium, sodium, potassium, calcium, magnesium, aluminum, indium, ruthenium, titanium, manganese, yttrium, silver, lead, tin, and chromium. Further, these metals may be combined to form an alloy. For example, alloys such as lithium-indium, sodium-potassium, magnesium-silver, aluminum-lithium, aluminum-magnesium, and magnesium-indium can be used. Also, metal oxides such as indium tin oxide (ITO) can be used. These electrode materials may be used alone or in combination of two or more. Moreover, the cathode may be composed of a single layer or a plurality of layers.

  Although it does not specifically limit as a board | substrate used with the organic light emitting element of this invention, Transparent substrates, such as opaque board | substrates, such as a metal board | substrate and a ceramic board | substrate, glass, quartz, a plastic sheet, are used. It is also possible to control the color light by using a color filter film, a fluorescent color conversion filter film, a dielectric reflection film or the like on the substrate.

  Note that a protective layer or a sealing layer can be provided for the manufactured element in order to prevent contact with oxygen, moisture, or the like. Examples of protective layers include diamond thin films, inorganic material films such as metal oxides and metal nitrides, polymer films such as fluororesins, polyparaxylene, polyethylene, silicone resins, and polystyrene resins, and photocurable resins. Can be mentioned. Further, it is possible to cover glass, a gas-impermeable film, a metal, etc., and to package the element itself with an appropriate sealing resin.

  The element of the present invention can be manufactured by forming a thin film transistor (TFT) on a substrate and connecting it.

  As for the light extraction direction of the element, either a bottom emission type (a configuration in which light is extracted from the substrate side) or a top emission type (a configuration in which light is extracted from the opposite side of the substrate) is possible.

  In the organic light emitting device of the present invention, the light emitting layer and other organic compound layers are formed by the following method. In general, it is manufactured using a vacuum deposition method, an ionization deposition method, sputtering, or plasma. Further, it may be dissolved in an appropriate solvent to form a thin film by a known coating method (for example, spin coating, dipping, casting method, LB method, ink jet method, etc.). In particular, when a film is formed by a coating method, the film can be formed in combination with an appropriate binder resin.

  The binder resin can be selected from a wide range of binder resins. For example, polyvinyl carbazole resin, polycarbonate resin, polyester resin, polyarylate resin, polystyrene resin, ABS resin, polybutadiene resin, polyurethane resin, acrylic resin, methacrylic resin, butyral resin, polyvinyl acetal resin, polyamide resin, polyimide resin, polyethylene resin, Examples include, but are not limited to, polyethersulfone resins, diallyl phthalate resins, phenol resins, epoxy resins, silicone resins, polysulfone resins, urea resins, and the like. Moreover, you may mix these 1 type, or 2 or more types as a single or copolymer polymer. Furthermore, you may use together additives, such as a well-known plasticizer, antioxidant, and an ultraviolet absorber, as needed.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

<Evaluation of HOMO energy and LUMO energy>
In Examples described later, HOMO energy and LUMO energy were evaluated for compounds used as constituent materials of the light emitting layer.

  First, a thin film (thickness 20 nm) made of the constituent material of the light emitting layer was formed on a glass substrate by vacuum deposition. Next, the HOMO energy of this thin film was measured using an atmospheric photoelectron spectrometer (measuring instrument name: AC-2, manufactured by Riken Kikai Co., Ltd.). Moreover, about this thin film, the ultraviolet-visible light absorption spectrum measurement was performed using the spectrophotometer (measurement apparatus name: U-3010, Hitachi Ltd. make), and the energy gap was calculated | required from the absorption edge of the said absorption spectrum. Next, LUMO energy was calculated using the HOMO energy value and the energy gap value thus obtained. The results are shown in Table 1.

<Example 1>
The organic light emitting device shown in FIG. 1 was produced by the method shown below.

  On the glass substrate (substrate 1), indium tin oxide (ITO) was formed by sputtering to form the anode 2. At this time, the film thickness of the anode 2 was 120 nm. Next, this was ultrasonically washed successively with acetone and isopropyl alcohol (IPA), then washed with pure water and dried. Further, UV / ozone cleaning was performed. The substrate processed as described above was used as a transparent conductive support substrate.

  Next, Compound A1 shown below and chloroform were mixed to prepare a chloroform solution having a concentration of 0.1% by weight.

  Next, this chloroform solution was dropped on the anode 2 and spin coating was performed to form a thin film. Next, the hole transport layer 3 was formed by heating and drying in a vacuum oven at 80 ° C. for 10 minutes to completely remove the solvent in the thin film. At this time, the film thickness of the hole transport layer 3 was 10 nm.

Next, the exemplified compound No. which is a host is formed on the hole transport layer 3 by a vacuum deposition method. 2-2 and Exemplified Compound No. 1 which is a guest (first guest). 1-1 was co-evaporated to a weight ratio of 98: 2 to form the light emitting layer 4. At this time, the thickness of the light emitting layer 4 was 40 nm, the degree of vacuum during vapor deposition was 1.0 × 10 ⁻⁴ Pa, and the film formation rate was 0.1 nm / sec to 0.2 nm / sec.

Next, 2,9-bis [2- (9,9′-dimethylfluorenyl)]-1,10-phenanthroline is formed on the light-emitting layer 4 by vacuum deposition to form the electron transport layer 5. Formed. At this time, the thickness of the electron transport layer 5 was 20 nm, the degree of vacuum during vapor deposition was 1.0 × 10 ⁻⁴ Pa, and the film formation rate was 0.1 nm / sec to 0.2 nm / sec.

Next, a lithium fluoride film was formed on the electron transport layer 5 by a vacuum deposition method to form a LiF film. At this time, the film thickness of the LiF film was set to 0.5 nm, the degree of vacuum during vapor deposition was set to 1.0 × 10 ⁻⁴ Pa, and the film formation rate was set to 0.01 nm / sec. Next, aluminum was formed on the LiF film by vacuum deposition to form an Al film. At this time, the thickness of the Al film was set to 100 nm, the degree of vacuum at the time of vapor deposition was set to 1.0 × 10 ⁻⁴ Pa, and the film formation rate was set to 0.5 nm / sec to 1.0 nm / sec. Here, the LiF film and the Al film (aluminum-lithium alloy film) function as an electron injection electrode (cathode 6).

  Next, a protective glass plate was placed in a dry air atmosphere and sealed with an acrylic resin adhesive so as not to cause element degradation due to moisture adsorption. An organic light emitting device was obtained as described above.

When an electric current of 20 mA / cm ² was applied to the obtained device with an ITO electrode (anode 2) as a positive electrode and an Al electrode (cathode 6) as a negative electrode, red light emission was observed.

Next, the current applied to the device was set to 100 mA / cm ² and the reliability of the device was examined. Here, the reliability refers to the ratio of the luminance after 100 hours to the initial luminance when the element is continuously driven at 100 mA / cm ² . The results are shown in Table 2.

<Example 2>
In Example 1, instead of Compound A1, Compound A2 shown below and chloroform were mixed to prepare a chloroform solution having a concentration of 0.1% by weight.

  Except for this, an organic light emitting device was fabricated in the same manner as in Example 1. The obtained device was evaluated in the same manner as in Example 1. The results are shown in Table 2.

<Comparative Example 1>
In Example 1, Exemplified Compound No. Instead of 2-2, rubrene was used as the host of the light emitting layer. Except for this, an organic light emitting device was fabricated in the same manner as in Example 1. The obtained device was evaluated in the same manner as in Example 1. The results are shown in Table 2.

<Example 3>
In Example 1, Exemplified Compound No. Instead of 2-2, Exemplified Compound No. 3-3 was used as the host of the light emitting layer. As the second guest (assist dopant), Exemplified Compound No. 2-2 was used. Furthermore, Exemplified Compound No. 1-1, no. 2-2 and No. The light emitting layer 4 was formed by co-evaporation so that the weight ratio of 3-3 was 2: 1: 97. Except for this, an organic light emitting device was fabricated in the same manner as in Example 1. The obtained device was evaluated in the same manner as in Example 1. The results are shown in Table 2.

  From the above Table 2, it was shown that the organic light-emitting device containing both the condensed polycyclic compounds represented by the formula [1] and the formula [2] reduces luminance deterioration during continuous driving. In addition to the condensed polycyclic compound represented by the formula [1] and the formula [2], the organic light-emitting device including the condensed polycyclic compound having a pyrene skeleton can further reduce luminance deterioration during continuous driving. Indicated.

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Anode 3 Hole transport layer 4 Light emitting layer 5 Electron transport layer 6 Cathode 10 Organic light emitting element

Claims (2)

An anode and a cathode;
An organic compound layer sandwiched between the anode and the cathode and having at least a light emitting layer,
An organic light-emitting device, wherein the light emitting layer contains a condensed polycyclic compound represented by the following general formula [1] and a condensed polycyclic compound represented by the following general formula [2].

(In the formula [1], R _{1 to} R ₃₆ are each a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, respectively. A substituent selected from the group consisting of a substituted or unsubstituted aryloxy group, a substituted amino group, a halogen atom, a sulfide group and a silyl group, which may be the same or different.

(In the formula [2], R _{1 to} R ₃₂ are each a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, respectively. A substituent selected from the group consisting of a substituted or unsubstituted aryloxy group, a substituted amino group, a halogen atom, a sulfide group and a silyl group, which may be the same or different.   The organic light emitting device according to claim 1, further comprising a condensed polycyclic compound having a pyrene skeleton in the light emitting layer.

Images