JP2665788B2 - Organic electroluminescent device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an organic electroluminescent device,
More specifically, the present invention relates to an element which uses a perylene derivative as a light-emitting substance and emits light in response to an electric signal.

In particular, the present invention provides efficient light emission even at a low voltage,
The present invention relates to an electroluminescent element having a sufficient luminance.

[Conventional technology]

The organic electroluminescent element is configured such that an organic luminous body is sandwiched between opposed electrodes, and electrons are injected from one electrode and holes are injected from the other electrode.
It emits light when the injected electrons and holes recombine in the light emitting layer.

For such an element, a single-crystal substance such as single-crystal anthracene is used as a light emitter, but a single-crystal substance is expensive to manufacture and has many problems in terms of mechanical strength. Furthermore, it is not easy to reduce the thickness,
Light emission is weak in a single crystal of about m, and a driving voltage of 100 volts or more is often required, and has not reached a practical level.

Thus, for example, an attempt to obtain a film of anthracene of 1 μm or less has been made by a vapor deposition method (“Thin Solid Films”, Vol. 94, p. 171 1982).

However, in order to obtain sufficient performance, it is necessary to form a thin film of several thousand angstroms under strictly controlled film forming conditions, and although the light emitting layer is formed as a precise thin film, it is a carrier. Since the density of holes or electrons is very low and the probability of excitation of functional molecules due to carrier movement and recombination is low, efficient light emission cannot be obtained, and in particular, it is satisfactory in terms of power consumption and brightness. It is not at present.

Furthermore, JP-A-57-51781 and JP-A-59-51781 show that a hole injection layer is provided between the anode and the light-emitting layer, and high luminous efficiency can be obtained by increasing the density of holes as carriers.
No. 194393.

However, these use an electron-transporting compound as a light-emitting material, which requires a substance having both high luminous efficiency and high electron-transporting properties. However, such a substance having sufficiently satisfactory properties has not been found, and thus, at present, satisfactory performance in terms of luminance and power consumption has not been obtained.

[Problems to be solved by the invention]

The present invention solves these problems and provides a highly efficient electroluminescent element.

That is, an object of the present invention is to provide an organic electroluminescent device which has good luminous efficiency even at a low voltage and a low current density, can obtain sufficiently high luminance, is inexpensive and easy to manufacture.

[Means for solving the problem]

The present inventors have conducted intensive studies on an organic fluorescent material and an electron-transporting compound, and as a result, have found that a perylene derivative has both high luminous efficiency and high electron-transporting properties, and completed the present invention. Was.

That is, the present invention has: a hole injection transport layer, a light emitting layer, and a cathode in order on an anode;
An organic electroluminescence device in which at least one of these electrodes is transparent, wherein the light-emitting layer is a perylene derivative having a maximum fluorescence wavelength of 400 to 800.

 Hereinafter, the present invention will be described in detail.

The present invention is based on the discovery that in an organic electroluminescence device having a hole injection / transport layer, a light-emitting layer, and a cathode on an anode, high luminous efficiency and sufficient luminance can be obtained when a perylene derivative is used as a light-emitting layer. Is based on

One of the important applications of the organic electroluminescence device is a display device. Therefore, the perylene derivative used in the present invention has a maximum fluorescence wavelength of 400 to 800.
It must be in the visible region of nm, and must simultaneously satisfy a higher fluorescence yield and a higher electron transferability.

The perylene derivative used in the present invention can be synthesized by an ordinary well-known method, and can be further purified and used if necessary.

Purification is carried out, for example, by fractional precipitation from concentrated sulfuric acid, recrystallization from a high-boiling solvent which can be easily removed, or separation into individual components by boiling with the solvent under milling conditions. Alternatively, it can be carried out by a separation method by chromatography.

As the perylene derivative used in the present invention, for example, the following compounds can be exemplified.

[In the formula, R ¹ and R ² may be the same or different, and may be a linear or branched C ₁ -C ₁₈ alkyl group (the carbon chain of which is one or more groups -O-, -S- or Or a hydroxyl group, a cyano group, a halogen atom, a C _{1 to} C ₁₉ alkylcarbonyloxy group, a C _{2 to} C ₄ alkenylcarbonyloxy group, a C _{6 to} C
₁₂ cycloalkylcarbonyl group, or C ₅ -C ₁₈
May be substituted with a cycloalkyl group, and further a cyano group, a nitro group, a halogen atom, or a C ₁ to
A phenyl group, a phenoxy group, a naphthyl group, a naphthyloxy group, an anthryl group or an anthryloxy group which may be substituted by a C ₈ alkyl group), or an optionally substituted C ₅ ~ _C18 cycloalkyl group, or phenyl group, naphthyl group,
Anthryl group, a pyridyl group, a pyrazolyl group, quinolyl group, thiazolyl group or an oxazolyl group (which, hydroxyl, cyano group, a halogen atom, an alkyl group of C ₁ ~C _8, C ₁
Alkylcarbonyloxy group -C _19, alkenylcarbonyl group of C ₂ -C _4, a cycloalkyl carbonyl group of C ₆ -C _12, or C ₁₅ may be substituted by a cycloalkyl group -C _18, further substituted cyano group, a nitro group, a halogen atom, or C ₁ -C ₈ optionally substituted phenyl group by an alkyl group, a phenoxy group, a naphthyl group, a naphthyloxy group, a anthryl group or anthryl group May be. X ^{1 to} X ⁸ represent a hydrogen atom, a chlorine atom, a bromine atom, a group OR ³ ,
A group OCOR ³ or a group R ³ ; R ³ is a linear or branched C ₁ -C ₁₈ alkyl group having one or more carbon atoms of —O—, —S— or Or a hydroxyl group, a cyano group, a halogen atom, a C _{1 to} C ₁₉ alkylcarbonyloxy group, a C _{2 to} C ₄ alkenylcarbonyloxy group, a C _{6 to} C
₁₂ cycloalkylcarbonyl group, or C ₅ -C ₁₈
May be substituted with a cycloalkyl group, and further a cyano group, a nitro group, a halogen atom, or a C ₁ to
Alkyl phenyl group which may be substituted by a group of C _8, a phenoxy group, a naphthyl group, a naphthyloxy group, may be substituted by an anthryl group or anthryloxy group. ), Or a cycloalkyl group optionally C ₅ -C ₁₈ substituted or phenyl group, a naphthyl group, an anthryl group, a pyridyl group, a pyrazolyl group, quinolyl group,
Thiazolyl or oxazolyl groups (these are hydroxyl,
A cyano group, a halogen atom, an alkyl group of C ₁ ~C _8, C ₁ ~C
₁₉ alkylcarbonyloxy group, C ₂ -C ₄ alkenylcarbonyl group, a cycloalkyl carbonyl group of C ₆ -C _12, or C ₅ -C ₁₈ may be substituted by a cycloalkyl group, more Cyano group, nitro group,
It may be substituted by a halogen atom or a phenyl group, a phenoxy group, a naphthyl group, a naphthyloxy group, an anthryl group or an anthryloxy group which may be substituted by a C ₁ -C ₈ alkyl group. ). ] Wherein Y ^{1 to} Y ⁴ may be the same or different and represent a halogen atom, a cyano group or COOR ⁴ ; R ⁴ is a hydrogen atom, a linear or branched C _{1 to} C ₁₈ Alkyl group (the carbon chain of which is one or more groups -O-, -S
-Or Or a hydroxyl group, a cyano group, a halogen atom, a C _{1 to} C ₁₉ alkylcarbonyloxy group, a C _{2 to} C ₄ alkenylcarbonyloxy group, a C _{6 to} C
₁₂ cycloalkylcarbonyl group, or C ₅ -C ₁₈
May be substituted with a cycloalkyl group, and further a cyano group, a nitro group, a halogen atom, or a C ₁ to
Alkyl phenyl group which may be substituted by a group of C _8, a phenoxy group, a naphthyl group, a naphthyloxy group, may be substituted by an anthryl group or anthryloxy group. ), Or a cycloalkyl group optionally C ₅ -C ₁₈ substituted or phenyl group, a naphthyl group, an anthryl group, a pyridyl group, a pyrazolyl group, quinolyl group,
Thiazolyl or oxazolyl groups (these are hydroxyl,
A cyano group, a halogen atom, an alkyl group of C ₁ ~C _8, C ₁ ~C
₁₉ alkylcarbonyloxy group, C ₂ -C ₄ alkenylcarbonyl group, a cycloalkyl carbonyl group of C ₆ -C _12, or C ₅ -C ₁₈ may be substituted by a cycloalkyl group, more Cyano group, nitro group,
It may be substituted by a halogen atom or a phenyl group, a phenoxy group, a naphthyl group, a naphthyloxy group, an anthryl group or an anthryloxy group which may be substituted by a C ₁ -C ₈ alkyl group. X ^{1 to} X ⁸ are a hydrogen atom, a chlorine atom, a bromine atom, a group OR ³ , a group OCO
R ³ or a group R ³ ; R ³ is a linear or branched C ₁ -C ₁₈ alkyl group (the carbon chain of which has one or more groups —O—, —S— or Or a hydroxyl group, a cyano group, a halogen atom, a C _{1 to} C ₁₉ alkylcarbonyloxy group, a C _{2 to} C ₄ alkenylcarbonyloxy group, a C _{6 to} C
₁₂ cycloalkylcarbonyl group, or C ₅ -C ₁₈
May be substituted with a cycloalkyl group, and further a cyano group, a nitro group, a halogen atom, or a C ₁ to
Alkyl phenyl group which may be substituted by a group of C _8, a phenoxy group, a naphthyl group, a naphthyloxy group, may be substituted by an anthryl group or anthryloxy group. ) Or cycloalkyl group optionally C ₅ -C ₁₈ substituted or phenyl group, a naphthyl group, an anthryl group, a pyridyl group, a pyrazolyl group, a quinolyl group, a thiazolyl group or an oxazolyl group (which, hydroxyl, cyano group, halogen atom, an alkyl group of _{C 1 ~C 8, C 1 ~C} 19
Alkylcarbonyloxy group, C ₂ -C ₄ alkenylcarbonyl group, a cycloalkyl carbonyl group of C ₆ -C _12, or C ₅ -C ₁₈ may be substituted by a cycloalkyl group, more cyano group, a nitro group, a halogen atom, or C ₁ -C ₈ optionally substituted phenyl group by an alkyl group, a phenoxy group, a naphthyl group, a naphthyloxy group, optionally substituted by an anthryl group or anthryl group Good. ). More specifically, Japanese Patent Application Laid-Open No. 62-148571
A compound represented by the following general formula (III) described in JP-A No. (Wherein, R ⁵ and R ⁶ represent the same or different aliphatic, alicyclic, aromatic or heterocyclic residues, and X, Y and Z each represent a chlorine atom, a bromine atom or a group OR ⁷ means R
⁷ represents an unsubstituted or substituted phenyl group, naphthyl group or anthryl group. ) Or a compound represented by the following general formula (IV) described in JP-A-57-125260; (In the formula, R ⁸ and R ⁹ each represent an isopropyl group or a chlorine atom, or R ^{8 represents a} methyl group and R ⁹ represents a C ₃ or C ₄ alkyl group.) A compound represented by the following general formula (V) described in -89485; Wherein n is a number of 0, 2, 3 or 4, and R ¹⁰ and R ¹¹ are
Independently of each other, a linear or branched C ₄ -C ₁₈ alkyl group (the carbon chain of which is composed of one or more groups —O— or —S
- which may be interrupted by, and are separated by two -O- and / or -S- are at least two carbon atoms), or a hydroxyl group, a cyano group, alkylcarbonyl C ₁ -C ₁₉ oxy group, C ₂ -C ₄ alkenylcarbonyl group, or a C ₆ -C ₁₂ cycloalkylcarbonyl group of C ₂ -C ₁₈ substituted with oxy groups,
Alternatively, C ₅ -C ₁₈ substituted by a cycloalkyl group
₁ or C ₂ alkyl group or by or one or two 1-5 alkyl groups C ₁ -C ₄ carboxyalkyl -C ₁ -C _4,
A C ₅ -C ₁₈ cycloalkyl group which may be substituted by an alkoxy group or by one or two trifluoromethyl groups (this C ₅ -C ₁₈ cycloalkyl group or
_{The 6- C18} cycloalkyl group may include 1 to 6 rings. ). Or a compound represented by the following general formula (VI) described in JP-A-62-201966; (Wherein, Y ⁵ is a halogen atom or a cyano group, R ¹² is a hydrogen atom, a linear or branched C ₁ -C ₁₈ alkyl group, C ₅ -C ₁₈
Of a cycloalkyl group alkyl or C ₇ -C ₁₈ a C ₁ or C ₂ substituted by a cycloalkyl group, these cycloalkyl groups may contain up to four rings, X ⁹
Is a chlorine atom or a bromine atom, and n is 0, 1 or 2. ).

To use the perylene derivative of the present invention as a light emitting layer,
A light emitting layer is provided between the hole injection transport layer and the cathode, but the anode,
A hole injection transport layer, a light emitting layer, and a cathode may be provided in this order,
A cathode, a light emitting layer, a hole injection / transport layer, and a cathode may be provided in this order.

As the anode, a transparent or opaque conductive material formed on an insulating support is used. When the cathode is opaque, the anode needs to be transparent. Preferred examples include conductive oxides such as tin oxide, indium oxide and indium tin oxide (ITO) or metals such as gold, silver and chromium, inorganic conductive substances such as copper iodide, polythiophene, polypyrrole and polyaniline. A conductive polymer can be used.

Preferred as the cathode, for example, indium, silver,
Translucent or opaque electrodes formed from tin, aluminum, lead, magnesium, and the like.

To use the perylene derivative of the present invention as a light emitting layer,
It may be formed by vapor deposition or the like, or may be formed by coating with or without a binder as necessary.

As the binder, ordinary polymers can be used, for example, polystyrene, polymethyl methacrylate,
Examples include polyacrylonitrile, polyester, polycarbonate, polysulfone, and polyphenylene oxide. The amount of the binder used in this case is not particularly limited, but is preferably 100 parts by weight or less based on 1 part by weight of the perylene derivative.

The thickness of the light emitting layer at this time is desirably 50 ° or more and 1 μm or less.

Next, a hole injection / transport layer is provided on the anode or the light emitting layer. In this case, the hole injecting and transporting layer is a layer that facilitates injection of holes from the anode and transports the injected holes to the light emitting layer, and a hole transporting compound can be used. Desirably, it is transparent to the light generated in the layer.

Furthermore, in order to obtain an optimal organic electroluminescence device, it is necessary to adjust the energy levels (ionization potential, electron affinity, etc.) of the hole injection transport layer and the light emitting layer.

The hole-transporting compound is an electron-donating compound, and the hole-transporting compound alone or these are dissolved in a binder resin,
Used in dispersed form.

Preferred examples include the following compounds. Polyvinyl carbazole, 2,6-
Polyester obtained from dimethoxy-9,10-dihydroxyanthracene and dicarboxylic acid, anthracene derivative such as 2,6,9,10-tetraisopropoxyanthracene, 2,5-bis (4-diethylaminophenyl) -1,3 ,Four
Oxadiazoles such as oxadiazole, N, N '
-Diphenyl-N, N '-(3-methylphenyl) 1,1'-
Triphenylamine derivatives such as diphenyl-4,4'-diamine; pyrazoline derivatives such as 1-phenyl-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) 2-pyrazoline; 4- (diethylamino)
Styryl compounds such as styryl-2-anthracene; p-
Hydrazone compounds such as diethylaminobenzaldehyde- (diphenylhydrazone); stilbene compounds; metal or metal-free phthalocyanines; porphyrin compounds.

Examples of the binder resin include polyvinyl chloride, polycarbonate, polystyrene, polyester, polysulfone, polyphenylene oxide, polyurethane, and epoxy resin.

The hole injection transport layer does not necessarily have to be a single layer,
If necessary, two or more layers may be laminated. The thickness is preferably as thin as not to produce pinholes, usually 1 μm.
It is used in the following thickness.

(Examples) Hereinafter, the present invention will be described in more detail with reference to Examples.
This does not limit the scope of the invention. N, N 'on ITO glass (HOYA Co., Ltd.)
-Diphenyl-N, N '-(3-methylphenyl) 1,1'-
Diphenyl-4,4-diamine was heated to 150 ° C. at a vacuum of 3 × 10 ⁻⁶ Torr and deposited to a thickness of 750 °.

Next, as a light-emitting layer, perylene-3,4,9,10-tetracarboxylic acid-bis (2 ', 6'-diisocypropylanilide) (manufactured by BASF) was applied at a vacuum of 1.2 × 10 ⁻⁶ torr. 270 ℃
And evaporated to a thickness of 800 mm.

Next, metal indium was deposited thereon as a negative electrode through a shadow mask in an area of 0.1 cm ² to define the area of the device.

When a DC voltage was applied to the device thus prepared using the ITO electrode as an anode, orange light of 620 nm was emitted.
Its luminance was ²⁰ cd / m ² at 16 V and 70 mA / cm ² .

Example 2 Perylene-3,4,9,10-tetracarboxylic acid-bis-isobutylimide (manufactured by BASF) as a light emitting layer was 2.2 × 10 ^−6.
A device was prepared in the same manner as in Example 1 except that the device was heated to 205 ° C. under a vacuum of torr and provided in a thickness of 450 °.

The emission wavelength of this device was 604 nm, and the luminance was 30 cd / m ² at 15 V and 60 mA / cm ² .

Example 3 1,6,7,12-tetraphenoxy-N, N'-
Using 2,6-diisopropylphenylperylene-3,4,9,10-tetracarboxylic diimide (manufactured by BASF), 3.2 × 10
^A device was prepared in the same manner as in Example 1 except that the device was heated to 210 ° C. under a vacuum of ⁻⁶ torr and provided in a thickness of 480 °.

This device has a luminance of 10 cd / m ^{2 at} 20 V, 100 mA / cm ² .
Showed light emission of 615 nm.

Example 4 1,7-dichloro-6,12-diphenoxy N,
N'-2,6-diisopropylphenylperylene-3,4,9,10
A device was prepared in the same manner as in Example 1 except that tetracarboxylic diimide was used and heated to 180 ° C. under a vacuum of 2.2 × 10 ⁻⁶ torr to provide a thickness of 550 °.

This device, 18V, when the 120 mA / cm ^2, the luminance is 15 cd / m ²
Showed light emission of 605 nm.

Example 5 Perylene-3,4,9,10-tetracarboxylic acid-bis- (2'-methyl-6'-isopropylanilide) was heated as a light emitting layer to 260 ° C. at a vacuum of 2.2 × 10 ^-6 torr. Then 70
An element was prepared in the same manner as in Example 1 except that the element was provided with a thickness of 0 °.

This device emitted an orange light of 25 cd / m ² at 15 V and 72 mA / cm ² .

Example 6 As a light emitting layer, And heated to 200 ° C. at a vacuum of 2.5 × 10 ⁻⁶ Torr,
An element was prepared in the same manner as in Example 1 except that the element was provided with a thickness of 0 °.

This device, 20V, when 35 mA / cm ^2, the luminance is 500 cd / m ²
Showed light emission of 560 nm.

Example 7 Except that 4,10-dicyanoperylene-3,9-dicarboxylic acid isobutyl ester was heated to 175 ° C. under a vacuum of 1.2 × 10 ⁻⁶ torr and provided in a thickness of 680 ° as a light emitting layer. An element was prepared in the same manner as in Example 1.

At 18 V, 90 mA / cm ² , emitted 508 nm light of 58 cd / m ² .

Example 8 1-phenyl-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) -2-pyrazoline was used as a hole injecting and transporting layer on ITO glass (manufactured by HOYA Corporation) at 2 × ^{Deposited to} a thickness of 500 ° C. at a vacuum of 10 ⁻⁶ Torr. Next, as a light emitting layer, perylene-3,4,9,10-tetracarboxylic acid-2 '-(2 "-butyl) -6'-ethylanilide was deposited at 650 ° at a vacuum of 1.2 × 10 ^-6 torr. Next, indium was vapor-deposited thereon as a cathode in the same manner as in Example 1 to form a device.
V, 85 mA / cm ² , emitted 85 cd / m ² of orange light.

Example 9 Metal-free phthalocyanine (manufactured by Toyo Ink Co., Ltd.) was used as a hole injecting and transporting layer on ITO glass (manufactured by HOYA).
At a vacuum of 1.2 × 10 ⁻⁶ Torr, the film is deposited to a thickness of 150 °, and 4- (diethylamino) styryl-2-anthracene is further deposited thereon at a vacuum of 2 × 10 ⁻⁶ Torr.
Evaporated to a thickness of Å. Next, as a light emitting layer, 1,6,7,12
-Tetrachloro-di-n-butylperylene-3,4,9,10-
Using a tetracarboxylic diimide, the film was deposited to a thickness of 650 ° at a vacuum of 2.8 × 10 ⁻⁶ Torr. Next, indium was deposited thereon as a cathode in the same manner as in Example 1 to form an element.

This device, 11V, with 62mA / cm ^2, of 120 cd / m ^2, a luminance 5
It emitted light at 51 nm.

〔The invention's effect〕

According to the present invention, an organic electroluminescent device comprising an anode, a hole injection / transport layer, a light emitting layer, and a cathode,
By using a perylene derivative having both high luminous efficiency and high electron transfer properties for the light-emitting layer, an organic electroluminescent device that has good luminous efficiency and sufficient luminance, is inexpensive and easy to manufacture, can get.

Claims (1)

(57) [Claims] 1. An organic electroluminescence device having a hole injection / transport layer, a light-emitting layer, and a cathode in order on an anode, wherein at least one of these electrodes is transparent. An organic electroluminescent device, which is a perylene derivative having a wavelength of up to 800 nm.