JPH08259939A - Electron transport material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electron transport material which has a low operating voltage and a high stability and is useful for an electroluminescent device such as a light-emitting diode by using a specific polymer having electron-deficient units.

SOLUTION: The electron transport material comprises a polymer having electron-deficient units having structures represented by Ar-R-Ar [wherein R is a group selected from among groups represented by the formulas (wherein R' is H, an alkyl, aryl, trifluoromethyl, cyano, or halo); and Ar is an optionally substd. phenyl, optionally substd. pyridyl, or optionally substd. naphthyl], the electron-deficient units having a reduction potential of about -1 V to -2.4 V based on a calomel electrode. The units can be incorporated into a polymer such as a polyaryl acrylate, a polyaryl methacrylate, polyformal, or a polyaryl ether. The material pref. has a mol.wt. of about 5,000 or higher and a Tg of 100°C or higher.

COPYRIGHT: (C)1996,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a light emitting diode (LE).
Ds) relates to electron-transporting materials useful in electroluminescent devices.

[0002]

BACKGROUND OF THE INVENTION Electroluminescent devices having an active polymer layer are known. An example of such an LED is shown in FIG. Such a device typically has a light emitting polymer 10 sandwiched between an anode 20 and a cathode 30. Typically, indium-tin-oxide (ITO)
Is used as the anode and a low work function metal such as calcium, Mg / Ag, or aluminum is used as the cathode.

A multilayer structure is formed on the substrate 40. K
ido, J .; , Et al. "1,2,4-as an electron transport layer in an organic electroluminescent device.
Triazole derivatives "Jpn. J. Appl. Phy
s. 32 (2; 7A) pp. 917-920 (199
As reported in 3), an electron transport layer is used in combination with a light emitting material. The light emitting polymer 10 is typically sandwiched between an electron transport layer 50 and a hole transport layer 60. When an electric current is applied to the device of this structure, following the injection of electrons into the conduction band of the light emitting polymer and the injection of holes into the valence band of the light emitting polymer, the holes and electrons recombine to form excitons. To generate. The radiatively decaying singlet excitons emit light.

[0004]

Poly (phenylene vinylidene) (PPV) and PPV derivatives are known as light emitting polymers that also transport holes. Therefore, when PPV and its derivatives are used in an electron transport device, the number of organic layers is reduced to two. The efficiency of PPV-containing light emitting devices depends, at least in part, on the material selected for the electron transport layer. Asachi, S .; , Et a
l. , Appl. Phys. Lett. , 57 p. 53
1 (1990) is 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1, shown in FIG.
3,4-oxadiazole) (PBD) is proposed as an electron transport material for a light emitting device. Kido, et a
l. Is 3- (4-biphenylyl) -4 shown in FIG.
-Phenyl-5- (4-tert-butylphenyl)-
1,2,4-triazole) (TAZ) is proposed as an electron transport material for a light emitting device. However, due to the properties of these materials, it is difficult to form stable films with them. For example, with PBD alone, a thin film (approximately 5
Recrystallize as 00Å). To make a usable PBD membrane, it is typical to enclose the PBD in an inert polymer matrix. However, this polymer matrix dilutes the PBD in the resulting membrane. PB
The electron-transporting capacity of D is reduced by dilution of PBD in the inert polymer matrix. When PBD is placed in a polymer matrix, the polymer matrix also plasticizes, impairing device stability over time, and also possible glass transition point (Tg) of host-matrix system.
Also decreases. Similar problems are expected when an electron transport film is formed using TAZ. That is, the performance and lifetime of LEDs with PBD-containing and TAZ-containing films is less than desired. Because of these drawbacks of the above materials, improved electron transport materials for use in light emitting devices are desired.

[0005]

The present invention relates to an electron transport material used in a light emitting device. These materials contain electron deficient units. Examples of these electron deficient units include heterocycles that allow materials such as thiadiazole, thiazole, oxadiazole, oxazole, triazole, or quinoxaline to function as an n-type semiconductor and thus have electron transport capability. . It is advantageous if at least two aromatic substituents are bound to the heterocycle. Typically, these electron deficient units have a reduction potential of about -1 V to about -2.4 V with respect to the calomel electrode. The electron-deficient unit of the present invention has a structure of the general formula Ar-R-Ar. In this formula, R is

[0006]

[Chemical 4]

And R'is H, alkyl, aryl,
Selected from the group consisting of trifluoromethyl (CF3), cyano (CN), or halo (eg, fluoro, chloro, bromo, or iodo), and Ar
Is a substituted or unsubstituted phenyl group, a substituted or unsubstituted pyridyl group, or a substituted or unsubstituted naphthyl group. If the aryl group is substituted, the aryl group may be hydroxy, alkyl, halo, CF ₃ , C
It may be substituted with one or more of N and aryl.

The electron deficient unit is incorporated into the polymer. In one embodiment of the invention, electron deficient units are incorporated into the backbone of the polymer chain. The electron deficiency unit is
A monomer having electron-deficient units (referred to herein as an electron-deficient monomer) is incorporated by copolymerizing with at least one other monomer. Examples of suitable comonomers include halogen-containing monomers that are susceptible to nucleophilic substitution. In this embodiment, the electron deficient monomer has the structure of the general formula HO-Ar-R-Ar-OH. In this formula, R and Ar are the same as defined above. This monomer is copolymerized with other conventional formal, aryl ether, or aryl ester polymer monomers used in the synthesis. Examples of such monomers include those of the formula:

[0009]

Embedded image Here, X is a halo group. It is advantageous if X is chlorine, bromine or fluorine.

In another embodiment of the invention, electron deficient units are attached to the polymer backbone. In this embodiment, the polymers are acrylates of these polymers,
It is either methacrylates, acrylamides, methacrylamides, styrenes, or methylstyrenes or derivatives of these polymers. In the case of styrenes, methylstyrenes and their derivatives,
The phenylene group of the styrene monomer is one of the phenyl groups of the electron deficient unit. The electron deficient units are attached to the acrylate and methacrylate monomers via ester bonds, to the acrylamide and methacrylamide monomers via amide bonds, and to the styrene and methylstyrene monomers via phenylene bonds.

In the present invention, the above-mentioned monomers can be copolymerized with other monomers having no electron-deficient unit. Examples of the above monomers for forming the electron transport material of the present invention by copolymerization include acrylate monomers, methacrylate monomers, acrylamide monomers, methacrylamide monomers, styrene monomers, and methylstyrene monomers. Derivatives of these monomers can also be used.

The resulting polymer having the electron-deficient units described above is cast into a film so that the polymer is at least about 500.
It is advantageous to have a molecular weight of 0. Advantageously, the polymer has a Tg of at least about 100 ° C. It is also advantageous for the polymer to have sufficient solubility in at least one of the standard spinning solvents to form films by spin coating. Examples of standard spinning solvents include cyclohexane, chlorobenzene, xylene,
And dimethylacetamide. Polymers and polymerizable materials having such properties can be easily applied on a substrate by spin coating. The resulting electron transport film is useful in light emitting devices such as LEDs.

[0013]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel group of materials useful as electron transport materials in electroluminescent devices such as LEDs. These materials have electron deficient units. These units can be incorporated into polymers such as, for example, poly (aryl acrylates), poly (aryl methacrylates), poly (formals), and poly (aryl ethers). The polymer is cast into a film on the electroluminescent device.

The electron deficient unit is a heterocycle such as oxadiazole, oxazole, triazole, or quinoxaline and their derivatives. In one embodiment of the invention, the electron deficient unit has the general formula HO-Ar-R-Ar-.
It is incorporated into a monomer having the structure of OH. In this formula, R and Ar are the same as defined above. A method for synthesizing the monomer having the above structure is shown in Examples 1 and 2 described later. The present invention is not limited to the individual material synthesis methods disclosed herein.

The above monomers are copolymerized with at least one monomer which is capable of polymerizing with the aforementioned monomers. Examples of such a monomer include a halogen-containing monomer that is easily subjected to nucleophilic substitution. The monomers used in the synthesis of conventional formal, aryl ether, or aryl ester polymers are suitable. Examples of the monomer that can be copolymerized with the monomer having an electron deficient unit include the following.

[0016]

[Chemical 6] Here, X is a halo group. It is advantageous if X is chlorine, bromine or fluorine. Examples of polymers produced by this copolymerization include the general formula

[0017]

[Chemical 7] And a diphenyloxadiazole-containing polymer. In the above formula, R is

[0018]

Embedded image Is one of. As another example of the polymer to be produced, a general formula

[0019]

[Chemical 9] The triazole-containing polymers of R in the above formula
Is

[0020]

[Chemical 10] Is one of. Representative synthesis methods of the copolymer having the above structure are shown in Examples 3 and 4 described later.

In another embodiment of the invention, the units are attached to the polymer backbone. In this embodiment, the polymerizable material capable of forming a polymer is any of acrylate, methacrylate, acrylamide, methacrylamide, styrene, and methylstyrene. Derivatives of these monomers can also be used. The electron deficient unit is bonded to the acrylate and methacrylate monomers via an ester bond, to the acrylamide and methacrylamide monomers via an amide bond, and to the styrene and methylstyrene monomers via a phenylene bond. In the case of styrene and methylstyrene monomers, one of the Ar groups in the electron deficient unit is a phenylene bond. Examples of polymers produced by the polymerization of these monomers include:

[0022]

[Chemical 11] And a diphenyloxadiazole-containing polymer such as As another example,

[0023]

[Chemical 12] And diphenyloxadiazole-containing acrylamide. Typical synthetic methods of the above-mentioned polyacrylate and its precursor are shown in Examples 5 to 10 described later.

In another embodiment, the above-mentioned monomers can be copolymerized with other monomers that do not have electron-deficient units. If the above-mentioned monomer is capable of copolymerizing with other monomers, it is advantageous if this comonomer is capable of polymerizing with the above-mentioned monomer. In this regard, the above-mentioned acrylate monomers, methacrylate monomers and derivatives of these monomers having electron-deficient units can be copolymerized with other acrylate monomers. Subsequently, the above-mentioned acrylamide monomer having an electron-deficient unit is copolymerized with another acrylamide monomer and its derivative, and the above-mentioned styrene monomer having an electron-deficient unit is copolymerized with a styrene monomer and its derivative.

The materials described above are used as electron-transporting materials in luminescent devices such as LEDs. The general structure of such a device is shown in FIG. In this device, the electron transport material 120 and the light emitting layer 100 are sandwiched between two electrodes 130 and 140. Electrode 130 is typically an anode made of ITO and electrode 140 is typically a cathode made of a material such as calcium, Mg / Ag, or aluminum. The device is typically formed on a glass substrate 150.

Such a device is formed by conventional methods. Methods of forming the various layers are well known to those skilled in the art.
One example of a light emitting polymer is a polymer such as polyphenylene vinylene (PPV) commercially available from Uniax Corporation of Santa Barbara, CA. However, any light emitting polymer and hole transporting polymer can be used with the electron transporting material of the present invention. The PPV layer is formed on the ITO layer by a conventional method. The electron transport material of the present invention on the PPV layer is formed by combining the electron transport material with a conventional spinning solvent such as cyclohexane, chlorobenzene, xylene, or dimethylacetamide. The concentration of the material in the solvent depends largely on the design choice and depends on the desired film thickness. The electron transport material film of the present invention has a thickness of about 100Å to about 5
It is typically 00Å. A single layer of electron transporting material is typically used to obtain the desired thickness of electron transporting material.

[0027]

Example 1 m-Anisoyl chloride (24 g: 0.144)
mol: obtained from Aldrich Chemical Company) and N, N
-Dimethylacetamide (hereinafter referred to as DMAc) (10
0 mL: obtained from Aldrich Chemical Co.)
The mixture was added to a dropping funnel and a 1-liter three-necked flask equipped with a nitrogen blowing port. Use this solution with dry ice-
Cooled to 10 ° C. m-anisick hydrazide (2
4.6 g: 0.144 mol: obtained from Aldrich Chemical Co.) in DMAc (100 mL) was added dropwise to the flask over 35 minutes. The dropping flask was then washed with dry DMAc (1 mL; 5 times). While stirring the obtained mixture, water (3
L). The white precipitate that formed was filtered, washed with water, then petroleum ether, and left to dry overnight to give an off-white solid (38.92 g). A recrystallized product from a mixture of toluene and DMAc (50: 1) was identified as 1,2-bis (3'-methoxybenzoyl) hydrazide with a melting point of 184 ° C to 190 ° C.

This 1,2-bis (3'-methoxybenzoyl) hydrazide (18.4 g: 61.3 mmol)
Was placed in a 250 mL flask and immersed in an oil bath at a temperature of 75 ° C. for 4 hours under reduced pressure to ensure drying.
The compound was then cooled to about 40 ° C. Phosphorus oxychloride (60 mL: obtained from Aldrich Chemical Co.) was slowly added to this compound and the mixture was heated to reflux. After 30 minutes the mixture was observed to be homogeneous. Thin layer chromatography (TLC) using a 1: 1 mixture of petroleum ether and ethyl acetate (EtOAc)
The reaction was shown to be complete after 30 minutes. TLC is silica gel F-254 (thickness 0.25m
m) coated commercially available Kiesel gel
el) plate. Add this mixture to ice water (1 L)
While stirring, the mixture was added little by little. KOH pellets were added to neutralize the pH of this water mixture. The produced precipitate was filtered and washed to obtain a white solid (16.8 g). Recrystallization from ethanol gave needle crystals of 2,5-bis (3'-methoxyphenyl) -1,3,4-oxadiazole.

2,5-bis (3'-methoxyphenyl)
500m of -1,3,4-oxadiazole (14g)
It was taken in a L round bottom flask and cooled to -78 ° C. Use a syringe in the flask to add BBr ₃ (1
M: 150 mL) was added with stirring. The mixture solidified after a few minutes and then warmed to room temperature. TLC showed that both methyl protection groups were cleaved. 2 mL of this solution was added to water (1.4 L) in a 2 L beaker while stirring. The white precipitate obtained was filtered, washed with water and dried overnight. White solid (11.66
g) was obtained. 2,5-bis (3'-hydroxyphenyl) -1,2 by ethanol recrystallization using activated carbon
Needle crystals of 3,4-oxadiazole (7.72 g) were obtained. The mode of this synthetic method is shown in FIG.

[0030]

Example 2 Triethylamine (60.9 g; 0.60
2 mol) to tetrahydrofuran (THF) (300
1L with m-anisic chloride (100 g; 0.602 mol) in mL; obtained from Aldrich)
Add to a round bottom flask at 0 ° C. over 10 minutes. 3-aminobenzotrifluoride (90g; 0.602mo
What melt | dissolved 1) in THF (100 mL) was added dropwise to this triethylamine solution over 50 minutes. The solution thus obtained was concentrated under reduced pressure to about 250 mL. Water (150 mL) was added to this mixture and residual THF
Was removed under reduced pressure. Diethyl ether (150 mL;
The organic compound was extracted from this water using (3 times). The extracts were combined, washed with water (350 ml; twice), dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. Long white crystals of N- (3'-methoxybenzoyl) -3-trifluoromethylaniline by recrystallization from cyclohexane (about 1.5 L) (146.6 g).
I got

N- (3 'in thionyl chloride (320 mL)
-Methoxybenzoyl) -3-trifluoromethylaniline (70 g; 0.241 mol) was added to a 1 L round bottom flask and the mixture was heated to reflux. After 3 hours the thionyl chloride was removed under reduced pressure to give a light brown liquid. Distilled under reduced pressure at a temperature of 140-145 ° C.
A transparent yellow liquid containing-(3-trifluoromethyl) -3-methoxybenzimidyl chloride (40.8 g) was obtained.

N- (3-trifluoromethyl) -3-methoxybenzimidyl chloride (33.05 g;
107 mol), toluene (50 mL), m-anisic hydrazide (17.76 g; 0.107 mol),
And dry DMAc (64 mL) with a thermometer, Dean-
Stark trap (Dean-Stark tra
p) and a 500 mL three-neck round bottom flask equipped with a nitrogen inlet. The mixture was heated to 135 ° C for 30 minutes. After 2 hours, the mixture was cooled and concentrated under reduced pressure. The dark yellow solid obtained was stirred under stirring with water (800 m
L). The mixture was then filtered and dried. White powder (3,5-bis (3'-methoxyphenyl) -4
-(3'-trifluoromethylphenyl) -1,2,4
-Triazole) was obtained.

BBr ₃ (165M 1M solution in CH ₂ Cl ₂
mL) to 5-bis (3'-methoxyphenyl) -4-
(3'-trifluoromethylphenyl) -1,2,4-
Triazole (23 g; 54.5 mmol) was added 5
Add to a 00 mL flask at -78 ° C using a syringe. A clear dark brown solution formed. The dry ice acetone bath was removed and the mixture was warmed to 23 ° C. After 1 hour, this solution was slowly added to water (1 L). KOH pellets were gradually added to this mixture to adjust the pH to about 10. Glacial acetic acid was then added to the mixture until the pH was about 5. The white precipitate obtained was filtered, washed first with water and then with petroleum ether and dried to give an off-white product (23.68 g). Recrystallized from isopropanol: DMAc (about 900 mL: 30 mL) to give 3,5-bis (3′-hydroxyphenyl) -4-.
(3'-trifluoromethylphenyl) -1,2,4-
Triazole (14.49 g) was obtained. This synthetic method is shown in FIG.

[0034]

Example 3 The poly (formal) synthetic route for the polymers of this invention is illustrated by this example. 3,5-
In a 15 mL round bottom flask containing bis (3′-hydroxyphenyl) -4- (3′-trifluoromethylphenyl) -1,2,4-triazole (1 g: 2.52 mmol) was added N-methyl (pyrrolidone) ( 2 mL) and CH ₂
Cl ₂ (1.33 mL) was added. The solution was stirred for 5 minutes. KOH pellets (0.5 g:
8.9 mmol) and 3,5-di-tert-butylphenol (0.012 g: 0.025 mmol) were added and the mixture was heated to 70 ° C. 4.5 hours later,
This solution was diluted with DMAc (about 4 mL) and stirred rapidly in a Waring blender while isopropanol: water: AcOH (80
(mL: 80 mL: 40 mL) was added dropwise to a 200 mL mixture. The white fibrous polymer was collected by filtration, washed alternately with isopropanol, water and isopropanol, then dried. This synthetic method is shown in FIG.

[0035]

Example 4 The polymer poly (aryl ether) synthesis route of the present invention is illustrated by this example. In a 15 mL three-necked round bottom flask equipped with a Dean Stark trap, a cold water condenser, a thermometer and a nitrogen inlet, 2,5-bis (3'-hydroxyphenyl) -1,
3,4-Oxadiazole (0.8g: 3.147mm
4,4′-difluorodiphenylsulfone (0.8 g: 3.147 mmol); anhydrous potassium carbonate (0.522 g; 3.78 mmol); toluene (6 m
L); and DMSO (8 mL). The mixture was heated to reflux and toluene was removed stepwise to reach the reaction temperature below: 137 ° C (0.5h) and 142-1.
45 ° C (4h). The mixture was diluted with DMAc (6 mL), filtered, isopropanol / water / AcOH (150 mL) with rapid stirring using a Waring blender.
(mL: 150 mL: 75 mL) was added dropwise. The precipitate was filtered, washed successively with isopropanol / water and isopropanol and dried to give a white fibrous precipitate (1.34 g). This synthetic method is shown in FIG.

[0036]

Example 5 Benzoyl chloride (21.65 g; 0.154 mol) in m-anisic hydrazide (25.6 g; 0.154 mol) and dry DMAc (180 mL) in 20 mL of dry DMAc were added to IL at 0 ° C. Add to round bottom flask. The clear brown solution was stirred for 1 hour.
The ice water bath was removed, the mixture was warmed to 23 ° C. and stirred for a further 2 hours. Completion of the reaction was confirmed by TLC as described in Example 1. This mixture is slowly mixed with water (2.5
L) was added with stirring. The liquid was filtered and dried to give an off-white solid (38.63g). toluene/
Recrystallization from DMAc gave a white powder (33.3 g).

White powder, 1-benzoyl-2- (3'-
Phosphorus oxychloride (150 mL) was added to a 500 mL flask containing methoxybenzoyl) hydrazide (33 g). The mixture was heated to its reflux temperature with stirring. The mixture became homogeneous within about 15 minutes, but the reaction continued for about 45 minutes. This solution was cooled to about 50 ° C., and 2 mL each was gradually added to stirred ice water (1.5 L). While cooling the solution to make the pH neutral,
Potassium hydroxide (KOH) pellets were added to this mixture. This solution was rapidly stirred in a Waring blender, and the formed precipitate was ground into a fine powder. Filtration,
Drying gave a tan solid (26.05g).
Refluxing in toluene gave a white solid (22.4 g).

2- (3'-methoxyphenyl) -5-phenyl-1,3,4-oxadiazole (14.5 g)
To a 500 mL round bottom flask at the temperature of -78 ° C.
Boron tribromide (1M in dichloroethane solution; 86.2 mL) was added using a syringe. The mixture solidified to an off-white solid after 10 minutes. The flask was removed from the bath and the solution was warmed to room temperature over about 30 minutes to give a clear brown liquid. The TLC method described in Example 1 showed that the reaction was complete after 1.5 hours. The reaction mixture was added to water (1.5 L) in 2 mL portions with stirring. The white solid obtained is filtered and the pH of the filtrate is
Washed to about 7 with water. The solid was dried with suction for about 1 hour and then added to water (about 400 mL). The product was crushed to a powder by running a warning blender. It was filtered and dried to obtain an off-white solid (13.12 g). Recrystallization from an aqueous solution of methanol (MeOH) (1 part of water to 3 parts of MeOH; twice) in the presence of activated carbon
(3'-hydroxyphenyl) -5-phenyl-1,
White needle crystals of 3,4-oxadiazole (11.73 g) were obtained. This synthetic method is shown in FIG.

[0039]

Example 6 2,5-Diphenyl-1,3-oxazole (10 g; obtained from Aldrich) was gradually added to a 250 mL round bottom flask containing 40 mL of fuming nitric acid.
Add at 10 ° C. over 10 minutes. The resulting mixture was added to water (1 L) in 2 mL portions. The mixture was filtered to give a light yellow solid (12g). 5-by recrystallization from glacial acetic acid
Light yellow needle crystals of (4′-nitrophenyl) -2-phenyl-1,3-oxazole (10.35 g) were obtained.

Concentrated hydrochloric acid (HCl) (18 mL) was added to a 250 mL flask containing stannic chloride (11.7 g) to make a clear solution. Immediately 5- (4'-nitrophenyl) -2-phenyl-1,3-oxazole (5
g) was added and the dropping funnel was washed with glacial acetic acid (40 mL). The resulting mixture was heated to 75 ° C. and stirred for about 2 hours. The color of the solution changed from light brown to pale yellow. TLC
The completion of the reaction was confirmed by. The resulting mixture was stirred vigorously and aqueous potassium hydroxide solution (600 mL;
40%). The precipitate is filtered, washed with water until the filtrate is neutral, dried and a dark yellow solid (1
5.51 g) was obtained. MeOH on activated carbon (100m
L (2 times) and recrystallized from 5- (4′-aminophenyl) -2-phenyl-1,3-oxazole (3.5
Long pale yellow needle crystals of g) were obtained. This synthetic method is shown in FIG.

[0041]

Example 7 5- (3'-hydroxyphenyl) -2-
Phenyl-1,3,4-oxadiazole (3.106
g; 13 mmol) (prepared in the same manner as in Example 5), triethylamine (1.455 g; 14.4 mmol),
Trichloromethane (CHCl ₃ ) (25 mL) and dimethylacetamide (10 mL) were added to a 100 mL round bottom flask equipped with a magnetic stir bar, dropping funnel and drying tube.
Methyl acryloyl chloride (1.49g; 14.3mmo)
a solution of l) in CHCl ₃ (10 mL) at 0 ° C.
Added over minutes. The reaction mixture was allowed to warm to room temperature, stirred for several hours, then concentrated by evaporation under reduced pressure. This mixture was added to a water / ether mixture (100 m
L / 50 mL), allowed to separate and the ethereal phase was added to HCl.
Wash with (1N) then NaOH (1N) then brine. This ether phase was dried over MgSO ₄ , filtered, concentrated and recrystallized from cyclohexane to give 5- (3′-methacryloyloxyphenyl) -2-phenyl-1,3,4-oxadiazole as a white solid. (3.32 g) was obtained. This synthetic method is shown in FIG.

[0042]

Example 8 The following is an illustration of the synthesis of the methacrylic polymer of this invention. 5- (3'-methacryloyloxyphenyl) -2-phenyl-1,3,4-oxadiazole (1 g; 3.29 mmol) (prepared in the same way as in Example 7) was passed through a plug of basic alumina. THF
It was dissolved in (9 mL; anhydrous). Azobisisobutyronitrile (AIBN obtained from Alpha Chemicals)
(8.5 mg; 52 mmol) was added to this solution and the mixture was degassed by passing a stream of argon. 2 at 53 ° C
Polymerization was performed for 1.5 hours under an argon atmosphere. The reaction mixture was diluted to 20 mL, precipitated in 200 mL MeOH, filtered and collected. This crude polymer is
Redissolved in, filtered through celite, and precipitated in MeOH. A white solid of poly (5- (3′-methacryloyloxyphenyl) -2-phenyl-1,3,4-oxadiazole (0.726 g) was obtained, the synthesis of which is shown in FIG.

[0043]

Example 9 5- (4'-aminophenyl) -2-phenyl-1,3-oxazole (2.373 g; 10 mm)
ol) (prepared by the same method as in Example 6), triethylamine (1.106 g; 10.9 mmol), CHCl.
₃ (6 mL) and dimethylacetamide (19 mL) were added to a 100 mL round bottom flask equipped with a magnetic stir bar, addition funnel and drying tube. Methyl acryloyl chloride (1.4
CHCl ₃ (10 mL) solution of 9 g; 14.3 mmol) was added at 0 ° C. over about 15 minutes. The reaction product was warmed to room temperature, then stirred for several hours and concentrated by rotary evaporation. The mixture was poured into a flask of water and the solution was filtered and dried under vacuum. This solid was dissolved in EtOAc and passed through a pad of silica gel with EtOAc. This solid was recrystallized from toluene to give 5- (4'-methacrylamidophenyl) -2.
-Phenyl-1,3-oxazole (2.58g) was obtained. This synthesis is shown in FIG.

[0044]

Example 10 The following is an illustration of the synthesis of the methacrylimide polymer of the present invention. 5- (4′-methacrylamidophenyl) -2-phenyl-1,3-oxazole (0.506 g; 1.66 mmol) was added to THF (2.5
mL; anhydrous; obtained from Aldrich Co.) and passed through a basic alumina plug. AIBN (3.5m
g; 21 mmol) was added to this solution and the mixture was degassed with a stream of argon. The polymerization reaction was carried out at 55 ° C. for 57 hours under an argon atmosphere. This reaction mixture was added to 5
Precipitated in 0 mL MeOH. This crude polymer is
Redissolved in HF, passed through a filter in a 0.45 micron syringe and precipitated in MeOH. Poly (5-
(4'-methacrylamidophenyl) -2-phenyl-
A white solid of (1,3-oxazole) was obtained. Figure 10
This synthesis is shown in.

[0045]

Example 11 LEDs were fabricated on ITO coated glass substrates obtained from Valzer of Fremont, Calif. 11 of PPV on the ITO layer
I made a layer with a thickness of 00Å. PPV was prepared by heating and converting a sulfonium precursor polymer at 200 ° C. in a 15% hydrogen atmosphere. This synthesis is based on Papadimitrako
poulos et al. , "The Role o
f Carbongroups in Photo
luminescence of Poly (P-Ph
enylenevinylene) ”Chem. Ma
t. , 6 (9), pp. 1563-1568 (199
4), which is incorporated herein by reference. This synthesis is conventional and well known to those skilled in the art. The PPV was formed as two consecutive 550Å layers. An electron transport material was molded onto this PPV layer using various materials. These materials are:

[0046]

Table 1 Material No. Content 1 Polymer of Example 8 2 Polyaryl acrylate of Example 10 3 Triphenyltriazole containing polymer where R is octafluorobiphenyl prepared as generally described in Example 4 4 A triphenyltriazole-containing polymer in which R is benzyl, prepared generally as described in Example 4.

In order to apply these materials on PPV, each material was treated with chlorobenzene, dimethylacetamide,
Alternatively, it was dissolved in a spinning solvent such as cyclohexane. The material was 2% in spinning solvent. These materials were spin coated on the substrate at 2000 rpm for 2 minutes to form these material layers. These electron transport layers were about 500Å to about 600Å thick. Also P
A device was prepared by spinning a film of BD / PMMA on ITO. The thickness of this film was about 250Å. Next, an aluminum electrode was formed on these electron transport layers.

The LEDs have an area of 1 mm ² .
Operates with a direct current of up to 5 A / cm ² and about 10 to about 60 V
Needed a bias. The internal quantum efficiency of these devices was calculated using a calibrated silicon photodiode. Table 2 compares the performance of these various devices. It can be seen from Table 2 that devices with a polymeric electron transport layer have lower operating voltage and greater stability than devices where the electron transport layer is not a polymeric material.

[0049]

[Table 2] Material Tg (° C) ¹ Imax Operating voltage stability (A / cm ² ) (V) C / cm ² PBD / 59 ° C Crystallization with PMMA 0.1 ± 0.01 18-23 to 11 153 0.2 ± 0.03 28-31 to 1 2 176 0.2 ± 0.03 22-30 to 1 3 186 3.0 ± 0.05 6-10 >> 20 4 168 0.5 ± 0.05 17-19> 10 ¹ DSC; heating rate = 10 ° C./min

[0050]

Table 2 compares the properties of LEDs made with the electron-transporting polymers of the present invention with LEDs having an electron-transporting layer of PBD dispersed in polymethylmethacrylate (PMMA). LEDs made using the electron transport polymer of the present invention are shown at 1-4,
1-4 correspond to the numbers in Table 1. All the LEDs 1 to 4 were able to pass a larger current (Imax) than the device using the PBD / PMMA electron transport material before the damage.
Each of the devices 3 and 4 had an Imax significantly higher than that of the device equipped with PBD / PMMA. The stability of devices 3 and 4 was also surprisingly superior to that of devices equipped with PBD / PMMA. Stability is
The LED was measured by applying repeated pulses of 0 to 250 μm. In addition, the devices 3 and 4 are not damaged before the PBD / PMM.
Significantly higher total current (integer than the equipment equipped with A)
It was a rated current (C / cm ² ). Therefore, devices 3 and 4 are expected to have a longer life than devices equipped with PBDs. Polymer (1-4) is 2
There was no change in performance after storage for a month, but PBD / PMM
The film A was cloudy and was inferior in stability depending on the number of days since production.

[Brief description of drawings]

FIG. 1 is a side view of a light emitting device.

FIG. 2 shows the molecular structure of PBD.

FIG. 3 shows the molecular structure of TAZ.

FIG. 4 shows the synthesis of one electron deficient unit compound which is a precursor of the polymer of the present invention.

FIG. 5 shows the synthesis of one electron deficient unit compound which is a precursor of the polymer of the present invention.

FIG. 6 shows the synthesis of one polymer of the invention.

FIG. 7 shows the synthesis of one polymer of the invention.

FIG. 8 shows the synthesis of one electron deficient unit compound which is a precursor of the polymer of the present invention.

FIG. 9 shows the synthesis of one electron deficient unit compound which is a precursor of the polymer of the present invention.

FIG. 10 shows the synthesis of one polymer of the invention.

FIG. 11 shows an LED of the present invention.

[Explanation of symbols]

 10 Light Emitting Polymer 20 Anode 30 Cathode 40 Substrate 50 Electron Transport Layer 60 Hole Transport Layer 100 Light Emitting Layer 120 Electron Transport Material 130 Electrode 140 Electrode 150 Substrate

Front Page Continuation (72) Inventor Marco Strachel United States 19805 Delaware Wilmington, Squirrel Lancon Dominiums Number 104, Northford Avenue 600

Claims (24)

[Claims] 1. A first electrode is formed on a substrate, and a light emitting polymer layer is formed on the first electrode.
Ar (where R is R'is selected from the group consisting of H, alkyl, aryl, trifluoromethyl, cyano, and halo, and Ar is
Is substituted phenyl, unsubstituted phenyl, substituted pyridyl, unsubstituted pyridyl, substituted naphthyl on this electron-emitting polymer,
Selected from the group consisting of unsubstituted naphthyls)
A method of manufacturing a light emitting device, comprising: forming a film of an electron transporting material made of a polymer having an electron deficient unit having the structure described above, and forming a second electrode on the electron transporting material. 2. The method of claim 1, wherein the electron transport material has a molecular weight of at least about 5000. 3. The method of claim 2, wherein the electron transport material has a glass transition temperature of at least about 100 ° C. 4. The method of claim 3, wherein the electron transport material is applied to the device by spinning. 5. The method of claim 4, wherein the electron transport material is combined with a spinning solvent. 6. The method of claim 1, wherein the electron deficient unit has a reduction potential with respect to the calomel electrode of about -1V to about -2.4V. 7. The method of claim 6, wherein the electron deficient unit is incorporated into the polymer by copolymerizing a monomer having the structure of general formula HO—Ar—R—Ar—OH with another monomer. 8. The method of claim 6, wherein said electron deficient unit is attached to said polymer and said polymer comprises acrylates, methacrylates and their derivatives, acrylamides, methacrylamides and their derivatives, And a polymer of at least one monomer selected from the group consisting of styrenes, methylstyrenes and derivatives thereof. 9. The method according to claim 8, wherein the monomer is copolymerized with another monomer forming an electron transporting polymer, and the other monomer is an acrylate and its derivative, a methacrylate and its A method which is a monomer selected from the group consisting of derivatives, acrylamides and derivatives thereof, methacrylamides and derivatives thereof, styrenes and derivatives thereof, and methylstyrenes and derivatives thereof. 10. A first electrode formed on a substrate, a light emitting polymer layer formed on the first electrode, and a general formula Ar—R—Ar, wherein R is R'is selected from the group consisting of H, alkyl, aryl, trifluoromethyl, cyano, and halo, and Ar is a substitution on the electron-emitting polymer. Selected from the group consisting of phenyl, unsubstituted phenyl, substituted pyridyl, unsubstituted pyridyl, unsubstituted naphthyl, unsubstituted naphthyl), and an electron transporting material having a polymer having an electron deficient unit. A light emitting device comprising a second electrode formed on a transport material. 11. The device of claim 10, wherein the electron transport material has a molecular weight of at least about 5000. 12. The device of claim 11, wherein the electron transport material has a glass transition temperature of at least about 100 ° C. 13. The device of claim 10, wherein the electron deficiency unit is from about -1V to about -2.4 relative to the calomel electrode.
A method having a reduction potential of V. 14. The device of claim 13, wherein the electron deficient unit is incorporated into the polymer by copolymerizing a monomer having the structure of general formula HO—Ar—R—Ar—OH with another monomer. apparatus. 15. The device of claim 13, wherein the electron deficient unit is attached to the polymer and the polymer is methacrylates and derivatives thereof, acrylamides and derivatives thereof, methacrylamides and derivatives thereof, styrenes and thereof. A device comprising a derivative, and a polymer of at least one monomer selected from methylstyrenes and derivatives thereof, in which at least one electron-deficient unit is bonded. 16. The device according to claim 15, wherein the monomer is copolymerized with another monomer forming an electron transporting polymer, and the other monomer is an acrylate and its derivative, a methacrylate and its A device which is a monomer selected from the group consisting of derivatives, acrylamides and derivatives thereof, methacrylamides and derivatives thereof, styrenes and derivatives thereof, and methylstyrenes and derivatives thereof. 17. A structure of the general formula Ar-R-Ar, wherein Ar is selected from the group consisting of substituted phenyl, unsubstituted phenyl, substituted pyridyl, unsubstituted pyridyl, substituted naphthyl, unsubstituted naphthyl. An electron-transporting material having a polymer containing an electron-deficient unit having, and wherein the electron-deficient unit is about -1 V to about -2.
An electron transport material having a reduction potential of 4V. 18. The electron transport material according to claim 17, wherein R is An electron-transporting material selected from the group consisting of: R'wherein R'is selected from the group consisting of H, alkyl, aryl, trifluoromethyl, cyano, and halo. 19. The material of claim 18, having a molecular weight of at least about 5000. 20. The material of claim 19, having a glass transition temperature of at least about 100 ° C. 21. The material of claim 18, wherein the electron deficient unit is incorporated into the polymer by copolymerizing a monomer of the general formula HO-Ar-R-Ar-OH with other monomers. 22. The material of claim 18, wherein the electron deficient unit is attached to the polymer and the polymer is an acrylate and its derivative, a methacrylate and its derivative, an acrylamide and its derivative, a methacrylamide and its. A material, which is a polymer of at least one monomer selected from the group consisting of derivatives, styrenes and derivatives thereof, and methylstyrenes and derivatives thereof, in which at least one electron-deficient unit is bonded. 23. The method of claim 22, wherein the monomers polymerize to form an electron transport polymer. 24. The method of claim 22, wherein the monomer is copolymerized with another monomer to form an electron transport polymer, and the other monomer is an acrylate and its derivative, a methacrylate and its derivative, acrylamide. And a derivative thereof, methacrylamide and a derivative thereof, styrenes and a derivative thereof, and a monomer selected from the group consisting of methylstyrene and a derivative thereof.