JPH09188756A - Aromatic diamine-containing polyether and organic element using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aromatic diamine-containing polyether, comprising a polyether having an aromatic diamine in the main chain, having a high glass transition temperature, hardly crystallizable without clouding for a long period of time, having fluorescence, heat resistance, etc., and useful as an organic thin-film element. SOLUTION: This aromatic diamine-containing polyether comprises a recurring unit of formula I [Ar is a group of formula II, III, etc.; R<1> to R<8> are each independently H, an alkyl, an alkoxy, a (substituted)phenyl or a halogen] and having 1000-1000000 number-average molecular weight. The polymer is obtained by condensing, e.g., N,N'-diphenyl-N,N'-(4-hydroxyphenyl)-1,1-biphenyl-4,4'-diamine with a compound of the formula X-Ar-X (X is a halogen).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel polymer compound composed of a polyether having an aromatic diamine in the main chain, and the use of the same as an organic hole transport layer (also referred to as a hole transport layer) and / or an organic light emitting layer. The organic thin film device.

[0002]

2. Description of the Related Art In recent years, attempts have been actively made to realize new functional devices by thinning organic molecules. For example, organic electroluminescence (EL) devices and other devices using organic thin films formed by vapor deposition. The research on optical elements of the above has become active.

Organic EL whose light emitting layer is composed of an organic thin film
The device has been attracting attention as a device for realizing a low-voltage driven large-area display device. A device structure in which organic layers with different carrier transport properties are laminated is effective for improving device efficiency. A device using a low molecular aromatic amine for the hole transport layer and an aluminum chelate complex for the electron transport light emitting layer is reported. [C.
W. Tang, Appl. Phys. Lett. , 5
1, p. 913 (1987)]. With this element, a high brightness sufficient for practical use of 1000 cd / m ² was obtained with an applied voltage of 10 V or less.

However, the glass transition temperature of the material is 60 ° C. in the hole transport layer of the low molecular weight aromatic amine which has been conventionally studied.
The degree is low, and the element structure is destroyed by recrystallization and aggregation,
Even after driving for several tens of hours, the luminous efficiency was significantly reduced. Therefore, even an element having good initial characteristics is not suitable for long-term use, and due to the low reliability of the element, it has not been put to practical use.

[0005]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a novel carrier-transporting polymer material having a high glass transition temperature of a polymer, being difficult to crystallize, and having a high physical strength capable of maintaining a transparent state for a long period of time. There is a point to do.

Another object of the present invention is to provide an organic EL device using this polymer and having a long life.

[0007]

Means for Solving the Problems A first aspect of the present invention is the following general formula (1):

[Chemical 6] [In the formula, -Ar- is

Embedded image

Embedded image

Embedded image A group selected from the group consisting of R ¹ , R ² and
R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , Q ¹ , Q ² , Q ³ and Q ⁴ are hydrogen, an alkyl group, an alkoxy group, or a phenyl group which may have a substituent. And a number average molecular weight of 1,000 to 1,000,0 containing a repeating unit represented by the following: independently selected from the group consisting of
00 aromatic diamine-containing polyether. It should be noted that any single bond in the chain molecule whose bond position is not specified does not limit the bond position, but it is preferable that the bond position be at the p position, and then the m position. Examples of the alkyl group include methyl, ethyl,
It may be a linear or branched alkyl group having any carbon number such as a propyl group and a butyl group, and the alkoxy group may be an alkoxy group having any carbon number such as a methoxy group, an ethoxy group, a propoxy group and a butoxy group. The phenyl group can have a substituent such as the above-mentioned alkyl group and alkoxy group. There is no particular limitation on these groups as long as they do not interfere with the condensation reaction.

A second aspect of the present invention relates to an organic EL device using the aromatic diamine-containing polyether according to claim 1.

An example of the method for producing the polymer of the present invention will be described. N, N'-diphenyl-N, N '-(4-hydroxyphenyl) -1,1'-biphenyl-4,4'-diamine ( TPD-OH)

[Image Omitted] X-Ar-X (wherein X is halogen and Ar is the same as the above) can be produced by condensation as shown in the following formula.

[0010]

Embedded image

In the present invention, 1,2,4-triazole, 1,3,4-oxadiazole or 1,3,4
The polymer having an -oxathiazole moiety exhibits a bipolar property because these moieties play a role of accepting and transporting an electron, and the amine moiety plays a role of accepting and transporting a hole (for example, Examples 5 to 7). Also, it can be used as a single layer type element (see Example 10 and FIG. 7).
However, the single layer type element generally has lower carrier recombination efficiency and lower luminance than the laminated type element. Therefore, even when used as a laminated element, the light emitting layer is preferably a bipolar polymer.

[0012]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited thereto.

Raw material synthesis example (1) Synthesis of N, N'-diphenyl-N, N '-(4-methoxyphenyl) -1,1'-biphenyl-4,4'-diamine (TPD-MeO)

Embedded image N, N'-diphenyl-1,1'-biphenyl-4,
4'-diamine (5.0 mmol) and 4-iodide dissolved and door two sole (10.0 mmol) in nitrobenzene 20 ml, copper catalyst (50.0 mmol) and of K ₂ CO ₃ (10.0 mmol) The reaction was carried out in the presence of nitrogen atmosphere at 220 ° C. for 24 hours. As a result, formula (3)
To obtain TPD-MeO (1.59 g). Yield 58.0%, purity (measured by HPLC in methanol) 9
The melting point was 3.5% and the melting point was 158 to 159.2 ° C.

(2) N, N'-diphenyl-N, N'-
(4-hydroxyphenyl) -1,1'-biphenyl-
Synthesis of 4,4'-diamine (TPD-OH)

Embedded image TPD-MeO (5.1 mmol) was dissolved in 20 ml of ethylene dichloride, cooled in ice water under a nitrogen stream, and boron tribromide (51.0 mmol) dissolved in 10 ml of ethylene dichloride was added dropwise thereto. did. After the dropping, the temperature was returned to room temperature and the reaction was stirred for 1 hour. As a result, TPD-OH (0.8
8 g) were obtained. Yield 42.6%, melting point 232.8-2
It was 34.2 ° C.

Example 1 [Polyethersulfone (PES
Synthesis of -1)]

Embedded image Presence of K ₂ CO ₃ (1.73 mmol) in 4.0 ml of dimethylacetamide (DMAc) of TPD-OH (0.288 mmol) and bis (4-fluorophenyl) sulfone (0.288 mmol). Bottom 1
A condensation reaction was carried out at 40 ° C. for 3 hours. As a result, poly (ether sulfone) (PES-1) 0.
214 g were obtained. This polymer has a weight average molecular weight (Mw) of 9324 and a number average molecular weight (M
n) is 4226, the thermal decomposition temperature under N ₂ is 558 ° C.,
The yield was 95.0%. The molecular weight is measured by GPC in tetrahydrofuran, and the measuring method is the same below.

Example 2 [Polyether sulfone (PES
-2) Synthesis] A condensation reaction was performed in the same manner as in Example 1 except that the condensation reaction time in Example 1 was set to 18 hours. The resulting polyether sulfone (PES-2) has Mw 67251, Mn
5805, Tg 217 ° C., thermal decomposition temperature: N ₂ under 520
And 500 ° C. in air. The thermal decomposition temperature is 10
The temperature is shown when the temperature is reduced from the Tg temperature by 10% by weight at a heating rate of ° C / min. Table 1 shows the dissolution characteristics of this polymer in each solvent.

Example 3 [Polyetherketone (PEK-
Synthesis of 1)]

Embedded image In TPD-OH (0.192 mmol) and 4,4'-difluorobenzophenone (0.192 mmol) and dimethylacetamide (DMAc) in 3.9 ml, the presence of K ₂ CO ₃ (1.15 mmol) , 14
The condensation reaction was carried out at 0 ° C. for 3 hours. As a result, 0.129 g of the polyether ketone (PEK-1) represented by the formula (6)
was gotten. This polymer had a weight average molecular weight (Mw) of 10310 and a number average molecular weight (Mn) of 4278.
The Tg was 180 ° C., the thermal decomposition temperature under N _{2 was} 566 ° C., the thermal decomposition temperature in air was 566 ° C., and the yield was 91.0%.

Example 4 [Polyetherketone (PEK-
Synthesis of 2)] The same condensation reaction as in Example 3 was performed except that the condensation reaction time in Example 3 was 12 hours. As a result, the obtained polyether ketone (PEK-2) had Mw 27750, M
n 6200, Tg 180 ° C., pyrolysis temperature 566 under N ₂
C., and the thermal decomposition temperature in air was 562.degree. Table 1 shows the dissolution characteristics of this polymer in each solvent.

Example 5 [Synthesis of main chain type bipolar polymer, polyether triazole (PETAZ)]

Embedded image TPD-OH (0.192 mmol) and 3,5-di (4
-Fluorophenyl) -4-phenyl-triazole (0.192 mmol) and dimethylacetamide 3.
The condensation reaction was carried out in the presence of K ₂ CO ₃ (1.15 mmol) in 9 ml at 140 ° C. for 24 hours. As a result, polyether triazole (PETAZ) 0.071, which is the main chain type bipolar polymer represented by the formula (7), is obtained.
2 g were obtained. This polymer has a weight average molecular weight (M
w) 2379, number average molecular weight (Mn) 1419, Tg2
The decomposition temperature was 05 ° C., the decomposition temperature under N _{2 was} 380 ° C., the decomposition temperature in air was 453 ° C., and the yield was 43.4%. Table 1 shows the dissolution characteristics of this polymer in each solvent.

Example 6 [Synthesis of polyether m-ethyltriazole (PEm-EtTAZ)]

Embedded image In Example 5, instead of 3,6-di (4-fluorophenyl) -4-phenyl-triazole, 3,6-
Polyether m-ethyltriazole 0.0735 in the same manner as in Example 5 except that di (4-fluorophenyl) -4- (3-ethylphenyl) -triazole was used.
g was obtained. This polymer has a weight average molecular weight (Mw) of 32.
90, number average molecular weight (Mn) 1695, Tg 200 ℃,
Thermal decomposition temperature under N ₂ 382 ° C., thermal decomposition temperature in air 44
It was 3 degreeC and the yield was 43.4%. Table 1 shows the dissolution characteristics of this polymer in each solvent.

Example 7 [Synthesis of polyether oxadiazole (PEOXD)] (1) Synthesis of 4-fluoro-1-naphthoyl chloride

Embedded image 4-Fluoro-1-naphthenic acid (5.52 mmol) was added to 10 ml of SOCl _{2 and} reacted at 80 ° C. for 4 hours to give 4-fluoro-1-naphthoyl chloride 1.
1 g (yield 95.8%) was obtained.

(2) Synthesis of N, N'-4-fluoro-naphthoylhydrazine

Embedded image 4-Fluoro-1-naphthoyl chloride (5.29 mmol) and NH ₂ · NH ₂ · H ₂ O (2.64 mmol)
And 6 in 20 ml of pyridine at 120 ° C
After reacting for a time, 0.653 g (yield 65.6%) of N, N'-4-fluoro-naphthoylhydrazine was obtained.

(3) Synthesis of 2,5-di (4-fluoro-1-naphthoyl) -1,3,4-oxadiazole

Embedded image N, N'-4-fluoro-naphthoylhydrazine (5.
29 mmol) was added to a mixed solution of 9.8 ml of SOCl ₂ and 0.2 ml of pyridine, and the mixture was stirred at 80 ° C. for 3 hours.
The reaction was carried out for a time to obtain 0.59 g (yield 95.4%) of 2,5-di (4-fluoro-1-naphthoyl) -1,3,4-oxadiazole.

(4) Polyether oxadiazole (P
EOXD) synthesis

Embedded image TPD-OH (0.192 mmol) and 2,5-di (4
-Fluoro-1-naphthoyl) -1,3,4-oxadiazole (0.192 mmol) in 4.0 ml of dimethylacetamide (DMAc).
18 at 140 ° C. in the presence of ₂ CO ₃ (1.15 mmol)
The condensation reaction was carried out for a time. As a result, polyether oxadiazole (PEOXD) 0.194 represented by the formula (9) was obtained.
g was obtained. Tg of this polymer is 210 ° C., weight average molecular weight (Mw) 9585, number average molecular weight (Mn) 288
9, the thermal decomposition temperature under N _{2 was} 451 ° C., the thermal decomposition temperature in air was 438 ° C., and the yield was 11.0%. Table 1 shows the dissolution characteristics of this polymer in each solvent.

[0025]

[Table 1] ++ Completely soluble + Partially soluble-Insoluble ¹⁾ Dimethylformamide ²⁾ Dimethylsulfoxide ³⁾ Dimethylacetamide ⁴⁾ N-methylpyrrolidone ⁵⁾ Tetrahydrofuran ⁶⁾ Dichloromethane ⁷⁾ Dichloroethane

Example 8 The polyether sulfone obtained in Example 2 (PES-
2) in the hole transport layer and the electron transporting light emitting layer in the following formula

Embedded image The tri- (8-quinolinolato) aluminum (III) complex (Alq) shown in (3) was used to form a two-layer organic electroluminescent (EL) device shown in FIG. The device structure was ITO / polymer (200Å) / Alq (700Å) / Mg: Ag, and the polymer layer was formed by spin coating from a THF solution. Alq was 1.0 × 10 ⁻⁵ Torr and Mg: A.
g (10: 1) was formed by vacuum evaporation at 6 × 10 ⁻⁶ Torr. Using the ITO as an anode, M
When a direct current voltage was applied with g: Ag as the cathode, green light emission with a peak wavelength of 520 nm was observed from the device.
The EL spectrum from the device is shown in FIG.
It agrees with the PL spectrum of 1q, and it is found that the emission is of Alq. The brightness-voltage characteristics of this element are shown by the circled graph in FIG. 4, and the current density-voltage characteristics are shown by the triangular graph in FIG. The maximum brightness was 14,000 cd / cm ^{2 at} 14 V regardless of the molecular weight of the polymer.
Further, when this device was continuously driven, it was found that light emission continued for 1000 hours or more, and the polymer layer had an effect of improving the life of the device.

Example 9 Example 8 was repeated except that the polyether sulfone of Example 8 was replaced by the polyether ketone (PEK-2) obtained in Example 4. The brightness-voltage characteristics of this element are shown in the graph of the circle in FIG. 5, and the current density-voltage characteristics are shown in the graph of the triangle in FIG. The maximum brightness was 9500 cd / cm ^{2 at} 15 V regardless of the molecular weight. When the PL spectrum of this polymer film was measured, broad emission was observed on the longer wavelength side than that of polyether sulfone as shown by the curve in FIG. It is considered that a complex such as excibrex is formed, and the site where the complex is formed serves as a trap for holes, which causes a decrease in mobility and an increase in driving voltage.

Example 10 The polyether oxadiazole (P obtained in Example 7)
EOXD) re-precipitation purification with chloroform / methanol 3
A 20 g / liter chloroform solution was spin-coated on the glass substrate, and the polymer was spun onto a glass plate at 800Å (2
The film was formed at 000 rpm). This is E by the structure of FIG.
I made an L element. As shown in FIG. 8, ITO / PEOX
The EL element composed of D (900Å) / Mg: Ag has a maximum luminance of 12 V and 26.0 cd / m ² , and the luminance-
The voltage characteristics are shown by the circled graph in FIG. 8, and the current density-voltage characteristics are shown by the triangular graph in FIG. E from this element
The L spectrum is shown in b of FIG. Since this almost coincides with the film PL spectrum of the polymer (a in FIG. 9), it was confirmed that the light was emitted from the polymer. Therefore, it was presumed that holes were injected and transported from the amine site and electrons were transported from the oxadiazole site, and recombined in the polymer, and it was also found that this polymer exhibits a bipolar property.

[0029]

【effect】

(1) Each of the polymers of the present invention exhibits fluorescence, has a high glass transition temperature, and has heat resistance. (2) Since the polymer of the present invention is soluble in a solvent, what has heretofore been applicable only to a film forming method by vapor deposition can now be formed into a film by a coating method. Of course, the film formation can also be performed by vapor deposition. (3) Since the polymer of the present invention has a high Tg and has a property that it is extremely difficult to crystallize, it does not become cloudy for a long period of time and is extremely useful as a constituent material of an EL device. (4) Polyethersulfone, polyetherketone, and polyetherphosphone are polymers showing a hole-transporting property, and thus can be used as a hole-transporting layer of an EL device. (5) Polyether triazole, polyether oxadiazole, polyether thiadiazole, and polyether oxazole are bipolar polymers having both hole transporting site and electron transporting site in the polymer main chain. And electrons can be transported. If this polymer is used, an EL device can be produced with a single polymer layer.

[Brief description of the drawings]

FIG. 1 shows fluorescence spectra of solutions and films of PES of Examples 1 and 2.

2 shows fluorescence spectra of PEK solutions and films of Examples 3 and 4. FIG.

FIG. 3 shows a configuration example of a two-layer organic EL device of Example 8.

FIG. 4 is a graph showing luminance-voltage characteristics (indicated by a circle) and current density-voltage when the PES obtained in Example 2 is used as a polymer in the structure of the two-layer organic EL device of Example 8. It is a characteristic (indicated by a triangle mark) graph.

5 is a graph showing a luminance-voltage characteristic (indicated by a circle) and a current density-voltage characteristic (indicated by a triangle) in the case of using PEK-2 obtained in Example 4 as a polymer in Example 9. FIG. Is.

FIG. 6 shows EL spectra of EL devices of Examples 8 and 9.

FIG. 7: Single-layer organic EL made of a bipolar polymer
The structural example of an element is shown.

8 is a PEOXD of Example 7 in the device configuration of FIG.
-900nm thickness-brightness-voltage characteristics (indicated by circles) and current density-voltage characteristics (indicated by triangles)
It is a graph.

9 is a PEOXD of Example 7 in the device configuration of FIG.
2 shows an EL spectrum (b) and a PL spectrum (a) of the polymer film when was used at a thickness of 900Å.

Claims (2)

[Claims] 1. The following general formula (1): [In the formula, -Ar- represents Embedded image Embedded image Embedded image A group selected from the group consisting of R ¹ , R ² and
R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , Q ¹ , Q ² , Q ³ and Q ⁴ are hydrogen, an alkyl group, an alkoxy group, or a phenyl group which may have a substituent. And a number average molecular weight of 1,000 to 1,000,0 containing a repeating unit represented by the following: independently selected from the group consisting of
00 aromatic diamine containing polyether. 2. An organic EL device using the aromatic diamine-containing polyether according to claim 1.