KR0146019B1 - Organic compounds for EL devices and EL devices - Google Patents

Abstract

Provided are organic compounds for EL devices and EL devices which can emit blue light or blue green light with higher luminance than conventional organic light emitting materials.

2- (O-hydroxyphenyl) benzoxazolezol complex which is a compound represented by General formula (1), or the light emitting material used for EL element is 2- (O-hydroxyphenyl) benzoxa represented by General formula (2) It is characterized by being a sleepy complex.

Formula 1

Formula 2

Description

Organic compounds for EL devices and EL devices

1 is an explanatory diagram for explaining an embodiment of the EL element of the present invention.

2 is an explanatory diagram for explaining another embodiment of the EL element of the present invention.

3 is a diagram showing the mass spectrum of the organic compound for EL devices of the present invention

4 shows light emission spectra of the EL device of the present invention.

5 is a diagram showing the mass spectrum of the organic compound for EL devices of the present invention.

The present invention relates to an organic compound for EL devices and an EL device, and more particularly to an organic compound for EL devices exhibiting electroluminescence by applying a voltage, and an EL device using the organic compound for EL devices.

Conventionally, EL devices using light emitting materials that emit electroluminescence by applying a voltage have been used for display of OA devices such as word processors and backlights of automobiles.

Inorganic compounds have conventionally been employed as such light emitting materials for EL devices. However, if the organic compounds for EL devices are to emit light with high luminance, it is necessary to make the driving voltage high.

For this reason, in recent years, studies on organic compounds for EL devices capable of lowering the driving voltage have been made (see, for example, CWTang and S.A. VanSlyke: Appl. Phys. Lett. 51.913 (1987)). .

According to the thin film EL device using such an organic compound, the driving voltage can be lowered as compared with the EL device using the inorganic compound for EL devices in the related art.

In addition, organic compounds emitting blue light have been reported, which can be suitably used for backlights such as displays of OA devices and meters of automobiles. (For example, Jpn. J. Appl. Phys. Vol. 32 (1993). ) L511).

However, since the light emission luminance of conventional organic light emitting blue compounds is insufficient, there is a demand for an EL device using an organic compound for EL devices and an organic compound for EL devices that can emit blue light with higher brightness.

In addition, in order for a display such as an OA device or the like to use the EL element for display, the EL element needs to be multicolored.

It is therefore an object of the present invention to provide an organic compound for an EL device and an EL device which can emit blue light or color light with high brightness.

MEANS TO SOLVE THE PROBLEM The present inventors examined in order to achieve the said objective, As a result, according to the EL element which used 2- (O-hydroxyphenyl) benzoxazole zinc complex as a light emitting material, it is blue with high brightness by application of a drive voltage. I found luminescence.

Moreover, according to the EL element which used 2- (O-hydroxyphenyl) benzooxazole sol complex as a light emitting material, it discovered that color luminescence was carried out with high brightness by application of a drive voltage, and came to this invention.

That is, in the present invention, the light-emitting material used in the EL element is 2- (O-hydroxyphenyl) benzoxazolezol complex represented by the formula (1) or 2- (O-hydroxyphenyl represented by the formula (2). The organic compound for EL devices characterized by the above-mentioned.

In addition, the present invention relates to a 2- (O-hydroxyphenyl) benzoxazole zinc complex represented by formula (1) as a light emitting material in an EL device in which an organic compound is used as a light emitting material used in an EL device. Or an EL device characterized by using a 2- (O-hydroxyphenyl) benzoxazolezole complex represented by the formula (2).

According to the organic compound for EL devices represented by the general formula (1) of the present invention, it is possible to emit blue light with high luminance as compared with the brightness of the conventional organic light emitting organic compound for EL devices.

In addition, according to the organic compound for EL devices represented by the general formula (2) of the present invention, since it emits color different from the blue light emitted by the conventional organic EL device organic compound, it can contribute to multicolorization of the EL device. In addition, the EL element of the present invention can emit light with higher luminance than a conventional blue-emitting EL element, and can be suitably used for backlights such as displays such as OA devices.

In the present invention, the 2- (O-hydroxyphenyl) benzoxazole azoplex represented by formula (1) or 2- (O-hydroxyphenyl) benzoxazole azoplex represented by formula (2) is used as a light emitting material. use.

In particular, in the case where 2- (O-hydroxyphenyl) benzoxazolezole complex is used as the light emitting material, high luminance blue light emission can be exhibited when a driving voltage is applied.

Moreover, when 2- (O-hydroxyphenyl) benzoxazole zinc complex is used as a light emitting material, high luminance color light emission can be exhibited when a drive voltage is applied.

The 2- (O-hydroxyphenyl) benzoxazolezole complex represented by formula (1) used in the present invention or 2- (O-hydroxyphenyl) benzoxazolezole complex represented by formula (2) is represented by It is obtained by making zinc acetate react with 2- (O-hydroxyphenyl) benzoxazole shown by 3) or 2- (O-hydroxyphenyl) benzothiazole shown by General formula (4).

This reaction is a solution obtained by dissolving 2- (O-hydroxyphenyl) benzoxazole represented by formula (3) or 2- (O-hydroxyphenyl) benzoxazole represented by formula (4) in a solvent such as methanol. After adding the solution which melt | dissolved zinc acetate to it, it can carry out by stirring at room temperature for predetermined time.

The obtained reactant is purified as necessary and then used as a light emitting material of the EL element.

As the EL element, one having a structure shown in FIG. 1 is used. The EL element 10 shown in FIG. 1 is a hole injection layer 16, represented by the tetraphenyldiamine derivative, on the ITO transparent electrode 14 (alloy of indium tin) formed on the transparent glass plate 12, represented by the formula (1). A light emitting layer 18 made of 2- (O-hydroxyphenyl) benzoxazoleazole complex or 2- (O-hydroxyphenyl) benzoxazoleazole complex represented by formula (2), and an upper electrode made of metal such as aluminum Each of 20 is formed one by one.

Each of the hole injection layer 16, the light emitting layer 18, and the upper electrode 20 is formed by a vacuum deposition method. Among them, the hole injection layer 16 and the light emitting layer 18 are formed by continuous deposition without breaking the vacuum state under a high vacuum of about 10 ⁻⁶ Torr.

In such an EL element 10, the light emitting material of the light emitting layer 18 is applied when a direct current or a pulse voltage is applied from a power source with the ITO transparent electrode 14 as the anode and the upper electrode 20 as the cathode. Is excited to emit light.

As the EL element according to the present invention, one having a structure shown in FIG. 2 is used. The EL element 50 shown in FIG. 2 has a hole injection layer 56 made of a resin such as polycarbonate, on the ITO transparent electrode 54 (alloy of indium tin) formed on the transparent glass plate 52, formula (1). A light emitting layer 58 made of 2- (O-hydroxyphenyl) benzoxazole azocondenser represented by the formula (2) or 2- (O-hydroxyphenyl) benzoxazolezole complex represented by the formula (2), and a metal such as aluminum. Each of the upper electrodes 60 is sequentially formed.

Here, the hole injection layer 56, by dissolving a polyester resin in the carbonate, and the like in a solvent such as chloroform, formed by dip coating or spin coating, and the luminescent layer 58 and upper electrode 60 are 10 ^-6 to ^{10- It} is formed by continuous deposition without breaking the vacuum under high vacuum of about ⁵ Torr.

Also in the EL element 50, the light emitting layer 58 emits light by applying a direct current or a pulse voltage from the power supply with the ITO transparent electrode 54 as the anode and the upper electrode 60 as the cathode.

The EL element of the present invention can obtain high luminance blue or color light emission at a low driving voltage as compared with the light emission luminance of a conventional EL element. Moreover, since it can emit light for a long time, it can be used suitably for the display of OA apparatuses, such as a computer, and the backlight of an automobile meter.

EXAMPLE

The present invention will be explained in more detail in the Examples.

Example 1

(1) Synthesis of 2- (O-Hydroxyphenyl) benzoxazolezol Complex A methanol solution in which 226 mg of zinc acetate was dissolved in a methanol solution of 430 mg of 2- (O-hydroxyphenyl) benzoxazole was slowly added at room temperature. It was.

Subsequently, after stirring for 4 hours at room temperature, the precipitate was filtered off. The filtered precipitate was filtered off for 3 hours while dispersing in methanol, and after filtration, the nucleic acid was washed and dried in vacuo.

The yield was 357 mg (yield 36%), and the melting point was 351 ° C. [differential scanning calorimetc (DSC) measurement]. Moreover, as shown in FIG. 3, the main peak was confirmed in the vicinity of the mass number 485 which is a spectrum peculiar to 2- (O-hydroxyphenyl) benzoxazolezol complex by the measurement of a mass spectrum.

(2) Manufacture of EL element

A hole injection layer 16 having a thickness of 100 nm made of tetraphenyldiamine derivative on the ITO transparent electrode 14 (alloy of indium tin) having a thickness of 200 nm formed on the transparent glass plate 12, synthesized in the above (1). A light emitting layer 18 having a thickness of 100 nm made of 2- (O-hydroxyphenyl) benzoxazole azole complex and a top electrode 20 having a thickness of 100 nm made of a metal such as aluminum were sequentially formed, The EL device shown in FIG. 1 was manufactured.

Each of these hole injection layers 16, the light emitting layer 18, and the upper electrode 20 was formed by a vacuum deposition method. Among them, the hole injection layer 16 and the light emitting layer 18 were formed by continuous vapor deposition without breaking the vacuum state under a high vacuum of about 10 ⁻⁶ Torr. For this reason, the surface area of the hole injection layer 16 and the light emitting layer 18 became the same area.

(3) Luminescence test

As a result of applying a DC or pulsed voltage of 18 V from the power source, the ITO transparent electrode 14 of the EL element 10 shown in FIG. ), Blue light with luminance exceeding several hundred cd / m 2 was generated.

In addition, as a result of the continuous light emission experiment, light emission of blue light stably lasted for several hundred hours or more.

4 shows the state of the light emission spectrum of the EL device manufactured in this embodiment. As apparent from this spectrum, the wavelength became a peak wavelength in the vicinity of 475 nm, and it was confirmed that it is blue light emission.

[Comparative Example]

Example 1 WHEREIN: The blue light emission of Jpn. J. Appl. Phys. Vol. 32 (1993) L511 mentioned above instead of 2- (O-hydroxyphenyl) benzoxazole zinc complex used as a light emitting material. An EL device was fabricated in the same manner as in Example 1 except that the azomethine zinc complex represented by Formula (V) described as a light emitting material was used.

Subsequently, a pulse voltage of 40 Hz and 25 V was applied to each of the EL device manufactured in this comparative example and the EL device manufactured in Example 1, and the light emission degrees of both were visually compared.

As a result, the blue light emission of the EL device manufactured in Example I was higher than the blue light emission of the EL device produced in this Comparative Example.

R represents "-(CH2)-".

Example 2

In Example 1, the luminescence test was conducted as in Example 1 except that the EL element 10 having the structure shown in FIG. 1 was used instead of the EL element 10 having the structure shown in FIG. .

Here, the EL element 50 having the structure shown in FIG. 2 has a thickness of 100 made of polycarbonate resin on the ITO transparent electrode 54 (alloy of indium tin) having a thickness of 200 nm formed on the transparent glass plate 52. A hole injection layer 56 of nm, a 2- (O-hydroxyphenyl) benzoxazolezol-composite synthesized in Example (1), a 100 nm light emitting layer 58, and a metal such as aluminum It was prepared by manually forming each of the upper electrodes 60 having a thickness of 100 nm. The hole injection layer 56 is formed by dissolving in chloroform with polycarbonate resin and tip coating or spin coating, and the light emitting layer 58 and the upper electrode 60 have a high vacuum of about 10 ⁻⁶ P to 10 ⁻⁵ Torr. It was formed by continuous deposition without breaking the vacuum state under. For this reason, the surface area of the light emitting layer 58 and the upper electrode 600 became the same area.

In the luminescence test of the obtained EL element 50, the ITO transparent electrode 54 was used as the anode, and the upper electrode 60 was used as the cathode, and a direct current or pulse voltage of 18 V was applied from the power supply. ), Blue light with luminance exceeding several hundred cd / m 2 was generated.

Moreover, as a result of the continuous light emission test, light emission of blue light was stably lasted for several hundred hours or more.

In addition, the emission spectrum of the EL device fabricated in this embodiment was able to obtain a peak wavelength in the vicinity of 475 nm similarly to the spectrum shown in FIG.

Example 3

(1) Synthesis of 2- (O-hydroxyphenyl) benzothiazole zinc complex 226 mg of zinc acetate (1.03) in 50 ° C methanol solution dissolved in 484 mg (2.13 mmol) of 2- (O-hydroxyphenyl) benzothia 50 ° C methanol solution was dissolved slowly added.

Subsequently, after stirring for 1 hour and 45 minutes, keeping a methanol solution at 50 degreeC, a precipitate was filtered out. The precipitate precipitated was washed with water, saturated aqueous solution of sodium bicarbonate, and methanol, followed by nucleic acid washing followed by vacuum drying.

The yield was 316 mg (yield 59%), and melting | fusing point was 304 degreeC (DSC measurement). Moreover, as shown in FIG. 5, the main peak was confirmed by the mass spectrum 515 vicinity by mass number 515 which is a spectrum characteristic peculiar to 2- (O-hydroxyphenyl) benzothiazole zinc complex.

(2) Manufacture of EL element

On the ITO transparent electrode 14 (alloy of indium tin) formed in the transparent glass plate 12, the hole injection layer 16 which consists of tetraphenyldiamine derivatives, 2- (O-hydroxyphenyl synthesize | combined by said (1) Each of the light emitting layer 18 made of benzothiazole azoconductor and the upper electrode 20 made of metal such as aluminum were sequentially formed to manufacture the EL device 10 shown in FIG.

Here, the organic compound used for the light emitting layer 18 is the same as the EL element 10 of the first embodiment except that it is different.

Each of these hole injection layers 16, the light emitting layer 18, and the upper electrode 20 was formed by a vacuum deposition method. Among them, the hole injection layer 16 and the light emitting layer 18 were formed by continuous deposition without breaking the vacuum state under high vacuum of about 10 ⁻⁶ Torr. For this reason, the surface area of the hole injection layer 16 and the light emitting layer 18 became the same area.

(3) Luminescence test

As a result of applying a DC pulse voltage of 18 V from the power supply, with the ITO transparent electrode 14 of the EL element 10 shown in FIG. 1 as the anode and the upper electrode 20 as the cathode, the light emitting layer 18 Luminescence luminance from the light emitted blue green light exceeding several hundred cd / m 2. The emission spectrum of this blue-green light had a peak wavelength in the vicinity of 500 nm. In addition, as a result of the continuous light emission test, light emission of blue green light stably lasted for several hundred hours or more.

[Comparative Example]

Jpn.J.Appl. Described above in place of 2- (O-hydroxyphenyl) benzothiazole zinc complex used in Example 3 as a light emitting material. An EL device was fabricated in the same manner as in Example 3 except that the azomethine zinc complex represented by Formula (V) described in Phys. Vol. 32 (1993) L511 as a blue light emitting material.

Subsequently, a pulse voltage of 40 Hz and 25 V was applied to each of the EL element manufactured in this comparison and the EL element manufactured in Example 3, and the degree of emission of both was visually compared.

As a result, the light emitting color of the EL device manufactured in Example 3 was blue-green light emission, whereas the light emitting color of the EL device manufactured in this Comparative Example was blue light emission, which was clearly higher than that of the EL device manufactured in this Comparative Example.

Example 4

In Example 3, the light emission test was carried out as in Example 3 except that the EL element 50 having the structure shown in FIG. 2 was used instead of the EL element 10 having the structure shown in FIG.

In this embodiment, the hole injection layer 56 having a thickness of 100 nm made of polycarbonate resin is formed on the ITO transparent electrode 54 (alloy of indium tin) having a thickness of 200 nm formed on the transparent glass plate 12. , The light emitting layer 58 having a thickness of 100 nm made of 2- (O-hydroxyphenyl) benzothiazole zinc complex synthesized in Example (1) of Example 3, and an upper electrode having a thickness of 100 nm made of metal such as aluminum It produced by forming each of (20) sequentially. The hole injection layer 16 is formed by dissolving a polycarbonate resin in chloroform and then dip coating or spin coating, and the light emitting layer 58 and the upper electrode 60 have a high vacuum of about 10 ⁻⁶ P to 10 ⁻⁵ Torr. It was formed by continuous deposition without breaking the vacuum state under. For this reason, the surface area of the light emitting layer 58 and the upper electrode 60 became the same area.

The luminescence test of the obtained EL element 50 was made from the light emitting layer 58 by applying a DC or pulsed voltage of 18V from the power supply with the ITO transparent electrode 54 as the anode and the upper electrode 60 as the cathode. Blue-green light of luminance exceeding cd / m 2 was generated.

In addition, as a result of the continuous light emission test, light emission of blue green light stably lasted for several hundred hours or more.

The emission spectrum of the EL device fabricated in this example was the same as the spectrum shown in Example 3 and had a peak wavelength in the vicinity of 500 nm.

According to the present invention, since it emits blue or blue-green light with high brightness as compared with the conventional organic compound for EL devices, it can be used for displays such as OA devices and the like. It can also contribute to the multicoloring of the EL element.

Claims (4)

An organic compound for an EL device, wherein the light emitting material used in the EL device is 2- (O-hydroxyphenyl) benzoxazolezole complex represented by the formula (1). Formula 1 An organic compound for an EL device, characterized in that the light emitting material used for the EL device is 2- (O-hydroxyphenyl) benzothiazole azole complex represented by the formula (2). Formula 2 In an EL device in which an organic compound is used as the light emitting material used for the EL device, an EL compound characterized by using 2- (O-hydroxyphenyl) benzoxazole zinc binder represented by the formula (1) as the light emitting material. device. Formula 1 As the light emitting material used in the EL device, in the EL device in which an organic compound is used, the 2- (O-hydroxyphenyl) benzothiazole zinc complex represented by the formula (2) is used as the light emitting material. EL element. Formula 2