KR20000006345A - Novel organometallic luminescent material and organic electroluminescent device containing same - Google Patents

Abstract

PURPOSE: A new organic metal light-emitting material has a light luminescent characteristic of red, green, or blue, and has a high heat stability, and organic electric light-emitting device having the same is provided. CONSTITUTION: The organic electric light-emitting device has an electric light-emitting characteristic of Red, Green, and Blue, and embodies all colors. Organic metal compound is expressed as a selected one equation among the chemical equation(1)-the chemical equation(5). In the chemical equation, M1 and M4 are selected from Li, Na, K, Zr, Si, Ti, Sn, Cs, Fr, Rb, Hf, Pr, Pa, Ge, Pb, Tm, and Md. M2 is selected from Li, Na, K, Ca, Be, Ga, Zn, Cd, AL, Cs, Fr, Rb, Mg, Mn, Ti, Cu, Zr, Si, Hf, Pr, Pa, Ge, Sn, Pb, Tm, and Md. R is a hydrogen, or alkyl. X and Y are hydrogen, Cl, F, I, Br, SO3H. A is a hydrogen, F, Cl, Br or I. B is O, S, Se or Te. D is O or S. n is an integer of 1-4. M3 is Li+, Na+, K+, Cs+, Fr+, Rb+, Ca2+, Be2+, Ga3+, Zn2+, AL3+, Mg2+, Ti2+, and Cu2+.

Description

Novel organometallic luminescent material and organic electroluminescent device containing same

The present invention relates to an organic metal light emitting material, and more particularly, to a novel organic metal compound having a photoluminescent property of blue, green or red, and high thermal stability, and an organic electroluminescent device comprising the same.

Conventional organometallic compounds for organic electroluminescent devices are mainly complexes of divalent or trivalent metals such as zinc and aluminum. For example, US Pat. No. 5,456,988 as an organometallic light emitting material describes complexes of zinc, aluminum and magnesium with 8-hydroxyquinoline; US Patent No. 5,837,390 discloses complexes of 2- (o-hydroxyphenylbenzoxazole) with metals such as magnesium and cadmium chloride; Japanese Patent Application Laid-Open No. 07-133483 reports a complex of 2- (o-hydroxyphenylbenzoxazole) with a divalent metal such as magnesium or copper; U.S. Patent Nos. 5,529,853, and JP 06-322362, 08-143548, and 10-072580 disclose complexes of 10-hydroxybenzo [10] quinoline with divalent or trivalent metals.

The organometallic light emitting material including such a divalent or trivalent metal has a structure in which ligands are relatively loosely connected and have a long conjugate length. As a result, they are relatively unstable and green and red light emission are possible but not blue light emission.

Accordingly, there has been a need for development of organic light emitting materials having improved stability and improved photoluminescent properties such as blue light emission.

Accordingly, an object of the present invention is to provide a novel organometallic light emitting material having high stability and having a photoluminescent property of blue, green or red, and an organic electroluminescent device including the same.

1A, 1B and 1C are diagrams showing the structure of an organic electroluminescent device manufactured according to the present invention, each having an organic thin film layer having a single layer, a double layer and a multilayer structure,

Figure 2 is a photoluminescence curve of the organometallic light emitting material prepared according to the present invention,

3 is a current density (A / m 2) curve 3-1 and an electroluminescence intensity (cd / m 2) curve 3-2 according to an applied voltage (V) of an organic electroluminescent device manufactured according to the present invention. ,

4A and 4B are light emission efficiency (lm / W) curves according to current density (A / m 2) and electroluminescence intensity (cd / m 2) of the organic electroluminescent device manufactured according to the present invention, respectively.

5 shows electroluminescent spectra at various applied voltages of organic electroluminescent devices manufactured according to the present invention.

In order to achieve the above object, the present invention provides an organic electroluminescent device having an organometallic compound represented by any one formula selected from the following general formulas (1) to (5), and an organic light emitting layer comprising the same as an organic metal light emitting material to provide:

Where

M ¹ and M ⁴ are each independently selected from the group consisting of Li, Na, K, Zr, Si, Ti, Sn, Cs, Fr, Rb, Hf, Pr, Pa, Ge, Pb, Tm and Md Is a valent or tetravalent metal;

M ² is Li, Na, K, Ca, Be, Ga, Zn, Cd, Al, Cs, Fr, Rb, Mg, Mn, Ti, Cu, Zr, Si, Hf, Pr, Pa, Ge, Sn, Pb Is a monovalent, divalent, trivalent or tetravalent metal selected from the group consisting of Tm and Md;

M ³ is Li ⁺ , Na ⁺ , K ⁺ , Cs ⁺ , Fr ⁺ , Rb ⁺ , Ca ²⁺ , Be ²⁺ , Ga ³⁺ , Zn ²⁺ , Al ³⁺ , Mg ²⁺ , Mn ²⁺ , Ti ²⁺ and Cu ²⁺ ;

R is hydrogen or a C _1-10 alkyl group;

X and Y may each be the same or different and are hydrogen, Cl, F, I, Br or SO ₃ H;

A is hydrogen, F, Cl, Br or I;

B is O, S, Se or Te;

D is O or S;

n is an integer of 1-4.

Hereinafter, the present invention will be described in more detail.

According to the present invention, the 8-hydroxyquinoline-metal complex of the general formula (1), the 8-hydroxyquinoline-5-sulfonate-metal complex of the general formula (2), the benz of the general formula (3) Oxazole- or benzthiazole-metal complex, the benzotriazole-metal complex of the general formula (4) and the benzoquinoline-metal complex of the general formula (5).

Preferred among the organometallic luminescent materials of the present invention are shown in Table 1 below.

The organometallic compounds of the present invention may be prepared by reacting a ligand compound with a metal compound in a suitable solvent.

Suitable solvents for use in the present invention include water, ethanol, methanol, propanol and the like.

Suitable metal compounds for use in the present invention include lithium hydroxide, sodium hydroxide, KOH, NaCl, KCl, LiCl, ZrCl ₄ , SnCl ₄ , TiCl ₄ , SiCl ₄ , BeCl ₂ , MgCl ₂ , AlCl ₃ , CaCl ₂ , ZnCl ₂ and the like.

Ligand compounds suitable for use in the present invention include 2- (2-hydroxyphenyl) benzoxazole, 8-hydroxyquinoline, 8-hydroxyquinoline-5-sulfonic acid, 2- (2-benzotriazolyl)- p-cresol, 10-hydroxybenzoquinoline and the like.

The reaction between the organic compound and the metal compound for preparing the organometallic compound of the present invention is carried out at 25 to 100 ° C. for 1 to 24 hours. In this case, the two compounds are used in stoichiometric molar ratios, and are appropriately changed according to n.

In particular, the 8-hydroxyquinoline-5-sulfonic acid-metal complex of the general formula (2) is reacted with a metal compound giving 8-hydroxyquinoline-5-sulfonic acid and the substituent M ² to the following general formula (6). It can be prepared by converting the 8-hydroxyquinoline-5-sulfonic acid derivative intermediate of) and then reacting it with a metal compound that provides M ³ again.

In addition to the wet method, each of the 8-hydroxyquinoline-5-sulfonic acid derivative of the general formula (6) and the metal derivative of the general formula (7) is separately deposited under vacuum to perform In-Situ reaction. It may also be prepared by a dry method (reaction conditions: vacuum degree 10 ⁻⁶ Torr, deposition temperature 150 to 450 ° C., which may vary depending on the type of metal derivative). When a metal is introduced into the sulfonic acid group according to the in-situ process of Scheme 1, the emission wavelength of the compound shifts toward the short wavelength (ie, blue shift).

For example, the photoluminescent color of the derivative of the general formula (6) is green (photoluminescence maximum wavelength is about 510 nm), but when the derivative of the general formula (2) is obtained through the reaction, the maximum wavelength of the photoluminescence becomes blue at about 460 nm. Will emit light.

Where

M ² , M ³ , R, A and n are as defined above and Z is a halogen atom or a hydroxy group.

The organometallic complex of the present invention may be used not only as an organic light emitting material but also as a luminescent doping material. For example, when a small amount of about 2% is doped into the blue organic light emitting layer having good luminous efficiency, the luminous color may be changed, and devices of various colors may be manufactured with high efficiency.

The organic electroluminescent device of the present invention has an organic thin film layer including the organometallic light emitting material of the present invention as a single layer (FIG. 1A) or a double layer (FIG. 1B) or a multilayer (FIG. 1c). In this case, the organometallic light emitting material of the present invention may be used alone, or mixed with a polymer and an inorganic material, or doped into a polymer to be used as a phosphor thin film. That is, as shown in Figure 1, the organic electroluminescent device of the present invention is a glass (i), an ITO (indium-tin-oxide) layer (ii) which is an anode transparent electrode layer, an organic light emitting layer containing the organic light emitting material of the present invention (iii) and the structure of the metal electrode (cathode) layer (iv) sequentially stacked (FIG. 1A) or (i), (ii), the hole transport layer (iii-1), (iii) and (iv) This sequentially stacked structure (FIG. 1B) or (i), (ii), (iii-1), (iii) (multilayer of one or more layers), electron transport layers (iii-2) and (iv) are sequentially It may have a stacked structure (FIG. 1C) and operates as direct current or alternating current, but typically uses direct current.

The organic light emitting layer (iii) according to the method of the present invention is subjected to dry processes such as vacuum deposition, vacuum thermal deposition, sputtering and electron-beam deposition as well as wet processes such as spin coating. It can be prepared using.

The present invention will be described in more detail with reference to the following examples (see FIGS. 2, 3, 4 and 5). However, the scope of the present invention is not limited only to the following Examples.

Example 1: Preparation of 2- (2-hydroxyphenyl) benzoxazole-lithium complex (Compound 13)

2- (2-hydroxyphenyl) benzoxazole and lithium hydroxide were added to 250 mL of ethanol in a molar ratio of 1: 1, and the mixture was refluxed at 78 DEG C for 4 hours. The reaction mixture was filtered to remove residual solvent and water under vacuum to prepare 2- (2-hydroxyphenyl) benzoxazole-lithium complex (Compound 13) of the following general formula (8).

Fig. 2 shows the photoluminescence curve of this compound, which shows a blue color with a maximum wavelength of photoluminescence of about 450 nm.

Example 2

An indium-tin-oxide (ITO) was coated on the glass substrate to form a transparent anode layer. The coated ITO glass was photolithography in a uniform shape and the patterned ITO glass was washed with a solution containing a non-phosphorus surfactant, acetone and ethanol.

After dissolving a mixture (50:50 weight ratio) of polyetherimide having a compound of the following formula (9) as a repeating unit and triphenyldiamine of the following formula (10) at a concentration of 0.5% by weight in chloroform, the mixture was The hole transport layer thin film was prepared by spin-coating on the ITO glass.

Wherein m is an integer of 2 or more.

On this thin film, the 2- (2-hydroxyphenyl) benzoxazole-lithium complex prepared in Example 1 was vacuum deposited to a thickness of about 20 nm as a light emitting material to prepare an organic light emitting layer, and aluminum was then used as the metal electrode layer. An organic electroluminescent device was manufactured by depositing and packaging to a thickness of about 500 nm under vacuum.

3, 4 and 5 show the characteristics of the organic electroluminescent device.

3 is a current density (A / m 2) curve 3-1 and an electroluminescence intensity (cd / m 2) curve 3-2 according to an applied voltage (V) of an organic electroluminescent device manufactured according to the present invention. The current injection starts at about 6V, but the turn-on voltage is about 7 to 8V, and the brightness is about 500 cd / m ² at a voltage of about 11V.

4A and 4B are light emission efficiency (lm / W) curves according to current density (A / m 2) and electroluminescence intensity (cd / m 2) of the organic electroluminescent device manufactured according to the present invention, respectively. From about 200A / m ^{2, the} luminous efficiency was constant at about 1.2 lm / W or more.

5 shows electroluminescence spectra at various applied voltages (8, 9, 10, 11, 12, and 13 V) of the organic electroluminescent device manufactured according to the present invention. The main peak is about 456 nm, and 430 and 487 nm. A shoulder peak was found at. Overall electroluminescent color was blue.

Example 3: Preparation of Compounds 5 and 6

8-hydroxyquinoline-5-sulfonic acid and LiOH were added to 250 mL of ethanol in a molar ratio of 1: 1 and the mixture was refluxed at 78 ° C. for 4 hours. The reaction mixture was filtered and dissolved in excess water. Subsequently, water was removed under vacuum to obtain a reaction intermediate, 8-hydroxyquinoline- (5-sulfonic acid) -lithium complex (LiQSA).

The obtained LiQSA and LiOH (or NaOH) were added to 100 mL of ethanol in a 1: 1 equivalent ratio and reacted at room temperature for 1 hour. The precipitates were separated from the reaction mixture and dried in vacuo for at least 24 hours to form an 8-hydroxyquinolinate- (5-sulfonic acid lithium salt) lithium complex (LiQSLi-compound 5) and 8-hydroxyquinolinate- (5-Sulfonic acid sodium salt) lithium complex (LiQSNa-compound 6) was obtained.

Table 1 shows the maximum light emission wavelength and emission color of the synthesized compound.

Example 4: Preparation of Compounds 7 and 8

8-hydroxyquinoline-5-sulfonic acid and NaOH were added to 250 mL of ethanol in a molar ratio of 1: 1 and the mixture was refluxed at 78 ° C. for 4 hours. The reaction mixture was filtered and dissolved in excess water. Subsequently, water was removed under vacuum to obtain a reaction intermediate, 8-hydroxyquinoline- (5-sulfonic acid) -sodium complex (NaQSA).

NaOH was added to LiQSA and LiOH (or NaOH) obtained in a 1: 1 equivalent ratio to 100 ml of ethanol and reacted at room temperature for 1 hour. The precipitates were separated from the reaction mixture and dried in vacuo for at least 24 hours to give 8-hydroxyquinolinate- (5-sulfonic acid lithium salt) sodium complex (NaQSLi-compound 7) and 8-hydroxyquinolinate- (5-Sulfonic acid sodium salt) sodium complex (NaQSNa-compound 8) was obtained.

Table 1 shows the maximum light emission wavelength and emission color of the synthesized compound.

Example 5: Preparation of Compounds 9 and 10

8-hydroxyquinoline-5-sulfonic acid and ZnCl ₂ were added to 250 mL of ethanol at a molar ratio of 2: 1, and refluxed at 78 ° C. for 4 hours. The reaction mixture was filtered and dissolved in excess water. Subsequently, water was removed under vacuum to obtain bis (8-hydroxyquinoline-5-sulfonic acid) zinc (Zn (QSA) ₂ ) as a reaction intermediate.

The obtained Zn (QSA) ₂ and LiOH (or NaOH) were added to 100 mL of ethanol in a 1: 2 equivalent ratio and reacted at room temperature for 1 hour. The precipitates were separated from the reaction mixture and dried in vacuo for at least 24 hours to give a bis (8-hydroxyquinolinate-5-sulfonic acid lithium salt) zinc complex (Zn (QSLi) ₂ )-compound 9) and bis (8 -Hydroxyquinolinate-5-sulfonic acid sodium salt) zinc complex (Zn (QSNa) ₂ )-compound 10) was obtained.

Table 1 shows the maximum light emission wavelength and emission color of the synthesized compound.

Example 6: Preparation of Compounds 11 and 12

8-hydroxyquinoline-5-sulfonic acid and AlCl ₃ were added to 250 ml of ethanol as a reaction solvent in a molar ratio of 3: 1, and the mixture was refluxed at 78 DEG C for 4 hours. The reaction mixture was filtered and dissolved in excess water. Subsequently, water is removed under vacuum to obtain tris (8-hydroxyquinoline-5-sulfonic acid) aluminum (Al (QSA) ₃ ) as a reaction intermediate.

The Al (QSA) ₃ and LiOH (or NaOH) obtained above were added to 100 ml of ethanol in a 1: 3 equivalent ratio, and reacted at room temperature for 1 hour. The precipitate was separated from the reaction mixture and dried in vacuo for at least 24 hours to give the final product tris (8-hydroxyquinolinato-5-sulfonic acid lithium salt) aluminum complex (Al (QSLi) ₃ )-compound 11) and Tris (8-hydroxyquinolinate-5-sulfonic acid sodium salt) aluminum complex (Al (QSNa) ₃ )-compound 12) was obtained.

Table 1 shows the maximum light emission wavelength and emission color of the synthesized compound.

Example 7: Preparation of Compound 14

2- (2-hydroxyphenyl) benzoxazole and sodium hydroxide were injected into 250 mL of ethanol in a molar ratio of 1: 1 and refluxed at 78 ° C. for 4 hours. The reaction mixture was filtered and the remaining solvent and water were removed under vacuum to give the desired 2- (2-hydroxyphenyl) benzoxazole-sodium complex) (Compound 14).

It can be seen that this compound has a maximum light emission wavelength of about 455 nm and is blue as summarized in Table 1.

Example 8: Preparation of Compounds 15 and 16

2- (2-hydroxybenzotriazole) -p-cresol and LiOH (or NaOH) were added to 250 mL of ethanol in a molar ratio of 1: 1 and the mixture was refluxed at 78 ° C. for 4 hours. The reaction mixture was filtered and the remaining solvent and water were removed under vacuum to yield the desired 2- (2-hydroxybenzotriazole) -p-cresol lithium complex (LiBTZC) (compound 15) and 2- (2-hydroxybenzo Triazole) -p-cresol sodium complex (NaBTZC) (Compound 16) was prepared.

It can be seen that these compounds have green light with maximum light emission wavelengths of about 508 nm and 512 nm, as summarized in Table 1.

Example 9: Preparation of Compounds 17 and 18

10-hydroxyquinoline and LiOH (or NaOH) were injected into the reaction solvent ethanol in a molar ratio of 1: 1 and refluxed at 78 ° C. for 4 hours. The reaction mixture was filtered and the residual solvent and water were removed under vacuum to prepare the desired 10-hydroxyquinoline lithium complex (LiBQ) (Compound 17) and 10-hydroxyquinoline sodium complex (NaBQ) (Compound 18).

These compounds have a photoluminescence maximum wavelength of about 515 nm and 650 nm, as summarized in Table 1, showing green and red color.

Example 10 Preparation of Compound ZrQ4 (Compound 3)

8-hydroxyquinoline and ZrCl ₄ were added to 250 mL of the reaction solvent ethanol at a molar ratio of 4: 1, and the mixture was refluxed at 78 ° C for 4 hours. The reaction mixture was filtered to remove residual solvent and water under vacuum to obtain the desired tetra (8-hydroxyquinolinate) zirconium (ZrQ ₄ ).

The maximum wavelength of the photoluminescent compound of the synthesized compound was about 530 nm, light green.

The organometallic light emitting material of the present invention is a novel compound having photoluminescent properties of blue, green, or red. The organic electroluminescent device including the same may also have blue, green, or red electroluminescent properties, thereby realizing all colors. It can be usefully used in the development of organic electroluminescent display.

Claims (5)

An organometallic compound represented by any one formula selected from the following general formulas (1) to (5): Formula 1 Formula 2 Formula 3 Formula 4 Formula 5 Where M ¹ and M ⁴ are each independently selected from the group consisting of Li, Na, K, Zr, Si, Ti, Sn, Cs, Fr, Rb, Hf, Pr, Pa, Ge, Pb, Tm and Md Is a valent or tetravalent metal; M ² is Li, Na, K, Ca, Be, Ga, Zn, Cd, Al, Cs, Fr, Rb, Mg, Mn, Ti, Cu, Zr, Si, Hf, Pr, Pa, Ge, Sn, Pb Is a monovalent, divalent, trivalent or tetravalent metal selected from the group consisting of Tm and Md; M ³ is Li ⁺ , Na ⁺ , K ⁺ , Cs ⁺ , Fr ⁺ , Rb ⁺ , Ca ²⁺ , Be ²⁺ , Ga ³⁺ , Zn ²⁺ , Al ³⁺ , Mg ²⁺ , Mn ²⁺ , Ti ²⁺ and Cu ²⁺ ; R is hydrogen or a C _1-10 alkyl group; X and Y may each be the same or different and are hydrogen, Cl, F, I, Br or SO ₃ H; A is hydrogen, F, Cl, Br or I; B is O, S, Se or Te; D is O or S; n is an integer of 1-4. By a dry method in which the 8-hydroxyquinoline-5-sulfonic acid metal complex of the following general formula (6) and each of the metal derivatives of the following general formula (7) are individually deposited in vacuo and reacted in-situ To prepare an 8-hydroxyquinoline-5-sulfonic acid-metal derivative of the general formula (2): Formula 2 M ³ Z (7) Where A, M ² , M ³ , R and n are as defined in claim 1, and Z is a halogen atom or a hydroxy group. An organic electroluminescent device having an organic light emitting layer comprising the organic metal compound according to claim 1 as an organic metal light emitting material. The method of claim 3, wherein An organic electroluminescent device comprising an organometallic compound alone, or mixed with a polymer and an inorganic material, or doped into a polymer to form an organic light emitting layer. The method of claim 3, wherein An organic electroluminescent device characterized in that the organic light emitting layer is deposited by spin coating, vacuum deposition, vacuum thermal deposition, sputtering or electron beam deposition.