KR101335548B1 - platinum complex for phosphorescent materials and organic electroluminescent device containing the same - Google Patents

Abstract

The present invention relates to a mononuclear or binuclear platinum complex for phosphorescent materials, wherein the organic electroluminescent device employing the mononuclear or binuclear platinum complex for phosphorescent materials exhibits high luminous efficiency and low power consumption.

Description

Platinum complex for phosphorescent materials and organic electroluminescent device containing the same}

The present invention relates to a dopant compound that can be used in the light emitting layer of an organic light emitting device, and more particularly, to a platinum complex for a phosphorescent material.

In recent years, the information society is accelerating the need to send and receive information anytime, anywhere. Accordingly, the weight of the flat panel display is increasing as compared to the conventional CTR display. On the other hand, as the flat panel display adopts an organic light emitting diode device capable of self-emission as a display device, it is not only possible to manufacture a thin product, but also has advantages such as low voltage driving, wide viewing angle, and fast response speed. Accordingly, organic light emitting diode display devices are rapidly growing as display devices of next generation displays.

Light emission from organic light emitting diodes can be classified into fluorescence and phosphorescence. If fluorescence is emitted when organic molecules fall from the singlet excited state to the ground state, phosphorescence Is a phenomenon in which organic molecules emit light when they are dropped from the triplet excited state to the ground state.

In more detail, the band formed by the bond orbit formed in the molecular electron orbit is called a valence band, and the band formed by the semi-bonded orbit is called a conducting band. The highest energy level of the valence band is called HOMO (Highest Occupied Molecular Orbital), the lowest energy level of the conductive band is called LUMO (Lowest Unoccupied Molecular Orbital), and the gap between HOMO energy and LUMO energy is band gap It is called). Electrons and holes injected into the organic light emitting layer constituting the organic light emitting device are recombined to form an exciton, and the light of the color corresponding to the band gap of the light emitting layer is realized in the process of converting the exciton electric energy into light energy. do. In this process, spin splitting produces a ratio of 1: 3 between singlet excitons and triplet excitons.

According to the selection rule for the electric dipole transition, the spin quantum number should not change when transitioning from the excited state to the ground state. Since the ground state of the organic molecule is the singlet state, the singlet excitons can shine and transition to the ground state. However, triplet excitons glow and cannot transit. Therefore, the maximum quantum efficiency is generally limited to 25%.

However, if the spin-orbital coupling is large, the singlet and triplet forms are mixed to cause inter-system crossing in the singlet-triplet state, so the triplet excitons are also phosphorescent to the ground state. You can metastasize. After all, if the triplet excitons can be used to emit light, the internal quantum efficiency of the organic light emitting diode can theoretically be improved to 100%.

That is, since the phosphorescence uses light emission in the excited triplet excited state, the internal quantum efficiency can reach 100%, compared to the fluorescence using only the singlet excitation light emission (Baldo, et al., Nature, Vol. 395). 151-154, 1998). When heavy metals such as ruthenium, iridium, and platinum are introduced into organic molecules, the complex is in singlet state ( ¹ MLCT) and triplet through spin-orbital coupling caused by the heavy atom effect. As a result of the mixing of the always ( ³ MLCT), a forbidden transition is possible, and phosphorescence can be effectively performed even at room temperature.

In the organic light emitting device, a paraphenyl vinylidene (PPV) -based polymer material is mainly used as a host material as a polymer light emitting material. A heavy metal complex compound is used as a dopant material to increase luminous efficiency. A cheaper process for fabricating an organic light emitting display device is a spin coating method, in which a dopant material is dissolved in an organic solvent and uniformly mixed with a host polymer material to improve luminous efficiency.

As phosphorescent light emitting materials, many complexes using iridium as a center metal have been studied, but recently, complexes using platinum as a center metal have been studied. For example, Korean Patent Laid-Open Publication No. 2011-0064026 discloses a platinum complex having a pyridine ligand, and Japanese Patent Laid-Open No. 2001-181617 uses a compound having an arylpyridine skeleton as a ligand and ortho having platinum as a central atom. Metallized platinum complexes are disclosed as useful as phosphorescent materials, and Japanese Patent Laid-Open No. 2002-175884 discloses platinum complexes having bipyridine biaryl skeleton compounds as ligands.

However, since the organic light emitting device using phosphorescent light emission is currently limited to red and green light emission, the application range for the color display is narrow, the light emission characteristics are improved for other colors, the light emission wavelength can be adjusted, and the light emission efficiency. The development of this excellent compound for phosphorescent materials is desired.

Baldo, et al., Nature, Vol. 395. 151-154, 1998

Korean Patent Publication No. 2011-0064026 Japanese Laid-Open Patent No. 2001-181617 Japanese Patent Laid-Open No. 2002-175884

The present invention exhibits excellent luminescence properties and provides a mononuclear or binuclear platinum complex for phosphorescent materials capable of controlling the emission wavelength.

In another aspect, the present invention provides an organic EL device having excellent internal quantum efficiency, including the mononuclear or binary nucleus platinum complex of the present invention.

The present invention relates to a platinum complex for a phosphorescent material applicable to an organic light emitting device that exhibits high luminous efficiency and low power consumption even at high brightness, and an organic light emitting device including the same. Provided is a mononuclear platinum complex for a phosphorescent material represented by the following Chemical Formula 1, or a heteronuclear platinum complex for a phosphorescent material represented by the following Chemical Formula 2, and an organic electroluminescent device comprising the same.

[Formula 1]

(2)

(In Chemical Formulas 1 and 2, R ₁ to R ₈ are each independently hydrogen, halogen, C ₁ -C ₂₀ alkyl, C ₂ -C ₂₀ alkenyl, C ₂ -C ₂₀ alkynyl, C ₁ -C ₂₀ alkoxy C ₆ -C ₂₀ aryl, C ₆ -C ₂₀ aryloxy mono or diC ₁ -C ₂₀ alkylamino, mono or diC ₆ -C ₂₀ arylamino, 5- to 7-membered heterocycloalkyl, cyano, Carboxyl, nitro, mercapto group or C ₃ -C ₂₀ heteroaryl, the alkyl, alkenyl, alkynyl, alkoxy, aryl, alkylamino, arylamino, heterocycloalkyl and heteroaryl of R ₁ to R ₈ May be further substituted with halogen, cyano or nitro,

p is an integer of 1 to 3,

q is an integer of 1 to 4 and when p and q are 2 or more, R ₁ to R ₈ may be the same or different from each other.)

In addition, the present invention preferably in Formula 1 and Formula 2 R ₁ to R ₂ is C ₁ -C ₂₀ alkyl and R ₇ to R ₈ may be C ₁ -C ₂₀ alkyl or halogen.

Specifically, in Formula 1 and Formula 2, R ₁ to R ₈ are each independently hydrogen, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonane group, decane group, and nonanedecane. Group, isopropyl group, tert-butyl group, methoxy group, phenyloxy group, benzyloxy group, amino group, dimethyl amino group, diphenylamino group, pyrrolidine group, phenyl group, carboxyl group, fluorine atom, bromine atom, chlorine atom, iodine atom , Cyano group, nitro group, trifluo methyl group, mercapto group.

The mononuclear platinum complex for phosphorescent material represented by Formula 1 may be exemplified in more detail by the following compounds, but the following compounds are not intended to limit the present invention.

In addition, the mononuclear platinum complex for phosphorescent material represented by Formula 1 of Formula 2 may be more specifically exemplified by the following compounds, but the following compounds are not intended to limit the present invention.

 It is preferable that λmax (maximum emission wavelength) of the phosphorescence obtained from the mononuclear or binuclear platinum complexes represented by the general formulas (1) and (2) of the present invention is 400 nm or more and 610 nm or less in a green to blue light emitting material, and specifically, The phosphorescent wavelength of the mononuclear platinum complex is characterized in that it appears in the range from 450 nm to 600 nm, the internal phosphorescence efficiency is characterized by 40 to 60% / Pt-atoms.

 The phosphorescence emission wavelength of the dinuclear platinum complex represented by Formula 2 is characterized in that it appears in the range of 450 nm to 600 nm, the internal phosphorescence efficiency is characterized in that 40 to 60% / Pt-atoms.

In addition, the mononuclear or binuclear platinum complex of the present invention may increase solubility in an organic solvent by introducing various substituents into the spiro (sipro) structure of fluorene, and may also increase compatibility with existing polymer materials.

The mononuclear platinum complex represented by the formula (1) of the present invention can be prepared by the following reaction formula.

[Reaction Scheme]

(In the above scheme, R ₁ to R ₈ and p, q are the same as the definition of formula 1.)

The dinuclear platinum complex represented by the formula (2) may be prepared by reacting two platinum complex precursors (1) with formula (B) in the scheme or reacting the platinum complex precursors with the mononuclear platinum complex represented by the formula (1).

In the said manufacturing process, reaction temperature is 40-300 degreeC normally, Preferably it is 60-250 degreeC, More preferably, it selects suitably at 80-200 degreeC. The reaction time depends on the reaction conditions depending on the reaction temperature, the solvent, and the additives, but is usually appropriately selected in the range of 30 minutes to 1 week, preferably 30 minutes to 48 hours, even more preferably 1 hour to 12 hours.

The platinum complex precursor used for preparing the compound of the present invention is selected from an inorganic platinum compound and an organic platinum complex. Preferred examples of the inorganic platinum compound include platinum halides such as platinum chloride, platinum bromide and platinum iodide, and halogenated platinates such as sodium chloride, potassium chloride, potassium bromide and potassium iodide. Platinum chloride and potassium chloroplatinic acid are more preferred because of the availability of water.

The present invention also provides an organic electroluminescent device comprising the mononuclear or binuclear platinum complex of the present invention.

The complexes having the skeletal structures of Chemical Formulas 1 and 2 prepared in the present invention are novel platinum complexes which are organic light emitting dopant materials, and exhibit light emission characteristics and very high internal quantum efficiency.

Therefore, the platinum complex having a skeletal structure of Formulas 1 and 2 may be usefully used as a phosphorescent material of an organic light emitting device having excellent luminous efficiency.

The mononuclear or binuclear platinum complex of the present invention exhibits excellent luminescence properties with short wavelengths and can control emission wavelengths by controlling substituents on the main ligand, bipyridine.

In addition, the mononuclear or binuclear platinum complex of the present invention has high solubility in organic solvents by introducing various substituents into the spiro (sipro) structure of fluorene.

In addition, the organic electroluminescent device including the mononuclear or binary nucleus platinum complex of the present invention has high internal quantum efficiency and high luminescence properties even at high luminance.

Figure 1 shows the absorption spectrum (CH ₂ Cl ₂ solvent) of the compound synthesized in Example 1 of the present invention,
Figure 2 shows the emission spectrum (CH ₂ Cl ₂ solvent) of the compound synthesized in Example 1 of the present invention,
Figure 3 shows the absorption spectrum (CH ₂ Cl ₂ solvent) of the compound synthesized in Example 2 of the present invention,
Figure 4 shows the emission spectrum (CH ₂ Cl ₂ solvent) of the compound synthesized in Example 2 of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the following examples are illustrative of the present invention and the scope of the present invention is not limited thereto.

Example 1

Synthesis of - [(bpy) Pt (2,2 '(9,9-dioctyl-9 H -fluorene-2,7-diyl-bis (2,2'-bipyridine)] [PF 6] 2

After removing argon and vacuum three times to remove oxygen and water in 100cc Schlenk tube, Pt (bpy) Cl ₂ (50mg, 0.115mmol) and

2,2 '- Add (9,9-dioctyl-9 H -fluorene -2,7-diyl-bis (2,2'-bipyridine)) (90mg, 0.126mmol). After maintaining the argon state, add a mixed solution of 25 ml of DMSO and 25 ml of CH ₂ Cl ₂ .

The Schlenk tube containing the mixture was refluxed at 110 ° C. for 48 hours under argon gas atmosphere. After confirming the completion of the reaction by TLC, the mixture is cooled to room temperature.

After cooling, NH ₄ PF ₆ (185mg) was added and stirred for about 10 minutes. H ₂ O (25ml) was added thereto. Then, the phases were separated using a syringe. The lower liquid was removed with impurities using H ₂ O (25 ml), and the precipitate was vacuum dried to obtain the title compound (yield: 65%).

¹ H-NMR (CD ₂ Cl ₂ / ppm): 9.82 (d, 1H), 9.05 (s, 1H), 8.73 (s, 2H), 8.58 (dd, 2H), 8.23-8.17 (m, 4H), 8.05 (d, 2H), 7.92-7.74 (m, 4H), 7.38 (d, 2H), 2.16 (m, 4H), 1.1 (m, 24H), 0.8 (m, 6H).

¹³ C-NMR (400 MHz, CD ₂ Cl ₂ -d ₂ / ppm): 157.11, 156.0, 153.41, 150.43, 148.88, 141.96, 140.74, 138.07, 137.99, 136.23, 130.09, 127.26, 124.91, 122.76, 122.05, 121.95, 120.73, 84.99, 41.52, 32.96, 32.96, 31.16, 30.91, 30.39, 25.97, 25.11, 23.80, 15.02

[Example 2]

[(bpy) Pt (2,2 '-(9,9-dioctyl-9 H -fluorene-2,7-diyl-bis (2,2'-bipyridine)]] Synthesis of [PF ₆ ] ₄

100cc Schlenk for the removal of oxygen and moisture present in the tube after the vacuum with argon replacement three times, who contributed to _{Pt (bpy) Cl 2 (20mg} , 0.047mmol) and (2,2 '- (9,9-dioctyl -9 H -fluorene-2,7-diyl-bis (2,2'-bipyridine) (11.2mg, 0.016mmol)

After maintaining the argon state, add a mixed solution of DMSO (10ml) and CH ₂ Cl ₂ (10ml). The Schlenk tube containing the mixture was refluxed at 110 ° C. for 48 hours under argon gas atmosphere.

After confirming the completion of the reaction by TLC, the mixture is cooled to room temperature. After cooling, NH ₄ PF ₆ (185mg) was added and stirred for about 10 minutes. H ₂ O (10ml) was added thereto. Then, phase separation was performed using a syringe. The lower liquid was removed with impurities using H ₂ O (10 ml), and the precipitate was vacuum dried to obtain the title compound (yield: 70%.).

¹ H-NMR (CD ₂ Cl ₂ / ppm): 9.82 (d, 4H), 9.05 (s, 2H), 8.73 (s, 2H), 8.58 (dd, 6H), 8.23 (m, 6H), 8.0 ( m, 8H), 7.8-7.6 (m, 6H), 7.5 (m, 2H), 2.16 (m, 4H), 1.1 (m, 24H), 0.8 (m, 6H)

¹³ C-NMR (400 MHz, CD ₂ Cl ₂ -d ₂ / ppm): 158.1, 154.8, 153.5, 150.8, 149.3, 148.6, 140.8, 140.2, 137.2, 128.5, 127.4, 125.8, 124.0, 122.8, 122.6, 121.9, 41.5, 32.9, 31.1, 30.9, 30.4, 25.9, 25.1, 23.8, 15.0

[Test Example] Measurement of the luminescence properties of the complex

To investigate the luminescence properties, the heteronuclear complex synthesized in Examples 1 and ₂ was dissolved in 5 ₂ 10 ^-5 M CH ₂ Cl ₂ and measured. The instrument used was JASCO FP-6500. The excitation wavelength of the complex was based on the absorption wavelength. Based on the measured data, the luminous efficiencies of the complexes were calculated according to the following formula (1), and the results are shown in Table 1 below. As a comparative example, a platinum complex (Pt (iqdz) ₂ ) (Adv. Funct. Mater., 2005, 15 (2), 223-229) synthesized according to the previously reported literature was used. The reference light emitting material used in the present invention is [Ru (bpy) ₃ ] ²⁺ and its internal quantum efficiency is 0.062.

[Equation 1]

? _S = (A _std / A _s ) (I _s / I _std )? _Std

[Wherein, A _std ,: UV absorbance coefficient of ([Ru (bpy) ₃ } ²⁺ complex)

A _s ,: UV absorbance coefficient of the sample complex

I _s ,: Intensity of eye light of the standard ([Ru (bpy) ₃ } ²⁺ complex)

I _std ,: Phosphorescence intensity of sample complex

Φ _std : internal quantum efficiency of standard ([Ru (bpy) ₃ } ²⁺ complex (0.062)]]

division Example 1 Example 2 Comparative Example Internal quantum efficiency (Φ) 0.6 / Pt-atom 0.65 / Pt-atom 0.45 / Pt-atom Maximum emission wavelength (nm) 477, 519 573,522 635

As shown in Table 1, it can be seen that the mononuclear or binuclear transition metal complex of the present invention has a short wavelength emission characteristic and a very high internal quantum efficiency as compared with the conventional platinum complex.

Claims (10)

Mononuclear platinum complex for phosphorescent materials represented by the following formula (1).
[Chemical Formula 1]

(In Formula 1, R ₁ to R ₈ are independently of each other hydrogen, halogen, C ₁ -C ₂₀ alkyl, C ₂ -C ₂₀ alkenyl, C ₂ -C ₂₀ alkynyl, C ₁ -C ₂₀ alkoxy, C _6- C ₂₀ aryl, C ₆ -C ₂₀ aryloxy mono or di (C ₁ -C ₂₀ ) alkylamino, mono or diC ₆ -C ₂₀ arylamino, 5- to 7-membered heterocycloalkyl, cyano, Carboxyl, nitro, mercapto group or C ₃ -C ₂₀ heteroaryl, the alkyl, alkenyl, alkynyl, alkoxy, aryl, alkylamino, arylamino, heterocycloalkyl and heteroaryl of R ₁ to R ₈ May be further substituted with halogen, cyano or nitro,
p is an integer of 1 to 3,
q is an integer of 1 to 4 and when p and q are 2 or more, R ₁ to R ₈ may be the same or different from each other.) The method of claim 1,
A mononuclear platinum complex for phosphorescent material, wherein R ₁ to R ₂ are C ₁ -C ₂₀ alkyl and R ₇ to R ₈ are C ₁ -C ₂₀ alkyl or halogen. The method of claim 1,
R ₁ to R ₈ are each independently hydrogen, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonane group, decane group, nonanedecane group, isopropyl group, tert-butyl Group, methoxy group, phenyloxy group, dimethyl amino group, diphenylamino group, pyrrolidine group, phenyl group, carboxyl group, fluorine atom, bromine atom, chlorine atom, iodine atom, cyano group, nitro group, trifuluromethyl group, mercap A mononuclear platinum complex for phosphorescent material, characterized by being earthenware. The method of claim 1,
Mononuclear platinum complex for phosphorescent materials selected from the following compounds.

A binuclear platinum complex for phosphorescent materials represented by the following formula (2).
(2)

(In Formula 1, R ₁ to R ₈ are independently of each other hydrogen, halogen, C ₁ -C ₂₀ alkyl, C ₂ -C ₂₀ alkenyl, C ₂ -C ₂₀ alkynyl, C ₁ -C ₂₀ alkoxy, C _6- C ₂₀ aryl, C ₆ -C ₂₀ aryloxy mono or di (C ₁ -C ₂₀ ) alkylamino, mono or diC ₆ -C ₂₀ arylamino, 5- to 7-membered heterocycloalkyl, cyano, Carboxyl, nitro, mercapto group or C ₃ -C ₂₀ heteroaryl, the alkyl, alkenyl, alkynyl, alkoxy, aryl, alkylamino, arylamino, heterocycloalkyl and heteroaryl of R ₁ to R ₈ May be further substituted with halogen, cyano or nitro,
p is an integer of 1 to 3,
q is an integer of 1 to 4 and when p and q are 2 or more, R ₁ to R ₈ may be the same or different from each other.) 6. The method of claim 5,
R ₁ to R ₂ are C ₁ -C ₂₀ alkyl and R ₇ to R ₈ is C ₁ -C ₂₀ alkyl or halogen. 6. The method of claim 5,
R ₁ to R ₈ are each independently hydrogen, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonane group, decane group, nonanedecane group, isopropyl group, tert-butyl Group, methoxy group, phenyloxy group, dimethyl amino group, diphenylamino group, pyrrolidine group, phenyl group, carboxyl group, fluorine atom, bromine atom, chlorine atom, iodine atom, cyano group, nitro group, trifuluromethyl group, mercap A binuclear platinum complex for phosphorescent material, characterized by being earthenware. 6. The method of claim 5,
A binuclear platinum complex for phosphorescent material selected from the following compounds.

An organic electroluminescent device comprising a mononuclear platinum complex selected from any one of claims 1 to 4. An organic electroluminescent device comprising a binuclear platinum complex selected from any one of claims 5 to 8.

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