KR101754969B1 - platinum complexes, a preparation method thereof and organic light emitting diode containing the same - Google Patents

Abstract

The present invention relates to a mononuclear platinum complex, a method for producing the same, and an organic light emitting device containing the same. The organic light emitting device employing the monoclinic platinum complex according to the present invention exhibits high luminous efficiency and low power consumption.

Description

[0001] The present invention relates to a monoclinic platinum complex, a method for producing the same, and an organic light emitting device containing the same,

More particularly, the present invention relates to a monoclinic platinum complex which is a phosphorescent dopant compound which can be used for a light emitting layer of an organic light emitting device, a method for producing the monoclinic platinum complex, To an organic light emitting device.

In order to make a PMOLED (Passive Matrix OLED) or an AMOLED (Active Matrix OLED) with an OLED element, basic three primary color OLED elements of Red, Green and Blue are required. When these three primary color elements are driven into a pixel type structure, Is created.

Generally, since the visibility of the human eye is different for each of the three primary colors, the luminance ratios of Red, Green and Blue required for the display are different. When we try to create a display with a brightness of 100 cd / m2 (= nits), the ratio of brightness required for Red, Green, and Blue is about 30:50:20. This ratio also varies according to the intrinsic color of each red, green, and blue element.

In 1998, Princeton University in the United States developed a phosphorescent organic EL capable of 100% utilization of excitons formed by recombination of Pt (OEP) and Ir (ppy) ₃ . blue) color organic light emitting devices have been actively studied. In the development of phosphorescent materials, ruthenium, iridium, platinum, europium, and terbium are widely used as metals. When iridium or platinum complex having high atomic number is used, phosphorescence can be efficiently obtained even at room temperature, And platinum have been actively studied.

On the other hand, displays using electroluminescent devices are the application fields of polymer semiconductors that are the most commercialized. The life of the device is improving at a rapid rate each year, especially in the last five years.

In particular, low-molecular OLEDs are improving at an annual average rate of about 1.7 times. The lifetime of a low molecular weight light emitting device using a low molecular weight charge transport material and a light emitting material has been increased due to the development of a new material and optimization of the device structure and the lifetime of the phosphorescent device as well as the lifetime of the fluorescent device has reached a practical level. In the case of a red device, a lifetime of more than 40,000 hours was secured for both a fluorescent device and a phosphorescent device. In the case of a green device, the lifetime of the fluorescent device was more than 40,000 hours, and that of the phosphorescent device was more than 20,000 hours. The blue element has a lower life than the red and green elements. Typical element lifetime reduction is known as charge accumulation in the device, electrochemical modification of organic materials, photolysis of organic materials, etc. However, Is a part that needs to be investigated so many factors are combined and appear.

The luminance reduction of the device itself can be largely divided into deterioration due to the material itself and deterioration at the interface, and deterioration of the material itself can be classified into thermal deterioration and electrochemical deterioration. In the case of deterioration of the material itself, development of new materials is indispensably required, and lifetime characteristics are improved each year by development of new light emitting materials and common layer materials. The current lifetime level is about 20,000 hours, and further lifetime improvement is required. To this end, several research groups are currently developing materials and device structures for improving the lifetime of blue devices.

Phosphorescent devices with high luminous efficiency are still inferior in life span compared to fluorescent devices, but are expected to reach the level of fluorescent devices within a few years in terms of current improvement rate and development situation. Polymer OLED devices using polymeric materials have improved lifetime every year, but the life span of OLED devices has not reached the practical level yet compared with low molecular weight devices.

Korean Patent Publication No. 2012-0038319 (Publication date: April 23, 2012)

The present invention provides a mononuclear platinum complex having long lifetime characteristics with high luminous efficiency and low power consumption even at high luminance, and a method for producing the same.

The present invention also provides an organic luminescent device containing the mononuclear platinum complex of the present invention and having excellent efficiency.

The present invention relates to a mononuclear platinum complex having excellent luminescent properties, a method for producing the mononuclear platinum complex, and an organic light emitting device containing the same, wherein the mononuclear platinum complex of the present invention is represented by the following formula (1).

[Chemical Formula 1]

(In the formula 1,

R ₁ to R ₄ are independently hydrogen, halogen, C ₁ -C ₂₀ alkyl, C ₂ -C ₂₀ alkenyl, C ₂ -C ₂₀ alkynyl or a C ₁ -C ₂₀ alkoxy, wherein R ₁ to R ₄ each Alkyl, alkenyl, alkynyl and alkoxy may be further substituted with C ₁ -C ₂₀ alkyl, halogen, cyano or nitro;

p ₁ to p ₄ are each independently an integer of 1 to 3;

When p ₁ to p ₄ are 2 or more, R ₁ to R ₄ may be the same or different from each other.)

In Formula 1, R ₁ to R ₄ may independently be hydrogen, C ₁ -C ₂₀ alkyl or halogen, and preferably, R ₁ to R ₄ are each independently hydrogen or C ₁ -C ₂₀ alkyl.

The formula 1 according to an embodiment of the present invention may be selected from the following compounds, but is not limited thereto.

Preferably, the monoclinic platinum complex according to an embodiment of the present invention may have a maximum phosphorescence emission wavelength of 350 to 600 nm.

The present invention also provides a process for preparing a mononuclear platinum complex of the present invention, comprising the step of reacting the following formula (2) with the following formula (3)

[Chemical Formula 1]

(2)

(3)

[In the formulas (1) to (3)

R ₁ to R ₄ are independently hydrogen, halogen, C ₁ -C ₂₀ alkyl, C ₂ -C ₂₀ alkenyl, C ₂ -C ₂₀ alkynyl or a C ₁ -C ₂₀ alkoxy, wherein R ₁ to R ₄ each Alkyl, alkenyl, alkynyl and alkoxy may be further substituted with C ₁ -C ₂₀ alkyl, halogen, cyano or nitro;

X ₁ and X ₂ are independently of each other halogen;

p ₁ to p ₄ are each independently an integer of 1 to 3;

When p ₁ to p ₄ are 2 or more, R ₁ to R ₄ may be the same or different from each other.)

The formula 3 according to an embodiment of the present invention may be used in an amount of 1 to 1.5 moles per 1 mole of the compound of formula (2).

The reaction according to an embodiment of the present invention may be carried out in the presence of a base, and the base may be NH ₄ PF ₆ , AgBF _4, AgNO ₃ or AgPF ₆ as a preferred example.

The present invention also provides an organic light emitting device comprising the mononuclear platinum complex of the present invention.

The mononuclear platinum complex of the present invention is a low-molecular simple structure having high internal quantum efficiency, excellent thermal stability, and excellent long-life characteristics and light emission characteristics.

Further, the organic light emitting device containing the mononuclear platinum complex of the present invention has excellent light emission characteristics even at high luminance, and has long life and high efficiency characteristics.

1 shows the absorption spectrum (CH ₂ Cl ₂ solvent) of the platinum complex prepared in Example 1 of the present invention,
2 shows the luminescence spectrum (CH ₂ Cl ₂ solvent) of the platinum complex prepared in Example 1 of the present invention.

The present invention provides a mononuclear platinum complex having a high internal quantum efficiency and high thermal stability and excellent in light emission characteristics, efficiency and lifetime characteristics of an organic light emitting device employing the mononuclear platinum complex. The mononuclear platinum complex of the present invention is represented by the following formula (1).

[Chemical Formula 1]

(In the formula 1,

R ₁ to R ₄ are independently hydrogen, halogen, C ₁ -C ₂₀ alkyl, C ₂ -C ₂₀ alkenyl, C ₂ -C ₂₀ alkynyl or a C ₁ -C ₂₀ alkoxy, wherein R ₁ to R ₄ each Alkyl, alkenyl, alkynyl and alkoxy may be further substituted with C ₁ -C ₂₀ alkyl, halogen, cyano or nitro;

p ₁ to p ₄ are each independently an integer of 1 to 3;

When p ₁ to p ₄ are 2 or more, R ₁ to R ₄ may be the same or different from each other.)

The mononuclear platinum complex of the present invention has excellent luminescence characteristics in a short wavelength because it emits light by exciting electrons with low energy due to electrons-rich nitrogen atoms around the central metal platinum. In addition to the nitrogen atoms around the platinum, there are four more nitrogen atoms, and the electron density of these nitrogen atoms moves around the platinum and has better luminescence characteristics.

In addition, the central metal, platinum, and the non-coordinated nitrogen atom have the advantage of being able to form a platinum complex with another platinum atom, and have high thermal stability and long life characteristics.

Preferably, R ₁ to R ₄ in the formula (1) may independently be hydrogen, C ₁ -C ₂₀ alkyl or halogen. R ₁ to R ₄ are more preferably in terms of light emitting property, Independently of one another, may be hydrogen or C ₁ -C ₂₀ alkyl.

From the viewpoints of light emission characteristics, lifetime characteristics and thermal stability, the above-mentioned formula (1) may be represented by the following formula (1-1).

[Formula 1-1]

[In the formula 1-1,

R ₁₁ to R ₁₄ are preferably hydrogen or C ₁ -C ₂₀ alkyl.]

The formula (1) according to an embodiment of the present invention may be selected from the following compounds, but is not limited thereto.

The substituents comprising the "alkyl", "alkoxy" and other "alkyl" moieties described in this invention include both straight and branched chain forms and have from 1 to 20 carbon atoms, preferably from 1 to 10, Is a straight or branched chain hydrocarbon radical having 1 to 5 carbon atoms.

The term " alkenyl ", alone or as part of another group described herein, means a straight, branched or cyclic hydrocarbon radical containing from 2 to 20 carbon atoms and at least one carbon to carbon double bond. More preferred alkenyl radicals are lower alkenyl radicals having 2 to 10 carbon atoms. The most preferred lower alkenyl radical is a radical having 2 to 5 carbon atoms. The alkenyl group may also be substituted at any available point of attachment. Examples of alkenyl radicals include ethenyl, propenyl, allyl, propenyl, butenyl, and 4-methylbutenyl. The terms alkenyl and lower alkenyl include cis and trans orientation, or alternatively, radicals having an E and Z orientation.

The term " alkynyl ", alone or as part of another group described herein, means a straight, branched or cyclic hydrocarbon radical containing from 2 to 20 carbon atoms and at least one carbon to carbon triple bond. More preferred alkynyl radicals are lower alkynyl radicals having from 2 to 10 carbon atoms. Most preferred is a lower alkynyl radical having 2 to 5 carbon atoms. Examples of such radicals include propargyl, butynyl, and the like. The alkynyl group may also be substituted at any available attachment point.

The maximum phosphorescence emission wavelength (? Max, maximum emission maximum wavelength) of the platinum complex according to an embodiment of the present invention may be 350 to 600 nm, more preferably 350 to 450 nm, and the internal phosphorescent efficiency may be 80 to 100% / Pt < - > atom.

The present invention also provides a process for preparing a monoclinic platinum complex represented by the formula 1 of the present invention. The process for preparing a monoclinic platinum complex represented by the formula 1 of the present invention comprises reacting the following formula 2 with the following formula 3: (1).

[Chemical Formula 1]

(2)

(3)

[In the formulas (1) to (3)

R ₁ to R ₄ are independently hydrogen, halogen, C ₁ -C ₂₀ alkyl, C ₂ -C ₂₀ alkenyl, C ₂ -C ₂₀ alkynyl or a C ₁ -C ₂₀ alkoxy, wherein R ₁ to R ₄ each Alkyl, alkenyl, alkynyl and alkoxy may be further substituted with C ₁ -C ₂₀ alkyl, halogen, cyano or nitro;

X ₁ and X ₂ are independently of each other halogen;

p ₁ to p ₄ are each independently an integer of 1 to 3;

When p ₁ to p ₄ are 2 or more, R ₁ to R ₄ may be the same or different from each other.)

The formula (3) according to one embodiment of the process of the present invention may be used in an amount of 1 to 1.5 moles per mole of the compound of the formula (2).

The reaction according to one embodiment of the process of the present invention may be carried out in the presence of a base, and preferred examples of the base include NH ₄ PF ₆ , AgBF _4, AgNO ₃ or AgPF ₆ .

The reaction according to an embodiment of the present invention is usually carried out at 40 to 120 ° C, preferably 60 to 100 ° C, more preferably 90 to 100 ° C in terms of the reaction yield. The reaction time varies depending on the reaction temperature, the solvent and the reaction conditions depending on the addition, but is usually carried out in the range of 5 to 48 hours, preferably 5 to 24 hours, more preferably 5 to 20 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 containing the novel platinum complex of the present invention.

The novel platinum complex of the present invention is a dopant substance of organic luminescence and exhibits a very high luminescence property with an internal quantum efficiency.

Accordingly, the novel platinum complex having the skeleton structure of formula (1) can be usefully used as a phosphorescent material of an organic light emitting device having excellent luminous efficiency.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, it is not intended to limit the scope of the present invention.

[Example 1] 3-3. Synthesis of Pt (5,5-diethyl-pyrimidine) ₂ Manufacturing

After replacing argon and vacuum three times to remove oxygen and moisture present in the 100cc Schlenk tube, Pt (5,5-diethyl-pyrimidine) Cl ₂ (0.1184 mmol) and 5,5-diethyl-pyrimidine (0.1302 mmol) 1: 1.2 molar ratio, and 50 ml of CH ₃ CN was further added thereto. The reaction mixture was refluxed at 85 캜 for 5 hours under an argon atmosphere, and then cooled to room temperature. To this was slowly added 5 ml of EtOH containing 0.296 mmol of AgPF ₆ and the mixture was refluxed at 85 캜 for 15 hours. After the reaction was completed, the precipitate was filtered off and the filtrate was dried under reduced pressure to give the title compound (67%).

¹ H-NMR (DMSO / ppm): 7.65 (t, 4H), 7.46 (t, 4H), 4.17 (m, 8H)

[Example 2] Measurement of luminescence property of platinum complex

The platinum complex prepared in Example 1 was dissolved in 5 x 10 < ^-5 > M DMSO and the apparatus 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 ((4,4'-di-tert-butyl-2,2'-bipyridine) Pt (bis (phenylethynyl) (Mehdi Rashidi, The reference luminescent material used in the present invention is [Ru (bpy) ₃ ] ²⁺ and its internal quantum efficiency is 0.062 (bpy) _3. to be.

[Comparative Example Structure]

[Equation 1]

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

[In the above formula, A _std : UV absorption coefficient of the [Ru (bpy) ₃ ] ²⁺ complex as a standard material

A _s : UV absorption coefficient of the SAMPL complex

I _s : intensity of phosphorescence of [Ru (bpy) ₃ ] ²⁺ complex as a standard material

I _std : phosphorescence intensity of the sample complex

Φ _std : Internal quantum efficiency (0.062) of the standard material [(Ru (bpy) ₃ ] ²⁺ complex)

division Example 1 Comparative Example Internal quantum efficiency (Φ) 0.89 / Pt-atom 0.4 / Pt-atom Maximum emission wavelength (nm) 467 570

As shown in Table 1, the monoclinic platinum complex of the present invention has a short wavelength luminescence characteristic and a very high internal quantum efficiency as compared with the conventional platinum complex.

Claims (10)

A monoclinic platinum complex represented by the following general formula (1).
[Chemical Formula 1]

(In the formula 1,
R ₁ to R ₄ are independently of each other hydrogen or C ₁ -C ₂₀ alkyl;
p ₁ to p ₄ are each independently an integer of 1 to 3;
When p ₁ to p ₄ are 2 or more, R ₁ to R ₄ may be the same or different from each other.) The method according to claim 1,
Wherein the monouclear platinum complex represented by Formula 1 is represented by Formula 1-1.
[Formula 1-1]

[In the formula 1-1,
R ₁₁ to R ₁₄ are hydrogen or C ₁ -C ₂₀ alkyl. The method according to claim 1,
Wherein R ₁ to R ₄ independently of one another are hydrogen or C ₁ -C ₅ alkyl. The method of claim 3,
And a monocyclic platinum complex selected from the following compounds.

The method according to claim 1,
Wherein the monoclinic platinum complex comprises a mononuclear platinum complex having a maximum phosphorescence emission wavelength of 350 to 600 nm. delete delete delete delete delete

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