WO2016127754A1

WO2016127754A1 - Phosphorescent compound, preparation method and organic light emitting diode device thereof

Info

Publication number: WO2016127754A1
Application number: PCT/CN2016/070790
Authority: WO
Inventors: 赵洪玉
Original assignee: 北京拓彩光电科技有限公司
Priority date: 2015-02-11
Filing date: 2016-01-13
Publication date: 2016-08-18
Also published as: CN104725373A; KR20170118113A; CN104725373B

Abstract

The present invention relates to a phosphorescent compound, which has a structural formula as follows. The phosphorescent compound of the present invention has a triplet state energy level of not less than 2.80 and can be used as a phosphorescent main body. The triplet state energy level is higher than the triplet state energy level of 2.7ev of doped materials; there is no energy reversion; and an efficient phosphorescent device is obtained. The blue phosphorescent compound with a high triplet state energy of the present invention is used as the main body of a light emitting layer of an organic light emitting diode, so that the energy transfer in the light emitting layer is promoted, and the blue emission efficiency and the service life of the organic light emitting diode is improved.

Description

Phosphorescent compound, preparation method and organic light emitting diode device

Technical field

The invention belongs to the field of organic electroluminescent materials, relates to a phosphorescent compound and an organic light emitting diode (OLED) device, and more particularly to a phosphorescent light having improved luminous efficiency due to high triplet energy and wide band gap. A compound and an OLED device using the phosphorescent compound.

Background technique

In recent years, organic electroluminescent devices have been extensively researched and developed. In the basic structure of such a light-emitting element, a layer containing a light-emitting substance is interposed between a pair of electrodes, and by applying a voltage to the element, light emission from the light-emitting substance can be obtained.

Since such light-emitting elements are self-luminous elements, they have advantages in terms of high pixel visibility and elimination of backlighting requirements with respect to liquid crystal displays, and thus are considered to be suitable for flat panel display elements. Light-emitting elements are also highly advantageous because they are thin and lightweight. Very high speed response is one of the features of this component.

Further, since such a light-emitting element can be formed in the form of a film, planar light emission can be provided. Therefore, an element having a large area can be easily formed. This is a feature that is difficult to obtain with a point light source typified by an incandescent lamp and an LED or a linear light source typified by a fluorescent lamp. Therefore, the light-emitting element also has a large potential as a planar light source or the like applicable to illumination.

The excited state formed by the organic compound may be singlet or triplet. The emission from the singlet excited state (S ^* ) is fluorescence, and the emission from the triplet excited state (T ^* ) is called phosphorescence. Further, it is considered that the statistical generation ratio in the light-emitting element is S ^* :T ^* =1:3. In the compound which converted the energy of the singlet excited state into light emission, no emission from the triplet excited state was observed at room temperature, and only emission from the singlet excited state was observed. Therefore, it is considered that the internal word efficiency of a light-emitting element using a fluorescent compound has a theoretical limit of 25%, based on a ratio of S ^* to T ^* of 1:3. Therefore, the organic electrophosphorescent material is a recently-appearing type of material, and is an organic electroluminescent material having high luminous efficiency and luminescent brightness. By introducing a heavy metal atom, the triplet state of the originally forbidden at room temperature is utilized. Transition, so that the internal quantum efficiency theory can reach 100%, which is four times that of a single fluorescent material (1, Cao Y., Parker ID, Heeger J., Nature, 1999, 397: 414-417.2, Wohlgenann M., et al .Nature, 2001, 409: 494-497.). Most of the heavy metal atoms commonly used in organic electrophosphorescent materials are transition metals. Among them, ruthenium is the most widely used and most studied. This is because metal ruthenium complexes have high efficiency, strong phosphorescence at room temperature, and can pass through ligands. The adjustment of the structure adjusts the wavelength of the illumination such that the color of the electroluminescent device covers the entire visible region. Therefore, designing and synthesizing new and highly efficient metal ruthenium complexes is of great significance for the development of phosphorescent materials.

However, the efficiency of the dopant is drastically reduced due to the quenching phenomenon, and thus exists for the light-emitting layer of the dopant having no host. limit. Therefore, it is desirable to form a layer of luminescent material by a dopant and a host having higher thermal stability and triplet energy.

In an OLED device comprising a phosphorescent compound, holes from the anode and electrons from the cathode are combined at the body of the layer of luminescent material. The single-state exciton of the host undergoes an energy level transition to the singlet or triplet level of the dopant, and an energy level transition from the triplet exciton of the host to the triplet level of the dopant occurs. The excitons that transition to the singlet state of the dopant again transition to the triplet level of the dopant. The exciton of the triplet level of the dopant transitions to the ground state, causing the luminescent layer to emit light.

To achieve a high-level transition of the transition to the dopant, the triplet energy of the bulk should be greater than the triplet energy of the dopant. When the triplet energy level of the body is smaller than the triplet energy of the dopant, a reverse transition from the dopant to the bulk energy occurs, thereby reducing the luminous efficiency.

CBP, which is widely used in the main body, has a triplet level of 2.6 eV, a maximum energy level of about -6.3 eV, and a lowest energy level of about -2.8 eV. Therefore, using the triplet level 2.8eV, the highest level -5.8eV and the lowest level -3.0eV blue dopant FCNIr, the energy level reverse transition from dopant to host occurs, resulting in reduced luminous efficiency. In particular, the occurrence of a decrease in luminous efficiency is more remarkable under low temperature conditions.

Summary of the invention

It is an object of the present invention to provide a phosphorescent compound having a high triplet energy and a broad energy band gap.

Another object of the present invention is to provide an OLED having improved luminous efficiency.

The phosphorescent compound of the present invention has the following structural formula:

Among them, only one of A, B, and C is a hetero atom N, and the others are C atoms;

Only one of 1, 2, 3, and 4 is a hetero atom N, and the others are C atoms;

Ar is a substituted or unsubstituted aryl, heteroaryl or fused ring aryl group of C6-30.

5, 6, 7, and 8 indicate the position at which the Ioxazoline ring is coupled to the C atom on the II oxazole ring.

The Ar is the following structural formula:

Preferably, Ar is phenyl, naphthyl, phenyl substituted phenyl or naphthyl, heteroaryl or fused ring aryl.

Preferably, the Ioxazoline ring and the II oxazole ring are attached to the 6 or 7 position,

Preferred:

Wherein Ar is a phenyl group.

Preferably, A or B is an N atom.

In the method for synthesizing the phosphorescent compound, the Ioxazoline ring and the II oxazole ring are respectively prepared into a bromine, a boric acid or a boric acid ester, and are bonded together by a SUZUKI coupling reaction.

The Ioxazoline cyclobromide is obtained by reacting an Ioxazoline with a bromopyridine to form an N atom substituted oxazoline, which is then brominated by NBS.

An organic light emitting diode device comprising: a first electrode; a second electrode opposite to the first electrode; a light emitting layer between the first electrode and the second electrode, wherein the light emitting layer comprises the phosphorescent compound.

The luminescent layer material includes a host and a dopant, and the phosphorescent compound serves as a host material.

The phosphorescent compound acts as a blue phosphorescent host material.

In the general formula of the compound of the present invention, the three positions A, B and C are the positions of the nitrogen atom, and the structures respectively constituted are 2-pyridine, 3-pyridine and 4-pyridine.

The 1, 2, 3, and 4 positions of the Icarbazole ring are nitrogen atoms, which constitute the four isomers of the oxazoline:

The 5, 6, 7 and 8 positions of the II carbazole ring are the positions at which the two rings are coupled.

The phosphorescent compound of the present invention has a triplet energy level of 2.80 or more, and is used as a phosphorescent host. The triplet energy level is greater than the triplet energy level of the doping material of 2.7 ev, and no energy is reversed to obtain a high-efficiency phosphorescent device.

The blue phosphorescent compound having high triplet energy of the present invention, and using the blue phosphorescent compound as a main body of the light emitting layer of the organic light emitting diode, thereby promoting energy transfer in the light emitting layer, and improving the organic light emitting diode Blue emission efficiency and longevity.

DRAWINGS

1 is a nuclear magnetic diagram of the D structure of Embodiment 1.

Figure 2 is a partial enlarged view of Figure 1,

Figure 3 is a nuclear magnetic diagram of Compound 1 in Example 1,

Figure 4 is a structural magnetic nucleus of the structure A in the third embodiment

Figure 5 is a structural magnetic nucleus of Embodiment A in Embodiment 4

detailed description

The present invention provides a novel phosphorescent material. In order to make the objects, technical solutions and effects of the present invention clearer and more complete, the following is a further detailed description of the present invention. It is to be understood that the examples herein are merely illustrative of the invention and are not intended to limit the scope of the invention. The compounds A, B, and E referred to below were synthesized according to literature reports (Chem. Commun., 2013, 49, 5948-5950), and the structure was confirmed by nuclear magnetic resonance.

Example 1. Preparation of the first body

Synthesis of intermediate C:

0.1mol A, 0.2mol B, sodium t-butoxide 0.2mol, 0.002mol palladium acetate were added to 2L four-necked flask, 1L toluene was added to 2L four-necked bottle, stirred, nitrogen was filled for 30 minutes, and 1ML (50% toluene solution) was added. The tert-butylphosphine was heated to reflux for 4 hours, cooled and filtered to give a mother liquid. The mother liquor was concentrated to give a pale yellow solid. Mass Spectrometry (ESI, 245.3)

Synthesis of intermediate D:

0.1 mol C was dissolved in 300 ML DMF, completely dissolved at 50 degrees, 0.1 mol of NBS was added dropwise, and an off-white solid was gradually precipitated with the dropwise addition. The NBS was added dropwise, stirred overnight, and cooled to give a white solid. The detection is shown in Figure 1 of the nuclear magnetic spectrum, and the enlarged view is shown in Figure 2. Synthesis of Compound 1:

0.1mol D, 0.1mol E was added to 2L four-necked bottle, add 400ML of toluene, 200ML of ethanol, 200ML of water, stir, add 0.2mol of potassium carbonate in batches, add nitrogen for 30 minutes, add palladium acetate 0.5G, tri-tert-butylphosphine ( 50% toluene solution) 1 mL, refluxed overnight. Cool, filter to give a pale yellow solid, mass spectrum detection 486.5 (MODI-TOF)

(HNMR (CDCl3, 8.73, 1H, 8.45, 3H, 8.35-8.40, 3H, 7.99, 1H, 7.90, 1H, 7.75-7.78, 1H, 7.62-7.64, 4H, 7.4-7.5, 4H, 7.42, 3H) figure 2.

Example 2: Preparation of second body

Synthesis of Compound 2:

0.1mol D, 0.1mol E2 was added to a 1L four-necked bottle, add 400ML of toluene, 200ML of ethanol, 200ML of water, stir, add 0.2mol of potassium carbonate in batches, add nitrogen for 30 minutes, add palladium acetate 0.5G, tri-tert-butylphosphine 1ML , reflux overnight. Cooled, filtered to give a pale yellow solid, pristine detection 486.5 (MODI-TOF)

Nuclear magnetic

H NMR (CDCl3, 8.74, 1H, 8.46, 3H, 8.36-8.41, 3H, 7.98, 1H, 7.91, 1H, 7.77-7.79, 1H, 7.65-7.67, 4H, 7.5-7.6, 4H, 7.47, 3H).

Example 3, third body synthesis

The α-oxazoline of Compound 1 was replaced by δ-oxazoline to give Compound 3.

The nuclear magnetic map of A3 is shown in Figure 4.

Nuclear magnetic

HNMR (CDCl 3, 8.77, 1H, 8.48, 3H, 8.38-8.42, 3H, 7.99, 1H, 7.92, 1H, 7.75-7.78, 1H, 7.63-7.67, 4H, 7.4-7.5, 4H, 7.42, 3H)

Example 4

According to the synthesis process of the

compound

1, 2, the compound 4 can be easily obtained.

The nuclear magnetic map of A4 is shown in Figure 5.

Nuclear magnetic

H NMR (CDCl 3 , 8.71, 1H, 8.42, 3H, 8.35-8.41, 3H, 7.99, 1H, 7.92, 1H, 7.71-7.74, 1H, 7.62-7.64, 4H, 7.4-7.5, 4H, 7.29, 3H).

Example 5

The ultraviolet absorption spectrum and the photoluminescence spectrum of the materials of the first to fourth host materials prepared by the above-described synthesis examples and the comparative examples represented by the following chemical formulas at a low temperature (for example, 77 K) according to the method of the present invention were measured, and the results thereof were measured. In the table below.

Table 1:

It can be seen from Table 1 that the main body two to the main body four-trip state are higher than 2.92 ev, which can meet the requirements of the main body of the blue phosphorescent material.

The organic light emitting diode performance test using the blue phosphorescent compound formed of the first and second host materials described above and the material of the comparative example as a blue host is described below.

Example 6

The ITO substrate was patterned to have a light-emitting area of 3 mm × 3 mm, and then washed. After the ITO substrate was placed in a vacuum chamber, the bottom pressure was set to 1×10 ^-6 Torr. Then, on the ITO for forming the anode, HATCN having a thickness of about 50 angstroms was formed for the hole injection layer, and NPD having a thickness of about 550 angstroms was formed for the hole transport layer to form a TAPC having a thickness of about 100 angstroms. In the hole injection layer, a first host material having a thickness of about 300 angstroms and a FCNIr having a doping concentration of about 15% were formed for the light-emitting layer. Then, TmPyPb having a thickness of 400 angstroms was formed for the electron transport layer, LiF having a thickness of about 5 angstroms was formed for the electron injection layer, and an Al layer cathode of 1,100 angstroms was formed. Then, a packaging process is performed using a UV curable encapsulant and a moisture absorbent to form a light emitting diode.

Example 7

The organic light emitting diode was fabricated using the same manufacturing process as described above, except that the second body was used as the light emitting body.

Comparative example

An organic light emitting diode was fabricated in the same manner as in Production Example 1, except that the comparative example main body was used as the light emitting body.

Table 2

As shown in Table 2, it was confirmed that the organic light-emitting diodes manufactured according to Examples 1 and 2 exhibited improvement in luminous efficiency, quantum efficiency, and service life when displaying the same level of color coordinates as compared with the comparative examples. In particular, the service life of the organic light emitting diode is greatly improved.

As described above, the blue phosphorescent compound having high triplet energy of the present invention, and using the blue phosphorescent compound as a main body of the light emitting layer of the organic light emitting diode, thereby promoting energy transfer in the light emitting layer, and improving The blue emission efficiency and lifetime of the organic light emitting diode.

While the embodiments of the present invention have been described by reference to the various embodiments of the embodiments of the present invention, it will be understood that those skilled in the art may have many other modifications and embodiments that fall within the scope of the principles disclosed herein. More specifically, various variations and modifications are possible in the component parts and/or arrangement of the subject combination arrangement in the scope of the disclosure, the drawings and the appended claims. Alternative uses will also be apparent to those skilled in the art, in addition to variations and modifications in the component parts and/or arrangement.

Claims

Phosphorescent compound, its structural formula is as follows:

Among them, only one of A, B, and C is a hetero atom N, and the others are C atoms;

Only one of 1, 2, 3, and 4 is a hetero atom N, and the others are C atoms;

Ar is a substituted or unsubstituted aryl, heteroaryl or fused ring aryl group of C6-30.

5, 6, 7, and 8 indicate the position at which the Ioxazoline ring is coupled to the C atom on the II oxazole ring.
The phosphorescent compound according to claim 1, wherein said Ar is of the following structural formula:
The phosphorescent compound according to claim 2, wherein Ar is a phenyl group, a naphthyl group, a phenyl-substituted phenyl or naphthyl group, a heteroaryl group or a fused ring aryl group.
The phosphorescent compound according to claim 3, wherein the Ioxazoline ring is bonded to the II oxazole ring at a position of 6 or 7.
The phosphorescent compound according to claim 4, which has the following structural formula:

Wherein Ar is a phenyl group.
The method for synthesizing a phosphorescent compound according to any one of claims 1 to 5, wherein the Ioxazoline ring and the II oxazole ring are separately prepared into a bromine, a boric acid or a boric acid ester, and are bonded together by a SUZUKI coupling reaction.
The synthesis method according to claim 6, wherein the Ioxazoline ring bromine is obtained by reacting Ioxazoline with bromopyridine to form an N atom substituted oxazoline, and then bromination by NBS. .
An organic light emitting diode device comprising: a first electrode; a second electrode opposite to the first electrode; a light emitting layer between the first electrode and the second electrode, wherein the light emitting layer comprises claims 1-5 Any phosphorescent compound.
The organic light emitting diode device according to claim 8, wherein the material of the light emitting layer comprises a host and a dopant, and the phosphorescent compound is used as a host material.
The organic light emitting diode device according to claim 8, wherein the phosphorescent compound is a blue phosphorescent host material.