TWI507411B - Boron-contained carbazole derivatives and electroluminescent devices employing the same - Google Patents

Description

Boron-containing carbazole derivative and organic electroluminescent device therefor

The present invention relates to a boron-containing carbazole derivative and an organic electroluminescent device therefor; and more particularly to a boron-containing carbazole derivative having bipolar properties and an organic electroluminescent device therefor.

For example, a conventional organic electroluminescent material, such as the electroluminescent material of the Republic of China, No. I383033, discloses an organic organic electroluminescent material. The electroluminescent material is a carbazole derivative. In addition, the electroluminescent material adopts carbazole as a starting material, first forms an intermediate with an aromatic group by a coupling reaction, and then introduces a boron group into the intermediate to synthesize a blue light electric excitation with high color purity. Light material.

However, the above-mentioned No. I383033 discloses only the first use of a coupling reaction to form an intermediate having an aromatic group, and then introducing a boron group to the intermediate to synthesize an electroluminescent material, but it does not disclose an organic electric device having a bipolar characteristic. Excitation light materials or their manufacturing techniques. The foregoing patents are only for the purpose of reference to the present invention, and are not intended to limit the scope of the present invention.

In addition, regarding domestic and foreign patent inquiries regarding electroluminescent materials and their manufacturing methods, there are no related electro-optic materials with bipolar characteristics or their manufacturing techniques, so in the conventional electroluminescent materials and their manufacturing techniques. There is a need for further provision of electroluminescent materials or related fabrication techniques with dipole characteristics.

In view of the above, in order to meet the above technical problems and needs, the present invention provides a boron-containing carbazole derivative and an organic electroluminescent device therefor, which are suitably introduced into an arazole material to introduce an aromatic boron-substituted group. The carbazole material is suitably synthesized with the aromatic boron-substituted group, and since the carbazole material has a hole transporting property, and since the aromatic boron-substituted group has an electron-transporting property, an organic electroluminescent material having a bipolar characteristic is obtained, and thus Conventional organic electroluminescent materials can greatly improve the fluorescence emission characteristics and simplify the process.

The main object of the present invention is to provide a boron-containing carbazole derivative which is suitably introduced into an aromatic boron-substituted group by using a carbazole material, so that the carbazole material and the aromatic boron-substituted group are appropriately synthesized, since the carbazole material has The hole transfer characteristic, and because the aromatic boron-substituted group has electron-transporting characteristics, an organic electroluminescent material having a bipolar characteristic is obtained in such a manner as to achieve the purpose of improving the fluorescent light-emitting characteristics and simplifying the process thereof.

In order to achieve the above object, a boron-containing carbazole derivative according to a preferred embodiment of the present invention comprises: a carbazole material having a hole transporting property, the carbazole material being a host material; and an aromatic boron-substituted group having An electron transfer property; wherein the aromatic boron-substituted group is appropriately introduced into the carbazole material to appropriately synthesize the carbazole material and the aromatic boron-substituted group, thereby obtaining a bipolar characteristic organic electroluminescent material.

The carbazole material of the preferred embodiment of the present invention has an introduction position for appropriately introducing the aromatic boron-substituted group at the introduction position of the carbazole material.

In the preferred embodiment of the invention, the introduction position is the position 1, 3, and 9 of the carbazole material.

The main material of the carbazole material in the preferred embodiment of the present invention It is selected from OBC materials, PBC materials, NBPC materials, OBXC materials or PBXC materials.

The organic electroluminescent material having the dipole characteristics of the preferred embodiment of the invention has a dark blue to purple illumination range.

Another object of the present invention is to provide an organic electroluminescent device which utilizes an arsenic boron-substituted group appropriately introduced into a carbazole material to appropriately synthesize the carbazole material and the aromatic boron-substituted group, since the carbazole material has The hole transfer characteristic, and because the aromatic boron-substituted group has electron-transporting characteristics, the organic electroluminescent material obtained by obtaining a dipole characteristic is applied to an organic electroluminescent device to achieve improved fluorescent light-emitting characteristics and simplifying the process thereof. The purpose.

In order to achieve the above object, an organic electroluminescent device according to a preferred embodiment of the present invention comprises: a substrate; an anode; a hole transport layer; an electron transport layer; and a light-emitting layer comprising a carbazole material and an aromatic boron. a substituted group, the carbazole material is a host material, the carbazole material has a hole transporting property, and the aromatic boron-substituted group has electron transporting property; a buffer layer; and a cathode; wherein the carbazole material is appropriately introduced into the group The aromatic boron is substituted to properly synthesize the carbazole material and the aromatic boron substituent, thereby obtaining a bipolar characteristic organic electroluminescent material.

The carbazole material of the preferred embodiment of the present invention has an introduction position for appropriately introducing the aromatic boron-substituted group at the introduction position of the carbazole material.

The introduction position of the preferred embodiment of the present invention is the carbazole material Position 1, 3, 9.

The host material of the carbazole material in the preferred embodiment of the invention is selected from the group consisting of OBC materials, PBC materials, NBPC materials, OBXC materials or PBXC materials.

The organic electroluminescent material having the dipole characteristics of the preferred embodiment of the invention has a dark blue to purple illumination range.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing the molecular structure of a series of host materials using a boron-containing carbazole derivative according to a preferred embodiment of the present invention.

2A to 2E are schematic views showing a synthesis method of a boron-containing carbazole derivative according to a preferred embodiment of the present invention.

Fig. 3 is a view showing the luminescence range of the dipole characteristic of the boron-containing carbazole derivative of the preferred embodiment of the present invention.

Fig. 4 is a view showing the high triplet energy of the dipole characteristics of the boron-containing carbazole derivative of the preferred embodiment of the present invention.

Fig. 5 is a schematic view showing the ability of a phosphorescent host material containing a boron-containing carbazole derivative to transmit electrons and holes [dipoles] in a preferred embodiment of the present invention.

6A to 6D: The organic electroluminescent device of the preferred embodiment of the present invention selects a PXBC material as a component body, and is doped with a phosphorescent dopant Ir(ppy) ₃ material as a green phosphorescent component for component configuration and materials. Schematic diagram of structure and various component efficiencies.

In order to fully understand the present invention, the preferred embodiments of the present invention are described in detail below, and are not intended to limit the invention.

The boron-containing carbazole derivative of the preferred embodiment of the present invention and the organic electroluminescent device thereof are widely applicable to flat panel displays or related technical fields, solid state lighting devices and various lighting fixtures (for example: plants) The related art field of the invention is not departing from the spirit and technical scope of the invention.

For example, the organic electroluminescent device of the preferred embodiment of the present invention is an organic light emitting diode structure that can be selectively disposed on a glass substrate, but is not intended to limit the present invention. In addition, the glass substrate is selected to have an indium tin oxide (ITO) coated material (ITO-coated material) to form an ITO substrate layer or have other transparent conductive oxide (TCO) materials. However, it is not intended to limit the invention. The ITO substrate layer of the preferred embodiment of the present invention is used as an anode of an organic light emitting diode, but it is not intended to limit the present invention.

For example, the organic light emitting diode structure of the organic electroluminescent device of the preferred embodiment of the present invention includes a hole transport layer, a body light emitting layer, and a buffer layer. A layer and an electron transport layer are suitably arranged between the ITO substrate layer [anode] and the aluminum metal layer [cathode], but are not intended to limit the present invention.

The organic electroluminescent device of the preferred embodiment of the invention comprises a boron-containing carbazole derivative. The boron-containing carbazole derivative comprises a carbazole material and an aromatic boron-substituted group. The carbazole material is a host material, and the carbazole material has a hole transporting property. The aromatic boron-substituted group has electron transport properties. The aromatic boron-substituted group is appropriately introduced into the carbazole material to appropriately synthesize the carbazole material and the aromatic boron-substituted group, thereby obtaining a bipolar characteristic organic electroluminescent material. The organic electroluminescent device of the preferred embodiment of the invention achieves the effects of low driving voltage, low doping amount and high current efficiency.

In order to improve the luminous efficiency of the element, in addition to the phosphorescent dopant having high luminous efficiency doped in the main body light-emitting layer, the main body light-emitting layer itself must also have a host material which has good compatibility with the dopant. The host material must have high triplet energy [E _T ] and the ability to increase the electron/hole recombination rate. In order to obtain a phosphorescent element with high performance, the present invention chooses to utilize a molecular structure design to develop a high triplet energy [E _T ~ 2.74 eV] characteristic, and at the same time has a transfer electron / hole characteristic [μ _h , μ _e ~ 10 ^-4 〕 Bipolar phosphorescent host material, that is, it has the advantage of reducing the driving voltage.

For example, a boron-containing carbazole derivative of a preferred embodiment of the invention The synthesis method is carried out by using a synthesis method, and the carbazole material has an introduction position to facilitate introduction of the aromatic boron substitution group at the introduction position of the carbazole material. The introduction position of the preferred embodiment of the invention is the position 1, 3, 9 of the carbazole material or other suitable position, but it is not intended to limit the invention.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view showing the molecular structure of a series of host materials using a boron-containing carbazole derivative according to a preferred embodiment of the present invention, which mainly comprises the molecular structure of five host materials. Referring to FIG. 1, for example, the host material of the carbazole material in the preferred embodiment of the present invention is selected from the group consisting of an OBC material, a PBC material, an NBPC material, an OBXC material, or a PBXC material. The PXBC material of the preferred embodiment of the present invention has been confirmed in green phosphorescent elements to greatly improve the performance of the device, for example, various efficiency characteristics of the phosphorescent element [L _max = 57600 cd/m ² , η _{c, max} = 42.8 cd/ A, η _{p, max} = 30.1 lm/W and EQE = 12.9%], but it is not intended to limit the invention.

2A to 2E illustrate boron-containing bismuth in accordance with a preferred embodiment of the present invention The azole derivative is a schematic diagram of a synthetic method comprising a synthesis method of five host materials. Referring to Figures 2A to 2E, the synthesis method of the five host materials corresponds to the synthesis method selected by the OBC material, the PBC material, the NBPC material, the OBXC material or the PBXC material shown in Fig. 1, but it is not used. To limit the invention.

The Chinese name of OBC material is 1-(1,1-bis((1,3,5-trimethylphenyl)boryl)-3,6,9-triphenyl-9H-carbazole, the English name is 1 -(1,1-dimesitylboryl)-3,6,9-triphenyl-9H-carbazole; the Chinese name of PBC material is 3-(1,1-bis((1,3,5-trimethylphenyl)boron) 6,6-diphenyl-9H-carbazole, its English name is 3-(1,1-dimesitylboryl)-6,9-diphenyl-9H-carbazole; the Chinese name of NBPC material is 9-[3 -(1,1-bis((1,3,5-trimethylphenyl)boryl)phenyl)-3,6-diphenyl-9H-carbazole, the English name is 9-[3-(1 , 1-dimesitylboryl)phenyl]-3,6-diphenyl-9H-carbazole; Chinese name for OBXC material is 1-[5-(1,1-bis((1,3,5-trimethylphenyl)boryl)) -2,4-dimethylphenyl)]-9-ethyl-3,6-diphenyl-9H-carbazole, the English name is 1-[5-(1,1-dimesitylboryl)-2, 4-dimethylphenyl]-9-ethy1-3,6-diphenyl-9H-carbazole; the Chinese name of PBXC material is 3-[5-(1,1-bis((1,3,5-trimethylphenyl)) boron) -2,4-Dimethylphenyl)]-9-phenyl-9H-carbazole, the English name is 3-[5-(1,1-dimesitylboryl)-2,4-dimethylphenyl]-9- phenyl-9H-carbazole.

Fig. 3 is a view showing the light-emitting range of the dipole characteristic of the boron-containing carbazole derivative of the preferred embodiment of the present invention, which comprises the relationship between the four wavelengths and the normalized FL intensity. For example, the organic electroluminescent material having the bipolar characteristics of the preferred embodiment of the invention has a dark blue to purple illumination range. Please refer to Figure 3, for example, the maximum emission wavelength of NPBC material is 404nm [violet light], the maximum emission wavelength of PXBC material is 443nm [dark blue light], and the maximum emission wavelength of OPBC material is 445nm [dark blue] Light〕.

Figure 4 is a schematic view showing the high triplet energy of the dipole characteristic of the boron-containing carbazole derivative of the preferred embodiment of the present invention, which comprises a relationship between four wavelengths and a normalized intensity (au). It corresponds to the boron-containing carbazole derivative of Figure 3. Referring to FIG. 4, for example, the dipole molecule of the preferred embodiment of the present invention has a triplet energy [E _T ] of about 2.74 eV, which can be used as a sky blue phosphorescent dopant [FIrpic: E _T ~2.65eV], green phosphorescent dopant light [Ir(PPy) ₃ :E _T ~2.4eV] and red phosphorescent dopant [Ir(Pq) ₂ acac:E _T ~2.0eV] and other phosphorescent dopants Body material.

Figure 5 is a schematic view showing the ability of a phosphorescent host material containing a boron-containing carbazole derivative to transmit electrons and holes [dipoles] according to a preferred embodiment of the present invention, which comprises electric field strength and electrons and holes of two materials. The relationship between mobility (mobility (cm ² /Vs)]. Referring to FIG. 5, for example, in the preferred embodiment of the present invention, the carrier mobility of the molecules of the OXBC material and the PXBC material is selected from 1 to 4×10 ⁻⁴ cm ² /Vs, and the electrons and holes thereof are selected. The mobility is quite matched and it contributes to the recombination of electrons and holes, so there are currently a few well-matched bipolar properties.

For example, in the preferred embodiment of the present invention, after the PXBC material is selected as the main body of the element and the phosphorescent dopant Ir(ppy) ₃ material is doped as the green phosphorescent element, the performance evaluation is further performed. 6A to 6D show that the organic electroluminescent device of the preferred embodiment of the present invention selects a PXBC material as a component body, and a doped phosphorescent dopant Ir(ppy) ₃ material as a green phosphorescent component for component configuration and material. Schematic diagram of structure and various component efficiencies. Referring to Figures 6A through 6D, the PXBC material of the preferred embodiment of the present invention has been demonstrated in green phosphorescent elements to provide a significant increase in the performance of the components.

Referring to FIG. 6A again, the green phosphorescent device of the preferred embodiment of the present invention uses PXBC material as the main body of the component and is doped with the phosphorescent dopant Ir(ppy) ₃ material, which displays the energy formed by the structural configuration. Band distribution and its molecular structure are incorporated herein by reference.

As shown in Fig. 6B, for example, the maximum lumen of the green phosphorescent element is about L _max = 57600 cd/m ² . As shown in Fig. 6C, for example, the maximum current efficiency and maximum power efficiency of the green phosphorescent element are about η _{c, max} = 42.8 cd/A and η _{p, max} = 30.1 lm/W, respectively. As shown in Fig. 6D, for example, the external quantum efficiency [EQE] of the green phosphorescent element is about 12.9%, which is incorporated herein by reference.

As shown in Figures 3, 4, 5, 6A, 6B, 6C and 6D, on The experimental data is preliminary experimental results obtained under specific conditions, which are only used to easily understand or refer to the technical content of the present invention, and other experiments are still required. The experimental data and its results are not intended to limit the scope of the invention.

The foregoing preferred embodiments are merely illustrative of the invention and the technical features thereof, and the techniques of the embodiments can be carried out with various substantial equivalent modifications and/or alternatives; therefore, the scope of the invention is subject to the appended claims. The scope defined by the scope shall prevail. The copyright limitation of this case is used for the purpose of patent application in the Republic of China.

Claims (10)

A boron-containing carbazole derivative comprising: a carbazole material having a hole transporting property, wherein the carbazole material is a host material; and an aromatic boron-substituted group having an electron transporting property; The azole material is appropriately introduced into the aromatic boron-substituted group to appropriately synthesize the carbazole material and the aromatic boron-substituted group to form a phosphorescent host material, thereby obtaining a bipolar characteristic organic electroluminescent material, and the phosphorescent host material The choice is OBC material, PBC material, NBPC material, OBXC material or PBXC material. The boron-containing carbazole derivative according to claim 1, wherein the carbazole material has an introduction position so that the aromatic boron-substituted group is appropriately introduced at the introduction position of the carbazole material. The boron-containing carbazole derivative according to claim 2, wherein the introduction position is the position 1, 3, and 9 of the carbazole material. The boron-containing carbazole derivative according to claim 1, wherein the phosphorescent host material is doped with a phosphorescent dopant Ir(ppy) ₃ material when the PBXC material is selected. The boron-containing carbazole derivative according to claim 1, wherein the organic electroluminescent material having a dipolar characteristic has a dark blue to purple light-emitting range. An organic electroluminescent device comprising: a substrate; an anode; a hole transport layer; an electron transport layer; a light-emitting layer comprising a carbazole material and an aromatic boron-substituted group, the carbazole material being a a host material, the carbazole material has a hole transporting property, and the aromatic boron-substituted group has an electron transporting property; a buffer layer; a cathode; wherein the aromatic boron-substituted group is appropriately introduced into the carbazole material, so that the carbazole material and the aromatic boron-substituted group are appropriately synthesized to form a phosphorescent host material, thereby obtaining a bipolar characteristic organic electroluminescence The material, and the phosphorescent host material is selected to be an OBC material, a PBC material, an NBPC material, an OBXC material, or a PBXC material. The organic electroluminescent device according to claim 6, wherein the carbazole material has an introduction position to facilitate introduction of the aromatic boron substitution group at the introduction position of the carbazole material. The organic electroluminescent device according to claim 7, wherein the introduction position is the position 1, 3, and 9 of the carbazole material. The organic electroluminescent device according to claim 6, wherein the phosphorescent host material is doped with a phosphorescent dopant Ir(ppy) ₃ material when the PBXC material is selected. The organic electroluminescent device according to claim 6, wherein the organic electroluminescent material having a bipolar characteristic has a dark blue to purple light emitting range.