CN100422285C - Light-emitting layer of organic electroluminescent device and organic electroluminescent material thereof - Google Patents

Abstract

A light-emitting layer of an organic electroluminescent device is composed of a main light-emitting body and a dopant, wherein the dopant is doped into the main light-emitting body, and the chemical structure of the dopant can be the following formulas.

Description

Light-emitting layer of organic electroluminescent device and its organic electroluminescent material

technical field

The invention relates to an organic electroluminescent device, in particular to a light-emitting layer of the organic electroluminescent device and its organic electroluminescent material.

Background technique

In recent years, in the flat panel display industry, Organic Light Emitting Diode Display (OLED Display) has the advantages of self-luminescence, high brightness, ultra-wide viewing angle, high response speed, low driving voltage and light weight. gradually gained attention. However, the current market share of electroluminescent displays is still limited. Therefore, all major display manufacturers are committed to finding the best manufacturing method to improve production yield and product characteristics, hoping to promote the early development of electroluminescent displays. popularized in the market.

Organic electroluminescence display is a self-illuminating flat-panel display. Its light source is converted from the pixel current of organic light-emitting diode itself. Therefore, the maximum brightness of the panel can be determined by adjusting the current, and then through the coupling Connected thin film transistors are used to define different grayscale brightness.

The conventional full-color technology of organic electroluminescent displays uses metal shielding to limit the positions of the three primary colors of red, blue and green. In addition, there is another method that does not require metal shielding, which is to use a color filter to filter the white light emitted by a white organic light emitting diode (White Organic Light Emitting Diode; WOLED), and pass through the light that passes through the color filter. color to achieve the purpose of full color.

Generally speaking, the white light emitted by a conventional WOLED is composed of light of different wavelengths mixed together. After such white light passes through the color filter, the light of a specific wavelength will be absorbed by the photoresist on the color filter, and the remaining unabsorbed light will form monochromatic light. However, the photoresist of the green filter of the general color filter has a too large penetration range, so that the orange light with a wavelength of about 600nm will also pass through the green filter. In general, the peak of the white light emitted by WOLED in the red part is between 580nm and 600nm, so about half of the red light will pass through the green filter of the color filter, so that the organic electroluminescent display is in green light. Part of the display efficiency and color saturation are insufficient.

Contents of the invention

Therefore, one aspect of the present invention is to provide an organic electroluminescent material, which can be applied to WOLEDs, so that WOLEDs emit white light with an appropriate luminous spectrum, and then the green light that passes through the color filter has better Color saturation.

According to a preferred embodiment of the present invention, an organic electroluminescent material is proposed, the light intensity of the light emission spectrum below the wavelength of 588nm is less than 20% of the light intensity of the peak of the spectrum. Generally speaking, the penetration range of the green filter of the color filter is between about 480nm-600nm, so when the light intensity of the light emission spectrum of the organic electroluminescent material is extremely small relative to the peak at a wavelength of 588nm, it will be possible Effectively prevent orange light with a wavelength below 588nm from penetrating the green filter of the color filter.

More specifically, the luminescence spectrum of the organic electroluminescent material covers a range of 560nm-750nm. In other words, the organic electroluminescent material according to this embodiment is a red light emitting material. If the organic electroluminescent material is combined with a green light emitting material and a blue light emitting material to form a WOLED, the WOLED will emit light with an appropriate light emitting spectrum. The white light, which in turn makes the green light after passing through the color filter have better color saturation.

In addition, according to the luminescent spectrum of the organic electroluminescent material of this embodiment, its peak is located between 620nm-750nm. That is to say, the application of the organic electroluminescent material of the present invention can further increase the peak of the white light emitted by WOLED in the red light part at 580nm-600nm, so that the orange light can be avoided from passing through the color filter in the conventional technology. problem with the green filter of the film.

Another aspect of the present invention is to provide an organic electroluminescent material, which can be applied to WOLED, so that the peak of the white light emitted by WOLED in the red light part can be further improved at 580nm-600nm, so that it can avoid the conventional technology. The problem with the green filter of the medium orange light passing through the color filter.

According to another preferred embodiment of the present invention, an organic electroluminescence material is proposed, the peak of its luminescence spectrum is located between 620nm-750nm. That is to say, the application of the organic electroluminescent material of the present invention can further increase the peak of the white light emitted by WOLED in the red light part at 580nm-600nm, so that the orange light can be avoided from passing through the color filter in the conventional technology. problem with the green filter of the film.

In addition, according to the organic electroluminescent material proposed in this embodiment, the light intensity of the light emission spectrum below the wavelength of 588 nm is less than 20% of the light intensity of the peak of the spectrum. Generally speaking, the penetration range of the green filter of the color filter is between about 480nm-600nm, so when the light intensity of the light emission spectrum of the organic electroluminescent material is extremely small relative to the peak at a wavelength of 588nm, it will be possible Effectively prevent orange light with a wavelength below 588nm from penetrating the green filter of the color filter.

Another aspect of the present invention is to provide a light-emitting layer of an organic electroluminescent device, which can emit visible light with an appropriate light-emitting spectrum, so that an organic electroluminescent display using the organic electroluminescent device can display a higher color saturation. High green light.

According to yet another preferred embodiment of the present invention, a light-emitting layer of an organic electroluminescent device is provided, which is composed of a main light emitter and a dopant. Wherein, the dopant is doped in the main light emitter, and the chemical structure of the dopant can be:

Chemical formula I Chemical formula II

Chemical formula III Chemical formula IV

Chemical formula V Chemical formula VI

In addition, the above-mentioned dopant can be doped in the main light emitter with a concentration of 6%-15% by weight. In this way, the organic electroluminescent device can emit visible light with an appropriate luminous spectrum, so that the organic electroluminescent display using the organic electroluminescent device can display green light with higher color saturation.

More specifically, the light intensity of the emission spectrum of the above-mentioned emitting layer below the wavelength of 588 nm is less than 20% of the light intensity of the peak of the spectrum. Generally speaking, the penetration range of the green filter of the color filter is between about 480nm-600nm, so when the light intensity of the emission spectrum of the emission layer is extremely small relative to the peak at a wavelength of 588nm, it will be effectively avoided. Orange light with a wavelength below 588nm passes through the green filter of the color filter.

In addition, the emission spectrum of the emission layer according to this embodiment covers a range of 560 nm˜750 nm. In other words, the light-emitting layer is a red light-emitting layer. If the light-emitting layer is combined with a green light-emitting material and a blue light-emitting material to form a WOLED, the WOLED will emit white light with an appropriate light-emitting spectrum, thereby allowing the light to pass through the color filter. The post-film green light has better color saturation.

In addition, in the light-emitting layer proposed in this embodiment, the peak of the light-emitting spectrum is located between 620nm-750nm. That is to say, the application of the light-emitting layer of this embodiment will further increase the peak of the white light emitted by the WOLED in the red light part at 580nm-600nm, thus avoiding the problem of orange light penetrating the color filter in the conventional technology. The problem with the green filter.

Therefore, the use of the light-emitting layer of the organic electroluminescent device disclosed in the present invention and its organic electroluminescent material can effectively solve the problems of insufficient display efficiency and color saturation of conventional organic electroluminescent displays in displaying green light.

Description of drawings

In order to make the above and other objects, features, advantages and embodiments of the present invention more obvious and understandable, the detailed description of the accompanying drawings is as follows:

FIG. 1 is a graph showing a light emission spectrum of an organic electroluminescent material according to a preferred embodiment of the present invention.

FIG. 2 is a schematic diagram showing a light emitting layer of an organic electroluminescent device according to another preferred embodiment of the present invention.

Fig. 3 is a diagram showing a light emission spectrum of a blue light emitting material according to an example of the present invention.

Fig. 4 is a graph showing a light emission spectrum of a green light emitting material according to an example of the present invention.

FIG. 5 is a graph showing a light emission spectrum of a WOLED according to an example of the present invention.

Description of main device symbols

110: crest

200: luminous layer

210: main illuminant

220: Adulterants

Detailed ways

In order to make the light-emitting layer of the organic electroluminescent device provided by the present invention and its organic electroluminescent material clearer, the spirit of the present invention will be clearly described below with diagrams and detailed descriptions. Those skilled in the art will understand the preferred aspects of the present invention After the examples, the techniques taught in the present invention can be changed and modified without departing from the spirit and scope of the present invention.

Referring to FIG. 1 , it shows a light emission spectrum diagram of an organic electroluminescent material according to a preferred embodiment of the present invention. As shown in FIG. 1 , in this embodiment, an organic electroluminescent material is proposed, the light intensity of the luminescent spectrum below the wavelength of 588 nm is less than 20% of the light intensity of the spectral peak 110 . Generally speaking, the penetration range of the green filter of the color filter is between about 480nm-600nm, so when the light intensity of the light emission spectrum of the organic electroluminescent material is extremely small relative to the peak at a wavelength of 588nm, it will be possible Effectively prevent orange light with a wavelength below 588nm from penetrating the green filter of the color filter.

Continuing to refer to FIG. 1 , the luminescence spectrum of the organic electroluminescence material covers a range of 560 nm to 750 nm. In other words, the organic electroluminescent material according to this embodiment is a red light emitting material. If the organic electroluminescent material is combined with a green light emitting material and a blue light emitting material to form a WOLED, the WOLED will emit light with an appropriate light emitting spectrum. The white light, which in turn makes the green light after passing through the color filter have better color saturation.

In addition, the organic electroluminescence material of this embodiment has a peak of its luminescence spectrum located between 620nm-750nm. That is to say, the application of the organic electroluminescent material of the present invention can further increase the peak of the white light emitted by WOLED in the red light part at 580nm-600nm, so that the orange light can be avoided from passing through the color filter in the conventional technology. problem with the green filter of the film.

Referring to FIG. 2 , it shows a schematic diagram of a light-emitting layer of an organic electroluminescent device according to another preferred embodiment of the present invention. It should be noted that, for convenience of explanation, Fig. 2 is not drawn in actual scale. In this embodiment, a light emitting layer 200 of an organic electroluminescent device is proposed, which is composed of a main light emitter 210 and a dopant 220 . Wherein, the dopant is doped in the main light emitter, and the chemical structure of the dopant can be:

Chemical formula I Chemical formula II

Chemical formula III Chemical formula IV

Chemical formula V Chemical formula VI

Wherein, the dopant represented by each chemical formula can be referred to as follows: Chemical formula I: Adachi, M.A.Baldo, S.R.Forrest, S.Lamansky, M.E.Thompson, R.C.Kwong, Apply.Phys.Lett., 78,1662 (2001); Chemical formula II : Y.J.Su, H.L.Huang, C.L.Li, C.H.Chien, Y.T.Tao, P.T.Chou, S.Datta, R.S.Liu, Adv.Mater., 15,884 (2003); Chemical formula III: US2003/0072964A1; Chemical formula IV: J.P.Duan , P.P.Sun, C.H.Cheng, Adv, Mater., 15, 224 (2003); Chemical formula V: C.H.Yang, C.C.Tai, I.W.Sun, J.ater.Chem., 14, 947 (2004); Chemical formula VI: US2003/ 0072964A1.

In addition, the above-mentioned dopant can be doped in the main light emitter with a concentration of 6%-15% by weight. In this way, the organic electroluminescent device can emit visible light with an appropriate luminous spectrum, so that the organic electroluminescent display using the organic electroluminescent device can display green light with higher color saturation.

In addition, the emission spectrum of the emission layer according to this embodiment covers a range of 560 nm˜750 nm. In other words, the light-emitting layer is a red light-emitting layer. If this light-emitting layer is combined with a green light-emitting material and a blue light-emitting material to form a WOLED, the WOLED will emit white light with an appropriate light-emitting spectrum, thereby allowing the light to pass through the color filter. The post-film green light has better color saturation.

In the light emitting layer proposed in this embodiment, the peak of the light emitting spectrum is located between 620nm-750nm. That is to say, the application of the light-emitting layer of this embodiment will further increase the peak of the white light emitted by the WOLED in the red light part at 580nm-600nm, thus avoiding the problem of orange light penetrating the color filter in the conventional technology. The problem with the green filter.

The display effect of the organic electroluminescent display manufactured according to the preferred embodiment of the present invention will be described below with a non-limiting example of the present invention. The color filter used in the organic electroluminescence display of this example is a conventional color filter, and the penetration range of the green filter is about 580nm-620nm. After the white light emitted by the conventional WOLED passes through the color filter, the three color lights of red, blue and green and the color coordinate CIE values of the white light are shown in Table 1:

Table 1: Color coordinates of white light emitted by conventional WOLEDs after passing through color filters

CIEx CIEy white light 0.312 0.339 red light 0.632 0.354 green light 0.290 0.513 Blu-ray 0.136 0.124

It can be known from Table 1 that after the white light emitted by the conventional WOLED passes through the color filter, the displayed green light has poor color saturation. The reason is that the photoresist of the green filter of the color filter has a too large penetration range, so that the orange light with a wavelength of about 600nm will also pass through the green filter.

In this example, the WOLED part will be composed of the red light emitting material disclosed in the present invention, the blue light emitting material and the green light emitting material. Wherein, the emission spectrum of the red light emitting material is shown in FIG. 1 , the light emitting spectrum of the blue light emitting material is shown in FIG. 3 , and the light emitting spectrum of the green light emitting material is shown in FIG. 4 . The luminescent spectrum of the WOLED composed of the above-mentioned red luminescent material, blue luminescent material and green luminescent material is shown in FIG. 5 . It is worth noting that the peak of the white light emitted by the WLOED in the red part is located at about 625nm, which is higher than that of the conventional WOLED. After the white light emitted by the WOLED of this example passes through the color filter, the displayed red, blue and green colors and the CIE values of the color coordinates of the white light are shown in Table 2:

Table 2: The color coordinates of the white light emitted by the WOLED of this example after passing through the color filter

CIEx CIEy white light 0.312 0.339 red light 0.644 0.318 green light 0.267 0.604 Blu-ray 0.113 0.226

It can be seen from Table 2 that after the white light emitted by the WOLED of this example passes through the color filter, the displayed green light is indeed better than the conventional WOLED in terms of color saturation.

In summary, the use of the light-emitting layer of the organic electroluminescent device disclosed in the present invention and its organic electroluminescent material can effectively solve the problems of insufficient display efficiency and color saturation of conventional organic electroluminescent displays in displaying green light .

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of protection of the invention is subject to the scope of the appended claims.

Claims (8)

1. An organic electroluminescent material, characterized in that: The ratio of the light intensity of the luminescent spectrum of the organic electroluminescent material at a wavelength below 588 nm to the light intensity of the peak of the luminescent spectrum is at least less than 20%, and The organic electroluminescent material at least includes: the main illuminant; and Dopant, doped in the main luminous body, wherein the dopant is the structure of chemical formula I, chemical formula IV or chemical formula V:

Chemical formula I Chemical formula IV Chemical formula V. 2. The organic electroluminescence material as claimed in claim 1, wherein the coverage of the luminescence spectrum is 560nm～750nm. 3. The organic electroluminescent material as claimed in claim 1, wherein the peak of the luminescent spectrum is between 620nm and 750nm. 4. A light-emitting layer of an organic electroluminescent device comprising at least: the main illuminant; and Dopant, doped in the main luminous body, wherein the dopant is the structure of chemical formula I, chemical formula IV or chemical formula V:

Chemical formula I Chemical formula IV

Chemical formula V. 5. The light-emitting layer as claimed in claim 4, wherein the dopant is doped in the main light emitter with a concentration of 6-15% by weight. 6. The light-emitting layer according to claim 4, wherein the ratio of the light intensity of the light-emitting spectrum of the light-emitting layer below the wavelength of 588nm to the light intensity of the peak of the light-emitting spectrum is at least less than 20%. 7. The light-emitting layer according to claim 6, wherein the light-emitting spectrum covers a range of 560nm to 750nm. 8. The light-emitting layer according to claim 6, wherein the peak of the light-emitting spectrum is between 620nm and 750nm.

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