阅读说明：本技术 有机电致发光器件及显示面板 (Organic electroluminescent device and display panel ) 是由 梁丙炎 于 2021-07-26 设计创作，主要内容包括：本公开提供一种有机电致发光器件及显示面板。有机电致发光器件包括：基板；阴极层,设置于所述基板上；光取出层,设置于所述阴极层上；所述光取出层的折射率大于所述阴极层的折射率,以增加有机电致发光器件的发光表面的光线射出量。通过在基板上设置阴极层；并在所述阴极层上设置光取出层；且所述光取出层具有高折射率,能够扩大出光边界,从而增加有机电致发光器件的发光表面的光线射出量,进而提高有机电致发光器件的出光效率。(The present disclosure provides an organic electroluminescent device and a display panel. The organic electroluminescent device includes: a substrate; a cathode layer disposed on the substrate; a light extraction layer disposed on the cathode layer; the refractive index of the light extraction layer is greater than that of the cathode layer to increase the light emission from the light-emitting surface of the organic electroluminescent device. By providing a cathode layer on a substrate; and providing a light extraction layer on the cathode layer; and the light extraction layer has high refractive index, and can enlarge the light extraction boundary, thereby increasing the light emission quantity of the light emitting surface of the organic electroluminescent device and further improving the light extraction efficiency of the organic electroluminescent device.)

1. An organic electroluminescent device, comprising:

a substrate;

a cathode layer disposed on the substrate; and

a light extraction layer disposed on the cathode layer; the refractive index of the light extraction layer is greater than that of the cathode layer to increase the light emission from the light-emitting surface of the organic electroluminescent device.

2. The organic electroluminescent device according to claim 1, wherein the refractive index of the light extraction layer at a wavelength of 460nm is greater than or equal to 2.0.

3. The organic electroluminescent device according to claim 1, wherein the material of the light extraction layer has a general structural formula shown in formula (1):

wherein Ar is selected from at least one of single bond, benzene, naphthalene and carbazole compounds;

a, B, C and D are each independently selected from hydrogen, naphthalene and naphthalene derivatives.

4. The organic electroluminescent device according to claim 3, wherein the carbazole-based compound is selected from at least one of formula (2), formula (3), formula (4), or formula (5);

and/or

The naphthalene and the naphthalene derivative are selected from at least one of formula (6), formula (7), formula (8), formula (9) or formula (10);

5. the organic electroluminescent device of claim 3, wherein the material of the light extraction layer comprises at least one of the following structural formulas:

6. the organic electroluminescent device according to claim 1, wherein the light extraction layer has a thickness of 45 to 55 nm.

7. The organic electroluminescent device according to claim 1, further comprising a lifetime improvement layer provided on a side of the light extraction layer away from the cathode layer; the lifetime-improving layer is used to absorb ultraviolet light.

8. The organic electroluminescent device as claimed in claim 7, wherein the lifetime improvement layer has an absorption coefficient at a wavelength of 440nm or less which is greater than an absorption coefficient at a wavelength of 450nm or more.

9. The organic electroluminescent device according to claim 8, wherein the lifetime-improving layer has an absorption coefficient at a wavelength of 420nm of 0.02 or more; and an absorption coefficient at a wavelength of 460nm of 0.0001 or less.

10. The organic electroluminescent device according to claim 7, wherein the lifetime improvement layer has a refractive index smaller than that of the light extraction layer.

11. The organic electroluminescent device as claimed in claim 10, wherein the difference between the refractive index of the light extraction layer at a wavelength of 460nm and the refractive index of the lifetime improvement layer at a wavelength of 460nm is greater than or equal to 0.2.

12. The organic electroluminescent device as claimed in claim 7, wherein the material of the lifetime-improving layer has a general structural formula shown in formula (13):

wherein Ar is₁Selected from fluorene or fluorene fused ring derivatives;

l is selected from single bond, substituted or unsubstituted C₁～₃₀Alkyl, substituted or unsubstituted C_6～60Aryl, substituted or unsubstituted C_3～60At least one of heteroaryl;

Ar₂and Ar₃Each independently selected from at least one of benzene and benzene derivatives, naphthalene and naphthalene derivatives, fluorene and fluorene derivatives, dibenzofuran and its derivatives, and dibenzothiophene and its derivatives.

13. The organic electroluminescent device according to claim 7, wherein the material of the lifetime-improving layer comprises at least one of the following structural formulae:

14. the organic electroluminescent device according to claim 1 or 7, further comprising a light auxiliary layer provided on a side of the light extraction layer away from the cathode layer or on a side of the lifetime improvement layer away from the cathode layer; the refractive index of the light assist layer is lower than the refractive index of the light extraction layer.

15. A display panel comprising the organic electroluminescent device according to any one of claims 1 to 14.

Technical Field

The present disclosure relates to the field of display technologies, and in particular, to an organic electroluminescent device and a display panel.

Background

In recent years, Organic Light-Emitting diodes (abbreviated as OLEDs) have been attracting more attention as a new type of flat panel display. The display has the characteristics of active light emission, high brightness, high resolution, wide viewing angle, high response speed, low energy consumption, flexibility and the like, so that the display becomes a popular mainstream display product in the market at present. With the continuous development of products, the requirements on the resolution of the products are higher and higher, and the requirements on the power consumption are lower and lower.

The light extraction rate of the current organic electroluminescent device is not good enough. Therefore, there is a need for an organic electroluminescent device having high light emitting efficiency.

Disclosure of Invention

In view of the above, the present disclosure is directed to an organic electroluminescent device and a display panel.

In view of the above object, the present disclosure provides an organic electroluminescent device comprising:

a substrate;

a cathode layer disposed on the substrate;

a light extraction layer disposed on the cathode layer; the refractive index of the light extraction layer is greater than that of the cathode layer to increase the light emission from the light-emitting surface of the organic electroluminescent device.

In some embodiments, the light extraction layer has a refractive index greater than or equal to 2.0 at a wavelength of 460 nm.

In some embodiments, the material of the light extraction layer has a general structural formula shown in formula (1):

wherein Ar is selected from at least one of single bond, benzene, naphthalene and carbazole compounds;

a, B, C and D are each independently selected from hydrogen, naphthalene and naphthalene derivatives.

In some embodiments, the carbazole-based compound is selected from at least one of formula (2), formula (3), formula (4), or formula (5);

and/or

The naphthalene and the naphthalene derivative are selected from at least one of formula (6), formula (7), formula (8), formula (9) or formula (10);

in some embodiments, the material of the light extraction layer comprises at least one of the following structural formulas:

in some embodiments, the light extraction layer has a thickness of 45 to 55 nm.

In some embodiments, a lifetime improvement layer is further included, disposed on a side of the light extraction layer away from the cathode layer; the lifetime-improving layer is used to absorb ultraviolet light.

In some embodiments, the lifetime-improving layer has an absorption coefficient below a wavelength of 440nm that is greater than an absorption coefficient above a wavelength of 450 nm.

In some embodiments, the lifetime-improving layer has an absorption coefficient greater than or equal to 0.02 at a wavelength of 420 nm; and an absorption coefficient at a wavelength of 460nm of 0.0001 or less.

In some embodiments, the lifetime-improving layer has a refractive index less than a refractive index of the light extraction layer.

In some embodiments, the difference between the refractive index of the light extraction layer at wavelength 460nm and the refractive index of the lifetime improvement layer at wavelength 460nm is greater than or equal to 0.2.

In some embodiments, the material of the lifetime-improving layer has a general structural formula shown in formula (13):

wherein Ar is₁Selected from fluorene or fluorene fused ring derivatives;

l is selected from single bond, substituted or unsubstituted C₁～₃₀Alkyl, substituted or unsubstituted C_6～60Aryl, substituted or unsubstituted C_3～60At least one of heteroaryl;

Ar₂and Ar₃Each independently selected from benzene and benzene derivatives, naphthalene and naphthalene derivatives, fluorene and fluorene derivatives, dibenzofuran and its derivativesAt least one of biological and dibenzothiophene and derivatives thereof.

In some embodiments, the material of the lifetime-improving layer comprises at least one of the following structural formulae:

in some embodiments, a light assist layer is further included, disposed on a side of the light extraction layer away from the cathode layer or on a side of the lifetime improvement layer away from the cathode layer; the refractive index of the light assist layer is lower than the refractive index of the light extraction layer.

Embodiments of the present disclosure also provide a display panel including the organic electroluminescent device as described in any one of the preceding claims.

As can be seen from the above, the present disclosure provides an organic electroluminescent device by providing a cathode layer on a substrate; and providing a light extraction layer on the cathode layer; the light extraction layer has high refractive index, and can enlarge the light-emitting boundary, thereby increasing the light-emitting quantity of the light-emitting surface of the organic electroluminescent device, further improving the light-emitting efficiency of the organic electroluminescent device, reducing the overall power consumption of the OLED display panel, and prolonging the service life of the OLED light-emitting device.

Drawings

In order to more clearly illustrate the technical solutions in the present disclosure or related technologies, the drawings needed to be used in the description of the embodiments or related technologies are briefly introduced below, and it is obvious that the drawings in the following description are only embodiments of the present disclosure, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic structural diagram of an organic electroluminescent device according to an embodiment of the present disclosure.

Detailed Description

For the purpose of promoting a better understanding of the objects, aspects and advantages of the present disclosure, reference is made to the following detailed description taken in conjunction with the accompanying drawings.

It is to be noted that technical terms or scientific terms used in the embodiments of the present disclosure should have a general meaning as understood by those having ordinary skill in the art to which the present disclosure belongs, unless otherwise defined. The word "comprising" or "comprises", and the like, in the embodiments of the present disclosure means that the element or item presented before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

At present, the development of organic electroluminescent devices has higher and higher requirements for resolution. Meanwhile, the development of Virtual Reality (VR)/virtual Reality (AR) products also requires very high resolution. The improvement of resolution and the reduction of aperture ratio require the improvement of light-emitting efficiency of the device, so that the efficiency of the device is more tested and required. With the improvement of product requirements, how to improve the light emitting efficiency becomes a problem to be solved urgently. And it is a primary task in the field of organic electroluminescence to develop an organic electroluminescent device that overcomes the above problems and thus improves device efficiency.

The embodiment of the disclosure provides an organic electroluminescent device, and the light extraction layer is arranged on the outer side of the cathode, so that the light extraction efficiency of the organic electroluminescent device is improved, the light emission efficiency of the organic electroluminescent device is improved, and the overall power consumption of the organic electroluminescent device is reduced.

As shown in fig. 1, an embodiment of the present disclosure provides an organic electroluminescent device including:

a substrate 108;

a cathode layer 105 disposed on the substrate 108;

a light extraction layer 104 disposed on the cathode layer 105; the refractive index of the light extraction layer 104 is larger than that of the cathode layer 105 to increase the light emission amount from the light emitting surface of the organic electroluminescent device.

The organic electroluminescent device provided by the embodiment of the present disclosure is formed by disposing a cathode layer 105 on a substrate 108; and a light extraction layer 140 is provided on the cathode layer 105; the light extraction layer 104 has a high refractive index, and can enlarge the light-emitting boundary, thereby increasing the light emission quantity of the light-emitting surface of the organic electroluminescent device, further improving the light-emitting efficiency of the organic electroluminescent device, reducing the overall power consumption of the OLED display panel, and prolonging the service life of the OLED light-emitting device.

In some embodiments, the refractive index (n) of the light extraction layer 104 at a wavelength of 460nm₁) Greater than or equal to 2.0. That is, n₁(460nm) ≥ 2.0, the light extraction layer 104 has a high refractive index. By setting the refractive index of the light extraction layer 104 to light having a wavelength of 460nm to be 2.0 or more, the light exit boundary can be enlarged better, thereby increasing the light emission amount of the light emitting surface of the organic electroluminescent device.

In some embodiments, the material of the light extraction layer 104 has a general structural formula shown in formula (1):

wherein Ar is at least one selected from single bond, benzene, naphthalene, carbazole compound and the like;

a, B, C and D are each independently selected from hydrogen, naphthalene and naphthalene derivatives.

In some embodiments, the carbazole-based compound is selected from at least one of formula (2), formula (3), formula (4), or formula (5);

in some embodiments, the naphthalene and derivatives of naphthalene are selected from at least one of formula (6), formula (7), formula (8), formula (9), or formula (10);

in some embodiments, the material of the light extraction layer 104 includes at least one of the following structural formulas:

in some embodiments, the light extraction layer 104 has a thickness of 45-55 nm.

In some embodiments, a lifetime improvement layer 103 is further included, disposed on a side of the light extraction layer 104 away from the cathode layer 105; the lifetime-improving layer 103 is used to absorb Ultraviolet light (UV). By arranging the life improving layer 103, UV light can be absorbed, so that the organic electroluminescent device has good ultraviolet aging resistance, and the life of the organic electroluminescent device is prolonged.

In some embodiments, the lifetime-improving layer 103 has an absorption coefficient below a wavelength of 440nm that is greater than an absorption coefficient above a wavelength of 450 nm. With this arrangement, the lifetime improvement layer 103 has a high absorption coefficient in a range of 440nm or less and a low absorption coefficient in a range of 450nm or more, thereby enabling the lifetime improvement layer 103 to absorb UV light without affecting the blue light emission of the OLED. That is, the provision of the lifetime improvement layer 103 hardly affects the light emission of the OLED, but can improve material degradation.

In some embodiments, the lifetime-improving layer 103 has an absorption coefficient (k) at a wavelength of 420nm₂) Greater than or equal to 0.02; and an absorption coefficient (k) at a wavelength of 460nm₁) Less than or equal to 0.0001. That is, k is the lifetime improvement layer 103₁(460nm) is less than or equal to 0.0001 and k is₂(420nm)≥0.02。

In some embodiments, the refractive index (n) of the lifetime-improving layer 103₂) Less than the refractive index of the light extraction layer 104. By setting the refractive index of the lifetime-improving layer 103 to be smaller than the refractive index of the light-extracting layer 104, the light-extracting layer 104 and the lifetime-improving layer 103 can form a high-low refractive index structure, and the light-emitting efficiency of the organic electroluminescent device can be further improvedAnd (4) rate.

In some embodiments, the difference between the refractive index of the light extraction layer 104 at the wavelength of 460nm and the refractive index of the lifetime improvement layer 103 is greater than or equal to 0.2. That is, n₁(460nm)–n₂(460nm) is not less than 0.2. By setting the refractive index difference between the light extraction layer 104 and the lifetime improvement layer 103 at a wavelength of 460nm to be not less than 0.2, the light extraction layer 104 and the lifetime improvement layer 103 can form a high-low refractive index structure better, and the light extraction efficiency of the organic electroluminescent device can be improved better.

In some embodiments, the material of the lifetime-improving layer 103 has a general structural formula shown in formula (13):

wherein Ar is₁Selected from fluorene or fluorene fused ring derivatives;

l is selected from single bond, substituted or unsubstituted C₁～₃₀Alkyl, substituted or unsubstituted C_6～60Aryl, substituted or unsubstituted C_3～60At least one of heteroaryl;

Ar₂and Ar₃Each independently selected from at least one of benzene and benzene derivatives, naphthalene and naphthalene derivatives, fluorene and fluorene derivatives, dibenzofuran and its derivatives, and dibenzothiophene and its derivatives.

In some embodiments, the material of the lifetime-improving layer 103 comprises at least one of the following structural formulas:

in some embodiments, a light assist layer 102 is further included, the light assist layer 102 being disposed on a side of the light extraction layer 104 remote from the cathode layer 105 or on a side of the lifetime improving layer 103 remote from the cathode layer 105. The refractive index of the light assist layer 102 is lower than the refractive index of the light extraction layer 104. It is understood that the light auxiliary layer 102 is disposed outside the cathode layer 105 in the organic electroluminescent device according to the embodiment of the present disclosure. When the organic electroluminescent device does not comprise the lifetime-improving layer 103, the light-assisting layer 102 may be arranged on the side of the light extraction layer 104 remote from said cathode layer 105. When the organic electroluminescent device comprises a lifetime-improving layer 103, the light assisting layer 102 may be arranged at a side of the lifetime-improving layer 103 facing away from said cathode layer 105. By providing the light auxiliary layer 102, the light extraction layer 104 and the light auxiliary layer 102 can form a high-low refractive index structure, thereby further improving the light extraction efficiency of the organic electroluminescent device.

In some embodiments, the material of the light assist layer 102 can be LiF. That is, the photo-assist layer 102 may be a LiF layer.

In some embodiments, the organic electroluminescent device comprises a substrate 108, an anode layer 107, an organic functional layer 106, a cathode layer 105, a light extraction layer 104, a lifetime improvement layer 103, a light assist layer 102, and an encapsulation layer 101, which are arranged in sequence.

In some embodiments, the anode layer is ITO-plated conductive glass.

In some embodiments, the organic functional layer 106 includes at least a light emitting layer. The material of the light-emitting layer may be an existing material such as DPAVB (1, 4-bis [4- (di-p-tolylamino) styryl ] benzene).

In some embodiments, the organic functional layer 106 further includes a hole injection layer, a hole transport layer, an electron blocking layer, a hole blocking layer, and an electron transport layer, which are sequentially stacked, and the electron blocking layer and the hole blocking layer are respectively stacked on both surfaces of the light emitting layer. The specific structures, material compositions and preparation methods of the luminescent layer, the hole injection layer, the hole transport layer, the electron blocking layer, the hole blocking layer and the electron transport layer in the embodiment of the disclosure are the prior art, and the disclosure does not relate to the improvement of the existing luminescent layer, the hole injection layer, the hole transport layer, the electron blocking layer, the hole blocking layer and the electron transport layer.

In some embodiments, the material of the cathode layer 105 may be, for example, Al.

In some embodiments, the specific structure and material of the encapsulation layer 101 are the prior art, and may be, for example, a TFE encapsulation layer, and the disclosed embodiments do not relate to an improvement on the prior art.

In the organic electroluminescent device provided by the embodiment of the present disclosure, the light extraction layer 104, the lifetime improvement layer 103, and the LIF layer (i.e., the light auxiliary layer 102) are sequentially disposed on the side of the cathode layer 105 away from the substrate 108; and n is₁(460nm)≥2.0，n₁(460nm)–n₂(460nm) is not less than 0.2, a high-low refractive index structure can be formed, and the light emitting boundary is enlarged, so that the light emitting quantity of the light emitting surface of the organic electroluminescent device is increased, the light emitting efficiency of the organic electroluminescent device is further improved, and the overall power consumption of the OLED display panel is reduced. While k is₁(460nm) is less than or equal to 0.0001 and k is₂The wavelength of (420nm) is not less than 0.02, and the UV light can be absorbed under the condition of not influencing the blue light emission of the OLED, so that the damage of the light aging to the OLED is improved, and the service life of the OLED is prolonged.

The structure of the organic electroluminescent device can be specifically expressed as: ITO/HAT-CN/NPB/HT-A/Host + 3% Dopan/HBL/ETL + 50% AlQ/LiF/Al/formula (11) or formula (12)/formula (14) or formula (15).

The organic electroluminescent device of the present disclosure is further illustrated by the following specific examples.

Comparative example 1:

ITO/HAT-CN(20nm)/NPB(50nm)/HT-A(6nm)/Host+3％Dopant(20nm)/HBL(50nm)/ETL+50％AlQ(30nm)/LiF(1nm)/Al(100nm)。

comparative example 2:

ITO/HAT-CN (20nm)/NPB (50nm)/HT-A (6nm)/Host + 3% Dopant (20nm)/HBL (50nm)/ETL + 50% AlQ (30nm)/LiF (1nm)/Al (100 nm)/formula (14) (100 nm).

Example 1:

ITO/HAT-CN (20nm)/NPB (50nm)/HT-A (6nm)/Host + 3% Dopant (20nm)/HBL (50nm)/ETL + 50% AlQ (30nm)/LiF (1nm)/Al (100 nm)/formula (11)/formula (14) (50 nm).

Example 2:

ITO/HAT-CN (20nm)/NPB (50nm)/HT-A (6nm)/Host + 3% Dopant (20nm)/HBL (50nm)/ETL + 50% AlQ (30nm)/LiF (1nm)/Al (100 nm)/formula (12) (50 nm)/formula (14) (50 nm).

Example 3:

ITO/HAT-CN (20nm)/NPB (50nm)/HT-A (6nm)/Host + 3% Dopant (20nm)/HBL (50nm)/ETL + 50% AlQ (30nm)/LiF (1nm)/Al (100 nm)/formula (12) (50 nm)/formula (15) (50 nm).

In examples 1 to 3 and comparative examples 1 to 2, the anode was made of ITO-coated conductive glass, and the cathode was made of Al. HAT-CN (shown below) is a material of the hole injection layer. NPB (shown below) is a material of the hole transport layer. HTA (shown below) is the material of the electron blocking layer. In the material of the light-emitting layer, Host (described below) is a Host material, and span (described below) is a guest material. HBL (shown below) is a material of the hole blocking layer. ETL (shown below) and AlQ₃Is the material of the electron transport layer. LIF is the material of the light assist layer 102. Formula (11) or formula (12) is a material of the light extraction layer 104; the lifetime improving layer 103 is made of a material of formula (14) or (15).

The parameters of the materials of the light extraction layer 104 and the lifetime improvement layer 103 are shown in table 1 below.

TABLE 1 parameters of the materials

The organic electroluminescent devices of examples 1 to 3 and comparative examples 1 to 2 were tested for luminous efficiency and lifetime, and the results are shown in table 2.

TABLE 2 parameters of organic electroluminescent devices of examples and comparative examples

	Light extraction layer	Life-span improving layer	Luminous efficiency	Life span
					Comparative example 1	-	-	100％	100％
Comparative example 2	-	Formula (14)	101％	108％
					Example 1	Formula (11)	Formula (14)	113％	106％
Example 2	Formula (12)	Formula (14)	109％	107％
					Example 3	Formula (12)	Formula (15)	110％	111％

As can be seen from table 2, the organic electroluminescent devices of examples 1 to 3 of the present disclosure can improve the light emission efficiency and prolong the lifetime of the organic electroluminescent device by providing the light extraction layer 104 and the lifetime improvement layer 103 on the side of the cathode layer 105 away from the substrate 108, that is, between the cathode layer 105 and the LIF layer, compared to comparative example 1. In comparison with comparative example 2, in the organic electroluminescent devices of examples 1 to 2 of the present disclosure, the light extraction layer 104 is provided between the cathode layer 105 and the lifetime improvement layer 103, so that the light emission efficiency of the organic electroluminescent device can be improved.

Based on the same inventive concept, embodiments of the present disclosure also provide a display panel including the organic electroluminescent device according to any one of the previous technical solutions. The display panel has the beneficial effects of the corresponding organic electroluminescent device embodiment, and the details are not repeated herein.

Those of ordinary skill in the art will understand that: the discussion of any embodiment above is meant to be exemplary only, and is not intended to intimate that the scope of the disclosure, including the claims, is limited to these examples; within the idea of the present disclosure, also technical features in the above embodiments or in different embodiments may be combined, steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present disclosure as described above, which are not provided in detail for the sake of brevity.

Additionally, for simplicity of explanation and discussion, and so as not to obscure the embodiments of the present disclosure, apparatus may be shown in block diagram form in order to avoid obscuring the embodiments of the present disclosure, and this also takes into account the fact that specifics with respect to implementation of such block diagram apparatus are highly dependent upon the platform within which the embodiments of the present disclosure are to be implemented (i.e., such specifics should be well within purview of one skilled in the art). Where specific details (e.g., circuits) are set forth in order to describe example embodiments of the disclosure, it should be apparent to one skilled in the art that the embodiments of the disclosure can be practiced without, or with variation of, these specific details. Accordingly, the description is to be regarded as illustrative instead of restrictive.

While the present disclosure has been described in conjunction with specific embodiments thereof, many alternatives, modifications, and variations of these embodiments will be apparent to those of ordinary skill in the art in light of the foregoing description.

The disclosed embodiments are intended to embrace all such alternatives, modifications and variances which fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalents, improvements, and the like that may be made within the spirit and principles of the embodiments of the disclosure are intended to be included within the scope of the disclosure.