CN111293227B

CN111293227B - Display panel

Info

Publication number: CN111293227B
Application number: CN202010113587.2A
Authority: CN
Inventors: 娄振花
Original assignee: Kunshan Govisionox Optoelectronics Co Ltd
Current assignee: Kunshan Govisionox Optoelectronics Co Ltd
Priority date: 2020-02-24
Filing date: 2020-02-24
Publication date: 2022-09-30
Anticipated expiration: 2040-02-24
Also published as: CN111293227A

Abstract

The application provides a display panel, including: a device layer including a light emitting layer; and the optical function layer is stacked on one side of the light emitting surface of the device layer and comprises extinction materials, and the extinction coefficient of the extinction materials in the blue light wavelength range is larger than that of the extinction materials in the red light wavelength range and the green light wavelength range. Through the mode, blue light attenuation under each visual angle can be accelerated.

Description

Display panel

Technical Field

The present application relates to the field of display, and in particular, to a display panel.

Background

Red, green and blue are the three primary colors in the display panel, but red, green and blue have different tendencies of luminance decay as the viewing angle increases. For example, the red light attenuates most rapidly with increasing viewing angle, and the blue light attenuates most slowly with increasing viewing angle, so that the display panel is prone to color shift to blue under a large viewing angle.

Disclosure of Invention

The technical problem that this application mainly solved provides a display panel, can accelerate the blue light decay under each visual angle.

In order to solve the technical problem, the application adopts a technical scheme that: provided is a display panel including: a device layer including a light emitting layer; and the optical function layer is stacked on one side of the light emitting surface of the device layer and comprises an extinction material, and the extinction coefficient of the extinction material in a blue light wavelength range is larger than the extinction coefficients of the extinction material in a red light wavelength range and a green light wavelength range.

The optical function layer further comprises a light extraction layer, and the extinction material is doped in the light extraction layer.

The optical function layer further comprises a light extraction layer and a first extinction layer, the light extraction layer is located between the first extinction layer and the device layer, and the first extinction layer contains the extinction material.

The optical function layer further comprises a second extinction layer, the second extinction layer is located between the light extraction layer and the device layer, and the second extinction layer contains the extinction material.

Wherein an absolute value of a difference in refractive index between the first extinction layer and the light extraction layer is 0.2 or less; and/or the absolute value of the difference between the refractive indexes of the second extinction layer and the light extraction layer is less than or equal to 0.2.

The first extinction layer and the second extinction layer are made of the same material, thickness, refractive index and extinction coefficient.

The light-emitting layer comprises a blue light-emitting unit, the blue light-emitting unit is formed by a host material and a guest material doped in the host material, the blue light-emitting unit is divided into at least two sub-layers in the laminating direction of the device layer and the optical function layer, and the doping mass ratios of the guest material in the at least two sub-layers are different.

Wherein, in the lamination direction of the device layer and the optical function layer, the doping quality proportion of the guest material in the at least two sub-layers is gradually increased.

Wherein the proportion of the mass of the guest material in each sub-layer to the sum of the mass of the guest material and the mass of the host material in the sub-layer is less than or equal to 3% and greater than or equal to 1%.

In the lamination direction of the device layer and the optical function layer, the blue light-emitting unit is divided into three sub-layers, and the doping mass proportion of the guest materials of the three sub-layers is 1%, 2% and 3% in sequence.

Different from the prior art, the display panel provided by the application comprises a device layer and an optical functional layer, wherein the optical functional layer is stacked on one side of a light-emitting surface of the device layer, the optical functional layer comprises an extinction material, and an extinction coefficient of the extinction material in a blue light wavelength range is larger than extinction coefficients of the extinction material in a red light wavelength range and a green light wavelength range. After the blue light emitted by the light emitting layer in the device layer passes through the extinction material, the attenuation of the blue light at each viewing angle is accelerated, so that the white light track moves in the reverse direction of the blue light, the condition that the color of the display panel is easy to deviate from blue under the condition of a large viewing angle is reduced, and the display quality is improved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts. Wherein:

FIG. 1 is a schematic structural diagram of a display panel according to an embodiment of the present disclosure;

FIG. 2 is a schematic structural diagram of another embodiment of a display panel according to the present application;

FIG. 3 is a schematic diagram illustrating a structure of one embodiment of the blue light-emitting unit in FIG. 1;

FIG. 4 is a graph showing the wavelength and refractive index of comparative example A and example A;

FIG. 5 is a graph showing the wavelength and extinction coefficient curves corresponding to the comparative example A and the example A;

FIG. 6 is a schematic diagram showing chromaticity variation at each field angle in a white field for the comparative example A and the example A;

FIG. 7 is a schematic representation of the thickness and degree of color shift of various optically functional layers of comparative example A and example A;

fig. 8 is a color coordinate graph of comparative example two and example two at 5 ° intervals.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Referring to fig. 1, fig. 1 is a schematic structural diagram of an embodiment of a display panel according to the present application, which includes a device layer 10 and an optical function layer 12.

Specifically, the device layer 10 includes an emission layer 100, and the emission layer 100 may include blue emission units B-EML, green emission units G-EML, and red emission units R-EML. In addition, in order to improve the light output efficiency of the light emitting layer 100, the light emitting layer 100 may further include a blue microcavity adjusting layer BPL, a green microcavity adjusting layer GPL, and a red microcavity adjusting layer RPL, which are respectively disposed on the sides of the blue light emitting cells B-EML, the green light emitting cells G-EML, and the red light emitting cells R-EML. In addition, a hole transport layer HTL, a hole injection layer HIL, and an anode layer 102 may be sequentially stacked on the side of the light emitting layer 100 where the blue microcavity adjusting layer BPL, the green microcavity adjusting layer GPL, and the red microcavity adjusting layer RPL are disposed, and the anode layer 102 is far from the light emitting layer 100 relative to the hole transport layer HTL, where the anode layer 102 may be made of indium tin oxide ITO, silver Ag, or the like. A hole blocking layer HBL, an electron transport layer ETL, a cathode layer 104, etc. may be sequentially stacked on the side of the light emitting layer 100 where the blue light emitting unit B-EML, the green light emitting unit G-EML, and the red light emitting unit R-EML are disposed, and the cathode layer 104 is far from the light emitting layer 100 with respect to the hole blocking layer HBL. Of course, in other embodiments, the device layer 10 may add other layer structures, such as an electron injection layer, or delete some layer structures, as the case may be.

The optical function layer 12 is stacked on the light emitting surface of the device layer 10 (for example, on the cathode layer 104 side of the device layer 10), and includes an extinction material (not illustrated in fig. 1) having an extinction coefficient in the blue light wavelength range larger than that in the red light wavelength range and the green light wavelength range. In this embodiment, the extinction material may be metal or nonmetal, the metal may be magnesium Mg, silver Ag, or the like, and the nonmetal may be silicon oxide SiO ₂ And so on. After the blue light emitted by the light emitting layer 100 in the device layer 10 passes through the extinction material, the attenuation of the blue light at each viewing angle is accelerated, so that the white light track moves in the reverse direction of the blue light, the phenomenon that the color of the display panel is easy to deviate from blue at a large viewing angle is reduced, and the display quality is improved.

Preferably, in this embodiment, the extinction coefficient of the extinction material has a maximum value in the wavelength range of 400nm to 440 nm. When the extinction coefficient of the extinction material has a maximum value in the above wavelength range, the extinction material has the best effect of attenuating blue light at various viewing angles.

In one embodiment, as shown in fig. 1, the optically functional layer 12 further includes a light extraction layer 120 and a first matting layer 122, the light extraction layer 120 is located between the first matting layer 122 and the device layer 10, and the first matting layer 122 contains a matting material therein, preferably, the first matting layer 122 is formed entirely of the matting material. In this embodiment, when light passes through the cathode layer 104, since the material of the cathode layer 104 is generally metal, light waves enter the interface between metal and dielectric, free electrons on the metal surface are collectively oscillated, and the electromagnetic waves are coupled with the free electrons on the metal surface to form a near-field electromagnetic wave propagating along the metal surface. Because the near-field electromagnetic wave is not matched with the wave vector in the air, the near-field electromagnetic wave in the metal cannot be coupled into the air, and the energy is finally dissipated on the surface of the metal, so that the optical loss effect is generated. At this time, the light extraction layer 120 on the device layer 10 side (i.e., the cathode layer 104 side) can improve the wave vector of the free light to match the wave vector of the near-field electromagnetic wave on the metal surface, so that the energy of the near-field electromagnetic wave confined on the outer surface of the metal can be coupled into the light extraction layer 120 in the form of light, thereby achieving the effect of enhancing the light extraction efficiency. The specific structure of the light extraction layer 120 can be found in any one of the prior art, and will not be described in detail here. At this time, the first extinction layer 122 on the light extraction layer 120 side can further accelerate the blue light attenuation at each viewing angle to reduce the color cast blue phenomenon.

In order to reduce the influence of the first extinction layer 122 on the light extraction action of the light extraction layer 120, the thickness of the first extinction layer 122 is small, and for example, the thickness of the first extinction layer 122 is about 5A. In order to improve the light emission efficiency of the display panel, the absolute value of the difference between the refractive indices of the first extinction layer 122 and the light extraction layer 120 is 0.2 or less, for example, 0.15, 0.1, 0.05, or the like.

Further, referring to fig. 1 again, in order to further reduce the phenomenon of color shift blue, the optical function layer 12 further includes a second extinction layer 124, the second extinction layer 124 is located between the light extraction layer 120 and the device layer 10, and the second extinction layer 124 includes an extinction material therein, and preferably, the second extinction layer 124 is formed entirely of the extinction material.

In addition, in order to reduce the influence on the interface between the light extraction layer 120 and the cathode layer 104, the thickness of the second matte layer 124 is also small, and for example, the thickness of the second matte layer 124 is about 5A. In order to improve the light emission efficiency of the display panel, the absolute value of the difference between the refractive indices of the second extinction layer 124 and the light extraction layer 120 is 0.2 or less, for example, 0.15, 0.1, 0.05, or the like.

It is assumed that the influence of the refractive index changes of the first extinction layer 122 and the second extinction layer 124 on red light and green light is unchanged. When the refractive index of the first extinction layer 122 or the second extinction layer 124 is smaller than the refractive index of the light extraction layer 120, and the difference between the two refractive indexes is greater than 0.2, the blue light attenuation speed is too fast, so that the white light track moves in the reverse direction of the blue light, the problem of color-crossing over blue or red may occur, and the user visual experience is not good. When the refractive index of the first extinction layer 122 or the second extinction layer 124 is greater than the refractive index of the light extraction layer 120, and the difference between the two refractive indices is greater than 0.2, the blue light attenuation speed is too slow, the white light trajectory is very blue, and especially, the user visual experience is not good at a large viewing angle. Therefore, the refractive index selection conditions of the first extinction layer 122 and the second extinction layer 124 can improve the luminous efficiency of the display panel and improve the visual experience of the user.

When the first matte layer 122 and the second matte layer 124 are included in the optical function layer 12, the first matte layer 122 and the second matte layer 124 are all the same in material, thickness, refractive index and matte coefficient, that is, the first matte layer 122 and the second matte layer 124 are the same. The design mode can reduce the difficulty of process preparation. Of course, in other embodiments, the first matte layer 122 and the second matte layer 124 may also be different, for example, the refractive indices of the matte materials in the first matte layer 122 and the second matte layer 124 may be different.

In another embodiment, as shown in fig. 2, fig. 2 is a schematic structural diagram of another embodiment of a display panel of the present application. The optically functional layer 12a further includes a light extraction layer 120a, a matting material 126a is doped in the light extraction layer 120a, preferably, the matting material 126a is uniformly doped in the light extraction layer 120a, and the grain size of the matting material 126a can be as small as possible. For example, the material for forming the light extraction layer 120a may be mixed with the matting material 126a during the production process to form the optically functional layer 12 a. The optical function layer 12a has a simple structure, and the process is easy to implement.

In another embodiment, referring to fig. 3, fig. 3 is a schematic structural diagram of an embodiment of the blue light emitting unit in fig. 1. The blue light emitting unit B-EML in the light emitting layer 100 is formed by a host material 140 and a guest material 142 doped in the host material 140, wherein in the lamination direction of the device layer 10 and the optical function layer 12, that is, the direction indicated by the arrow in fig. 3, the blue light emitting unit B-EML is divided into at least two sub-layers, and the doping quality ratio of the guest material 142 in at least two sub-layers is different, so that the main peak of the eigenspectrum of the blue light emitting unit B-EML moves toward the long wavelength direction, and the attenuation degree of the blue light at each viewing angle is adjusted and increased, and the white light track moves toward the reverse direction, thereby reducing the phenomenon that the display panel easily color shifts to blue at a large viewing angle, and further improving the display quality.

In the present embodiment, the guest material 142 includes: α -AND-2-PBD (2- (4-tert-butylphenyl) -5- (4- (2- (9, 10-di (α -naphthyl)) anthryl) biphenyl) -1,3, 4-oxadiazole), GDI691, TBP (2,5,8, 11-tetra (tert-butyl) perylene), TBPe (1,4,7, 10-tetra-tert-butylphthalene), FCNIr AND the like. The host material 140 includes at least one of TPA-SBFF (spirobenzofluorene dimer-N, N ', -tetraphenylspiro [ benzo [ c ] fluorene-7, 9-fluorene ] -5, 9-diamine), TPBi (1,3, 5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene), AND (9, 10-di (β -naphthyl) anthracene), Spiro-FPA (2,2 ' -bis (10-phenyl-9-yl) -9' -spirofluoroalkane), AND the like.

Preferably, the doping quality ratio of the guest material 142 in at least two sub-layers gradually increases in the stacking direction of the device layer 10 and the optically functional layer 12. The design mode is simple in structure, and the attenuation degree of the blue light under each angle of visual angle can be better adjusted and increased.

In this embodiment, the ratio of the mass of the guest material 142 in each sub-layer to the sum of the mass of the guest material 142 and the mass of the host material 140 in the sub-layer is not more than 3% and not more than 1%. If the doping mass proportion of the guest material 142 is too high, the more pronounced the TTA (up-conversion) effect is; if the doping level of guest material 142 is too low, energy transfer is incomplete. Therefore, guest material 142 within the above-described doping amount ratio range works well.

In addition, in the present embodiment, the guest material 142 in each sub-layer is doped in the host material 140 of the sub-layer in a uniform doping manner.

In one embodiment, as shown in fig. 3, in the lamination direction of the device layer 10 and the optically functional layer 12, the blue light emitting unit B-EML is divided into three sub-layers, and the doping mass ratios of the guest material 142 of the three sub-layers are 1%, 2%, and 3% in this order. The blue light attenuation effect of each visual angle that above-mentioned design can reach is better.

Of course, in other embodiments, referring again to fig. 1, the display panel may further include other structures, for example, a LiF layer 16 and an encapsulation layer 18, wherein the LiF layer 16 is located on the side of the optically functional layer 12 away from the device layer 10, and the encapsulation layer 18 is located on the side of the LiF layer 16 away from the device layer 10. Among other things, the LiF layer 16 may reduce the effect of certain strong oxidizing materials in the encapsulation layer 18 on other layers; the encapsulation layer 18 may be formed by stacking a first inorganic layer, an organic layer, and a second inorganic layer.

The display panel provided in the present application will be further described with reference to several embodiments and data.

Comparative example one: an optically functional layer is provided, which only comprises a light extraction layer.

The first embodiment is as follows: and providing an optical function layer, wherein the optical function layer comprises a light extraction layer, a first extinction layer and a second extinction layer, the first extinction layer and the second extinction layer are respectively positioned on two sides of the light extraction layer, and are the same, the material and the structure of the light extraction layer in the first comparative example and the first embodiment are the same, and the first extinction layer and the second extinction layer are the same.

Referring to fig. 4, fig. 4 is a graph illustrating the wavelength and refractive index of the comparative example and the example. As can be seen from fig. 4, the refractive index curves of the first comparative example and the first example are completely overlapped, and the refractive index of the entire optical function layer is not greatly changed after the first extinction layer and the second extinction layer are added, so that the light extraction efficiency of the display panel formed subsequently is not substantially changed.

Referring to fig. 5, fig. 5 is a graph illustrating the wavelength and extinction coefficient curves of the comparative example and the example. As can be seen from fig. 5, the maximum value of the extinction coefficient in the blue wavelength range in the first example provides an optically functional layer that can effectively attenuate blue light compared to the first comparative example.

Referring to fig. 6-7, fig. 6 is a schematic diagram showing the chromaticity variation under each field angle in white field of the first comparative example and the first example, and fig. 7 is a schematic diagram showing the thickness and degree of color shift of different optical functional layers of the first comparative example and the first example. Fig. 6 and 7 represent the same meaning. Generally, a smaller value of the degree of color shift is better. As can be seen from fig. 7, the degree of color shift is smaller for the same thickness of the optical functional layer after the first extinction layer and the second extinction layer are added.

Comparative example two: a display panel is provided, in which a guest material is uniformly doped in a blue light emitting cell.

Example two: the method comprises the steps of providing a display panel, wherein guest materials in a blue light-emitting unit in the display panel are doped in a gradient mode, in the laminating direction of a device layer and an optical function layer of the display panel, the blue light-emitting unit is divided into three sub-layers, and the doping mass proportion of the guest materials of the three sub-layers is 1%, 2% and 3% in sequence.

Referring to fig. 8, fig. 8 is a color coordinate graph of comparative example two and example two at 5 ° intervals. As can be seen from fig. 8, the chromaticity of white light of the display panel varies. The white light tracks under different visual angles are under the same angle, the horizontal and vertical coordinates are small, and the color cast degree is small. As can be seen from fig. 8, in the second embodiment, the degree of color shift can be effectively reduced by adopting the guest material gradient doping method.

The above description is only for the purpose of illustrating embodiments of the present application and is not intended to limit the scope of the present application, and all modifications of equivalent structures and equivalent processes, which are made by the contents of the specification and the drawings of the present application or are directly or indirectly applied to other related technical fields, are also included in the scope of the present application.

Claims

1. A display panel, comprising:

a device layer including a light emitting layer;

the optical function layer is stacked on one side of the light emitting surface of the device layer and comprises an extinction material, and the extinction coefficient of the extinction material in a blue light wavelength range is larger than the extinction coefficients of the extinction material in a red light wavelength range and a green light wavelength range;

the optical function layer further comprises a light extraction layer and a first extinction layer, the light extraction layer is located between the first extinction layer and the device layer, the first extinction layer contains the extinction material, and the absolute value of the difference between the refractive indexes of the first extinction layer and the light extraction layer is less than or equal to 0.2.

2. The display panel according to claim 1,

3. The display panel according to claim 2,

the absolute value of the difference between the refractive indexes of the second extinction layer and the light extraction layer is less than or equal to 0.2.

4. The display panel according to claim 2,

5. The display panel according to claim 1,

the light-emitting layer comprises a blue light-emitting unit, the blue light-emitting unit is formed by a host material and a guest material doped in the host material, the blue light-emitting unit is divided into at least two sub-layers in the laminating direction of the device layer and the optical function layer, and the doping quality proportion of the guest material in the at least two sub-layers is different.

6. The display panel according to claim 5,

in the stacking direction of the device layer and the optical function layer, the doping quality proportion of the guest material in the at least two sub-layers is gradually increased.

7. The display panel according to claim 6,

the proportion of the mass of the guest material in each sub-layer to the sum of the mass of the guest material and the mass of the host material in the sub-layer is less than or equal to 3% and greater than or equal to 1%.

8. The display panel according to claim 7,

in the laminating direction of the device layer and the optical function layer, the blue light-emitting unit is divided into three sub-layers, and the doping mass proportion of the guest materials of the three sub-layers is 1%, 2% and 3% in sequence.