CN111463362A - Display panel, manufacturing method and driving method thereof, and display device - Google Patents

Abstract

The present application discloses a display panel, a method for manufacturing the same, a method for driving the same, and a display device, which are used to increase the driving current, avoid abnormal lighting of sub-pixels, and improve the display effect. An embodiment of the present application provides a display panel, the display panel includes: a plurality of sub-pixel units, an encapsulation layer that seals the sub-pixel units, and a saturable absorber located on the encapsulation layer; the sub-pixel unit includes an electroluminescent device; the saturable absorber at least covers the light-emitting region of the sub-pixel unit; the saturable absorber has a preset light absorption brightness threshold, and the saturable absorber is configured to: absorb no part of the sub-pixel unit Light greater than the preset light absorption brightness threshold.

Description

A display panel and its manufacturing method, driving method, and display device

technical field

The present application relates to the field of display technology, and in particular, to a display panel and a method for manufacturing the same, a method for driving the same, and a display device.

Background technique

Compared with LCD screens, organic light-emitting diode (OLED) displays have the advantages of flexibility and high contrast ratio, and more and more panel manufacturers are beginning to pay attention to or invest in this field. OLED includes an anode, a cathode, and a light-emitting layer between the anode and the cathode. The OLED display principle is as follows: holes are injected into the light-emitting layer from the anode, electrons are injected into the light-emitting layer from the cathode, and electrons and holes are combined in the light-emitting layer to emit light. Therefore, the brightness of the OLED screen is controlled by the current magnitude of the OLED device passing through the pixels. In the prior art, a thin film transistor (TFT) is usually used to drive an OLED device to emit light, and the control of the current by the TFT directly affects the luminous intensity of the OLED screen. As the resolution of the screen is getting higher and higher, and the brightness of the screen remains unchanged, the driving current of the pixel will become smaller and smaller, especially at very low gray scales, the driving current is very small. Therefore, the following situations may occur: at zero gray scale, the leakage current of the TFT may still light up the OLED, which will reduce the contrast of the screen and reduce the user experience. Moreover, at low gray scales, since the driving current is small, the brightness at low gray scales is not uniform.

To sum up, in the prior art, the driving current at a low gray scale is not easy to control, which is likely to cause abnormal lighting of pixels, resulting in uneven brightness of the display image.

SUMMARY OF THE INVENTION

Embodiments of the present application provide a display panel and a method for manufacturing the same, a method for driving the same, and a display device, which are used to increase the driving current, avoid abnormal lighting of sub-pixels, and improve the display effect.

An embodiment of the present application provides a display panel, the display panel includes: a plurality of sub-pixel units, an encapsulation layer that seals the sub-pixel units, and a saturable absorber located on the encapsulation layer; the sub-pixel unit includes an electroluminescent device; the saturable absorber covers at least the light-emitting region of the sub-pixel unit; the saturable absorber has a preset light absorption brightness threshold, and the saturable absorber is configured to: absorb not in the sub-pixel unit Light greater than the preset light absorption brightness threshold.

In the display panel provided by the embodiment of the present application, since the saturable absorber is provided with the saturable absorber, the saturable absorber can absorb light, that is, the luminous brightness of the electroluminescent device in the sub-pixel unit is higher than the light-emitting brightness of the sub-pixel unit, so that the electroluminescent device can be improved. drive current. The abnormal lighting of pixels can be avoided, and the contrast ratio of the display panel can be improved. It is also possible to avoid uneven display images caused by too low driving current of the electroluminescent device and difficult control in the case of low gray scale.

Optionally, the saturable absorbers of different sub-pixel units are integrally connected.

In the display panel provided by the embodiment of the present application, the saturable absorber is arranged in a whole layer, the process is simple, and the realization is easy.

Optionally, the material of the saturable absorber includes: a semiconductor material doped with chromium and/or cobalt.

Optionally, the electroluminescent device includes an anode, a hole injection layer, a hole transport layer, an organic light-emitting layer, an electron transport layer, an electron injection layer, and a cathode that are stacked in sequence; The hole transport layer is integrally connected.

The display panel provided in the embodiment of the present application is provided with a saturable absorber, even if holes flow through the integrally connected hole transport layer to other sub-pixel units that do not need to be lit, causing a weak leakage current, the leakage current caused by The light emitted by the electroluminescent device will be absorbed by the saturable absorber, that is, the light emitted by the electroluminescent device caused by the leakage current is invisible to the user, thereby improving the color purity and color gamut of the monochromatic image at low gray scale.

An embodiment of the present application provides a method for manufacturing a display panel, the method comprising:

forming an electroluminescent device corresponding to the light emission color of the sub-pixel unit on the base substrate;

forming an encapsulation layer encapsulating the electroluminescent device;

A saturable absorber covering at least the light-emitting region of the sub-pixel unit is formed on the encapsulation layer; wherein the saturable absorber has a preset light absorption brightness threshold, and the saturable absorber is configured to absorb the sub-pixels The light in the unit is not greater than the preset light absorption brightness threshold.

In the preparation method of the display panel provided by the embodiment of the present application, since the saturable absorber is provided, the saturable absorber can absorb light, that is, the luminescence brightness of the electroluminescent device in the sub-pixel unit is higher than the light-emitting brightness of the sub-pixel unit, so that the electric power can be improved. drive current of the luminescent device. The abnormal lighting of pixels can be avoided, and the contrast ratio of the display panel can be improved. It is also possible to avoid uneven display images caused by too low driving current of the electroluminescent device and difficult control in the case of low gray scale.

Optionally, forming a saturable absorber covering at least the light-emitting region of the sub-pixel unit on the encapsulation layer specifically includes:

Provide chromium and/or cobalt doped semiconductor material targets;

The chromium and/or cobalt-doped semiconductor material target is deposited by a chemical vapor deposition process to form a layer of saturable absorber.

Optionally, forming an electroluminescent device corresponding to the light output color of the sub-pixel unit on the base substrate specifically includes:

An anode, a hole injection layer, a hole transport layer, an organic light-emitting layer, an electron transport layer, an electron injection layer, and a cathode are sequentially formed on the base substrate; wherein the hole transport layers of the sub-pixel units are different from each other. All-in-one connection.

A method for driving a display panel provided by an embodiment of the present application includes:

determining the gray scale of each of the sub-pixel units in the image to be displayed;

determining the driving current of the sub-pixel unit according to the gray scale and the preset light absorption brightness threshold;

The driving current is supplied to the sub-pixel unit.

In the display panel driving method provided by the embodiment of the present application, since the display panel is provided with a saturable absorber, the saturable absorber can absorb light, that is, the luminescence brightness of the electroluminescent device in the sub-pixel unit is higher than the light-emitting brightness of the sub-pixel unit. In the prior art, for a display image of the same gray scale, the driving method of the display panel provided by the embodiment of the present application can increase the driving current of the sub-pixel unit, avoid abnormal lighting of pixels, and improve the contrast ratio of the display panel. It is also possible to avoid uneven display images caused by too low driving current of the electroluminescent device and difficult control in the case of low gray scale.

Optionally, determining the driving current of the sub-pixel unit according to the gray scale and the preset light absorption brightness threshold specifically includes:

If the gray scale is A, and the preset light absorption brightness threshold is B, the driving current corresponding to the gray scale A+B is determined as the driving current of the sub-pixel unit.

A display device provided by an embodiment of the present application includes the display panel provided by an embodiment of the present application.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present application more clearly, the following briefly introduces the drawings used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

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

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

FIG. 3 is a schematic structural diagram of another display panel provided by an embodiment of the present application;

FIG. 4 is a schematic diagram of a method for manufacturing a display panel according to an embodiment of the present application;

FIG. 5 is a schematic diagram of a driving method of a display panel provided by an embodiment of the present application.

Detailed ways

An embodiment of the present application provides a display panel. As shown in FIG. 1 , the display panel includes: a plurality of sub-pixel units 12 , an encapsulation layer 3 that seals the sub-pixel units 12 , and an encapsulation layer 3 located on the encapsulation layer 3 . The saturable absorber 4; the sub-pixel unit 12 includes an electroluminescent device 2; the saturable absorber 4 covers at least the light-emitting area of the sub-pixel unit 12; the saturable absorber 4 has a preset light absorption brightness threshold, so The saturable absorber 4 is configured to absorb light in the sub-pixel unit 12 that is not greater than the preset light absorption brightness threshold.

It should be noted that, in the display panel provided by the embodiment of the present application, the saturable absorber has a preset light absorption brightness threshold. When the light emission brightness of the electroluminescent device is lower than the preset light absorption brightness threshold, the light emitted by the electroluminescent device will be The saturable absorber absorbs. When the brightness emitted by the electroluminescent device is higher than the preset light absorption brightness, the saturable absorber cannot absorb all the light emitted by the electroluminescent device. When the absorbed light reaches saturation, the saturable absorber becomes transparent. For example, the preset light absorption brightness threshold is 1 nit (nit), and the driving current of the electroluminescent device is 1 nit, and the driving current is a1 ampere, then when the driving current is less than a1 ampere, the sub-pixel cannot be lit, for example, when the sub-pixel unit The light-emitting brightness is b1nit, then the actual light-emitting brightness of the electroluminescent device in the sub-pixel unit needs to be b1+1nit, and the driving current corresponding to b1+1nit needs to be provided to the electroluminescent device, that is, compared with the prior art, this In the display panel provided by the application example, the actual light-emitting brightness of the electroluminescent device in the sub-pixel unit is higher than the light-emitting brightness of the sub-pixel unit, and the driving current for driving the electroluminescent device to emit light needs to meet the actual light-emitting brightness of the electroluminescent device, so that The display panel provided by the embodiments of the present application can increase the driving current.

In the display panel provided by the embodiment of the present application, since the saturable absorber is provided with the saturable absorber, the saturable absorber can absorb light, that is, the luminous brightness of the electroluminescent device in the sub-pixel unit is higher than the light-emitting brightness of the sub-pixel unit, so that the electroluminescent device can be improved. drive current. The abnormal lighting of pixels can be avoided, and the contrast ratio of the display panel can be improved. It is also possible to avoid uneven display images caused by too low driving current of the electroluminescent device and difficult control in the case of low gray scale.

In FIG. 1 , the saturable absorber only covers the light-emitting region of the sub-pixel unit as an example for illustration. Of course, the saturable absorber may also be set in other manners.

Optionally, as shown in FIG. 2 , the saturable absorbers 4 of different sub-pixel units 12 are integrally connected. That is, in FIG. 2 , the saturable absorber 4 is provided in the entire layer.

In the display panel provided by the embodiment of the present application, the saturable absorber is arranged in a whole layer, the process is simple, and the realization is easy.

As shown in FIGS. 1-2 , the display panel further includes: a substrate 1 , and a pixel definition layer 8 disposed on the substrate 1 and spaced apart from the anode 5 . The electroluminescent device 2 includes: an anode 5 , an organic light-emitting layer 6 , and a cathode 7 . In the display panel provided by the embodiment of the present application, the sub-pixel unit 12 may include, for example, a red sub-pixel unit R, a green sub-pixel unit G, and a blue sub-pixel unit B. The red sub-pixel unit R includes a red light organic light-emitting layer 9 , the green sub-pixel unit G includes a green light organic light-emitting layer 10 , and the blue sub-pixel unit B includes a blue light organic light-emitting layer 11 . The encapsulation layer 3 may include, for example, a first inorganic encapsulation layer, a second inorganic encapsulation layer, and an organic encapsulation layer located between the first inorganic encapsulation layer and the second inorganic encapsulation layer. It should be noted that the sub-pixel unit further includes a thin film transistor that drives the electroluminescent device to emit light. The substrate can be, for example, a planarization layer overlying the thin film transistors, and the substrate also has vias (not shown in Figures 1 and 2) for electrically connecting the anodes to the thin film transistors.

Optionally, the material of the saturable absorber includes: a semiconductor material doped with chromium and/or cobalt.

The semiconductor material may be, for example, gallium arsenide. It should be noted that the percentage of doping elements and the thickness of the saturable absorber can be selected according to the preset light absorption brightness threshold actually required.

Optionally, as shown in FIG. 3 , the electroluminescent device 2 further includes: a hole injection layer 13 , a hole transport layer 14 , an electron transport layer 15 , and an electron injection layer 16 ; The hole transport layer 14 is integrally connected.

It should be noted that the hole injection layer is usually doped to improve hole injection, but this will lead to better conductivity of the hole transport layer. When the hole transport layers of sub-pixels of different colors are integrally connected For a monochromatic light picture, for example, when the green sub-pixel unit needs to be lit, a little hole flows into the red sub-pixel unit through the hole transport layer, so that the red sub-pixel unit is weakly lit. Therefore, at low gray scales, other sub-pixel units around the sub-pixel unit that needs to emit light are always lit, thereby reducing the color gamut of the panel at low gray scales.

The display panel provided in the embodiment of the present application is provided with a saturable absorber, even if holes flow through the integrally connected hole transport layer to other sub-pixel units that do not need to be lit, causing a weak leakage current, the leakage current caused by The light emitted by the electroluminescent device will be absorbed by the saturable absorber, that is, the light emitted by the electroluminescent device caused by the leakage current is invisible to the user, thereby improving the color purity and color gamut of the monochromatic image at low gray scale.

It should be noted that, in the display panel provided by the embodiment of the present application, the setting of the saturable absorber can especially avoid the abnormal lighting of the sub-pixel caused by the leakage current under low brightness, and can also reduce the difficulty of controlling the driving current of the sub-pixel unit under the low grayscale picture. . The saturable absorber set to improve the low-brightness display effect has a small preset light absorption brightness threshold. Therefore, in the case of high gray scale, the saturable absorber absorbs very little light, which will not affect the power consumption and luminous efficiency of the display panel. big impact.

Based on the same inventive concept, an embodiment of the present application also provides a method for manufacturing a display panel, as shown in FIG. 4 , the method includes:

S101, forming an electroluminescent device corresponding to the light emitting color of the sub-pixel unit on the base substrate;

S102, forming an encapsulation layer for sealing the electroluminescent device;

S103 , forming a saturable absorber covering at least the light-emitting region of the sub-pixel unit on the encapsulation layer; wherein the saturable absorber has a preset light absorption brightness threshold, and the saturable absorber is configured to absorb the The light in the sub-pixel unit is not greater than the preset light absorption brightness threshold.

In the preparation method of the display panel provided by the embodiment of the present application, since the saturable absorber is provided, the saturable absorber can absorb light, that is, the luminescence brightness of the electroluminescent device in the sub-pixel unit is higher than the light-emitting brightness of the sub-pixel unit, so that the electric power can be improved. drive current of the luminescent device. The abnormal lighting of pixels can be avoided, and the contrast ratio of the display panel can be improved. It is also possible to avoid uneven display images caused by too low driving current of the electroluminescent device and difficult control in the case of low gray scale.

Optionally, forming a saturable absorber covering at least the light-emitting region of the sub-pixel unit on the encapsulation layer in step S103 specifically includes:

Provide chromium and/or cobalt doped semiconductor material targets;

The chromium and/or cobalt-doped semiconductor material target is deposited by a chemical vapor deposition process to form a layer of saturable absorber.

Optionally, forming an electroluminescent device corresponding to the light output color of the sub-pixel unit on the base substrate specifically includes:

An anode, a hole injection layer, a hole transport layer, an organic light-emitting layer, an electron transport layer, an electron injection layer, and a cathode are sequentially formed on the base substrate; wherein the hole transport layers of the sub-pixel units are different from each other. All-in-one connection.

Based on the same inventive concept, an embodiment of the present application also provides a method for driving a display panel, as shown in FIG. 5 , the method includes:

S201. Determine the gray scale of each of the sub-pixel units in the image to be displayed;

S202. Determine the driving current of the sub-pixel unit according to the gray scale and the preset light absorption brightness threshold;

S203 , providing the driving current to the sub-pixel unit.

In the display panel driving method provided by the embodiment of the present application, since the display panel is provided with a saturable absorber, the saturable absorber can absorb light, that is, the luminescence brightness of the electroluminescent device in the sub-pixel unit is higher than the light-emitting brightness of the sub-pixel unit. In the prior art, for a display image of the same gray scale, the driving method of the display panel provided by the embodiment of the present application can increase the driving current of the sub-pixel unit, avoid abnormal lighting of pixels, and improve the contrast ratio of the display panel. It is also possible to avoid uneven display images caused by too low driving current of the electroluminescent device and difficult control in the case of low gray scale.

Optionally, determining the driving current of the sub-pixel unit according to the gray scale and the preset light absorption brightness threshold specifically includes:

If the gray scale is A, and the preset light absorption brightness threshold is B, the driving current corresponding to the gray scale A+B is determined as the driving current of the sub-pixel unit.

The embodiment of the present application further provides a display device, and the display device includes the above-mentioned display panel further provided by the embodiment of the present application.

The display device provided in the embodiment of the present application may be, for example, a mobile phone, a computer, a television, or other devices.

The display device provided by the embodiment of the present application further includes a driving chip, and the driving chip stores the signal of the driving current of the sub-pixel unit under different gray scales. Taking the need to display 0-255 grayscale as an example, the driver chip stores the driving current signal corresponding to 0 grayscale brightness + B~255 grayscale brightness + B, where B is the preset light absorption brightness threshold of the saturable absorber.

To sum up, in the display panel, the manufacturing method, the driving method, and the display device provided by the embodiments of the present application, since the saturable absorber is provided, the saturable absorber can absorb light, that is, the luminous brightness ratio of the electroluminescent device in the sub-pixel unit The light-emitting brightness of the sub-pixel unit is high, so that the driving current of the electroluminescent device can be improved. The abnormal lighting of pixels can be avoided, and the contrast ratio of the display panel can be improved. It is also possible to avoid uneven display images caused by too low driving current of the electroluminescent device and difficult control in the case of low gray scale.

Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims (10)

1. A display panel, comprising: the pixel structure comprises a plurality of sub-pixel units, an encapsulation layer for sealing the sub-pixel units, and a saturable absorber positioned on the encapsulation layer; the sub-pixel unit comprises an electroluminescent device; the saturable absorber at least covers the light emitting areas of the sub-pixel units; the saturable absorber has a preset absorbance luminance threshold, the saturable absorber configured to: and absorbing light which is not more than the preset light absorption brightness threshold value in the sub-pixel unit.

2. The display panel according to claim 1, wherein the saturable absorbers of different sub-pixel units are integrally connected.

3. The display panel according to claim 1, wherein the material of the saturable absorber comprises: a chromium and/or cobalt doped semiconductor material.

4. The display panel according to claim 1, wherein the electroluminescent device comprises an anode, a hole injection layer, a hole transport layer, an organic light emitting layer, an electron transport layer, an electron injection layer, and a cathode, which are sequentially stacked; the hole transport layers of different sub-pixel units are integrally connected.

5. A method for manufacturing a display panel, the method comprising:

forming an electroluminescent device corresponding to the light emitting color of the sub-pixel unit on the substrate;

forming an encapsulation layer sealing the electroluminescent device;

forming a saturable absorber at least covering the light emitting areas of the sub-pixel units on the packaging layer; wherein the saturable absorber has a preset absorbance luminance threshold, the saturable absorber configured to: and absorbing light which is not more than the preset light absorption brightness threshold value in the sub-pixel unit.

6. The method of claim 5, wherein forming a saturable absorber over the encapsulation layer at least covering the light emitting region of the sub-pixel cell comprises:

providing a semiconductor material target doped with chromium and/or cobalt;

and depositing the chromium and/or cobalt-doped semiconductor material target by adopting a chemical vapor deposition process to form a layer of saturable absorber.

7. The method of claim 5, wherein forming the electroluminescent device corresponding to the color of light emitted from the sub-pixel unit on the substrate comprises:

sequentially forming an anode, a hole injection layer, a hole transport layer, an organic light emitting layer, an electron transport layer, an electron injection layer and a cathode on the substrate; wherein the hole transport layers of different sub-pixel units are integrally connected.

8. A method for driving a display panel according to any one of claims 1 to 4, the method comprising:

determining the gray scale of each sub-pixel unit in an image to be displayed;

determining the driving current of the sub-pixel unit according to the gray scale and the preset light absorption brightness threshold;

providing the drive current to the sub-pixel cell.

9. The method of claim 8, wherein determining the driving current of the sub-pixel unit according to the gray scale and the predetermined absorption luminance threshold comprises:

and if the gray scale is A and the preset light absorption brightness threshold is B, determining the driving current corresponding to the gray scale of A + B as the driving current of the sub-pixel unit.

10. A display device comprising the display panel according to any one of claims 1 to 4.

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