CN114335370A - Light emitting device, display substrate and display panel - Google Patents
Light emitting device, display substrate and display panel Download PDFInfo
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- CN114335370A CN114335370A CN202111633374.3A CN202111633374A CN114335370A CN 114335370 A CN114335370 A CN 114335370A CN 202111633374 A CN202111633374 A CN 202111633374A CN 114335370 A CN114335370 A CN 114335370A
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Abstract
The present disclosure provides a light emitting device including a first electrode structure, a second electrode structure, and a light emitting functional layer between the first electrode structure and the second electrode structure. The first electrode structure includes a first electrode and a charge blocking layer for blocking holes, which are stacked on each other. Under the condition that the voltage from an external circuit is small, holes are difficult to enter the light-emitting functional layer over a potential barrier formed by the charge blocking layer, so that the light-emitting functional layer cannot be excited to emit light; under the condition that the voltage from an external circuit is large, the charge blocking layer does not play a role in blocking the holes and cannot influence the light emitting brightness of the light emitting device in a light emitting state.
Description
Technical Field
The present disclosure relates to the field of display, and in particular, to a light emitting device, a display substrate, and a display panel.
Background
An Organic Light-Emitting Diode (OLED) display device is an Organic thin film electroluminescent device, and has the advantages of simple manufacturing process, low cost, low power consumption, high brightness, wide viewing angle, high contrast, flexible display, and the like, so that people have great attention.
In the display stage, the image display is realized by adjusting the luminous intensity of the display device, and the contrast of the image directly influences the user experience. However, the current display device is limited by its structure, and when low gray scale display (low brightness or off state) is required, the display device can still emit light due to leakage current of the driving circuit, so that the display device cannot realize real low gray scale light emission or does not emit light at all, and thus the contrast of the display image of the display product is limited, and it is difficult to meet the user requirement.
Disclosure of Invention
The present disclosure provides a light emitting device, a display substrate and a display panel, in which a charge blocking layer is disposed on a first electrode of the light emitting device to block holes to a certain extent, so as to increase the difficulty of hole transition, thereby preventing the light emitting device from emitting light at a low gray scale current or voltage, and thus improving the contrast of display images of the display substrate and the display panel.
A first aspect of the present disclosure provides a light emitting device including a first electrode structure, a second electrode structure, and a light emitting functional layer between the first electrode structure and the second electrode structure. The first electrode structure includes a first electrode and a charge blocking layer for blocking holes.
In the above scheme, when the voltage from the external circuit is small, holes are difficult to enter the light emitting functional layer over the potential barrier formed by the charge blocking layer, so that the light emitting functional layer is not excited to emit light; under the condition that the voltage from an external circuit is large, the charge blocking layer does not play a role in blocking the holes and cannot influence the light emitting brightness of the light emitting device in a light emitting state.
In one embodiment of the first aspect of the present disclosure, the charge blocking layer is an insulating layer, and the thickness of the charge blocking layer is as small as being broken down at the non-lowest grayscale driving voltage, i.e., the thickness of the charge blocking layer is configured such that the charge blocking layer is broken down at the non-lowest grayscale driving voltage and is insulating at the lowest grayscale voltage. For example, the material of the charge blocking layer has a forbidden band width of not less than 4.5 eV.
In the above scheme, the voltage required by the charge blocking layer when the charge blocking layer allows carriers to pass through can be adjusted by designing the forbidden bandwidth of the charge blocking layer, so that the minimum driving voltage at which the light emitting device can emit light is adjusted, and the light emitting device is ensured not to emit light at the lowest gray scale (e.g. zero gray scale).
In one embodiment of the first aspect of the present disclosure, the charge blocking layer has a thickness of 1 to 30 nm.
In a specific embodiment of the first aspect of the present disclosure, the material of the charge blocking layer includes at least one of silicon oxide, silicon nitride, aluminum oxide, hafnium oxide, zirconium oxide, and magnesium oxide.
In one specific embodiment of the first aspect of the present disclosure, the first electrode is located between the charge blocking layer and the light emitting functional layer.
In the above scheme, the influence of the arrangement of the charge blocking layer on the film layer design of the first electrode, the second electrode structure and the light-emitting function layer of the light-emitting device can be reduced.
In another specific embodiment of the first aspect of the present disclosure, the charge blocking layer is located between the first electrode and the light emitting functional layer.
In the above scheme, the charge blocking layer is located between the first electrode and the light-emitting functional layer, and in the actual process, it is equivalent to preparing the charge blocking layer above the first electrode, so that holes must pass through the charge blocking layer before entering the light-emitting functional layer.
In another specific embodiment of the first aspect of the present disclosure, the first electrode includes a first sub-electrode, a second sub-electrode, and a third sub-electrode that are stacked, the second sub-electrode and the third sub-electrode are arranged in this order in a direction from the first sub-electrode to the light emission functional layer, the first sub-electrode is a light reflection electrode, the charge blocking layer is located between the first sub-electrode and the third sub-electrode, and a sum of optical thicknesses of the second sub-electrode and the charge blocking layer is an integral multiple of 1/2 of a center wavelength of outgoing light of the light emission functional layer. For example, further, the charge blocking layer is configured to be located between the second sub-electrode and the third sub-electrode.
In the scheme, the light rays meeting the conditions can generate interference constructive force to be emitted out of the first electrode structure again, and the wavelength range of the emitted light rays is more towards the central wavelength, so that the color purity is higher; in addition, undesirable light is consumed (e.g., destructive interference, etc.) in the first electrode structure, thereby reducing the proportion of interfering light exiting the light emitting device and further improving the color purity of the exiting light. In addition, the charge blocking layer is arranged, so that the thickness of the first electrode structure cannot be increased, and the design size of the light-emitting device cannot be adversely affected.
In one embodiment of the first aspect of the present disclosure, the light-emitting functional layer includes a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, and an electron injection layer, which are sequentially arranged from the first electrode structure to the second electrode structure.
A second aspect of the present disclosure provides a display substrate including an array substrate and a display functional layer. The array substrate comprises a substrate and a driving circuit layer positioned on the substrate. The display function layer comprises a plurality of light emitting devices as described above in the first aspect. The driving circuit layer includes a plurality of pixel driving circuits connected in one-to-one correspondence with the light emitting devices, each pixel driving circuit including a driving transistor, and the first electrode structure of the light emitting device is electrically connected to a source electrode or a drain electrode of the driving transistor of the corresponding pixel driving circuit.
In a specific embodiment of the second aspect of the present disclosure, the first electrode structure of the light emitting device is directly connected to the source or drain electrode of the corresponding driving transistor.
In another specific embodiment of the second aspect of the present disclosure, the pixel driving circuit includes a plurality of switching transistors, and the first electrode structure of the light emitting device and the source electrode or the drain electrode of the corresponding driving transistor are electrically connected through at least one switching transistor.
A third aspect of the present disclosure provides a display panel including the display substrate of the second aspect.
Drawings
Fig. 1 is a schematic plan view illustrating a display substrate according to an embodiment of the disclosure.
Fig. 2 is a cross-sectional view of the display substrate shown in fig. 1.
Fig. 3 is a schematic structural diagram of a pixel region in the display substrate shown in fig. 1.
Fig. 4 is a partial structural view of a light emitting device of the display substrate shown in fig. 3, and illustrates a connection manner of the light emitting device and a transistor.
Fig. 5 is a partial structural view of another light emitting device of the display substrate shown in fig. 3, and illustrates a connection manner of the light emitting device and a transistor.
Fig. 6 is a partial structural view of another light emitting device of the display substrate shown in fig. 3, and illustrates a connection manner of the light emitting device and a transistor.
Fig. 7 is a partial structural view of another light emitting device of the display substrate shown in fig. 3, and illustrates a connection manner of the light emitting device and a transistor.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of 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 invention.
An Organic Light-Emitting device (abbreviated as "OLED") is a device driven by current, and in the display field, the current input to the OLED is usually controlled by a Thin Film Transistor (TFT) in a driving circuit, where the TFT may be a driving Transistor, so that the magnitude of the current output by the TFT can be controlled by controlling the gate voltage of the TFT (different gate voltages correspond to the on-off state and the on-level of the TFT), and further, the Light-Emitting state (e.g., on or off) and the Light-Emitting brightness of the OLED can be controlled.
An OLED comprises a light-emitting layer in which electrons and holes recombine to excite light when the OLED is supplied with current. In practical applications, at least in view of reducing power consumption, the current for driving the OLED is reduced, and in view of the requirement of ensuring the luminance of the OLED, the material of the light-emitting layer is developed to be more favorable for the recombination of electrons and holes, which results in that the light-emitting layer can emit light under low-current driving, i.e., the OLED cannot be turned off in the true sense, i.e., the OLED can still emit light in a so-called black state (corresponding to turn off), so that the contrast of the displayed image is low.
At least one embodiment of the present disclosure provides a light emitting device, a display substrate, and a display panel, which may solve the above technical problems. The light emitting device includes a first electrode structure, a second electrode structure, and a light emitting function layer between the first electrode structure and the second electrode structure. The first electrode structure includes a first electrode and a charge blocking layer for blocking holes, so that carriers (for example, holes) injected from the light emitting functional layer on the side where the first electrode structure is located need to pass through the charge blocking layer before entering the light emitting functional layer. In this way, the first electrode and the charge blocking layer are stacked, and a current (holes) from an external circuit (for example, a pixel driving circuit described below) passes through the blocking of the charge blocking layer before entering the light emitting functional layer through the first electrode, and when a voltage from the external circuit is small, the current is limited by a potential barrier formed by a wide band gap of the charge blocking layer, and the holes hardly cross the potential barrier to enter the light emitting functional layer, so that the light emitting functional layer is not excited to emit light; under the condition that the voltage from an external circuit is large, charges (holes) are collected by the charge blocking layer under the blocking of the charge blocking layer, so that the built-in electric field between the first electrode and the charge blocking layer is changed, the energy band is bent, the potential barrier is reduced, the charge blocking layer cannot block the holes, and the arrangement of the charge blocking layer cannot influence the light emitting brightness of the light emitting device in a light emitting state.
It is to be noted that, in the embodiments of the present disclosure, the first electrode may be an anode of the light emitting device, and the second electrode may be a cathode of the light emitting device.
The following describes structures of a light emitting device, a display substrate, and a display panel according to at least one embodiment of the present disclosure with reference to the accompanying drawings. In addition, in the embodiments, the structure of the light emitting device in the display substrate will be described in detail by describing the display substrate. In addition, in the drawings, a spatial rectangular coordinate system is established with reference to a plane on which the display substrate is located (a direction from the first electrode structure to the second electrode structure of the light emitting device is perpendicular to the plane) to describe positions of respective elements in the light emitting device, the display substrate, and the display panel, and in the spatial rectangular coordinate system, an X axis and a Y axis are parallel to the plane on which the display substrate is located, and a Z axis is perpendicular to the plane on which the display substrate is located.
In an embodiment of the present disclosure, as shown in fig. 1 to 4, the display substrate 10 includes an array substrate 100 and a display functional layer 200 stacked together. The array substrate 100 includes a base 110 and a driving circuit layer 120. The driving circuit layer 120 and the display function layer 200 are sequentially stacked on the substrate 110. The display substrate 10 is divided into a display area 11 and a non-display area 12 located around the display area 11, and at least a partial area of the non-display area 12 may be used to constitute a bezel area in a final product (e.g., a display panel). The display function layer 200 is located in the display region 11 and includes a plurality of light emitting devices 201. The driving circuit layer 120 includes a plurality of pixel driving circuits connected in one-to-one correspondence with the light emitting devices 201, each pixel driving circuit including a driving transistor TFT, and the first electrode structure 210 of the light emitting device 201 is electrically connected to a source electrode or a drain electrode of the driving transistor TFT of the corresponding pixel driving circuit.
For example, the pixel driving circuit includes a plurality of transistors, capacitors, and the like, and is formed in various forms such as 2T1C (i.e., 2 thin film transistors (T) and 1 capacitor (C)), 3T1C, or 7T1C, in which at least one thin film transistor is a driving transistor, and the other thin film transistors may be switching transistors.
For example, in some embodiments of the present disclosure, a display substrate is provided in which a first electrode structure of a light emitting device is directly connected to a source electrode or a drain electrode of a corresponding driving transistor.
For example, some embodiments of the present disclosure provide a display substrate in which the pixel driving circuit includes a plurality of switching transistors, the first electrode structure of the light emitting device and the source electrode or the drain electrode of the corresponding driving transistor are electrically connected through at least one switching transistor, and the switching transistor for connecting the first electrode structure and the driving transistor may be configured to be independently controlled to further control the switching of the light emitting device, thereby cooperating with the pixel driving circuit to improve reliability of state control of the light emitting device.
In at least one embodiment of the present disclosure, the light emitting function layer includes a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer arranged from the first electrode structure to the second electrode structure. For example, the light emitting function layer may further include an electron blocking layer between the light emitting layer and the first electrode structure and a hole blocking layer between the light emitting layer and the second electrode structure.
In the embodiment as shown in fig. 3 and 4, the light emitting device 201 includes a first electrode structure 210, a light emitting function layer 220, and a second electrode structure 230 sequentially stacked on the driving circuit layer 120, and the first electrode structure 210 includes a first electrode 211 and a charge blocking layer 212 for blocking holes. The charge blocking layer generally has a wider forbidden bandwidth, and when a current is injected into the first electrode structure of the light emitting device through the TFT of the pixel driving circuit in the driving process of the light emitting device, the current is blocked by the charge blocking layer when the current is small, and charges (holes) cannot easily cross a potential barrier formed by the charge blocking layer to reach a light emitting function layer of the light emitting device, that is, the current of the light emitting device under low voltage is significantly reduced, so that the light emitting device is difficult to be turned on, the brightness of excitation light is further reduced or no excitation light is generated, so that the light emitting brightness of the light emitting device under a dark state is further reduced or no light is generated; in addition, if the current entering the first electrode structure is further increased, charges (here, holes) begin to gather on the side of the charge blocking layer away from the light emitting functional layer, which changes the built-in electric field on the side of the charge blocking layer away from the light emitting functional layer and causes band bending, so that the potential barrier formed by the charge blocking layer is reduced, and a large amount of charges are allowed to pass through the charge blocking layer, that is, at high current, the charge blocking layer itself does not play a role in blocking the charge entering, and in the case that the thickness of the charge blocking layer is very thin (for example, 1 to 30 nanometers), the internal resistance of the light emitting device hardly plays a role, so that the charge injection and the device voltage under high current density are not affected. In this way, for the panel (display substrate or display panel), in the case of a low gray scale of the panel, the presence of the charge blocking layer causes the light emitting device to provide a low current, charges are accumulated in the charge blocking layer and cannot enter the light emitting layer of the light emitting device for recombination, which makes the light emitting device not bright, and after further increasing the supply current of the TFT, charges start to cross the charge blocking layer and enter the light emitting layer, and the light emitting device starts to emit light.
It should be noted that both the electron blocking layer and the hole blocking layer have the function of blocking low charges, but the electron blocking layer is used for blocking electrons to allow holes to pass through, and the hole blocking layer is used for blocking holes to allow electrons to pass through, so that the electron blocking layer and the hole blocking layer are used for blocking electrons and holes from diffusing out of the light emitting layer, so as to improve the light emitting efficiency and the service life of the whole light emitting device. The charge blocking layer is used for blocking injection of charges (including electrons and holes), so that the difficulty of charge injection is improved, and the starting voltage of the light-emitting device is improved.
In a light emitting device provided in at least one embodiment of the present disclosure, the charge blocking layer is an insulating layer, and the thickness of the charge blocking layer is as small as being broken down at the non-lowest grayscale driving voltage, that is, the thickness of the charge blocking layer is set such that the charge blocking layer is broken down at the non-lowest grayscale driving voltage and is insulated at the lowest grayscale voltage. Therefore, by designing the forbidden bandwidth of the charge blocking layer, the voltage required by the charge blocking layer when the charge blocking layer allows carriers to pass can be adjusted, so that the minimum driving voltage capable of emitting light of the light emitting device is adjusted, and the light emitting device is ensured not to emit light at the lowest gray scale (such as zero gray scale). For example, the forbidden band width of the material of the charge blocking layer is not less than 4.5eV, so that, in the driving mode of the current display substrate, the light emitting device does not emit light under the driving voltage (e.g., voltage formed by the leakage current of the driving transistor) in the dark state (e.g., zero gray scale), thereby improving the contrast of the displayed image.
In a light emitting device provided in at least one embodiment of the present disclosure, a thickness (e.g., a dimension in a Z-axis direction in fig. 4) of the charge blocking layer is 1 to 30 nm, for example, 2 nm, 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, or the like. Within the thickness range, the charge blocking layer can remarkably reduce or avoid the light emission of the light-emitting device in a black state, and ensure that the light-emitting device is easy to break down when needing to emit light without influencing the light-emitting brightness of the light-emitting device in a bright state.
In a light emitting device provided in at least one embodiment of the present disclosure, a material of the charge blocking layer includes at least one of silicon oxide, silicon nitride, aluminum oxide, hafnium oxide, zirconium oxide, magnesium oxide, and the like.
In the embodiments of the present disclosure, the stacking order of the first electrode and the charge blocking layer in the first electrode structure is not limited on the premise that the charge (hole) in the first electrode structure is ensured to enter the light emitting function layer only from the charge blocking layer. For example, in some embodiments of the present disclosure, a charge blocking layer is located between the first electrode and the light emitting functional layer; alternatively, in other embodiments of the present disclosure, the first electrode is positioned between the charge blocking layer and the light emitting functional layer; alternatively, in other embodiments of the present disclosure, the first electrode is a multi-layer structure, and the charge blocking layer is located between adjacent structural layers of the first electrode so as to be located inside the first electrode, for example, the first electrode includes at least two sub-electrodes stacked, and the charge blocking layer is located between adjacent sub-electrodes. Next, the structures of the light emitting devices in the three cases will be described by different embodiments.
In some embodiments of the present disclosure, the charge blocking layer is located between the first electrode and the light emitting functional layer, specifically as shown in fig. 4 and fig. 5, the above scheme is equivalent to preparing the charge blocking layer 212, 212a on the first electrode 211, 211a, so as to avoid the charge blocking layer 212, 212a from being damaged by the first electrode 211, 211a preparation process (e.g., magnetron sputtering, photolithography, etc.); in addition, in an actual process, when the first electrodes 211, 211a are connected to an external circuit, the via holes are required to expose the output terminals of the external circuit (for example, the source electrodes or the drain electrodes of the transistors therein), and in order to make the light emitting functional layer 220 have high flatness, the portions of the first electrodes 211, 211a located in the via holes are kept away from the pixel openings (for example, the openings of a pixel defining layer described below), so that even if the charge blocking layers 212, 212a are broken at the via holes, the charge blocking layers 212, 212a can still separate the first electrodes 211, 211a and the light emitting functional layer 220 at the positions of the pixel openings, so that holes can enter the light emitting functional layer 220 only after passing through the charge blocking layers 212, 212 a.
The display function layer may include a pixel defining layer, and in the case where the charge blocking layer is positioned between the first electrode and the light emitting function layer, the charge blocking layer may be selectively formed before or after the pixel defining layer according to the requirements of an actual process. Illustratively, as shown in fig. 3, the display function layer 200 may further include a pixel defining layer 202 on the array substrate 100. The pixel defining layer 202 has a plurality of openings defined therein for defining a light emitting device (at least for accommodating a light emitting functional layer therein). Thus, if the charge blocking layer is formed first and then the pixel defining layer is formed on the charge blocking layer, as shown in fig. 4 in particular, the charge blocking layer 212 can have a higher flatness, thereby ensuring the continuity of the charge blocking layer 212; alternatively, if a pixel defining layer having an opening is formed first and then a charge blocking layer covering the pixel defining layer is deposited, as shown in fig. 5 in particular, it is possible to prevent the charge blocking layer from being damaged during the process of forming the opening in the pixel defining layer and to prevent the first electrode and the light emitting function layer from being in direct contact.
In other embodiments of the present disclosure, there is provided a light emitting device in which a first electrode is positioned between a charge blocking layer and a light emitting function layer. Therefore, the influence of the arrangement of the charge blocking layer on the film layer design of the first electrode, the second electrode structure and the light-emitting function layer of the light-emitting device can be reduced, namely, the light-emitting device can still use the current light-emitting function layer without redesigning the energy bands and the like of all the film layers of the light-emitting function layer, so that the design cost and the production process cost of the whole light-emitting device are reduced; in addition, the charge blocking layer is formed in front of the first electrode, so that a via hole for communicating the first electrode with an external circuit is covered, and even if the charge blocking layer is broken at the via hole, carriers output by the external circuit need to pass through a portion of the charge blocking layer located in the via hole and then enter the first electrode, so that the risk that the carriers (holes) directly enter the light emitting function layer without passing through the charge blocking layer due to the fact that the charge blocking layer is broken at the via hole can be reduced. Illustratively, as shown in fig. 6, in an actual process, the charge blocking layer 212b may cover a via hole for communicating the first electrode 211b with an external circuit, for example, the charge blocking layer 212b covers a drain surface of the thin film transistor exposed by the via hole, so as to ensure that the external circuit (for example, a drain of the thin film transistor included therein) and the first electrode 211b are still spaced by the charge blocking layer 212b, and thus holes originating from the external circuit must pass through the charge blocking layer 212b before entering the light emitting function layer 220, thereby solving the above technical problem.
In other embodiments of the present disclosure, a light emitting device is provided, in which the first electrode has a multi-layer structure, and the charge blocking layer is located inside the first electrode, i.e., between two adjacent layers of the first electrode, and in particular, refer to the structure shown in fig. 7. For example, the first electrode is formed by stacking three sub-electrodes, which are a first sub-electrode 2111c, a second sub-electrode 2112c, and a third sub-electrode 2113c stacked in this order, and the first sub-electrode 2111c, the second sub-electrode 2112c, and the third sub-electrode 2113c are arranged in this order in the direction from the first sub-electrode 2111c to the light emission function layer 220. The charge blocking layer 212c is located between the second sub-electrode 2112c and the third sub-electrode 2113 c.
In the case where the first electrode has a multilayer structure, the first electrode is not limited to include three sub-electrodes as shown in fig. 7, and the number of the sub-electrodes may be two, four, or four or more.
For example, in some embodiments of the present disclosure, in the case that the first electrode includes a first sub-electrode, a second sub-electrode, and a third sub-electrode as shown in fig. 7, the first sub-electrode and the third sub-electrode may be formed of a high work function oxide electrode material, such as indium tin oxide, and the like, and the second sub-electrode may be formed of a metal material, such as aluminum, silver, copper, titanium, and the like, so as to ensure that the first electrode has a relatively small sheet resistance, and also to enable the first electrode to have a light reflecting effect, so as to improve the light extraction efficiency of the light emitting device.
For example, in other embodiments of the present disclosure, in the case that the first electrode has a multilayer structure, the first electrode may be further configured in a structure similar to an optical resonant cavity to improve the luminance and color purity of the light emitting device (the higher the color purity, the less the stray light). Illustratively, as shown in fig. 7, the first sub-electrode 2111c is a light reflecting electrode, and the charge blocking layer 212c is located between the first sub-electrode 2111c and the third sub-electrode 2113 c. The sum of the optical thicknesses of the second sub-electrode 2112c and the charge blocking layer 212c is an integral multiple of 1/2 of the center wavelength of emitted light in the light-emitting functional layer 220. For example, further, the charge blocking layer 212c is configured to be located between the second sub-electrode 2112c and the third sub-electrode 2113 c. Thus, when light (light emitted by excitation of the light-emitting functional layer and/or ambient light) enters the first electrode structure, light satisfying the above conditions may exhibit interference contrast in the structure formed by the second sub-electrode 2112c and the charge blocking layer 212c and be emitted again from the first electrode structure, and the wavelength range of the emitted light is more likely to be the central wavelength, thereby having higher color purity; in addition, light that does not meet the above requirements is consumed (e.g., destructive interference, etc.) in the first electrode structure, thereby reducing the proportion of interfering light emitted in the light emitting device and further improving the color purity of the emitted light. In addition, in the scheme, the arrangement of the charge blocking layer does not increase the thickness of the first electrode structure (along with the arrangement of the charge blocking layer, the design thickness of the second sub-electrode is correspondingly reduced), so that the design size of the light-emitting device is not affected.
For example, the first sub-electrode may be made of a metal material having a high light reflection property, such as chromium, silver, lithium, magnesium, calcium, strontium, aluminum, indium, copper, gold, or an alloy thereof; for example, the second sub-electrode and the third sub-electrode may be transparent electrodes, such as Indium Tin Oxide (ITO), Indium Zinc Oxide (IZO), Indium Gallium Oxide (IGO), Gallium Zinc Oxide (GZO), Indium Gallium Zinc Oxide (IGZO), zinc oxide (ZnO), indium oxide (In2O3), Aluminum Zinc Oxide (AZO), carbon nanotubes, and the like, wherein the third sub-electrode may further select a material having a high work function, and may include one or a combination of ITO, IZO, GZO, IGZO, and the like, for example.
It should be noted that, in the embodiments of the present disclosure, each light emitting device corresponds to one sub-pixel of the display substrate (or display panel), the sub-pixels are divided into a plurality of types to emit light rays with different colors, and the colors of the light rays emitted by the different types of sub-pixels are different, so that, in the light emitting device in which the first electrode is provided in a structure similar to an optical resonator, the optical thicknesses of the structures formed by the second sub-electrode and the charge blocking layer are different among the light emitting devices in which the colors of the emitted light are different. For example, the sub-pixels of the display substrate may be classified into three types of sub-pixels of R (red), G (green), and B (blue), and the optical thickness of the structure formed by the second sub-electrode and the charge blocking layer in the R sub-pixel and the optical thickness of the structure formed by the second sub-electrode and the charge blocking layer in the G sub-pixel are not equal.
At least one embodiment of the present disclosure provides a display panel including the display substrate in any one of the above embodiments.
For example, in the display panel provided in some embodiments of the present disclosure, an encapsulation layer may be covered on the display functional layer of the display substrate to encapsulate the display substrate, or a cover plate may be provided to encapsulate the display substrate with a box. For example, a touch structure, an optical film (e.g., a polarizer, a condenser, or a color film) and the like may be further disposed on the display substrate after the packaging is completed, which may be referred to in particular for related designs of the current display panel and will not be described herein again.
For example, the device to which the display panel is applied in the embodiments of the present disclosure may be any product or component having a display function, such as a television, a digital camera, a mobile phone, a watch, a tablet computer, a notebook computer, and a navigator.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and the like that are within the spirit and principle of the present invention are included in the present invention.
Claims (10)
1. A light emitting device comprising a first electrode structure, a second electrode structure, and a light emitting functional layer between the first electrode structure and the second electrode structure, wherein,
the first electrode structure includes a first electrode and a charge blocking layer for blocking holes.
2. The light-emitting device according to claim 1,
the charge blocking layer is an insulating layer,
and the thickness of the charge blocking layer is configured to have a thickness that is broken down at a non-lowest grayscale driving voltage and is insulating at a lowest grayscale voltage,
preferably, the material of the charge blocking layer has a forbidden band width of not less than 4.5 eV.
3. The light-emitting device according to claim 2,
the thickness of the charge blocking layer is 1-30 nanometers.
4. The light-emitting device according to claim 2,
the material of the charge blocking layer comprises at least one of silicon oxide, silicon nitride, aluminum oxide, hafnium oxide, zirconium oxide and magnesium oxide.
5. The light-emitting device according to any one of claims 1 to 4,
the first electrode is positioned between the charge blocking layer and the light-emitting functional layer; or
The charge blocking layer is positioned between the first electrode and the light-emitting functional layer; or
The first electrode comprises at least two sub-electrodes which are overlapped, and the charge blocking layer is positioned between the adjacent sub-electrodes.
6. The light-emitting device according to any one of claims 1 to 4,
the first electrode comprises a first sub-electrode, a second sub-electrode and a third sub-electrode which are overlapped, the second sub-electrode and the third sub-electrode are sequentially arranged along the direction from the first sub-electrode to the light-emitting function layer, the first sub-electrode is a light reflection electrode, the charge blocking layer is positioned between the first sub-electrode and the third sub-electrode, and
the sum of the optical thicknesses of the second sub-electrode and the charge blocking layer is an integral multiple of 1/2 of the central wavelength of emergent light of the light-emitting functional layer,
preferably, the charge blocking layer is configured to be located between the second sub-electrode and the third sub-electrode.
7. The light-emitting device according to any one of claims 1 to 4, wherein the light-emitting functional layer comprises a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, and an electron injection layer arranged from the first electrode structure to the second electrode structure, and
the light emitting function layer further includes an electron blocking layer between the light emitting layer and the first electrode structure and a hole blocking layer between the light emitting layer and the second electrode structure.
8. A display substrate, comprising:
the array substrate comprises a substrate and a driving circuit layer positioned on the substrate; and
a display function layer comprising a plurality of light emitting devices according to any one of claims 1 to 7;
the driving circuit layer comprises a plurality of pixel driving circuits which are connected with the light-emitting devices in a one-to-one correspondence mode, each pixel driving circuit comprises a driving transistor, and the first electrode structure of each light-emitting device is electrically connected with the source electrode or the drain electrode of the corresponding driving transistor of the pixel driving circuit.
9. The display substrate of claim 8,
the first electrode structure of the light-emitting device is directly connected with the source electrode or the drain electrode of the corresponding driving transistor; or
The pixel driving circuit includes a plurality of switching transistors, and a first electrode structure of the light emitting device and a source electrode or a drain electrode of the corresponding driving transistor are electrically connected through at least one switching transistor.
10. A display panel comprising the display substrate according to claim 8 or 9.
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| CN103137882A (en) * | 2011-11-22 | 2013-06-05 | 海洋王照明科技股份有限公司 | Organic electroluminescent device and production method thereof |
| CN104124367A (en) * | 2013-04-24 | 2014-10-29 | 海洋王照明科技股份有限公司 | Organic light-emitting device and preparation method thereof |
| CN106848076A (en) * | 2017-01-06 | 2017-06-13 | 西安交通大学 | A kind of organo-mineral complexing perovskite LED device and preparation method thereof |
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| US20050088078A1 (en) * | 2003-01-28 | 2005-04-28 | Mei-Rurng Tseng | Organic electroluminescent device |
| CN103137882A (en) * | 2011-11-22 | 2013-06-05 | 海洋王照明科技股份有限公司 | Organic electroluminescent device and production method thereof |
| CN104124367A (en) * | 2013-04-24 | 2014-10-29 | 海洋王照明科技股份有限公司 | Organic light-emitting device and preparation method thereof |
| CN106848076A (en) * | 2017-01-06 | 2017-06-13 | 西安交通大学 | A kind of organo-mineral complexing perovskite LED device and preparation method thereof |
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