Top emission electroluminescent display

Abstract

The present disclosure relates to a top emission type electroluminescent display in which a portion of a gap between an anode electrode and a cathode electrode is formed to be narrow. An electroluminescent display according to the present disclosure includes a pixel on a substrate, a light emitting element in the pixel, the light emitting element including a first electrode, an emission layer on the first electrode, and a second electrode on the emission layer, and a light shielding layer under the emission layer, and there is a planarization layer between the emission layer and the light shielding layer, the light shielding layer overlapping a first portion of the emission layer. A first distance is formed between the first electrode and the second electrode at the first portion. A second distance is formed between the first electrode and the second electrode at a second portion of the emission layer different from the first portion, the first distance being smaller than the second distance.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of Korean Patent Application No. 10-2021-0188517, filed on December 27, 2021, which is incorporated herein by reference as if fully set forth herein. Technical Field

[0003] This disclosure relates to a top-emitting electroluminescent display. Background Technology

[0004] Recently, various types of displays have been developed, such as cathode ray tubes (CRTs), liquid crystal displays (LCDs), plasma display panels (PDPs), and electroluminescent displays. These types of displays are used to display image data for various products, such as computers, mobile phones, bank ATMs, and vehicle navigation systems, depending on their unique characteristics and applications.

[0005] In particular, electroluminescent displays, as self-emissive displays, possess excellent optical performance, such as viewing angle and color accuracy, leading to a gradual expansion of their application areas and attracting attention as image display devices. Due to these advantages, electroluminescent displays are considered the most suitable displays for achieving 4K ultra-high resolution displays and up to 8K ultra-high resolution displays. As resolution increases, pixel size becomes smaller, and the size of the light-emitting area within each pixel also becomes smaller. When the pixel size in an electroluminescent display becomes smaller, a top-emitting structure is preferably applied to maximize the size ratio of the light-emitting area within the pixel.

[0006] As resolution increases, pixel size decreases. To drive the light-emitting elements in smaller pixels, driving power consumption needs to be reduced. However, there are limitations in reducing driving power because it is very difficult to form a narrow distance between the anode and cathode electrodes included in the light-emitting diodes within the pixels. Even using existing manufacturing processes as is, it is necessary to develop electroluminescent displays with a new structure that can reduce driving power by achieving a narrower distance between the anode and cathode electrodes. Summary of the Invention

[0007] Regarding the solution to the above-mentioned problems, the object of this disclosure is to provide an electroluminescent display having a structure that reduces driving power consumption by forming a narrow distance (or gap) between the anode electrode and the cathode electrode. Another object of the present invention is to provide an electroluminescent display with lower overall driving power consumption, wherein after forming a light-emitting diode with a certain distance between the anode and cathode using existing manufacturing processes, heat energy is applied to partially narrow the distance between the anode and cathode. According to this disclosure, in a top-emitting electroluminescent display, a portion of the gap between the anode electrode and the cathode electrode can be narrowed by applying heat energy to a metal layer disposed below the light-emitting element.

[0008] To achieve at least one of the above-described objectives of this disclosure, the electroluminescent display according to this disclosure includes: a pixel on a substrate; a light-emitting element in the pixel, the light-emitting element including a first electrode, an emitting layer on the first electrode, and a second electrode on the emitting layer; a light-shielding layer below the emitting layer, and a planarization layer disposed between the emitting layer and the light-shielding layer, the light-shielding layer overlapping a first portion of the emitting layer. A first distance is formed between the first electrode and the second electrode in the first portion. A second distance is formed between the first electrode and the second electrode in a second portion of the emitting layer, different from the first portion, the first distance being smaller than the second distance.

[0009] In one embodiment, the electroluminescent display further includes a driving element connected to the light-emitting element and disposed below the planarization layer, the driving element overlapping the light-shielding layer, and a buffer layer disposed between the light-shielding layer and the driving element.

[0010] In one embodiment, the driving element includes a thin-film transistor having: a semiconductor layer; a gate electrode overlapping a middle portion of the semiconductor layer; a source electrode connected to one side of the semiconductor layer; and a drain electrode connected to the other side of the semiconductor layer. A light-shielding layer overlaps the semiconductor layer, and a buffer layer is disposed between the light-shielding layer and the semiconductor layer.

[0011] In one embodiment, the driving element further includes a storage capacitor that overlaps with the first electrode and is connected to the thin-film transistor.

[0012] In one implementation, the light-shielding layer overlaps with the storage capacitor.

[0013] In one embodiment, the first portion of the emitting layer that overlaps with the light-shielding layer covers 40% to 70% of the entire area of ​​the light-emitting element.

[0014] Furthermore, the electroluminescent display according to this disclosure includes: pixels on a substrate; light-emitting elements in the pixels, the light-emitting elements including a first electrode, an emitting layer on the first electrode, and a second electrode on the emitting layer; and a light-shielding layer below the emitting layer, and a planarization layer between the light-shielding layer and the emitting layer, the light-shielding layer overlapping a portion of the emitting layer. A first portion of the emitting layer that does not overlap with the light-shielding layer has a first thickness. A second portion of the emitting layer that overlaps with the light-shielding layer has a second thickness that is thinner than the first thickness.

[0015] In one embodiment, the electroluminescent display further includes a driving element connected to the light-emitting element and disposed below the planarization layer, the driving element overlapping the light-shielding layer, and a buffer layer disposed between the driving element and the light-shielding layer.

[0016] In one embodiment, the second portion of the emitting layer that overlaps with the light-shielding layer covers 40% to 70% of the entire area of ​​the light-emitting element.

[0017] Furthermore, the method for manufacturing an electroluminescent display according to this disclosure includes: forming a light-shielding layer on a substrate; depositing a buffer layer on the entire surface of the substrate to cover the light-shielding layer; forming a driving element on the buffer layer that overlaps with a portion of the light-shielding layer; depositing a planarization layer on the entire surface of the substrate to cover the driving element; forming a light-emitting element on the planarization layer that overlaps with the light-shielding layer, the light-emitting element including a first electrode, an emitting layer, and a second electrode; and applying heat energy to the light-shielding layer to narrow the gap between the first electrode and the second electrode at the portion of the emitting layer that overlaps with the light-shielding layer.

[0018] The electroluminescent display according to this disclosure has a top-emitting type, in which a driving element is disposed on a substrate, and a light-emitting element is disposed on the driving element. Specifically, since the light-emitting element is disposed overlapping the driving element, the ratio of the light-emitting area to the pixel area can be maximized. Furthermore, a metal layer, such as a light-shielding layer, data lines, scan lines (or gate lines), and storage capacitor electrodes, is stacked below the driving element. By applying heat to a portion of the metal layer, a portion of the planarization layer covering the metal layer beneath the light-emitting diode can be expanded. Therefore, a portion of the anode electrode disposed on the planarization layer can be pushed upwards by the expanded planarization layer, and the distance between the anode electrode and the cathode electrode can be narrowed. Therefore, the driving power of the light-emitting diode disposed throughout the pixel area can be reduced. Attached Figure Description

[0019] The accompanying drawings are included to provide a further understanding of this disclosure, and are incorporated in and constitute a part of this application. The drawings illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure. In the drawings:

[0020] Figure 1 This is a plan view showing a schematic structure of an electroluminescent display according to the present disclosure.

[0021] Figure 2 This is a circuit diagram illustrating the structure of a pixel according to this disclosure.

[0022] Figure 3 This is an enlarged plan view showing the structure of pixels arranged in an electroluminescent display according to the present disclosure.

[0023] Figure 4 It is along Figure 3 The cross-sectional view along tangent I-I' is used to illustrate the structure of the electroluminescent display according to the present disclosure.

[0024] Figure 5 It's enlarged. Figure 4 The cross-sectional view of the dashed box portion 'A' in the figure is used to illustrate the structure of the light-emitting diode obtained by using a heat treatment process with a laser in an electroluminescent display according to the present disclosure. Detailed Implementation

[0025] The advantages and features of this disclosure and its implementation methods will be illustrated by the following description of embodiments with reference to the accompanying drawings. However, this disclosure may be implemented in different forms and should not be construed as limited to the embodiments described herein. Rather, these embodiments are provided to make this disclosure thorough and complete, and to fully convey the scope of this disclosure to those skilled in the art. Furthermore, this disclosure is limited only by the scope of the claims.

[0026] The shapes, dimensions, scales, angles, and figures disclosed in the accompanying drawings, used to describe embodiments of this disclosure, are merely examples, and therefore, this disclosure is not limited to the details shown. Similar reference numerals always refer to similar elements. In the following description, detailed descriptions of related known functions or configurations will be omitted where it is determined that such detailed descriptions would unnecessarily obscure the focus of this disclosure.

[0027] Exemplary embodiments of the present disclosure will now be described in detail, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same or similar parts. It should be noted in this specification that similar reference numerals already used to denote similar elements in other drawings are used for elements wherever possible. In the following description, detailed descriptions of functions and configurations known to those skilled in the art that are unrelated to the basic configuration of the present disclosure will be omitted. The terms described in the specification should be understood to have the following meanings.

[0028] When using the terms "comprising," "having," and "including" as described in this specification, another part may also exist unless "only" is used. Unless otherwise stated, singular terms may include plural forms.

[0029] When describing a component, although not explicitly described, the component is interpreted as including a tolerance range.

[0030] When describing positional relationships, for example, when the positional order is described as "on," "above," "below," and "near," it may include cases where there is no contact between them, unless "exactly" or "directly" is used. If it is said that the first element is "on" the second element, it does not mean that the first element is substantially above the second element in the drawing. The upper and lower parts of an object can vary depending on the object's orientation. Therefore, in the drawing or in actual configuration, the case of the first element being "on" the second element includes both the case of the first element being "below" the second element and the case of the first element being "above" the second element.

[0031] For example, when describing temporal relationships, discontinuous cases can be included when the time sequence is described as "after", "following", "next", and "before", unless "exactly" or "directly" is used.

[0032] It will be understood that although the terms “first,” “second,” etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of this disclosure, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

[0033] In describing the elements of this disclosure, terms such as first, second, A, B, (a), and (b) may be used. These terms are merely for distinguishing elements from one another, and the terms do not limit the nature, order, sequence, or number of elements. When an element is described as “linked,” “coupled,” or “connected” to another element, that element may be directly or indirectly connected to the other element, unless otherwise stated. It should be understood that other elements may be “inserted” between each element that can be connected or coupled.

[0034] It should be understood that the term "at least one" includes all combinations relating to any one of the articles. For example, "at least one of the first element, the second element, and the third element" can include all combinations of two or more elements selected from the first, second, and third elements, as well as each of the first, second, and third elements.

[0035] Those skilled in the art will fully understand that the features of the various embodiments of this disclosure can be coupled or combined with each other in part or in whole, and can interoperate with each other and be technically driven in various ways. Embodiments of this disclosure can be implemented independently of each other or can be implemented together in an interdependent relationship.

[0036] In the following, examples of display devices according to this disclosure will be described in detail with reference to the accompanying drawings. When assigning reference numerals to elements in each drawing, identical components may be given the same reference numerals as much as possible, even if they are shown in different drawings. For ease of description, the scale of the elements shown in the drawings differs from the actual scale and is not limited to the scale shown in the drawings.

[0037] In the following sections, we will describe the contents of this disclosure in detail with reference to the accompanying drawings. Figure 1 This is a diagram illustrating a schematic structure of an electroluminescent display according to the present disclosure. Figure 1 In this diagram, the X-axis can be parallel to the direction of the scan line, the Y-axis can be parallel to the direction of the data line, and the Z-axis can represent the thickness direction of the display.

[0038] Reference Figure 1 The electroluminescent display includes a substrate SUB, a gate (or scan) driver 200, a data pad portion 300, a source driver IC (integrated circuit) 410, a flexible film 430, a circuit board 450, and a timing controller 500.

[0039] The substrate SUB may include electrically insulating or flexible materials. The substrate SUB may be made of glass, metal, or plastic, but is not limited to these. When the electroluminescent display is a flexible display, the substrate SUB may be made of a flexible material such as plastic. For example, the substrate SUB may include a transparent polyimide material.

[0040] The substrate SUB may include a display area AA and a non-display area NDA. The display area AA, which serves as the area for presenting video images, may be defined as most of the central area of ​​the substrate SUB, but is not limited thereto. Within the display area AA, multiple scan lines (or gate lines), multiple data lines, and multiple pixels may be formed or disposed. Each pixel may include multiple sub-pixels. Each sub-pixel includes both scan lines and data lines.

[0041] The non-display area NDA, which is a region that does not display video images, can be defined at the periphery of the substrate SUB, surrounding all or part of the display area AA. A gate driver 200 and a data pad portion 300 can be formed or disposed in the non-display area NDA.

[0042] The gate driver 200 can provide a scan (or gate) signal to the scan line according to the gate control signal received from the timing controller 500. The gate driver 200 can be formed on either side of the display area AA on the substrate SUB in the non-display area NDA in a GIP (in-panel gate driver) type. GIP type means that the gate driver 200 is formed directly on the substrate SUB.

[0043] The data pad section 300 can provide data signals to the data lines according to the data control signals received from the timing controller 500. The data pad section 300 can be made into a driver chip and mounted on the flexible film 430. In addition, the flexible film 430 can be attached to the non-display area NDA on either side of the display area AA on the substrate SUB in a TAB (tape-on-board) type.

[0044] The source driver IC 410 can receive digital video data and source control signals from the timing controller 500. The source driver IC 410 can convert the digital video data into analog data voltages based on the source control signals and then provide them to the data lines. When the source driver IC 410 is manufactured as a chip, it can be mounted on the flexible film 430 in either a COF (chip-on-film) or COP (chip-on-plastic) type.

[0045] The flexible film 430 may include multiple first connections connecting the data pad portion 300 to the source driver IC 410, and multiple second connections connecting the data pad portion 300 to the circuit board 450. An anisotropic conductive film can be used to attach the flexible film 430 to the data pad portion 300, allowing the data pad portion 300 to be connected to the first connections of the flexible film 430.

[0046] The circuit board 450 can be attached to the flexible film 430. The circuit board 450 may include multiple circuits implemented as driver chips. For example, the circuit board 450 may be a printed circuit board or a flexible printed circuit board.

[0047] The timing controller 500 can receive digital video data and timing signals from an external system board via cables from the circuit board 450. Based on the timing signals, the timing controller 500 can generate gate control signals for controlling the operating timing of the gate driver 200, and source control signals for controlling the source driver IC 410. The timing controller 500 can provide gate control signals to the gate driver 200 and source control signals to the source driver IC 410. Depending on the product type, the timing controller 500 and the source driver IC 410 can be integrated into a single chip and mounted on a substrate SUB.

[0048] Figure 1 This is a plan view showing a schematic structure of an electroluminescent display according to the present disclosure. Figure 2 This is a circuit diagram of the structure of a pixel according to the present disclosure. Figure 3 This is an enlarged plan view showing the structure of pixels arranged in an electroluminescent display according to the present disclosure. Figure 4 It is along Figure 3 The cross-sectional view along tangent I-I' is used to illustrate the structure of the electroluminescent display according to the present disclosure.

[0049] Reference Figures 2 to 4 A pixel of a light-emitting display may include a scan line SL, a data line DL, and a drive current line VDD. A pixel of a light-emitting display may also include a switching thin-film transistor ST, a driving thin-film transistor DT, a light-emitting diode OLE, and a storage capacitor Cst. The drive current line VDD may be supplied with a high-level voltage to drive the light-emitting diode OLE.

[0050] For example, a switching thin-film transistor ST can be located at the intersection of the scan line SL and the data line DL. The switching thin-film transistor ST may include a switching gate electrode SG, a switching semiconductor layer SA, a switching source electrode SS, and a switching drain electrode SD. The switching gate electrode SG may branch off from the scan line SL, or it may be defined as part of the scan line SL, such as... Figure 3 As shown, the switching source electrode SS can be connected to the data line DL, and the switching drain electrode SD can be connected to the driving thin-film transistor DT. The switching semiconductor layer SA overlaps with the switching gate electrode SG. One end of the switching semiconductor layer SA is connected to the switching source electrode SS, and the other end of the switching semiconductor layer SA is connected to the switching drain electrode SD. By providing a data signal to the driving thin-film transistor DT, the switching thin-film transistor ST can select the pixel to be driven.

[0051] The driving thin-film transistor (DT) drives the light-emitting diode (OLE) of the pixel selected by the switching thin-film transistor (ST). The driving DT includes a driving gate electrode (DG), a driving semiconductor layer (DA), a driving source electrode (DS), and a driving drain electrode (DD). The driving gate electrode (DG) is connected to the switching drain electrode (SD) of the switching DT. The driving source electrode (DS) is connected to the driving current line (VSS), and the driving drain electrode (DD) is connected to the anode electrode (ANO) of the OLE. The driving semiconductor layer (DA) overlaps with the driving gate electrode (DG). One end of the driving semiconductor layer (DA) is connected to the driving source electrode (DS), and the other end is connected to the driving drain electrode (DD). The storage capacitor (Cst) is disposed between the driving drain electrode (DD) of the driving DT and the anode electrode (ANO) of the OLE.

[0052] The driving thin-film transistor DT can be positioned between the driving current line VDD and the light-emitting diode OLE. The driving thin-film transistor DT can control the amount of current flowing from the driving current line VDD to the light-emitting diode OLE based on the voltage level of the driving gate electrode DG, which is connected to the switching drain electrode SD of the switching thin-film transistor ST.

[0053] Figure 4 Thin-film transistors ST and DT with top-gate structures are shown. A top-gate structure refers to gate electrodes SG and DG being disposed on semiconductor layers SA and DA, respectively. Specifically, the top-gate structure may have semiconductor layers SA and DA first formed on a substrate SUB, and gate electrodes SG and DG formed on a gate insulating layer GI covering the semiconductor layers SA and DA. In another example, the electroluminescent display according to this disclosure may have a bottom-gate structure. The bottom-gate structure may have gate electrodes SG and DG first formed on a substrate SUB, and semiconductor layers SA and DA on a gate insulating layer GI covering the gate electrodes SG and DG. Preferably, in achieving ultra-high resolution density, the electroluminescent display according to this disclosure may include thin-film transistors with top-gate structures to increase the aperture ratio, which is the ratio of the emission area to the pixel area.

[0054] In addition, according to Figure 4 The top gate structure shown has the switching source electrode SS, switching drain electrode SD, driving source electrode DS, and driving drain electrode DD formed on the same layer as the gate electrodes SG and DG. In other words, the source electrodes SS and DS, and the drain electrodes SD and DD, can be formed on the same layer as the layers forming the scan line SL and the gate electrodes SG and DG, but the data line DL and the driving current line VDD can be formed on different layers than the scan line SL. An intermediate insulating layer ILD can be stacked on top of the gate electrodes SG and DG, the source electrodes SS and DS, and the drain electrodes SD and DD. The data line DL and the driving current line VDD can be disposed on the intermediate insulating layer ILD.

[0055] An electroluminescent diode (OLE) may include an anode electrode (ANO), an emitter layer (EL), and a cathode electrode (CAT). The OLE emits light according to the amount of current controlled by a driving thin-film transistor (DT). In other words, the OLE can be driven by the voltage difference between a low-level voltage and a high-level voltage controlled by the DT, thereby controlling the brightness of the electroluminescent display. The anode electrode (ANO) of the OLE can be connected to the driving drain electrode (DD) of the DT, and the cathode electrode (CAT) can be connected to a low-level power supply line (VSS) supplying a low-level voltage. The OLE can be driven by the voltage difference between a high-level voltage and a low-level voltage controlled by the DT.

[0056] A passivation layer PAS can be deposited on a substrate SUB having thin-film transistors ST and DT. Preferably, the passivation layer PAS can be made of an organic material such as silicon oxide (SiOx) or silicon nitride (SiNx). A planarization layer PL can be deposited on the passivation layer PAS. The planarization layer PL can be a film layer used to planarize the non-uniform surface of the substrate SUB on which the thin-film transistors ST and DT are formed. To make the height difference uniform, the planarization layer PL can be made of an organic material. The passivation layer PAS and the planarization layer PL can have pixel contact holes PH that expose a portion of the drive drain DD of the driving thin-film transistor DT.

[0057] The anode electrode ANO can be formed on the upper surface of the planarization layer PL covering the thin-film transistors ST and DT. The anode electrode ANO can be connected to the driving drain DD of the driving thin-film transistor DT through the pixel contact hole PH. Depending on the emission structure of the light-emitting diode (OLE), the anode electrode ANO can have different structures. For a bottom-emitting type example where light generated from the emission layer is emitted in the direction set by the substrate SUB, the anode electrode ANO can include a transparent conductive material. For another example of a top-emitting type where light generated from the emission layer is emitted in the opposite direction to the substrate SUB, the anode electrode ANO can be made of a metallic material with excellent light reflectivity. For example, the anode electrode can include any one of the following metallic materials: silver (Ag), aluminum (Al), molybdenum (Mo), gold (Au), magnesium (Mg), calcium (Ca), and barium (Ba), or alloys thereof. Additionally, the anode electrode ANO of a top-emitting type can include a metallic layer with excellent light reflectivity and a transparent conductive material layer on the metallic layer.

[0058] In this disclosure, a top-emitting type suitable for achieving ultra-high resolution is preferred. In the top-emitting type, it is preferable that the anode electrode ANO has the largest area in the pixel region defined by the data line DL, the drive current line VDD, and the scan line SL. In this case, the thin-film transistors ST and DT can be arranged to overlap with the anode electrode ANO below it. Additionally, the data line DL, the drive current line VDD, and the scan line SL can also partially overlap with the anode electrode ANO.

[0059] A dam BA is formed on the anode electrode ANO. The dam BA can cover the peripheral area of ​​the anode electrode ANO and expose most of the central portion of the anode electrode ANO. The area of ​​the anode electrode ANO exposed through the dam BA can be defined as the light-emitting area of ​​the pixel.

[0060] In the top-emitting type, the thin-film transistors ST and DT can be configured as overlapping light-emitting regions. Additionally, portions of the data line DL, drive current line VDD, and scan line SL can also be configured as overlapping light-emitting regions.

[0061] An emitting layer EL is deposited on the anode electrode ANO and the dam BA. The emitting layer EL can be deposited over the entire display area AA to cover the anode electrode ANO and the dam BA. In one embodiment, the emitting layer EL may comprise two or more vertically stacked emitting layers for combining different colored lights and emitting white light. For example, the emitting layer EL may comprise a first emitting layer and a second emitting layer for combining a first color light and a second color light to emit white light.

[0062] In another embodiment, the emitting layer EL may include any one of a blue emitting layer, a green emitting layer, and a red emitting layer to provide colored light distributed at the pixel. In this case, the emitting layer EL may be configured to be isolated within each light-emitting region defined by the dam BA. Additionally, the light-emitting diode OLE may also include a functional layer for improving the luminous efficiency and / or emission time of the emitting layer EL.

[0063] The cathode electrode CAT is deposited on the emitter layer EL in contact with the surface of the emitter layer EL. The cathode electrode CAT is deposited to cover the entire surface of the substrate SUB in a manner that connects to the emitter layer EL disposed at all pixels. For top-emitting types, preferably, the cathode electrode CAT can be made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO).

[0064] Although not shown in the figure, after completing the light-emitting diode (OLE) by depositing the cathode electrode CAT, an encapsulation layer can be formed on the cathode electrode CAT. The encapsulation layer can have a structure in which inorganic layers, organic layers, and inorganic layers are stacked sequentially. Additionally, a color filter can be formed on the encapsulation layer. The color filter can be formed to have the same size as or slightly larger than the anode electrode ANO, and completely overlap with the anode electrode ANO.

[0065] The electroluminescent display according to this disclosure may further include a light-shielding layer LS. The light-shielding layer LS may be disposed below the semiconductor layers SA and DA to prevent light from penetrating the semiconductor layers SA and DA and altering the channel characteristics of the semiconductor channel region. For example, the light-shielding layer LS may be formed first on the substrate SUB. For example, after forming the light-shielding layer LS at the location where the semiconductor layers SA and DA are to be disposed on the substrate SUB, a buffer layer BUF may be deposited over the entire surface of the substrate SUB.

[0066] In addition to preventing external light from entering the semiconductor layers SA and DA, the light-shielding layer LS can be used as a repair element to connect defective pixels to adjacent normal pixels to restore the defective pixels to normal. Additionally, the light-shielding layer LS can be used as a data line DL or a drive current line VDD. In another example, the light-shielding layer LS can be used as a second gate electrode for implementing a thin-film transistor with a dual-gate structure.

[0067] In completing Figure 4 Following the electroluminescent display structure shown, a laser can be irradiated from below the substrate SUB to apply thermal energy to the metal layer, such as the light-shielding layer LS and the storage capacitor Cst. Therefore, the planarization layer PL, comprising organic material stacked on the metal layer, can expand upwards due to the thermal energy applied to the electrodes of the light-shielding layer LS and the storage capacitor Cst.

[0068] Therefore, as Figure 5 As shown, a portion of the anode electrode ANO can expand upward toward the cathode electrode CAT. Figure 5 It's enlarged. Figure 4 The cross-sectional view of the dashed box portion 'A' in the figure illustrates the structure of a light-emitting diode obtained by a heat treatment process using a laser in an electroluminescent display according to the present disclosure. In other words, before laser irradiation, the gap between the anode electrode ANO and the cathode electrode CAT can have a first height H1, but after laser irradiation, the gap between the anode electrode ANO and the cathode electrode CAT can have a second height H2 that is smaller than the first height H1.

[0069] Power consumption can be determined based on the distance (or gap) between the anode electrode (ANO) and the cathode electrode (CAT) in a light-emitting diode (OLE), i.e., the thickness of the emitter layer (EL). For example, as the thickness of the emitter layer (EL) increases, the potential difference between the anode electrode (ANO) and the cathode electrode (CAT) can increase, and this potential difference is applied to generate light from the emitter layer (EL). In other words, there can be a direct proportional relationship between the thickness of the emitter layer (EL) and the driving power. Therefore, reducing the thickness of the emitter layer (EL) can be a major factor in reducing power consumption.

[0070] However, the process of manufacturing an electroluminescent display involves setting a predetermined thickness and stacking thin films of suitable thickness, taking into account the materials used, manufacturing conditions, and functional characteristics of each layer being formed. Therefore, arbitrarily changing the thickness of a single layer is not easy to determine, as it affects the entire process. For example, under mass production conditions, the emitting layer (EL) of a light-emitting diode (OLE) can be formed by considering all conditions such as luminous efficiency, luminescent materials, and driving methods. In this case, it is difficult to easily change the manufacturing process because it is hard to predict how arbitrarily reducing the thickness of the EL will affect the overall quality of the display device.

[0071] In this disclosure, after manufacturing an electroluminescent display using existing manufacturing processes determined by considering various process conditions and performance characteristics, a localized heat treatment process using lasers (as a post-processing) is used to manufacture light-emitting diodes (OLEs) where the distance between the anode electrode (ANO) and the cathode electrode (CAT) can be formed narrower in some areas. Therefore, the driving voltage used to drive the OLEs throughout the pixel area can be set to be significantly lower than the driving voltage of conventional techniques.

[0072] exist Figure 3 In the diagram, the portion X, represented by the dashed line, is occupied by the light-shielding layer LS and the storage capacitor Cst. Even if not shown in the figure, the light-shielding layer LS can be formed with a large area below the storage capacitor Cst to completely overlap with it. In any case, the ratio of the area occupied by the light-shielding layer LS, or the area occupied by the light-shielding layer LS and the storage capacitor Cst, to the area of ​​the pixel region in the planar view can be at least 40% to 70%. When laser heat treatment is applied, the gap between the anode electrode ANO and the cathode electrode CAT can be formed narrower in 40% to 70% of the pixel region. Therefore, an effect of reducing driving power consumption by 40% to 70% can be achieved.

[0073] When the light-shielding layer LS is used as a repair line and applied with a laser in the 266nm band used in the repair process, the heat treatment process can be performed together during the repair process without the need for a separate heat treatment process. In this case, it is also possible to obtain the advantage of preventing an increase in manufacturing cycle time.

[0074] The repair process involves disconnecting the connection or melting two overlapping electrodes (or wires) with an insulating layer between them to connect them. On the other hand, heat treatment to narrow the distance between the anode electrode (ANO) and the cathode electrode (CAT) may not require the high energy required to cut or melt the components. Therefore, when using a repair process for heat treatment, it is preferable to reduce the laser irradiation time compared to a repair process to avoid damaging the LED.

[0075] Meanwhile, when using a different laser than the one used in the repair process for heat treatment, it is preferable to adjust the intensity of the laser used to avoid damaging other components in the pixel area, or to adjust the laser irradiation time.

[0076] The features, structures, effects, etc., described in the examples above of this disclosure are included in at least one example of this disclosure, but are not limited to one example. Furthermore, the features, structures, effects, etc., described in at least one example can be implemented by those skilled in the art with respect to other examples in combination or modification. Therefore, content relating to these combinations and variations should be construed as being included within the scope of this disclosure.

[0077] It will be apparent to those skilled in the art that various modifications and variations can be made to this disclosure without departing from its concept or scope. Therefore, this disclosure is intended to cover modifications and variations thereof, provided that such modifications and variations fall within the scope of the appended claims and their equivalents. These and other changes to the embodiments can be made based on the detailed description above. Generally, the terminology used in the appended claims should not be construed as limiting the claims to the specific embodiments disclosed in the specification and claims, but should be construed as including all possible embodiments and the full scope of the equivalents enjoyed by these claims. Therefore, the claims are not limited by this disclosure.

Claims

1. An electroluminescent display, comprising: Pixels on the substrate; The light-emitting element in the pixel includes a first electrode, an emitting layer on the first electrode, and a second electrode on the emitting layer; as well as A light-shielding layer is provided below the emitting layer, and a planarization layer is disposed between the light-shielding layer and the emitting layer. The light-shielding layer overlaps with a first portion of the emitting layer. In this first portion, a first distance is formed between the first electrode and the second electrode. Wherein, in the second portion of the emitter layer, which is different from the first portion, a second distance is formed between the first electrode and the second electrode, and The first distance is made smaller than the second distance by applying heat to the light-shielding layer to cause the first electrode above the light-shielding layer in the region corresponding to the first portion of the emitting layer to expand toward the second electrode.

2. The electroluminescent display according to claim 1, further comprising: A driving element is connected to the light-emitting element and disposed below the planarization layer. The driving element overlaps with the light-shielding layer, and a buffer layer is disposed between the driving element and the light-shielding layer.

3. The electroluminescent display according to claim 2, wherein, The driving element includes a thin-film transistor, the thin-film transistor having: Semiconductor layer; A gate electrode that overlaps with the middle portion of the semiconductor layer; A source electrode, wherein the source electrode is connected to one side of the semiconductor layer; as well as A drain electrode, which is connected to the other side of the semiconductor layer. The light-shielding layer overlaps with the semiconductor layer, and a buffer layer is disposed between the light-shielding layer and the semiconductor layer.

4. The electroluminescent display according to claim 3, wherein, The driving element further includes: A storage capacitor, which overlaps with the first electrode and is connected to the thin-film transistor.

5. The electroluminescent display according to claim 4, wherein, The light-shielding layer overlaps with the storage capacitor.

6. The electroluminescent display according to claim 1, wherein, The first portion of the emitting layer, which overlaps with the light-shielding layer, covers 40% to 70% of the entire area of ​​the light-emitting element.

7. An electroluminescent display, comprising: Pixels on the substrate; The light-emitting element in the pixel includes a first electrode, an emitting layer on the first electrode, and a second electrode on the emitting layer; as well as A light-shielding layer is provided below the emitting layer, and a planarization layer is provided between the light-shielding layer and the emitting layer. The light-shielding layer partially overlaps with the emitting layer. The first portion of the emitting layer that does not overlap with the light-shielding layer has a first thickness. Wherein, the second portion of the emitting layer that overlaps with the light-shielding layer has a second thickness, and The second thickness is made thinner than the first thickness by applying heat to the light-shielding layer to cause the first electrode above the light-shielding layer in the region corresponding to the second portion of the emitting layer to expand toward the second electrode.

8. The electroluminescent display according to claim 7, further comprising: A driving element is connected to the light-emitting element and disposed below the planarization layer. The driving element overlaps with the light-shielding layer, and a buffer layer is disposed between the driving element and the light-shielding layer.

9. The electroluminescent display according to claim 7, wherein, The second portion of the emitting layer, which overlaps with the light-shielding layer, covers 40% to 70% of the entire area of ​​the light-emitting element.

10. A method for manufacturing an electroluminescent display, comprising: A light-shielding layer is formed on the substrate; A buffer layer is deposited on the entire surface of the substrate to cover the light-shielding layer; A driving element is formed on the buffer layer that overlaps with a portion of the light-shielding layer; A planarization layer is deposited on the entire surface of the substrate to cover the drive element; A light-emitting element is formed on the planarization layer that overlaps with the light-shielding layer. The light-emitting element includes a first electrode, an emitting layer, and a second electrode. as well as Heat is applied to the light-shielding layer so that in the region corresponding to the portion of the emitting layer that overlaps with the light-shielding layer, the first electrode above the light-shielding layer expands toward the second electrode and the gap between the first electrode and the second electrode decreases.

11. An electroluminescent display, comprising: A plurality of pixels on a substrate, each of the plurality of pixels including a light-emitting element, wherein the light-emitting element includes a first electrode, an emitting layer on the first electrode, and a second electrode on the emitting layer; as well as A light-shielding layer beneath the light-emitting element of each pixel. The light-shielding layer is subjected to heat, causing a portion of the first electrode above the light-shielding layer to expand toward the second electrode, and the thickness of a portion of the emission layer between the expanded portion of the first electrode and the second electrode decreases.

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