Display device

Abstract

Display device. A display device is disclosed, which includes a substrate having a first region and a second region; an anode electrode provided at the first region; an organic layer provided over the anode electrode of the first region and the second region; a cathode electrode provided on the organic layer of the first region; an optical compensation layer provided over the cathode electrode of the first region and over the organic layer of the second region, and in contact with a layer having a lower refractive index than the organic layer; and an encapsulation layer provided on the optical compensation layer. The display device is used to improve the light transmittance and efficiency of light finally transmitted through a light-emitting unit and a light-transmitting unit due to a π phase difference at an interface between the organic layer and the optical compensation layer.

Description

Technical Field

[0001] The present invention relates to a display device, and more specifically, to a display device having high transparency and high efficiency characteristics in a structure with applied electrode patterning. Background Technology

[0002] Self-emissive display devices (such as organic light-emitting displays or quantum dot light-emitting displays) for compact and clear color display without a separate light source have been considered competitive applications.

[0003] A self-emissive display device includes a plurality of pixels on a substrate, two electrodes facing each other in each pixel, and a light-emitting diode having an emissive layer therebetween.

[0004] Recently, there has been consideration of applying this self-emissive display device to transparent display devices that can simultaneously emit light and display transparently. Summary of the Invention

[0005] In a device that includes both a light-emitting unit and a light-transmitting unit, the light-emitting unit and the light-transmitting unit may have different internal optical structures and may have a common covering layer, making it difficult to improve the light transmittance and efficiency of both.

[0006] To overcome this problem, according to the present invention, an optical compensation layer can be provided above the light-transmitting unit and the light-emitting unit, thereby improving the light transmittance and efficiency.

[0007] In the display device according to the present invention, the transmittance and efficiency of light that ultimately passes through the light-emitting unit and the light-transmitting unit due to the phase difference π between the organic layer and the optical compensation layer can be improved.

[0008] In one aspect, the present invention provides a display device comprising: a substrate having a first region and a second region; an anode disposed in the first region; an organic layer disposed above the anode in the first region and the second region; a cathode disposed on the organic layer in the first region; an optical compensation layer disposed above the cathode in the first region and above the organic layer in the second region, and in contact with a layer having a refractive index lower than that of the organic layer; and an encapsulation layer disposed on the optical compensation layer. Attached Figure Description

[0009] The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings:

[0010] Figure 1 This is a cross-sectional view of a display device according to a first embodiment of the present invention;

[0011] Figure 2 This is a cross-sectional view of a display device according to a second embodiment of the present invention;

[0012] Figure 3A and Figure 3B This is a plan view of a display device according to the third and fourth embodiments of the present invention;

[0013] Figure 4 This is a cross-sectional view of the optical compensation layer according to another embodiment of the present invention;

[0014] Figure 5 It is a graph showing the efficiency and transmittance of the optical compensation layer according to the first experimental example as a function of the thickness of the optical compensation layer;

[0015] Figure 6 This is a graph showing the efficiency and transmittance of the optical compensation layer according to the second experimental example, depending on the thickness of the optical compensation layer.

[0016] Figure 7 It is a graph showing the variation of CIEy with the thickness of the optical compensation layer according to the first and second experimental examples; and

[0017] Figure 8A and Figure 8B It is a graph showing the changes in transmittance as a function of the blue EL spectrum and the thickness of the coating layer according to the third to fifth experimental examples. Detailed Implementation

[0018] Exemplary embodiments of the invention will now be described in detail with reference to the accompanying drawings. In the following description of the embodiments and drawings, the same or similar elements are denoted by the same reference numerals throughout the specification. In the following description of embodiments of the invention, detailed descriptions of incorporated known functions and configurations will be omitted where such incorporated known functions and configurations might make the subject matter of the invention rather unclear. Furthermore, the component names used in the following description of embodiments of the invention have been chosen for ease of preparation of the specification and may therefore differ from the component names of actual products.

[0019] The shapes, dimensions, proportions, angles, and quantities of elements shown in the accompanying drawings to describe embodiments of the present invention are merely exemplary, and therefore, the present invention is not limited to the details shown. In the following description of embodiments, the terms "comprising," "including," and "having" should be interpreted as indicating the presence of one or more other features, quantities, steps, operations, elements, or components or combinations thereof stated in the specification, and do not preclude the presence of other features, quantities, steps, operations, elements, components, or combinations thereof, or the possibility of adding the same content, unless the term "only" is used. It should be understood that, unless otherwise stated, singular expressions of elements include plural expressions.

[0020] In interpreting elements included in the various embodiments of the invention, unless otherwise stated, these elements should be interpreted as including a range of tolerances.

[0021] In the following description of the embodiments, it will be understood that when expressing positional relationships, such as when one element is referred to as “above,” “under,” or “next to” another element, unless the terms “just” or “directly” are used, the two elements may be in direct contact with each other, or one or more other elements may be inserted between the two elements.

[0022] In the following description of the implementation, it will be understood that when expressing temporal relationships, such as when using terms that express the order of events (such as “after,” “following,” “next,” and “before”), these terms include both sequential and discontinuous relationships between events, unless the terms “exactly” or “directly” are used.

[0023] In the following description of the embodiments, it will be understood that when the terms "first," "second," etc., are used to describe various elements, these terms are used only to distinguish the same or similar elements. Therefore, the first element described below may be referred to as the second element without departing from the technical scope of the present invention.

[0024] The various features of the various embodiments of the present invention may be partially or wholly connected or combined with each other and interlocked or driven in various technical ways, and the various embodiments may be implemented independently of each other or together through the connection between them.

[0025] The invention will be described more fully below with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown.

[0026] Figure 1 This is a cross-sectional view of a display device according to a first embodiment of the present invention. All components of each display device according to all embodiments of the present invention are operatively connected and configured.

[0027] like Figure 1 As shown, a display device according to an embodiment of the present invention may include: a substrate having a first region E and a second region T; an anode 120 disposed in the first region E; an organic layer ETL 142 disposed above the anode 120 in the first region E and in the second region T; a cathode 170 disposed on the organic layer ETL 142 in the first region E; an optical compensation layer 180 disposed above the cathode 170 in the first region E and above the organic layer ETL 142 in the second region T, and including at least one layer with a refractive index lower than that of the organic layer; and an encapsulation layer 190 disposed above the optical compensation layer 180. At least one of the anode 120 and the cathode 170 is not required to be in the second region T.

[0028] In one or more embodiments of the present invention, the optical compensation layer (OPL) 180 may be referred to as a capping layer. Furthermore, the cathode 170 does not need to be formed on the organic layer ETL 142 in the second region T. Additionally, the optical compensation layer 180 may have different thicknesses in the first region E and the second region T. For example, the thickness of the optical compensation layer 180 over the second region T may be greater than the thickness of the optical compensation layer 180 over the first region E.

[0029] For example, the first region E can be a light-emitting unit that emits light through a light-emitting layer comprising a red EML (R-EML), a green EML (G-EML), and a blue EML (B-EML), while the second region T can be a light-transmitting unit. In the second region T, to improve light transmittance, metallic materials such as the reflector 300, anode 120, or cathode 170 can be omitted, and the light-emitting layers R-EML, G-EML, and B-EML can also be omitted. Therefore, the layer structure in the first region E can differ from the layer structure in the second region T.

[0030] Depending on the circumstances, the second region T can be applied to a structure with patterned electrodes. For example, the second region T can be defined in a camera hole used to position a camera therein.

[0031] The optical compensation layer 180 can contact the cathode 170 in the first region E and can also contact the organic layer ETL 142 in the second region T. The organic layer ETL 142 can be an electron transport layer.

[0032] According to the present invention, the optical compensation layer 180 can reverse the resonant phase between the light-emitting unit and the light-transmitting unit in a structure having a patterned cathode. For example, the light-emitting unit (e.g., the first region) E can be configured to induce RGB constructive interference within the OLED, and in the light-transmitting unit (e.g., the second region) T, a low refractive index is converted to a high refractive index in the direction in which light travels from the interface between the electron transport layer (ETL) 142 and the optical compensation layer 180, thus the interface has a phase opposite to that of the lower surface of the cathode 170 on the OLED side. Due to this opposite phase, light can be emitted by inducing interface reflection as light travels in the light-emitting unit E. In embodiments of the present invention, the light referred to includes light in the visible light range, but this is not necessary, and light outside the visible light range can be used.

[0033] Therefore, the optical structure of the display device according to the present invention can be designed to improve both transmittance and efficiency by improving the difference between the light ultimately emitted through the optical compensation layer via the light-transmitting unit and the light emitted directly from the light-transmitting unit.

[0034] For RGB cavities, when applying light-emitting units to optimize for constructive interference, transmittance can be optimized by satisfying the destructive interference in the light-transmitting units caused by the phase difference π between the final organic layer and the optical compensation layer in the light-emitting device.

[0035] The organic layer ETL 142 in contact with the cathode 170 and the optical compensation layer 180 can be an electron transport layer (ETL) 142, as shown in the example.

[0036] Depending on the circumstances, the organic layer ETL142 may be the uppermost component of the organic layers included in an OLED light-emitting device. For example, when the electron injection layer is formed as an organic layer, the optical compensation layer 180 may also be in contact with the electron injection layer.

[0037] When the electron injection layer is formed of an inorganic material, it can be patterned together with the cathode 170. In particular, when the electron injection layer includes a metal in the inorganic material, it can also be considered as a component of the cathode 170.

[0038] In the display device according to the invention, the cathode 170 can be patterned to improve the transmittance of the light-transmitting unit T, and an organic pattern (not shown) can be retained in the portion corresponding to the second region T before the cathode 170 is formed on the ETL 142, and then the cathode 170 can be formed by deposition in the portion without the organic pattern.

[0039] In the display device according to the present invention, the cathode 170 according to the present invention can be formed of, for example, magnesium, silver, magnesium alloy, silver alloy, zinc, etc., and the light-emitting unit E can emit light in a top-emitting manner. Although described as being formed of metal or metal alloy, the cathode 170 can be a non-metallic material with conductivity.

[0040] Although Figure 1 The diagram shows a configuration in which the reflector 300 contacts the anode 120, but the anode 120 can also be formed as a reflective electrode.

[0041] like Figure 1 As shown, when the anode 120 is formed alone on the reflector 300, the anode 120 can be a transparent electrode, which may optionally be formed of indium tin oxide (ITO) or indium zinc oxide (IZO) to reduce the interface barrier with the hole transport layer 141.

[0042] Hole transport layer 141 can be formed below the light-emitting layers R-EML, G-EML, and B-EML, and ETL 142 can be formed above the light-emitting layers R-EML, G-EML, and B-EML. Hole transport layer 141 and ETL 142 can be formed together independently of the light-emitting unit E and the light-transmitting unit T, and the optical compensation layer 180 formed after the cathode 170 is patterned can contact ETL 142.

[0043] Because the high refractive index changes to a low refractive index at the interface between the organic layer (especially ETL142) and the optical compensation layer 180, the phase of light can be changed by π.

[0044] In the first region E, the organic layer may include a hole transport layer (HTL) 141, a light-emitting layer R-EML / G-EML / B-EML and an ETL 142, and the hole transport layer 141 and the ETL 142 may extend into the second region T.

[0045] Light emitted from the light-emitting layer E can undergo constructive interference between the anode 120 and the cathode 170, while light transmitted through the light-transmitting unit T can undergo destructive interference between the ETL and the optical compensation layer 180.

[0046] An inorganic protective layer (or passivation layer) 185 may be further disposed between the optical compensation layer 180 and the encapsulation layer 190, and the refractive index of the inorganic protective layer 185 may be lower than that of the optical compensation layer 180.

[0047] The refractive index n of ETL142 ETL The refractive index n of the optical compensation layer 180 OCL It can satisfy

[0048] The optical compensation layer 180 can have a value greater than or equal to to less than or equal to The thickness of the optical compensation layer 180 is also considered. In the display device according to the present invention, since different optical phases are generated due to the contact of the ETL142 with different surfaces, the destructive interference light in the light-transmitting unit can be transmitted without light loss, thus optimizing the light transmittance. Accordingly, high color efficiency and high light transmittance can also be achieved through the optical compensation layer 180 with a very small thickness. The detailed effects will be described below with reference to experiments.

[0049] The substrate 100 can be divided into an active region (within the dashed area) comprising multiple sub-pixels and a non-active region NA outside the active region (e.g., see...). Figure 3A Each subpixel may include a light-emitting unit E and a light-transmitting unit T, and the light-emitting unit may be defined as an opening region of the embankment 130 (see, for example, [link to relevant documentation]). Figure 3B To represent various colors, light-emitting units E that emit different colors of light can be arranged adjacent to each other.

[0050] The light-emitting layers R-EML, G-EML, and B-EML can be organic light-emitting layers or quantum light-emitting layers. In embodiments of the invention, other modes of self-emissive structures, such as micro-LED elements, can be used.

[0051] The substrate 100 can be transparent, like glass or a transparent plastic film, or opaque, like a metal substrate. When the substrate 100 includes a light-transmitting unit, it can be formed of a transparent material to achieve bottom emission; for example, it can be formed as a glass substrate or a transparent plastic film. In many cases, the substrate 100 can be formed as a transparent plastic film when the device requires permanence or flexibility in use; however, when a glass substrate is used, it can be used when the thickness of the glass substrate is very small. Other transparent materials can be used for the substrate 100.

[0052] Figure 2 The display device according to the second embodiment of the present invention is shown together with a driving thin-film transistor (TFT) connected to an OLED light-emitting device.

[0053] That is, the display device according to the second embodiment of the present invention may include: a substrate 100 having a first region E and a second region T, an anode 120 disposed in the first region, at least one organic layer (HTL and ETL) 141 and 142 disposed above the anode 120 in the second region T and the first region E, an electron injection layer 160 disposed above the ETL 142 in the second region T and the first region E, and a cathode 170 disposed above the electron injection layer 160 in the first region E. Here, the electron injection layer 160 may be patterned together with the cathode 170.

[0054] In the display device according to the second embodiment of the present invention, the first region E may be a light-emitting unit and the second region T may be a light-transmitting unit.

[0055] The first region E may be included in the light-emitting layer 150 between the anode 120 and the cathode 170, and when a differential voltage is applied between the anode 120 and the cathode 170, current can flow between the anode 120 and the cathode 170, so the light-emitting layer 150 can emit light and function.

[0056] Compared to the first region E, the second region T may not have an anode 120, a light-emitting layer 150, and a cathode 170. Therefore, regardless of the light-emitting operation of the light-emitting unit E, the image below the substrate 100 can be emitted upwards without change.

[0057] A vertical structure including an anode 120, a cathode 170, an emissive layer 150 between the anode 120 and cathode 170, a hole transport layer HTL 141, and an ETL 142 will be referred to as an OLED. A portion of HTL 141 located below the emissive layer 150 can be configured by stacking multiple layers associated with hole injection and hole transport. ETL 142 above the emissive layer 150 may include multiple layers, including a hole blocking layer to prevent holes from being emitted from the emissive layer or an electron transport layer associated with electron transport.

[0058] The substrate 100 may include multiple light-emitting units E and multiple light-transmitting units T, and the anode 120 may optionally be included in the light-emitting units E. The light-emitting units E may be composed of... Figure 2 The embankment is divided into sections 130. The light-emitting unit E can have light-emitting units that emit different colors of light, such as red, green, and blue light-emitting units. However, the color of the light-emitting unit can be replaced by a combination of magenta, cyan, and yellow, and is not limited to red, green, and blue.

[0059] Hole transport layer 141 and ETL 142 can be formed together in the light-emitting unit E and the light-transmitting unit T. This is because, during the formation of hole transport layer 141 and ETL 142, they are integrally formed in the active region of the substrate without a fine metal mask. Hole transport layer 141 and ETL 142 can be very thin and optically transparent, and can hardly affect light transmission.

[0060] The anode 120 can be configured by stacking reflective metal and one or more transparent metals.

[0061] In the light-emitting device disposed in the light-emitting unit E, the light generated by the light-emitting layer 150 can resonate repeatedly between the anode 120 and the cathode 170 and eventually pass through the cathode 170. Therefore, the cathode 170 needs to be reflective, so that the light is repeatedly reflected again on the inner surface of the cathode 170 opposite to the anode 120, and it also needs to be translucent, because the light needs to eventually pass through the cathode 170.

[0062] Although the illustrated light-emitting device has a single light-emitting layer, the invention is not limited thereto, and the light-emitting device may include multiple light-emitting layers. Depending on the circumstances, the light-emitting device may include multiple stacked layers separated from each other by charge-generating layers, and may also be applied to structures that include at least one light-emitting layer in each stack.

[0063] In the specification, the anode 120 may include a reflective electrode, the cathode 170 may be semi-transparent and reflective, and the anode 120 and cathode 170 may be used as the anode and cathode of a light-emitting device, respectively. A transparent electrode may also be disposed on the upper and / or lower surface of the reflective electrode of the anode 120.

[0064] According to the invention, the cathode 170 can be integrally formed into a plurality of light-emitting units E included in the substrate 100, and can therefore be referred to as a common electrode. Depending on the circumstances, the anode 120 can be referred to as the first electrode of the light-emitting device and the cathode 170 can be referred to as the second electrode.

[0065] The cathode 170 according to the invention may be semi-transparent and reflective so as to be used as the cathode of a light-emitting device.

[0066] In the cathode 170 according to the present invention, when the cathode 170 is removed from the light-transmitting unit T, it is necessary to maintain a predetermined potential above the light-emitting unit E of the substrate 100. Therefore, the cathode 170 can be formed of a metal having low sheet resistance and low work function of less than or equal to 4 eV.

[0067] The following text will describe the unreferenced Figure 2 The component described.

[0068] A buffer layer 101 may be disposed on a substrate 100 to prevent the influence of impurities in the substrate 100. The display device may also include a thin-film transistor (TFT), which includes: an active layer 102 disposed on a predetermined portion of the buffer layer 101; a gate 104 overlapping a portion of the active layer 102 above the active layer 102 by inserting a gate insulating layer 103 between the active layer 102 and the gate 104; and a source 108a and a drain 108b, which are respectively in contact with opposite sides of the active layer 102.

[0069] The gate 104 may include a first interlayer insulating layer 105 and a second interlayer insulating layer 106 between the layers of the source 108a and the drain 108b. Either the first interlayer insulating layer or the second interlayer insulating layer may be omitted.

[0070] The storage capacitor can be configured by placing the first storage electrode 104a on the same layer as the gate and placing the second storage electrode 109 on the upper part of the first interlayer insulating layer 105 or the upper part of the second interlayer insulating layer 106, with the second storage electrode 109 overlapping the first storage electrode 104a.

[0071] A protective layer 107 for protecting the thin-film transistor TFT, a first planarization layer 111, and a second planarization layer 113 can be formed sequentially.

[0072] The drain 108b of the thin-film transistor TFT can be directly connected to the anode 120 of the light-emitting device through contact holes formed by penetrating the protective layer and the first planarization layer 111 and the second planarization layer 113, or as shown in the figure, it can be electrically connected to the anode 120 through the connecting metal 112b on the first planarization layer 111 and the contact holes above and below it.

[0073] Although not shown in the figure, the connecting metal 112b and the electrode pattern 112a may have an active layer different from that of the thin-film transistor described above, and may be used as the source and drain on a thin-film transistor on a different layer. In this case, the active layer 102 near the substrate 100 may be formed of polysilicon, and the active layer (not shown) located on the opposite upper side may be an oxide semiconductor layer.

[0074] The first planarization layer 111 and the second planarization layer 113 can be configured to planarize the step difference of the underlying layer and can be formed of organic materials such as photoacrylic acid or BCB. However, other materials such as inorganic materials can also be used for the first planarization layer 111 and the second planarization layer 113.

[0075] The first interlayer insulating layer 105, the second interlayer insulating layer 106, the buffer layer 101, the gate insulating layer 103, and the protective layer 107 may be formed of inorganic materials, such as oxide layers, nitride layers, or oxynitride layers.

[0076] In the light-transmitting unit T, in order to improve light transmittance, the first planarization layer 111 and the second planarization layer 113 formed of organic materials, as well as the embankment 130, can be removed from the light-transmitting unit T or are not present.

[0077] The example shown can correspond to the following state: the second interlayer insulating layer 106 and protective layer 107 formed of inorganic material, together with the first planarization layer 111 and the second planarization layer 113 formed of organic material, are removed from the light-transmitting unit T. Depending on the situation, the second interlayer insulating layer 106 and protective layer 107 may be retained in the light-transmitting unit T. Alternatively, depending on the situation, a material with relatively low light transmittance (which is used to form the insulating layer formed of inorganic material) may also be selectively removed from the light-transmitting unit T.

[0078] Encapsulation layer 190 may be disposed on cover layer 180 to facilitate sealing and protection of the underlying structure.

[0079] For example, the encapsulation layer 190 can be configured by alternately providing at least one of the inorganic encapsulation layer and the organic encapsulation layer, or an inorganic protective layer 185 can be formed on the cover layer 180, and a face seal can be applied to the inorganic protective layer and can be adhered to the substrate 100 to face the opposing substrate 200.

[0080] Depending on the circumstances, the substrate 100 on which the inorganic protective layer is formed and the opposing substrate can be adhered to each other by applying an edge seal instead of a surface seal to the edges of the substrate 100 and the opposing substrate. A filter can be filled inside the sealing layer between the substrate 100 and the opposing substrate 200.

[0081] The inorganic protective layer or inorganic encapsulation layer in the encapsulation layer 190 can be formed of SiNx, SiON, etc. Other materials can be used in the encapsulation layer 190 to seal the upper surface of the display device. The thickness of the encapsulation layer 190 can be different in the first region E and the second region T, but this is not necessary. Therefore, the thickness of the encapsulation layer 190 can be the same in both regions E and T.

[0082] Color filter layer 210 may be further disposed on encapsulation layer 190 to correspond to each light-emitting unit E, such that color filters 210a, 210b, and 210c may correspond to the light-emitting layers R-EML, G-EML, and B-EML of light-emitting unit E, respectively. In various embodiments, color filter layer 210 may be in the first region E but not in the second region T, but this is not necessary.

[0083] The refractive index of the optical compensation layer 180 can be less than or equal to the refractive index of the encapsulation layer 190.

[0084] The optical compensation layer 180 may include multiple layers, and the refractive index of the uppermost and lowermost layers of the optical compensation layer 180 may be less than the refractive index of ETL142.

[0085] The refractive indices of the uppermost and lowermost layers of the optical compensation layer 180 may be less than or equal to the refractive index of the encapsulation layer 190.

[0086] The opposing substrate 200 can be positioned corresponding to the display surface and can therefore be referred to as a capping layer, cover window, or cover film. Depending on the situation, the capping layer may have an air gap corresponding to at least a portion of the encapsulation layer 190.

[0087] The following describes a display device according to other embodiments.

[0088] Figure 3A and Figure 3B This is a plan view of a display device according to the third and fourth embodiments of the present invention.

[0089] like Figure 3A As shown, the light-emitting unit E can be, but is not limited to, a square shape, or other polygonal shapes. Furthermore, the corners of the light-emitting unit E can be rounded. The light-emitting unit E and the light-transmitting unit T can be formed with the same size and / or the same proportion, or they can be formed with different sizes and / or different proportions. For example, one light-transmitting unit can be arranged for each of the red, green, and blue light-emitting units, or light-transmitting units can be arranged for each of the red, green, and blue light-emitting units in a ratio of 1:1 or 1:n (where n is a natural number greater than or equal to 2).

[0090] like Figure 3B As shown, in the display device according to the fourth embodiment, by cutting each corner of an imaginary square, the light-transmitting unit T can be shaped like an octagon with eight sides. Two of the four sides inclined relative to the X-axis can be adjacent to the first light-emitting unit E1, and the remaining two sides can be adjacent to the third light-emitting unit E3.

[0091] The second light-emitting unit E2 can be located between the first light-emitting unit E1 and the third light-emitting unit E3, so as to be adjacent to the side of the light-transmitting unit T parallel to the X-axis.

[0092] The first to third light-emitting units E1, E2, and E3, arranged around the light-transmitting unit T, can emit light of different colors. The first light-emitting unit E1 and the third light-emitting unit E3 can have a larger area than the second light-emitting unit E2, and in this respect, when weights are applied to a specific color to express the target color of the display device, the light-emitting unit corresponding to that specific color can have a larger area. The first light-emitting unit E1 and the third light-emitting unit E3 can be octagonal, and the second light-emitting unit E2 can be rectangular.

[0093] The embankment 130 can be disposed between the first to third light-emitting units E1, E2 and E3 and between the first to third light-emitting units E1, E2 and E3 and the light-transmitting unit T.

[0094] According to a fourth embodiment of the present invention, the cathode 170 may be configured not to overlap with the area of ​​the light-transmitting unit T.

[0095] In this case, the cathode 170 can have the same transmittance relative to the area corresponding to the aperture ratio of the light-transmitting unit T to the substrate 100.

[0096] Figure 4 This is a cross-sectional view of an optical compensation layer according to another embodiment of the present invention.

[0097] like Figure 4 As shown, another optical compensation structure may include multiple units 381 and 382 having low-refractive-index layers 381a, ..., 382b and high-refractive-index layers 381b, ..., 382a. In this case, it is not necessary to alternately place the low-refractive-index layers and the high-refractive-index layers. The lowermost part of the optical compensation structure may correspond to the low-refractive-index layer 381a and may be connected with... Figure 1 The cathode 170 is in contact with the topmost layer, which can also contact the encapsulation layer 190. In this case, the thickness of the low-refractive-index layer can be further increased, and to satisfy the destructive interference characteristics, the thickness of the low-refractive-index layer can be 1.8 to 2.2 times the thickness of the high-refractive-index layer.

[0098] The aforementioned light-emitting display device according to the present invention can be used to achieve high brightness and high transparency, and the internal emission efficiency of the light-emitting device can be improved by the destructive interference of the optical compensation structure 180.

[0099] The optical compensation layer 180 can have a multilayer structure, but the refractive index of the layers adjacent to it needs to be lower than that of the organic layer.

[0100] In the following text, reference will be made to Table 1 and Figures 5 to 8B To describe the significance of the display device according to the present invention.

[0101] Figure 5 The graph shows that the efficiency and transmittance of the optical compensation layer according to the first experimental example depend on the thickness of the optical compensation layer. Figure 6 The graph shows that the efficiency and transmittance of the optical compensation layer according to the second experimental example depend on the thickness of the optical compensation layer. Figure 7 This is a graph showing the variation of CIEy with the thickness of the optical compensation layer according to the first and second experimental examples.

[0102] [Table 1]

[0103]

[0104] As shown in Table 1 above, experiments were conducted separately on the structures used to optimize device efficiency in the first experimental example Exl, in the cases where constructive interference structure was applied to the capping layer and destructive interference structure was applied to the capping layer. In this respect, the constructive interference structure has the best device efficiency but reduces the light transmission characteristics, while the destructive interference structure increases the light transmission but reduces the white light efficiency of the light-emitting unit.

[0105] In comparison, such as Figure 1 As shown in the structure, when the second experimental example Ex2 is applied, constructive interference is applied to the device unit, but the phase of the light is reversed by 180 degrees. At the same time, the reflection resonance of the light is repeated at the interface between the electron transport layer and the optical compensation layer with low refractive index in the region of the light-transmitting unit in which the cathode is patterned, and at the interface between the electron transport layer and the cathode in the light-emitting unit. Therefore, the light can be transmitted with characteristics similar to destructive interference.

[0106] For example, such as Figure 5 As shown, in the first experimental example Exl, as the thickness of the optical compensation layer decreases, the efficiency tends to decrease and the size of the light-transmitting unit tends to increase. For example, the light-transmitting unit and the efficiency have opposite trends.

[0107] In contrast, from Figure 6 As can be seen from this, when applying the present invention Figure 1 In the second experimental example Ex2 shown, if the thickness of the optical compensation layer is reduced, both the light transmission unit and the efficiency may be able to be adjusted to improve them.

[0108] from Figure 7 It can be seen that, for example, for the same optical compensation layer and thickness, The overlay layer increases the CIEy value in the first experimental example Ex1 and decreases the CIEy value in the second experimental example Ex2, thereby improving the color reproduction range.

[0109] The thicknesses of the covering layer in Experiments 3 through 5 (Ex3, Ex4, and Ex5) are respectively and

[0110] Figure 8A and Figure 8B This is a graph showing the changes in transmittance as a function of the blue EL spectrum and the thickness of the coating layer, based on experimental examples three through five.

[0111] like Figure 8B As shown, when the thickness of the coating layer decreases (Ex5->Ex4->Ex3), the transmittance of short wavelengths can be improved, but the transmittance of long wavelengths may be very poor, such as... Figure 8AAs shown, the wavelength distribution can be broad and the efficiency can deteriorate. Conversely, as the thickness of the capping layer increases (Ex3->Ex4->Ex5), as... Figure 8B As shown, the transmittance of short wavelengths can be reduced, such as Figure 8A As shown, efficiency can be improved, and it is evident that it is difficult or impossible to achieve the effects of the present invention simply by increasing the thickness of the covering layer.

[0112] In the third to fifth experimental examples Ex3, Ex4 and Ex5, the cathode can be applied to both the light-emitting unit and the light-transmitting unit without patterning, and a cover layer of the same thickness can be applied.

[0113] The significance of the display device according to the present invention can be seen from the second experimental example Ex2 above.

[0114] To achieve extremely high transparency in a display device, it may be necessary to pattern the cathode. However, when applying a resonant structure (constructive interference) optimized for a patterned cathode, the transmittance may be significantly reduced due to reflection and resonance based on the refractive index difference, while the efficiency may be reduced when applying a resonant structure optimized for transmittance.

[0115] To overcome this problem, the optical structure of the display device according to the present invention can be designed such that, by proposing an optical design standard specifically for transparent display devices in which the resonant phases between the light-emitting unit and the light-transmitting unit are opposite, efficiency and transparency are changed in the same trend and maximum transmittance is increased according to the change of optical distance, regardless of the light-emitting unit and the light-transmitting unit.

[0116] It can be seen that when an optical compensation layer with a refractive index lower than that of the upper and lower encapsulation layers is designed, extremely high transparency and maximum efficiency of the transparent display can be achieved. Figure 6 ).

[0117] According to the present invention, the refractive index of the optical compensation layer can be lower than that of the lower organic layer (electron transport layer) and the inorganic protective layer thereon.

[0118] from Figure 6 It can be seen that, under the condition that the optical compensation layer has the same thickness, compared with the first experimental example Ex1, the second experimental example Ex2 corresponding to the present invention has excellent transmittance and efficiency. In this case, the optical compensation layer can have a transmittance greater than or equal to that of the first experimental example Ex1. and less than or equal to The thickness.

[0119] The optical compensation layer can be an organic or inorganic layer, and can be formed of a material having a different refractive index than the upper and lower components. When the optical compensation layer comprises multiple layers, it can have a low refractive index at the interface that contacts the uppermost and lowermost components.

[0120] When the optical compensation layer has a thickness that satisfies the above conditions and has an optimized structure for RGB constructive interference, the transmittance can be optimized by satisfying the destructive interference in the light-transmitting unit caused by the phase difference π at the interface between the organic layer and the optical compensation layer.

[0121] It can be seen that the derivative of the display device according to the present invention lies in the need to develop a transparent display through a patterned cathode to achieve extremely high transparency, and the optical compensation layer can be applied to improve both transmittance and efficiency.

[0122] The display device according to this disclosure may include: a substrate having a first region and a second region; an anode in the first region; an organic layer above the anode in the first and second regions; a cathode on the organic layer in the first region; an optical compensation layer above the cathode in the first region and the organic layer in the second region, the optical compensation layer including at least one layer with a refractive index lower than that of the organic layer; and an encapsulation layer on the optical compensation layer.

[0123] The optical compensation layer can be in contact with the cathode in the first region and with the organic layer in the second region.

[0124] The display device may also include an organic pattern on an organic layer. The second region may be a light-transmitting unit, where the organic layer may include a hole transport layer and an electron transport layer, and the organic pattern may be in contact with an optical compensation layer.

[0125] At the interface between the organic layer and the optical compensation layer, the phase of light can be altered by π.

[0126] The organic layer may include an electron transport layer, and the electron transport layer is in contact with the optical compensation layer at the light-transmitting unit.

[0127] The organic layer in the first region may include a hole transport layer, a light-emitting layer, and an electron transport layer, and the hole transport layer and the electron transport layer may extend into the second region.

[0128] Light emitted from the light-emitting layer undergoes constructive interference between the electron transport layer and the cathode, while light emitted from the light-transmitting unit undergoes destructive interference between the electron transport layer and the optical compensation layer.

[0129] The display device may also include an inorganic protective layer located between the optical compensation layer and the encapsulation layer. The refractive index of the inorganic protective layer may be lower than that of the optical compensation layer.

[0130] The refractive index n of the electron transport layer ETL and the refractive index n of the optical compensation layer OCL satisfy

[0131] The optical compensation layer can have a value greater than or equal to or less than or equal to The thickness.

[0132] The refractive index of the optical compensation layer can be less than or equal to the refractive index of the encapsulation layer.

[0133] The optical compensation layer may include multiple layers, and the refractive index of the uppermost and lowermost layers of the optical compensation layer may be lower than that of the organic layer.

[0134] The refractive indices of the top and bottom layers of the optical compensation layer are less than or equal to the refractive index of the encapsulation layer.

[0135] The optical compensation layer may include multiple layers. Among the multiple layers, the bottom layer of the optical compensation layer may be a low refractive index layer and be in contact with the cathode, the top layer of the optical compensation layer may be another low refractive index layer, the middle layer of the optical compensation layer may be a higher refractive index layer and may be interposed between the bottom layer and the top layer, and the thickness of the low refractive index layer may be approximately 1.8 to 2.2 times the thickness of the higher refractive index layer.

[0136] The display device according to the present invention can have the following effects.

[0137] First, in a structure with a patterned cathode, an optical compensation layer can be applied to the cathode to reverse the resonant phase between the light-emitting unit and the light-transmitting unit. Therefore, the optical structure can be designed to improve transmittance and efficiency based on the difference in optical distance between the light ultimately emitted from the light-transmitting unit through the optical compensation layer and the light emitted directly from the light-emitting unit, thereby increasing maximum transmittance.

[0138] Secondly, for RGB cavities, when applying light-emitting units to optimize for constructive interference, transmittance can be optimized by satisfying the destructive interference in the light-transmitting units caused by the phase difference π between the final organic layer and the optical compensation layer in the light-emitting device.

[0139] It will be apparent to those skilled in the art that various modifications and variations can be made to this invention without departing from its spirit or scope. Therefore, this invention is intended to cover modifications and variations thereof, provided they fall within the scope of the appended claims and their equivalents.

[0140] This application claims the benefit of Korean Patent Application No. 10-2020-0190036, filed on December 31, 2020, which is incorporated herein by reference as if fully set forth herein.

Claims

1. A display device, the display device comprising: A substrate having a first region and a second region; One or more planarization layers, said one or more planarization layers being located in the first region; An anode, which is located above one or more planarization layers and in the first region; An organic layer, wherein the organic layer is located in the second region and at the anode of the first region; Cathode, the cathode being located on the organic layer in the first region; An optical compensation layer is located above the cathode in the first region and the organic layer in the second region, and includes at least one layer with a refractive index lower than that of the organic layer; as well as An encapsulation layer is located on the optical compensation layer at the first and second regions. In the second region, the distance between the optical compensation layer and the substrate is less than the distance between the anode and the substrate in the first region.

2. The display device according to claim 1, wherein The optical compensation layer is in contact with the cathode in the first region and with the organic layer in the second region.

3. The display device according to claim 1, further comprising an organic pattern located on the organic layer, in: The second area is a light-transmitting unit. The organic layer at the light-transmitting unit includes a hole transport layer and an electron transport layer, and The organic pattern is in contact with the optical compensation layer.

4. The display device according to claim 1, wherein The phase of light changes by π at the interface between the organic layer and the optical compensation layer.

5. The display device according to claim 1, wherein: The second area is a light-transmitting unit. The organic layer includes an electron transport layer, and The electron transport layer is in contact with the optical compensation layer at the light-transmitting unit located in the second region, and the light-transmitting unit is transparent.

6. The display device according to claim 1, wherein: The organic layer located in the first region includes a hole transport layer, a light-emitting layer, and an electron transport layer, and The hole transport layer and the electron transport layer extend into the second region.

7. The display device of claim 6, wherein, The second region is a light-transmitting unit, from which light emitted from the light-emitting layer undergoes constructive interference between the anode and the cathode, and from which light emitted from the light-transmitting unit undergoes both constructive and destructive interference between the electron transport layer and the optical compensation layer.

8. The display device according to claim 1, further comprising: An inorganic protective layer is located between the optical compensation layer and the encapsulation layer. The refractive index of the inorganic protective layer is lower than that of the optical compensation layer.

9. The display device according to claim 1, wherein, refractive index of the electron transport layer and the refractive index of the optical compensation layer satisfies .

10. The display device according to claim 1, wherein, The thickness of the optical compensation layer is greater than or equal to 100 Å or less than or equal to 2000 Å.

11. The display device according to claim 1, wherein, The refractive index of the optical compensation layer is less than or equal to the refractive index of the encapsulation layer.

12. The display device according to claim 1, wherein: The optical compensation layer comprises multiple layers, and The refractive indices of the uppermost and lowermost layers of the optical compensation layer are lower than those of the organic layer.

13. The display device according to claim 12, wherein, The refractive indices of the uppermost and lowermost layers of the optical compensation layer are less than or equal to the refractive index of the encapsulation layer.

14. The display device according to claim 1, wherein: The first region is a light-emitting unit.

15. The display device according to claim 1, wherein: The optical compensation layer comprises multiple layers. The bottom layer of the optical compensation layer is a low-refractive-index layer and is in contact with the cathode. The top layer of the optical compensation layer is another low-refractive-index layer. The middle layer of the optical compensation layer is a higher refractive index layer, and it is interposed between the bottommost layer and the topmost layer. The thickness of the low-refractive-index layer is 1.8 to 2.2 times the thickness of the higher-refractive-index layer.

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