Display device

Abstract

To provide a display device.SOLUTION: A display device with high light efficiency comprises: a circuit layer disposed on a substrate; a pixel electrode disposed on the circuit layer; an intermediate layer, disposed above the pixel electrode, which includes a first light-emitting layer, a second light-emitting layer, a third light-emitting layer, and a fourth light-emitting layer; a counter electrode disposed on the intermediate layer; a color filter layer, disposed above the counter electrode, which includes a first color filter, a second color filter, and a third color filter; and an optical auxiliary layer disposed between the pixel electrode and the intermediate layer. The thickness of each of the layers included in the intermediate layer and the thickness of each of optical auxiliary bodies included in the optical auxiliary layer are optimized to each other.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a display device, and more particularly to a display device having high light efficiency. [Background technology]

[0002] A display device is a device that receives information related to an image and displays the image. Display devices are used as display units of small products such as mobile phones and large products such as televisions.

[0003] A display device includes a plurality of pixels that emit light upon receiving an electrical signal to display an image externally. Each pixel includes a light emitting element, and in the case of an organic light emitting display device, for example, an organic light emitting diode (OLED) is used as the light emitting element. In general, an organic light emitting display device includes a thin film transistor and an organic light emitting diode formed on a substrate, and the organic light emitting diode emits light by itself.

[0004] Meanwhile, much research is being conducted to improve the light efficiency of such display devices. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 10692941 (US10692941B) [Patent Document 2] Korean Patent No. 10-2145759 (KR2145759B) [Patent Document 3] Korean Patent Publication No. 10-2021-0084047 (KR2021-0084047A) [Patent Document 4] Korean Patent No. 10-2387794 (KR2387794B) Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention is intended to provide a display device having high light efficiency by solving a number of problems, including those mentioned above, but the problems are merely examples and are not intended to limit the scope of the present invention. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, a display device according to one embodiment of the present invention includes: (1) a circuit layer disposed on a substrate and including at least one thin film transistor; (3) a pixel electrode disposed on the circuit layer; (4) an intermediate layer disposed on the pixel electrode, the intermediate layer including a first light-emitting layer that emits light in a first wavelength band, a second light-emitting layer that emits light in a second wavelength band, a third light-emitting layer that emits light in a third wavelength band, and a fourth light-emitting layer that emits light in the first wavelength band, the first light-emitting layer to the fourth light-emitting layer overlapping each other in a planar view; (5) a counter electrode disposed on the intermediate layer; and (6) a color filter layer disposed on the counter electrode, the color filter layer including a first light-emitting layer that emits light in the second wavelength band, the second light-emitting layer that emits light in the third wavelength band, and a fourth light-emitting layer that emits light in the first wavelength band, the first light-emitting layer to the fourth light-emitting layer overlapping each other in a planar view. and (7) an optical auxiliary layer disposed between the pixel electrode and the intermediate layer, the optical auxiliary layer including a first color filter that transmits light in the third wavelength band, a second color filter arranged alongside the first color filter and that transmits light in the third wavelength band, and a third color filter arranged alongside the second color filter and that transmits light in the first wavelength band; and (8) an optical auxiliary layer disposed between the pixel electrode and the intermediate layer, the first optical auxiliary body having a first thickness, and a second optical auxiliary body arranged alongside the first optical auxiliary body and that has a second thickness that is thicker than the first thickness, the first optical auxiliary body and the first color filter overlapping in a planar view, and the second optical auxiliary body and the third color filter overlapping in a planar view.

[0008] In an embodiment, the intermediate layer may further include a first hole transport layer disposed between the pixel electrode and the first light emitting layer.

[0009] In one embodiment, the sum of the optical thickness of the first hole transport layer in the first wavelength band and the optical thickness of the second optical auxiliary body in the first wavelength band may be equal to the sum of the optical thickness of the first hole transport layer in the second wavelength band and the optical thickness of the first optical auxiliary body in the second wavelength band.

[0010] In one embodiment, the optical thickness of the first hole transport layer in the first wavelength band may be complementary to the optical thickness of the second optical auxiliary body in the first wavelength band, i.e., an increase in one may correspond to a corresponding decrease in the other.

[0011] In one embodiment, a portion of the first hole transport layer in the first wavelength band may be replaced by a portion of the second optical auxiliary body in the first wavelength band.

[0012] In one embodiment, an optical thickness of a portion of the first hole transport layer in the first wavelength band may match an optical thickness of a portion of the second optical auxiliary body in the first wavelength band.

[0013] In one embodiment, the pixel electrode includes a reflective layer disposed on the substrate and a first transparent conductive layer disposed on the reflective layer, and the optical auxiliary layer may be disposed between the first transparent conductive layer and the intermediate layer.

[0014] In an embodiment, the pixel electrode further includes a second transparent conductive layer disposed under the reflective layer, and an upper surface of the second transparent conductive layer may be in contact with a lower surface of the reflective layer.

[0015] In one embodiment, the difference between the second thickness and the first thickness may be greater than the thickness of the first light emitting layer.

[0016] In one embodiment, the thickness of the first light emitting layer may be equal to the thickness of the fourth light emitting layer.

[0017] In one embodiment, the first wavelength band may be a blue visible light region, the second wavelength band may be a red visible light region, and the third wavelength band may be a green visible light region.

[0018] In one embodiment, a first connection layer may be disposed between the first light emitting layer and the second light emitting layer, and a second connection layer may be disposed between the third light emitting layer and the fourth light emitting layer.

[0019] In an embodiment, the first connection layer and the second connection layer may have a thickness greater than a thickness of the first light emitting layer.

[0020] In one embodiment, the first connecting layer may include a first electron transport layer disposed on the first light emitting layer, a first charge generation layer disposed on the first electron transport layer, and a second hole transport layer disposed on the first charge generation layer.

[0021] In one embodiment, the second connecting layer may include a second electron transport layer disposed on the third light emitting layer, a second charge transport layer disposed on the second electron transport layer, and a third hole transport layer disposed on the second charge generation layer.

[0022] In an embodiment, the top surface of the second light emitting layer and the bottom surface of the third light emitting layer may be in contact with each other.

[0023] In one embodiment, a capping layer may further be disposed between the counter electrode and the color filter layer.

[0024] In one embodiment, the difference between the second thickness and the first thickness may be 120 Å or more and 180 Å or less.

[0025] In one embodiment, the optical auxiliary layer may further comprise a third optical auxiliary body having a third thickness and arranged alongside the first optical auxiliary body and the second optical auxiliary body.

[0026] In one embodiment, the third thickness may be less than the first thickness and the second thickness.

[0027] In one embodiment, the difference between the third thickness and the second thickness may be 900 Å or more and 1020 Å or less.

[0028] In one embodiment, the difference between the second thickness and the third thickness may be six times the difference between the first thickness and the second thickness.

[0029] In one embodiment, the third optical auxiliary body may overlap the second color filter in a plan view.

[0030] In one embodiment, the thickness of the intermediate layer may be 2200 Å or more and 2800 Å or less. Effect of the Invention

[0031] According to the embodiment of the present invention as described above, a display device having high light efficiency can be realized, although the scope of the present invention is not limited to such an effect. [Brief description of the drawings]

[0032] [Figure 1] 1 is a plan view illustrating a display panel of a display device according to an embodiment of the present invention; [Diagram 2] 2 is an equivalent circuit diagram of one pixel included in the display panel of FIG. 1. [Diagram 3] FIG. 2 is a cross-sectional view illustrating a schematic view of a portion of the display panel of FIG. [Figure 4] FIG. 4 is a conceptual diagram illustrating a cross section of the intermediate layer of FIG. 3. [Diagram 5] 5 is a graph showing the refractive index of the optical auxiliary layer of FIG. 3 and the first hole transport layer of FIG. 4. [Figure 6] 4 is a cross-sectional view illustrating an example of a stacked structure of a pixel electrode, an optical auxiliary layer, an intermediate layer, a capping layer, and a color filter layer in FIG. 3; FIG. [Figure 7]7 is a table summarizing the optical efficiency for each wavelength band in the example shown in FIG. 6. [Figure 8] 7 is a table summarizing the optical efficiency for each wavelength band in the example shown in FIG. 6. [Figure 9] 7 is a table summarizing the optical efficiency for each wavelength band in the example shown in FIG. 6. [Figure 10] 4 is a cross-sectional view illustrating an example of a stacked structure of a pixel electrode, an optical auxiliary layer, an intermediate layer, a capping layer, and a color filter layer in FIG. 3; FIG. [Figure 11] 4 is a cross-sectional view illustrating an example of a stacked structure of a pixel electrode, an optical auxiliary layer, an intermediate layer, a capping layer, and a color filter layer in FIG. 3; FIG. [Figure 12] 4 is a cross-sectional view illustrating an example of a stacked structure of a pixel electrode, an optical auxiliary layer, an intermediate layer, a capping layer, and a color filter layer in FIG. 3; FIG. [Figure 13] 4 is a cross-sectional view illustrating an example of a cross section corresponding to a stacked structure of a pixel electrode, an optical auxiliary layer, an intermediate layer, a capping layer, and a color filter layer in FIG. 3 in a display device according to a comparative example. [Figure 14] 4 is a cross-sectional view illustrating an example of a cross section corresponding to a stacked structure of a pixel electrode, an optical auxiliary layer, an intermediate layer, a capping layer, and a color filter layer in FIG. 3 in a display device according to a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] The present invention can be modified in various ways and can have various embodiments, and specific embodiments are illustrated in the drawings and will be described in detail in the detailed description. The advantages and features of the present invention, as well as methods for achieving the same, will become apparent from the following detailed description of the embodiments in conjunction with the drawings. However, the present invention is not limited to the embodiments disclosed below, but may be embodied in various forms.

[0034] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. When describing with reference to the drawings, identical or corresponding components are given the same reference numerals, and duplicate descriptions thereof will be omitted.

[0035] In the following examples, when various components such as layers, films, regions, and plates are described as being "on" other components, this includes not only the case where they are "directly on" other components, but also the case where other components are interposed therebetween. In addition, for convenience of explanation, the size of the components may be exaggerated or reduced in the drawings. For example, the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of explanation, and the present invention is not necessarily limited to what is shown in the drawings.

[0036] In the following embodiments, the x-axis, y-axis, and z-axis are not limited to the three axes on a Cartesian coordinate system, but may be interpreted in a broad sense including the three axes. For example, the x-axis, y-axis, and z-axis may indicate different directions that are mutually orthogonal or non-orthogonal to each other.

[0037] Based on the above, a display device according to a preferred embodiment of the present invention will be described in detail as follows.

[0038] FIG. 1 is a plan view illustrating a display panel of a display device according to an embodiment of the present invention.

[0039] As shown in FIG 1, a display device according to an embodiment of the present invention may include a display panel 10. Such a display device may be any device including the display panel 10. For example, the display device may be a variety of devices such as a smartphone, a tablet, a laptop, a television, or an advertising board. The display device according to an embodiment of the present invention includes a thin film transistor and a capacitor, which may be realized by such a conductive layer and an insulating layer.

[0040] The display panel 10 includes a display area DA and a peripheral area PA located outside the display area DA. In Fig. 1, the display area DA is illustrated as having a rectangular shape. However, the present invention is not limited thereto. The display area DA may have various shapes, such as a circle, an ellipse, a polygon, or a specific graphic shape.

[0041] The display area DA is a portion for displaying an image, and may have a plurality of pixels PX arranged therein. Each pixel PX may include a display element such as an organic light emitting diode. Each pixel PX may emit, for example, red, green, or blue light. Such a pixel PX may be connected to a pixel circuit including a thin film transistor (TFT), a storage capacitor, and the like. Such a pixel circuit may be connected to a scan line SL for transmitting a scan signal, a data line DL for transmitting a data signal crossing the scan line SL, and a driving voltage line PL for supplying a driving voltage. The scan line SL extends in an X direction (hereinafter, a second direction), and the data line DL and the driving voltage line PL extend in a y direction (hereinafter, a first direction).

[0042] The pixels PX may emit light of a luminance corresponding to an electrical signal from a pixel circuit electrically connected thereto. The display area DA displays a predetermined image through the light emitted from the pixels PX. For reference, the pixels PX may be defined as light-emitting areas that emit light of any one of red, green, and blue colors as described above.

[0043] The peripheral area PA may be an area where the pixels PX are not arranged and where no image is displayed. Power supply wiring for driving the pixels PX may be located in the peripheral area PA. Pads may also be arranged in the peripheral area PA, and integrated circuit elements such as a printed circuit board including a driving circuit unit or a driver IC may be arranged to be electrically connected to the pads.

[0044] For reference, the display panel 10 includes the substrate 100, and therefore the substrate 100 may have the display area DA and the peripheral area PA. The substrate 100 will be described in detail below.

[0045] Also, a plurality of transistors may be arranged in the display area DA. In the plurality of transistors, the first terminal of the transistor may be a source electrode or a drain electrode, and the second terminal may be an electrode different from the first terminal, depending on the type of the transistor (N-type or P-type) and / or the operating conditions. For example, if the first terminal is a source electrode, the second terminal may be a drain electrode.

[0046] The plurality of transistors may include a driving transistor, a data write transistor, a compensation transistor, an initialization transistor, an emission control transistor, etc. The driving transistor is connected between a driving voltage line PL and an organic light emitting diode OLED, and the data write transistor is connected to a data line DL and the driving transistor and may perform a switching operation to transmit a data signal transmitted to the data line DL.

[0047] The compensation transistor is turned on by a scan signal transmitted through a scan line SL to connect the driving transistor to the organic light emitting diode OLED, thereby compensating for a threshold voltage of the driving transistor.

[0048] The initialization transistor may be turned on by a scan signal transmitted through a scan line SL and transmit an initialization voltage to a gate electrode of the driving transistor to initialize the gate electrode of the driving transistor. The scan line connected to the initialization transistor may be a separate scan line different from the scan line connected to the compensation transistor.

[0049] The light-emitting control transistor is turned on by a light-emitting control signal transmitted through a light-emitting control line, so that a driving current flows through the organic light-emitting diode OLED.

[0050] The organic light emitting diode OLED includes a pixel electrode 150 (anode) and a counter electrode 170 (cathode), and a second power supply voltage ELVSS may be applied to the counter electrode 170. The organic light emitting diode OLED may display an image by emitting light when a driving current is transmitted from a driving transistor.

[0051] Hereinafter, an organic light emitting display device will be described as an example of a display device according to an embodiment of the present invention, but the display device of the present invention is not limited thereto. In another embodiment, the display device of the present invention may be an inorganic light emitting display device (or inorganic EL display device) or a quantum dot light emitting display device. For example, the light emitting layer of a display element included in the display device may include an organic material or an inorganic material. The display device may also include a light emitting layer and quantum dots positioned on a path of light emitted from the light emitting layer.

[0052] FIG. 2 is an equivalent circuit diagram of one pixel included in the display panel of FIG.

[0053] As shown in FIG. 2, each pixel PX includes a pixel circuit PC connected to a scan line SL and a data line DL, and an organic light emitting diode OLED connected to the pixel circuit PC.

[0054] The pixel circuit PC includes a driving thin film transistor Td, a switching thin film transistor Ts, and a storage capacitor Cst. The switching thin film transistor Ts is connected to a scan line SL and a data line DL, and transmits a data signal Dm inputted through the data line DL to the driving thin film transistor Td in response to a scan signal Sn inputted through the scan line SL.

[0055] The storage capacitor Cst is connected to the switching thin film transistor Ts and the driving voltage line PL, and stores a voltage corresponding to the difference between the voltage transferred from the switching thin film transistor Ts and the first power voltage ELVDD supplied to the driving voltage line PL.

[0056] The second power supply voltage ELVSS may be a driving voltage having a relatively lower level than the first power supply voltage ELVDD. The level of the driving voltage supplied to each pixel PX may be the difference between the levels of the first power supply voltage ELVDD and the second power supply voltage EVLSS. The driving thin film transistor Td is connected to the driving voltage line PL and the storage capacitor Cst, and may control a driving current flowing from the driving voltage line PL to the organic light emitting diode OLED in response to the voltage value stored in the storage capacitor Cst. The organic light emitting diode OLED may emit light having a predetermined brightness according to the driving current.

[0057] 2, the pixel circuit PC includes two thin film transistors and one storage capacitor, but the present invention is not limited thereto, and the pixel circuit PC may include two or more storage capacitors.

[0058] FIG. 3 is a cross-sectional view that illustrates a schematic view of a portion of the display panel of FIG.

[0059] The substrate 100 may include a display area DA and an area corresponding to a peripheral area PA outside the display area, as described above. The substrate 100 may include various materials having flexible or bendable properties. For example, the substrate 100 may include glass, metal, or polymer resin. The substrate 100 may also include polymer resins such as polyethersulphone, polyacrylate, polyetherimide, polyethylene naphthalate, polyethylene terephthalate, polyphenylene sulfide, polyarylate, polyimide, polycarbonate, or cellulose acetate propionate. Substrate 100 can be modified in various ways, such as having a multi-layer (laminate) structure including two layers each containing such a polymer resin and a barrier layer containing an inorganic material (such as silicon oxide, silicon nitride, silicon oxynitride, etc.) interposed between the layers.

[0060] Alternatively, in order to realize a super high resolution, the substrate 100 may include a semiconductor material, for example, a group IV semiconductor, a group III-V compound semiconductor, or a group II-VI compound semiconductor. The substrate 100 may include a silicon layer. That is, the substrate 100 may be a semiconductor substrate including a semiconductor material. The substrate 100 may be a substrate made of a silicon wafer formed using a semiconductor process. In this case, an active layer may be formed inside the substrate 100 made of a silicon wafer, and a gate line, a data line, and a transistor may be disposed on the upper surface. An organic light emitting diode OLED using a substrate made of a silicon wafer in this manner is also called OLEDoS (OLED on Silicon). For example, in the case of OLEDoS, a CMOS process is required to form fine pixels, and an OLED element may be formed on an electrode formed by the CMOS process. In order to realize each color of R, G, and B in OLEDoS, a white OLED is generally formed, and a color filter may be disposed on the white OLED to realize the colors of R, G, and B. OLEDoS is mainly used for XR (Augmented Reality) and can realize ultra-high image quality of 8K or more in a small area of ​​about 1 to 2 inches. When a semiconductor substrate is used, dense control of pixels arranged at ultra-high resolution is possible. However, the present invention is not limited thereto.

[0061] The buffer layer 101 may be disposed on the substrate 100. The buffer layer 101 may function as a barrier layer and / or a blocking layer for preventing diffusion of impurity ions, preventing penetration of moisture or air, and planarizing the surface. The buffer layer 101 may include silicon oxide, silicon nitride, or silicon oxynitride. In addition, the buffer layer 101 may adjust the rate of heat supply during a crystallization process for forming the semiconductor layer 110, thereby allowing the semiconductor layer 110 to be uniformly crystallized.

[0062] The semiconductor layer 110 may be located on the buffer layer 101. The semiconductor layer 110 may be made of polysilicon and may include a channel region that is not doped with impurities, and a source region and a drain region that are doped with impurities on both sides of the channel region. Here, the impurities may be N-type or P-type impurities depending on the type of the thin film transistor.

[0063] The gate insulating film 102 may be located on the semiconductor layer 110. The gate insulating film 102 may be configured to ensure insulation between the semiconductor layer 110 and the gate layer 120. The gate insulating film 102 may include an inorganic material such as silicon oxide, silicon nitride, and / or silicon oxynitride, and may be interposed between the semiconductor layer 110 and the gate layer 120. The gate insulating film 102 may have a structure in which a contact hole is formed in a predetermined portion, with the gate insulating film 102 being formed corresponding to the entire surface of the substrate 100. In this manner, an insulating film including an inorganic material may be formed through chemical vapor deposition (CVD) or atomic layer deposition (ALD). This is the same in the following embodiments and their modified examples.

[0064] The first gate layer 120a may be located on the gate insulating film 102. The first gate layer 120a is located at a position vertically overlapping the semiconductor layer 110, and may include at least one metal selected from the group consisting of molybdenum (Mo), aluminum (Al), platinum (Pt), palladium (PD), silver (Ag), magnesium (Mg), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), lithium (Li), calcium (Ca), titanium (Ti), tungsten (W), and copper (Cu).

[0065] The first interlayer insulating film 103a may be located on the first gate layer 120a. The first interlayer insulating film 103a may cover the first gate layer 120a. The first interlayer insulating film 103a may be made of an inorganic material. For example, the first interlayer insulating film 103a may be made of a metal oxide or a metal nitride. Specifically, the inorganic material may be silicon oxide (SiO 2), silicon nitride (SiNx), silicon oxynitride (SiON), aluminum oxide (Al 2 O 3 ), titanium oxide (TiO 2 ), tantalum oxide (Ta 2 O 5 ), hafnium oxide (HfO 2 ), or zinc oxide (ZrO 2 In some embodiments, the first interlayer insulating film 103a may include SiO x / SiN y or SiN x / SiO y It consists of a double structure.

[0066] The second gate layer 120b may be located on the first interlayer insulating film 103a. The second gate layer 120b may be located at a position overlapping the first gate layer 120a, and may include at least one metal selected from the group consisting of molybdenum (Mo), aluminum (Al), platinum (Pt), palladium (PD), silver (Ag), magnesium (Mg), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), lithium (Li), calcium (Ca), titanium (Ti), tungsten (W), and copper (Cu).

[0067] The second gate layer 120b may form the storage capacitor Cst with the first gate layer 120a described above in FIG 2. The first gate layer 120a may be one electrode of the storage capacitor Cst, and the second gate layer 120b may be the other electrode of the storage capacitor Cst.

[0068] The second interlayer insulating film 103b may be located on the second gate layer 120b. The second interlayer insulating film 103b covers the second gate layer 120b. The second interlayer insulating film 103b may be made of an inorganic material. For example, the second interlayer insulating film 103b may be a metal oxide or a metal nitride. Specifically, the inorganic material may be silicon oxide (SiO 2 ), silicon nitride (SiN x ), silicon oxynitride (SiON), aluminum oxide (Al 2 O3 ), titanium oxide (TiO 2 ), tantalum oxide (Ta 2 O 5 ), hafnium oxide (HfO 2 ), or zinc oxide (ZrO 2 In some embodiments, the second interlayer insulating film 103b may include SiO x / SiN y or SiN x / SiO y It can be made up of a dual structure.

[0069] The first conductive layer 130 may be disposed on the second interlayer insulating layer 103b. The first conductive layer 130 serves as an electrode connected to a source / drain region of the semiconductor layer through a through hole included in the second interlayer insulating layer 103b. The first conductive layer 130 may include one or more metals selected from aluminum (Al), platinum (Pt), palladium (PD), silver (Ag), magnesium (Mg), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), lithium (Li), calcium (Ca), molybdenum (Mo), titanium (Ti), tungsten (W), and copper (Cu). For example, the first conductive layer 130 may include a Ti layer, an Al layer, and / or a Cu layer.

[0070] The first organic insulating layer 104 may be located on the first conductive layer 130. The first organic insulating layer 104 may be an organic insulating layer that covers the upper part of the first conductive layer 130 and has a substantially flat surface, acting as a planarizing film. The first organic insulating layer 104 may include an organic material such as acrylic, BCB (benzocyclobutene), or HMDSO (hexamethyldisiloxane). The first organic insulating layer 104 may be variously modified, such as being composed of a single layer or multiple layers (laminate film).

[0071] The second conductive layer 140 may be disposed on the first organic insulating layer 104. The second conductive layer 140 may function as an electrode connected to a source / drain region of the semiconductor layer through a through hole included in the first organic insulating layer 104. The second conductive layer 140 may include one or more metals selected from aluminum (Al), platinum (Pt), palladium (PD), silver (Ag), magnesium (Mg), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), lithium (Li), calcium (Ca), molybdenum (Mo), titanium (Ti), tungsten (W), and copper (Cu). For example, the second conductive layer 140 may include a Ti layer, an Al layer, and / or a Cu layer.

[0072] The second organic insulating layer 105 is located on the first conductive layer 130. The second organic insulating layer 105 may be an organic insulating layer that covers the upper part of the first conductive layer 130 and has a substantially flat surface, acting as a planarizing film. The second organic insulating layer 105 may include an organic material such as acrylic, BCB (benzocyclobutene), or HMDSO (hexamethyldisiloxane). The second organic insulating layer 105 may be variously modified, such as being composed of a single layer or multiple layers.

[0073] 3, an additional conductive layer and an additional insulating layer may be interposed between the conductive layer and the pixel electrode 150 for various embodiments. In this case, the additional conductive layer may include the same material and have the same layer structure as the conductive layer described above. The additional insulating layer may include the same material and have the same layer structure as the organic insulating layer described above.

[0074] The pixel electrode 150 may be disposed on the second organic insulating layer 105. The pixel electrode 150 may be connected to the second conductive layer 140 through a contact hole formed in the second organic insulating layer 105. A display element may be disposed on the pixel electrode 150. An organic light emitting diode (OLED) may be used as the display element. That is, the organic light emitting diode (OLED) may be disposed on the pixel electrode 150. The pixel electrode 150 may be formed of a material such as ITO, In, or the like.2 O 3 Alternatively, the pixel electrode 150 may include a transparent conductive layer made of a transparent conductive oxide such as IZO, and a reflective layer made of a metal such as Al or Ag. For example, the pixel electrode 150 has a three-layer structure of ITO / Ag / ITO.

[0075] The pixel defining (defining) film 106 may be disposed on the second organic insulating layer 105 to cover the edge of the pixel electrode 150. That is, the pixel defining (defining) film 106 covers the edge of the pixel electrode 150. The pixel defining (defining) film 106 may have an opening corresponding to the pixel PX, and the opening may be formed so that at least the center of the pixel electrode 150 is exposed. Such a pixel defining (defining) film 106 may include an organic material such as polyimide or HMDSO (hexamethyldisiloxane), or may be a silicon compound (e.g., SiN x , SiO x The inorganic substances may include inorganic substances such as cellulose, cellulose acetate, cellulose ether, etc.

[0076] Also, spacers (not shown) may be disposed on the pixel defining film 106. The spacers (not shown) are illustrated as being located on the peripheral area PA, but may also be located on the display area DA. The spacers (not shown) may prevent damage to the organic light emitting diode OLED due to bending or sagging of a mask during a manufacturing process using a mask. The spacers (not shown) may include an organic insulator and may be formed of a single layer or multiple layers.

[0077] The optical auxiliary layer 160 may be disposed on the pixel electrode 150. For example, the optical auxiliary layer 160 may be located on the opening of the pixel defining film 106. The optical auxiliary layer 160 may be a SiN x and / or SiO x As will be described in detail later with reference to FIG. 6, the optical auxiliary layer 160 may include a plurality of optical auxiliary bodies arranged in a direction parallel to the substrate 100. Each of the optical auxiliary bodies is an inorganic structure for optical resonance, which will be described later.

[0078] The intermediate layer 200 and the counter electrode 170 may be located on the opening of the pixel defining film 106. The intermediate layer 200 may include a low molecular weight or high molecular weight material, and may include a hole injection layer, a hole transport layer, an emission layer, an electron transport layer, and / or an electron injection layer. Details of the intermediate layer 200 will be described later in detail with reference to FIG. 4.

[0079] The counter electrode 170 is made of ITO, In 2 O 3 Alternatively, the counter electrode 170 may include a transparent conductive layer made of a transparent conductive oxide such as IZO. Alternatively, the counter electrode 170 may be a conductive layer containing Ag and / or Mg. The pixel electrode 150 is used as an anode, and the counter electrode 170 is used as a cathode. It goes without saying that the polarity of the electrodes may be reversed.

[0080] The structure of the intermediate layer 200 is not limited to the above and may have various structures. For example, at least one of the layers constituting the intermediate layer 200 may be formed integrally with the counter electrode 170. In another embodiment, the intermediate layer 200 may include layers patterned to correspond to each of the plurality of pixel electrodes 150.

[0081] The counter electrode 170 may be disposed on the upper portion of the display area DA and disposed on the front surface of the display area DA. That is, the counter electrode 170 may be integrally formed to cover a plurality of pixels. The counter electrode 170 may be electrically connected to a common power supply line (not shown) disposed in the peripheral area PA. In one embodiment, the counter electrode 170 may extend to a blocking wall (not shown).

[0082] The capping layer CPL is formed by stacking at least an organic capping layer and an inorganic capping layer on the counter electrode 170. The capping layer CPL may be formed by thermal evaporation deposition or e-beam evaporation deposition. Forming the capping layer CPL may include performing a deposition process at a relatively higher temperature than a deposition process for forming the light-emitting layer included in the intermediate layer 200. Alternatively, the capping layer CPL may have a multi-layer structure in which dielectric thin films having different refractive indices are alternately and repeatedly stacked.

[0083] The color filter layer CFL may be disposed on the capping layer CPL. The color filter layer CFL is configured to pass light of a specific wavelength band, and may be configured to pass light of wavelength bands of R, G, and B colors corresponding to each pixel. The color filter layer CFL includes a first color filter, a second color filter, and a third color filter, and each color filter will be described later.

[0084] Although not shown in FIG. 3, a light-shielding layer (not shown) for blocking emission of light generated in the intermediate layer 200 may be disposed between each color filter layer. The light-shielding layer (not shown) may be a black matrix and may include various materials that absorb at least a portion of light. For example, the light-shielding material layer (not shown) may include at least one of carbon black, graphite, a chromium-based material, a dye, a metal reflective film, and a light absorbing film. The light-shielding material layer (not shown) may not only block or prevent reflection of external light, but also prevent internal reflection of light generated in the display element.

[0085] 3, a thin-film encapsulation layer (not shown) may be disposed on the counter electrode 170. In some cases, the thin-film encapsulation layer (not shown) may be disposed between the counter electrode 170 and the capping layer CPL or may be disposed on the capping layer CPL. The thin-film encapsulation layer (not shown) may be disposed so as to cover the entire display area DA, extend toward the peripheral area PA, and cover at least a portion of the peripheral area PA.

[0086] The thin film encapsulation layer (not shown) includes a first inorganic encapsulation layer, a second inorganic encapsulation layer, and an organic encapsulation layer interposed therebetween, and the first inorganic encapsulation layer and the second inorganic encapsulation layer may include one or more inorganic materials selected from the group consisting of aluminum oxide, titanium oxide, tantalum oxide, hafnium oxide, zinc oxide, silicon oxide, silicon nitride, and silicon oxynitride.

[0087] The organic encapsulation layer may include a monomer-based material or a polymer-based material. Polymer-based materials may include acrylic resins, epoxy resins, polyimides, polyethylenes, etc. In one embodiment, the organic encapsulation layer may include acrylate.

[0088] A blocking wall (not shown) is located on the peripheral region PA of the substrate 100. As an example, the blocking wall (not shown) may include, but is not necessarily limited to, a part of the first organic insulating layer 104, a part of the second organic insulating layer 105, a part of the pixel defining film 106, and a part of a spacer (not shown).

[0089] In some cases, a blocking wall (not shown) may be disposed to surround the display area DA to prevent the material constituting the organic encapsulation layer of the thin film encapsulation layer (not shown) from overflowing outside the substrate 100.

[0090] Fig. 4 is a schematic conceptual diagram showing a cross section of the intermediate layer of Fig. 3. For reference, in the description of Fig. 4, contents that are the same as or overlap with those described above may be omitted.

[0091] 4, the intermediate layer 200 may include a first light emitting layer EML1, a second light emitting layer EML2, a third light emitting layer EML3, and a fourth light emitting layer EML4. The first light emitting layer EML1 to the fourth light emitting layer EML4 are vertically stacked layers, and the first light emitting layer EML1 and the fourth light emitting layer EML4 may emit light in the same wavelength band.

[0092] For example, the first and fourth emission layers EML1 and EML4 may emit blue visible light, the second emission layer EML2 may emit red visible light, and the third emission layer EML3 may emit green visible light.

[0093] For example, the first to fourth emission layers EML1 to EML4 may be overlapped in a plan view. In this case, the first emission layer EML1 and the second emission layer EML2 may be spaced apart in the thickness direction of each emission layer, and the third emission layer EML3 and the fourth emission layer EML4 may be spaced apart in the thickness direction of each emission layer. The second emission layer EML2 and the third emission layer EML3 may be disposed adjacent to each other.

[0094] The intermediate layer 200 may further include a first hole transport layer 201. The first hole transport layer 201 may be disposed on the pixel electrode 150. The first hole transport layer 201 is a layer that transports holes (electron holes) in an OLED and may be an organic layer into which holes can be injected from the pixel electrode 150. For convenience of explanation, the first hole transport layer 201 in this specification may be understood as a concept including a hole injection layer (e.g., a p-doped HTL).

[0095] The intermediate layer 200 may include a first light-emitting layer EML1 that emits light in a first wavelength band. The first light-emitting layer EML1 may be disposed on the first hole transport layer 201. The first light-emitting layer EML1 may have a thickness of 140 Å or more and 240 Å or less, and preferably has a thickness of about 190 Å. The first light-emitting layer EML1 may be an organic layer that emits blue visible light.

[0096] The intermediate layer 200 may include a second light-emitting layer EML2 that emits light in a second wavelength band. The second light-emitting layer EML2 may be disposed on the first light-emitting layer EML1. The second light-emitting layer EML2 may have a thickness of 30 Å or more and 70 Å or less, and preferably has a thickness of about 50 Å. The second light-emitting layer EML2 may be an organic layer that emits red visible light.

[0097] The intermediate layer 200 may include a third light-emitting layer EML3 that emits light in a third wavelength band. The third light-emitting layer EML3 may be disposed on the second light-emitting layer EML2. The third light-emitting layer EML3 may have a thickness of 250 Å or more and 450 Å or less, and preferably has a thickness of about 350 Å. The third light-emitting layer EML3 may be an organic layer that emits green visible light.

[0098] The intermediate layer 200 may include a fourth light-emitting layer EML4 that emits light in the first wavelength band. The fourth light-emitting layer EML4 may be disposed on the third light-emitting layer EML3. The fourth light-emitting layer EML4 may have a thickness of 140 Å or more and 240 Å or less, and preferably has a thickness of about 190 Å. The fourth light-emitting layer EML4 may be an organic layer that emits blue visible light.

[0099] The intermediate layer 200 may further include a first connection layer 202 disposed between the first emitting layer EML1 and the second emitting layer EML2. The first connection layer 202 may be an organic layer including a first electron transport layer 202A, a first charge generation layer 202B, and a second hole transport layer 202C. The first connection layer 202 may have a thickness of 450 Å to 750 Å, and preferably has a thickness of about 610 Å.

[0100] As a result of the numerical limitations on the thickness of each component, the display device according to the embodiment of the present invention may implement a more efficient resonant structure than the display device according to the comparative example described below, and as a result, a display device with high light efficiency may be provided.

[0101] The first electron transport layer 202A may be disposed on the first light-emitting layer EML1. A lower surface of the first electron transport layer 202A may be in contact with an upper surface of the first light-emitting layer EML1. The first electron transport layer 202A is a layer that serves to transport electrons in an OLED and may be an organic layer. For convenience of explanation, the first electron transport layer 202A in this specification may be understood as a concept including an electron injection layer.

[0102] The first charge generation layer 202B may be disposed on the first electron transport layer 202A. The lower surface of the first charge generation layer 202B may be in contact with the upper surface of the first electron transport layer 202A. The first charge generation layer 202B may include a P-type charge generation layer and an N-type charge generation layer. The P-type charge generation layer may include a host material having a hole transporting ability, and the N-type charge generation layer may include a host material having an electron transporting ability. For example, the N-type charge generation layer may inject electrons into the first light emitting layer EML1, and the P-type charge generation layer may inject holes into the second light emitting layer EML2.

[0103] The second hole transport layer 202C may be disposed on the first charge generation layer 202B. The lower surface of the second hole transport layer 202C may be in contact with the upper surface of the first charge generation layer 202B. The second hole transport layer 202C is a layer that transports electron holes in an OLED and may be an organic layer. For convenience of explanation, the second hole transport layer 202C may be understood as a concept including a hole injection layer in this specification.

[0104] 4, the intermediate layer 200 may further include a second connection layer 203 disposed between the third emitting layer EML3 and the fourth emitting layer EML4. The second connection layer 203 may be an organic layer including a second electron transport layer 203A, a second charge generation layer 203B, and a third hole transport layer 203C. The second connection layer 203 may have a thickness of 210 Å to 310 Å, and preferably has a thickness of about 265 Å.

[0105] As a result of the numerical limitations on the thickness of each component, the display device according to the embodiment of the present invention may implement a more efficient resonant structure than the display device according to the comparative example described below, and as a result, a display device with high light efficiency may be provided.

[0106] The second electron transport layer 203A may be disposed on the third light-emitting layer EML3. The lower surface of the second electron transport layer 203A may be in contact with the upper surface of the third light-emitting layer EML3. The second electron transport layer 203A is a layer that serves to transport electrons in an OLED and may be an organic layer. For convenience of explanation, the second electron transport layer 203A in this specification may be understood as a concept including an electron injection layer.

[0107] The second charge generation layer 203B may be disposed on the second electron transport layer 203A. The lower surface of the second charge generation layer 203B may be in contact with the upper surface of the second electron transport layer 203A. The second charge generation layer 203B may include a P-type charge generation layer and an N-type charge generation layer. The P-type charge generation layer may include a host material having a hole transporting ability, and the N-type charge generation layer may include a host material having an electron transporting ability. For example, the N-type charge generation layer may inject electrons into the third light emitting layer EML3, and the P-type charge generation layer may inject holes into the fourth light emitting layer EML4.

[0108] The third hole transport layer 203C may be disposed on the second charge generation layer 203B. The lower surface of the third hole transport layer 203C may be in contact with the upper surface of the second charge generation layer 203B. The third hole transport layer 203C is a layer that serves to transport holes (electron holes) in the OLED and may be an organic layer. For convenience of explanation, the third hole transport layer 203C may be understood as a concept including a hole injection layer in this specification.

[0109] As shown in FIG. 4, the intermediate layer 200 may further include a third electron transport layer 204 disposed on the fourth light-emitting layer EML4. The third electron transport layer 204 may be disposed on the fourth light-emitting layer EML4. The lower surface of the third electron transport layer 204 may be in contact with the upper surface of the fourth light-emitting layer EML4. The third electron transport layer 204 is a layer that serves to transport electrons in an OLED and may be an organic layer. For convenience of explanation, the third electron transport layer 204 may be understood as a concept including an electron injection layer in this specification. The counter electrode 170 described above may be disposed on the third electron transport layer 204.

[0110] FIG. 5 is a graph showing the refractive index of the optical auxiliary layer of FIG. 3 and the first hole transport layer of FIG.

[0111] For reference, in the description of Fig. 5, contents that are the same as or overlap with those described above may be omitted, however, the horizontal axis of Fig. 5 may represent the wavelength of light, and the vertical axis may represent the refractive index.

[0112] As shown in FIG. x and / or SIO x The optical auxiliary layer 160, which is an inorganic layer including the above, has a refractive index of about 1.5, and almost no change in the refractive index is observed depending on the wavelength of light passing through the optical auxiliary layer 160. However, the first hole transport layer 201, which is an organic layer, has a higher refractive index as the wavelength becomes shorter, and the refractive index of the first hole transport layer 201 may be in the range of about 1.6 to 2.2.

[0113] Therefore, since the optical path through the first hole transport layer 201 differs depending on the wavelength, the optical thickness of the first hole transport layer 201 can be considered to differ depending on the transmitted light or wavelength. However, since it is difficult to form the first hole transport layer 201 with a different thickness for each wavelength, the total length of the optical path through which the wavelength passes (i.e., the length of the path reflecting the refractive index) can be adjusted by adjusting the thickness of each optical auxiliary body included in the optical auxiliary layer 160.

[0114] FIG. 6 is a cross-sectional view illustrating an example of a stacked structure of the pixel electrode, the optical auxiliary layer, the intermediate layer, the capping layer, and the color filter layer of FIG.

[0115] For reference, in the description of FIG. 6, the same or overlapping content as that described above will be omitted, and for convenience of description, structures such as a pixel defining layer may be omitted.

[0116] In addition, although each layer shown in Fig. 6 is shown to be separated from each other, this is merely for the convenience of understanding and for the accurate illustration of each layer, and it should not be determined that each layer shown in Fig. 6 is separated from each other. Each layer may be in contact with each other, and other layers may be inserted between each layer in some cases. This applies equally to not only Fig. 6 but also other drawings.

[0117] 6, an example of the stacked structure of FIG. 3 may include a pixel electrode 150, an optical auxiliary layer 160, an intermediate layer 200, a counter electrode 170, a capping layer CPL, and a color filter layer CFL. For convenience of explanation, components located under the pixel electrode may be defined as a substrate 100 and a circuit layer.

[0118] For example, the circuit layer may be a layer disposed on a substrate and including at least one thin film transistor, and may include at least a semiconductor layer 110, a gate insulating film 102, a first gate layer 120a, a first interlayer insulating film 103a, a first conductive layer 140, and a first organic insulating layer 104.

[0119] In some cases, the circuit layer may be interpreted as a concept including the semiconductor layer 110, the second conductive layer 140, and the second organic insulating layer 105 covering the second conductive layer 140, but the scope of the present invention is not limited thereto. For example, the circuit layer may refer to a multi-layer structure disposed between the substrate 100 and the pixel electrode 150.

[0120] The pixel electrode 150 may include a reflective layer 152. The reflective layer 152 may include a metal material such as Ag or Al. The reflective layer 152 may be configured to reflect the color emitted from the intermediate layer 200 toward the color filter layer CFL. The thickness of the reflective layer 152 may be 700 Å or more and 1000 Å or less, and may be preferably about 850 Å.

[0121] The pixel electrode 150 may further include a first transparent electrode layer 153 disposed on the reflective layer 152. The first transparent electrode layer 153 may include a transparent conductive material such as ITO. The thickness of the first transparent electrode layer 153 is thinner than the thickness of the reflective layer 152. The thickness of the first transparent electrode layer 153 may be 40 Å to 100 Å, and may be preferably about 70 Å.

[0122] The pixel electrode 150 may further include a second transparent electrode layer 151 disposed under the reflective layer 152. Thus, the reflective layer 152 may be disposed between the first transparent electrode layer 153 and the second transparent electrode layer 151. The second transparent electrode layer 151 may include a transparent conductive material such as ITO. The thickness of the second transparent electrode layer 151 may be less than the thickness of the reflective layer 152. The thickness of the second transparent electrode layer 151 may be 40 Å to 100 Å, and may be about 70 Å. The upper surface of the second transparent conductive layer 151 may be in contact with the lower surface of the reflective layer 152. As shown in FIG. 6, the optical auxiliary layer 160 may include a first optical auxiliary body 160A having a first thickness Ta and a second optical auxiliary body 160C having a second thickness Tc. The second thickness Tc may be greater than the first thickness Ta, and the first optical auxiliary body 160A and the second optical auxiliary body 160C may be arranged side by side. x and / or SiO x The optical auxiliary layer 160 may be disposed between the first transparent conductive layer 153 and the intermediate layer 200 and may be an inorganic layer.

[0123] As a result of the numerical limitations on the thickness of each component, the display device according to the embodiment of the present invention may implement a more efficient resonant structure than a display device according to a comparative example described below, and as a result, a display device with high light efficiency may be provided.

[0124] 6, the pixel electrode 150 including the first transparent electrode layer 153, the second transparent electrode layer 151, and the reflective layer 152 has a structure divided into pixels PX. Each pixel PX corresponds to one of a first color filter CF1, a second color filter CF2, and a third color filter CF3, which will be described later. The optical auxiliary layer 160 may include an optical auxiliary body corresponding to each pixel PX.

[0125] For example, the first optical auxiliary body 160A may correspond to one pixel PX and the first color filter CF1. For example, the first optical auxiliary body 160A may overlap the first color filter CF1 in a plan view.

[0126] For example, the second optical auxiliary body 160C may correspond to another pixel and may correspond to the third color filter CF3 For example, the second optical auxiliary body 160C may overlap with the third color filter CF3 in a plan view.

[0127] The intermediate layer 200 may be disposed on the optical auxiliary layer 160. The intermediate layer 200 may include a first hole transport layer 201, a first emissive layer EML1, a first connecting layer 202, a second emissive layer EML2, a third emissive layer EML3, a second connecting layer 203, a fourth emissive layer EML4, and a third electron transport layer 204, as described above in FIG.

[0128] For example, a first coupling layer 202 may be disposed between the first light emitting layer EML1 and the second light emitting layer EML2, and a second coupling layer 203 may be disposed between the third light emitting layer EML3 and the fourth light emitting layer EML4. The thicknesses of the first coupling layer 202 and the second coupling layer 203 are greater than the thickness of the first light emitting layer EML1.

[0129] For example, the sum of the optical thickness of the first hole transport layer 201 in the first wavelength band and the optical thickness of the second optical auxiliary body 160C in the first wavelength band may be equal to the sum of the optical thickness of the first hole transport layer 201 in the second wavelength band and the optical thickness of the first optical auxiliary body in the second wavelength band. Here, the agreement of the sum of thicknesses may mean an agreement within an error range that may occur in measurement or fine processing.

[0130] The optical thickness may mean a value obtained by multiplying the thickness of a specific layer by the refractive index of the specific layer. Therefore, the optical thickness of the first hole transport layer 201 in the first wavelength band may be a value obtained by multiplying the thickness of the first hole transport layer 201 by the refractive index of the first hole transport layer 201 at about 460 nm (an example of a representative value of the first wavelength band). Similarly, the optical thickness of the second optical auxiliary body 160C in the first wavelength band may be a value obtained by multiplying the thickness of the second optical auxiliary body 160C by the refractive index of the second optical auxiliary body 160C at about 460 nm (an example of a representative value of the first wavelength band).

[0131] For example, the optical thickness of the first hole transport layer 201 in the first wavelength band has a complementary relationship with the optical thickness of the second optical auxiliary body 160C in the first wavelength band. Since the sum of the optical thickness of the first hole transport layer 201 in the first wavelength band and the optical thickness of the second optical auxiliary body 160C in the first wavelength band must be constant, the optical thickness of the second optical auxiliary body 160C in the first wavelength band must increase by the amount that the optical thickness of the first hole transport layer 201 in the first wavelength band decreases. Therefore, the complementary relationship can be expressed as follows:

[0132] <Formula 1> T1 reduction amount × n 201 =Tc increase × n 160

[0133] (However, n 201 is the refractive index of the first hole transport layer 201 in the first wavelength band, and n 160is the refractive index of the second optical auxiliary body 160C in the first wavelength band, T1 is the thickness of the first hole transport layer 201, and Tc is the thickness of the second optical auxiliary body 160C.

[0134] Therefore, according to the above Equation 1, a part of the first hole transport layer 201 in the first wavelength band can be replaced by a part of the second optical auxiliary body 160C in the first wavelength band, and the optical thickness of the part of the first hole transport layer 201 in the first wavelength band can be the same as the optical thickness of the part of the second optical auxiliary body 160C in the first wavelength band.

[0135] As a result of the numerical limitations on the thickness of each component, the display device according to the embodiment of the present invention may implement a more efficient resonant structure than the display device according to the comparative example described below, and as a result, a display device with high light efficiency may be provided.

[0136] For example, the first light-emitting layer EML1 may be an organic layer that emits light in a first wavelength band. The thickness of the first light-emitting layer EML1 may be smaller than the difference between the second thickness of the second optical auxiliary body 160C and the first thickness of the first optical auxiliary body. The difference between the second thickness of the second optical auxiliary body 160C and the first thickness of the first optical auxiliary body may be greater than the thickness of the first light-emitting layer EML1. For example, the fourth light-emitting layer EML4 may be an organic layer that emits light in a first wavelength band like the first light-emitting layer EML1, and the thickness of the fourth light-emitting layer EML4 may be the same as the thickness of the first light-emitting layer EML1.

[0137] For example, the first wavelength band may be a blue visible light region, the second wavelength band may be a red visible light region, and the third wavelength band may be a green visible light region.

[0138] 6, a counter electrode 170 may be disposed on the third electron transport layer 204, a capping layer CPL may be disposed on the counter electrode 170, and a color filter layer CFL may be disposed on the capping layer CPL. The color filter layer CFL may include a first color filter CF1 that transmits light of a second wavelength band, a second color filter CF2 that is disposed next to the first color filter CF1 and transmits light of a third wavelength band, and a third color filter CF3 that is disposed next to the second color filter CF2 and transmits light of the first wavelength band. That is, light of the first wavelength band may transmit through the third color filter CF3, light of the second wavelength band may transmit through the first color filter CF1, and light of the third wavelength band may transmit through the second color filter CF2.

[0139] In this case, the first optical auxiliary body 160A and the first color filter CF1 overlap in a planar view, and the second optical auxiliary body 160C and the third color filter CF3 may overlap in a planar view.

[0140] Examples including specific numerical values ​​are as follows.

[0141] For example, the difference between the first thickness Ta of the first optical auxiliary body 160A and the second thickness Ta of the second optical auxiliary body 160C may be 120 Å to 180 Å, and preferably about 160 Å.

[0142] For example, the thickness of the intermediate layer 200 may be greater than or equal to 2200 Å and less than or equal to 2800 Å, and preferably is about 2500 Å.

[0143] 6, the third optical auxiliary body 160B having the third thickness Tb is not shown, which means that the third thickness Tb is 0. In this case, the difference between the third thickness Tb and the first thickness Ta may be 900 Å or more and 1020 Å or less, and preferably about 960 Å. Since the third thickness Tb is 0, the difference between the third thickness Tb and the first thickness Ta may be the same as the first thickness Ta.

[0144] For example, the thickness of the first hole transport layer 201 may be greater than the thickness of the first connecting layer 202. Also, the thickness of the first connecting layer 202 may be greater than the thickness of the second connecting layer 203. The thickness of the first light-emitting layer EML1 and the thickness of the fourth light-emitting layer EML4 may be equal. The thickness of the second light-emitting layer EML2 may be less than the thickness of the third light-emitting layer EML3. The thickness of the third light-emitting layer EML3 may be greater than the thickness of the fourth light-emitting layer EML4.

[0145] As a result of the numerical limitations on the thickness, the display device according to the embodiment of the present invention may implement a more efficient resonant structure than the display device according to the comparative example described below, and thus a display device with high light efficiency may be provided.

[0146] 7 to 9 are tables summarizing the optical efficiency for each wavelength band in the example shown in FIG.

[0147] 7, the light efficiency of red visible light in the second wavelength band is relatively high when the first thickness Ta of the first optical auxiliary body 160A is about 700 Å and the distance between the second light emitting layer EML2 and the optical auxiliary layer (i.e., the distance between the lower surface of the second light emitting layer EML2 and the lower surface of the first hole transport layer 201) is about 1510 Å to 1710 Å. Preferably, the light efficiency of red visible light is relatively high when the first thickness Ta is about 700 Å and the distance between the second light emitting layer EML2 and the optical auxiliary layer is about 1610 Å.

[0148] 7, the optical efficiency of blue visible light in the first wavelength band is relatively high when the second thickness of the second optical auxiliary body 160C is about 960 Å and the distance between the first light emitting layer EML1 and the optical auxiliary layer (i.e., the distance between the lower surface of the first light emitting layer EML1 and the lower surface of the first hole transport layer 201) is about 660 Å to 810 Å. Preferably, when the second thickness is about 960 Å and the distance between the first light emitting layer EML1 and the optical auxiliary layer is about 760 Å, the optical efficiency of blue visible light is relatively high.

[0149] 8, the optical efficiency of green visible light in the third wavelength band is relatively high when the third thickness Tb of the third optical auxiliary body 160B is about 0 Å and the distance between the third light emitting layer EML3 and the optical auxiliary layer (i.e., the distance between the lower surface of the third light emitting layer EML3 and the lower surface of the first hole transport layer 201) is about 1610 Å to 1710 Å. Preferably, the optical efficiency of green visible light is relatively high when the third thickness Tb is about 0 Å and the distance between the third light emitting layer EML3 and the optical auxiliary layer is about 1660 Å.

[0150] 8, the light efficiency of blue visible light in the third wavelength band is relatively high when the second thickness of the second optical auxiliary body 160C is about 960 Å and the distance between the fourth light emitting layer EML4 and the optical auxiliary layer (i.e., the distance between the lower surface of the fourth light emitting layer EML4 and the lower surface of the first hole transport layer 201) is about 2025 Å to 2125 Å. Preferably, when the second thickness is about 960 Å and the distance between the fourth light emitting layer EML4 and the optical auxiliary layer is about 2075 Å, the light efficiency of blue visible light is relatively high.

[0151] As shown in FIG. 9, the example of FIG. 6 has the highest light efficiency of white visible light when the following conditions are satisfied.

[0152] (1) The distance between the first light-emitting layer EML1 and the optical auxiliary layer is about 760 Å. (2) The distance between the second light-emitting layer EML2 and the optical auxiliary layer is about 1610 Å. (3) The distance between the third light-emitting layer EML3 and the optical auxiliary layer is about 1660 Å. (4) The distance between the fourth light-emitting layer EML4 and the optical auxiliary layer is about 2075 Å. (5) The first thickness Ta is about 700 Å. (6) The second thickness Tc is about 960 Å. (7) The third thickness Tb is approximately 0 Å.

[0153] As a result of the numerical limitations on the thickness, the display device according to the embodiment of the present invention may implement a more efficient resonant structure than the display device according to the comparative example described below, and thus a display device with high light efficiency may be provided.

[0154] Fig. 10 is a cross-sectional view illustrating an example of a stacked structure of a pixel electrode, an optical auxiliary layer, an intermediate layer, a capping layer, and a color filter layer in Fig. 3. For reference, in the description of Fig. 10, contents that are the same as or overlap with those described above may be omitted.

[0155] 10, the optical auxiliary layer may further include a third optical auxiliary body 160B having a third thickness Tb and arranged alongside the first optical auxiliary body 160A and the second optical auxiliary body 160C described above. In this case, the third thickness Tb may be less than the first thickness Ta and the second thickness Tc.

[0156] For example, the difference between the third thickness Tb and the second thickness Tc may be 900 Å or more and 1020 Å or less. For example, the difference between the second thickness Tc and the third thickness Tb may be six times the difference between the first thickness Ta and the second thickness Tc. For example, in a plan view, the third optical auxiliary body 160B may overlap the second color filter CF2.

[0157] 10, the thickness T1 of the first hole transport layer 201 may be less than the thickness of the first connection layer 202. Also, the thickness T1 of the first hole transport layer 201 may be greater than the thickness of the second connection layer 203.

[0158] Examples including specific numerical values ​​are as follows.

[0159] For example, the difference between the first thickness Ta of the first optical auxiliary body 160A and the second thickness Tc of the second optical auxiliary body 160C may be 120 Å or more and 180 Å or less, and preferably the difference may be about 160 Å. The difference between the second thickness Tc of the second optical auxiliary body 160C and the third thickness Tb of the third optical auxiliary body 160B may be 900 Å or more and 1020 Å or less, and preferably the difference may be about 960 Å. For example, the thickness of the intermediate layer 200 may be 2200 Å or more and 2800 Å or less, and preferably the thickness may be about 2500 Å.

[0160] The first thickness Ta may be 900 Å or more and 1200 Å or less, and preferably the first thickness Ta may be about 1060 Å. The second thickness Tc may be 1100 Å or more and 1350 Å or less, and preferably the second thickness Tc may be about 1220 Å. The third thickness Tb may be 200 Å or more and 310 Å or less, and preferably the third thickness Tb may be about 260 Å. In this case, the thickness T1 of the first hole transport layer 201 may be 400 Å or more and 600 Å or less, and preferably the thickness T1 of the first hole transport layer 201 may be about 500 Å.

[0161] A comparison of the example in FIG. 6 with the example in FIG. 10 is as follows.

[0162] The thickness T1 of the first hole transport layer 201 in Fig. 6 is about 810 Å, and the thickness T1 of the first hole transport layer 201 in Fig. 10 is about 500 Å. Therefore, the thickness T1 of the first hole transport layer 201 in Fig. 10 is reduced by about 310 Å with respect to the thickness of the first hole transport layer 201 in Fig. 6. In Fig. 10, the second thickness Tc of the second optical auxiliary body 160C needs to be increased by the amount that the thickness of the first hole transport layer 201 is reduced.

[0163] The second thickness Tc in Fig. 6 is about 960 Å, and the second thickness Tc in Fig. 10 is about 1220 Å. Therefore, the second thickness Tc in Fig. 10 increases by about 260 Å. Considering that the optical refractive index of the optical auxiliary layer is about 1.5, and the optical refractive index of the first hole transport layer 201 at about 460 nm is about 1.9, the above-mentioned thickness reduction amount of the first hole transport layer 201 and the above-mentioned increase amount of the second thickness Tc satisfy the above-mentioned Equation 1.

[0164] As a result of the numerical limitations on the thickness, the display device according to the embodiment of the present invention may implement a more efficient resonant structure than the display device according to the comparative example described below, and thus a display device with high light efficiency may be provided.

[0165] Fig. 11 is a cross-sectional view illustrating an example of a stacked structure of the pixel electrode, the optical auxiliary layer, the intermediate layer, the capping layer, and the color filter layer of Fig. 3. In addition, in the description of Fig. 11, the same or overlapping content as that described above may be omitted.

[0166] 11, the optical auxiliary layer 160 may further include a third optical auxiliary body 160B having a third thickness Tb and arranged alongside the first optical auxiliary body 160A and the second optical auxiliary body 160C described above. In this case, the third thickness Tb may be less than the first thickness Ta and the second thickness Tc.

[0167] For example, the difference between the third thickness Tb and the second thickness Tc may be 900 Å or more and 1020 Å or less. For example, the difference between the second thickness Tc and the third thickness Tb may be six times the difference between the first thickness Ta and the second thickness Tc. For example, in a plan view, the third optical auxiliary body 160B may overlap the second color filter CF2.

[0168] 11, the thickness of the first hole transport layer 201 may be less than the thickness of the first connection layer 202. In addition, the thickness T1 of the first hole transport layer 201 may be greater than the thickness of the second connection layer 203.

[0169] Examples including specific numerical values ​​are as follows.

[0170] For example, the difference between the first thickness Ta of the first optical auxiliary body 160A and the second thickness Tc of the second optical auxiliary body 160C may be 120 Å or more and 180 Å or less, and preferably about 160 Å. The difference between the second thickness Tc of the second optical auxiliary body 160C and the third thickness Tb of the third optical auxiliary body 160B may be 900 Å or more and 1020 Å or less, and preferably about 960 Å. For example, the thickness of the intermediate layer 200 may be 2200 Å or more and 2800 Å or less, and preferably about 2500 Å.

[0171] The first thickness Ta may be 1200 Å or more and 1500 Å or less, and preferably the first thickness Ta may be about 1340 Å. The second thickness Tc may be 1300 Å or more and 1600 Å or less, and preferably the second thickness Tc may be about 1480 Å. The third thickness may be 400 Å or more and 650 Å or less, and preferably the third thickness may be about 540 Å. In this case, the thickness of the first hole transport layer 201 may be 200 Å or more and 400 Å or less, and preferably the thickness of the first hole transport layer 201 may be about 300 Å.

[0172] A comparison of the example in FIG. 10 with the example in FIG. 11 is as follows.

[0173] The thickness of the first hole transport layer 201 in Fig. 10 is about 500 Å, and the thickness of the first hole transport layer 201 in Fig. 11 is about 300 Å. Therefore, the thickness of the first hole transport layer 201 in Fig. 11 is reduced by about 200 Å with respect to the thickness of the first hole transport layer 201 in Fig. 10. In Fig. 11, the second thickness Tc of the second optical auxiliary body 160C needs to be increased by the amount that the thickness T1 of the first hole transport layer 201 is reduced.

[0174] The second thickness Tc in Fig. 10 is about 1220 Å, and the second thickness Tc in Fig. 11 is about 1480 Å. Therefore, the second thickness Tc in Fig. 11 is increased by about 260 Å. Considering that the optical refractive index of the optical auxiliary layer is about 1.5 and the optical refractive index of the first hole transport layer 201 at about 460 nm is about 1.9, the reduction in the thickness of the first hole transport layer 201 and the increase in the second thickness Tc satisfy the above-mentioned Equation 1.

[0175] As a result of the numerical limitations on the thickness, the display device according to the embodiment of the present invention may implement a more efficient resonant structure than a display device according to a comparative example described below, and thus a display device with high light efficiency may be provided.

[0176] Fig. 12 is a cross-sectional view illustrating an example of a stacked structure of a pixel electrode, an optical auxiliary layer, an intermediate layer, a capping layer, and a color filter layer in Fig. 3. For reference, in the description of Fig. 12, contents that are the same as or overlap with those described above may be omitted.

[0177] 12, the optical auxiliary layer may further include a third optical auxiliary body 160B having a third thickness and arranged alongside the first optical auxiliary body 160A and the second optical auxiliary body 160C described above. In this case, the third thickness Tb may be less than the first thickness Ta and the second thickness Tc.

[0178] For example, the difference between the third thickness Tb and the second thickness Tc may be 900 Å or more and 1020 Å or less. For example, the difference between the second thickness Tc and the third thickness Tb may be six times the difference between the first thickness Ta and the second thickness Tc. For example, in a plan view, the third optical auxiliary body 160B may overlap the second color filter CF2.

[0179] 12, the thickness of the first hole transport layer 201 may be less than the thickness of the first connection layer 202. In addition, the thickness of the first hole transport layer 201 may be greater than the thickness of the second connection layer 203.

[0180] Examples including specific numerical values ​​are as follows.

[0181] For example, the difference between the first thickness Ta of the first optical auxiliary body 160A and the second thickness Tc of the second optical auxiliary body 160C may be 120 Å or more and 180 Å or less, and preferably about 160 Å. The difference between the second thickness Tc of the second optical auxiliary body 160C and the third thickness Tb of the third optical auxiliary body 160B may be 900 Å or more and 1020 Å or less, and preferably about 960 Å. For example, the thickness of the intermediate layer 200 may be 2200 Å or more and 2800 Å or less, and preferably about 2500 Å.

[0182] The first thickness Ta may be 1300 Å or more and 1600 Å or less, and preferably the first thickness Ta may be about 1480 Å. The second thickness Tc may be 1600 Å or more and 1900 Å or less, and preferably the second thickness Tc may be about 1780 Å. The third thickness Tb may be 700 Å or more and 900 Å or less, and preferably the third thickness Tb may be about 820 Å. In this case, the thickness of the first hole transport layer 201 may be 80 Å or more and 120 Å or less, and preferably the thickness of the first hole transport layer 201 may be about 100 Å.

[0183] A comparison of the example in FIG. 11 with the example in FIG. 12 is as follows.

[0184] The thickness of the first hole transport layer 201 in Fig. 11 is about 300 Å, and the thickness of the first hole transport layer 201 in Fig. 12 is about 100 Å. Therefore, the thickness of the first hole transport layer 201 in Fig. 12 is reduced by about 200 Å with respect to the thickness of the first hole transport layer 201 in Fig. 11. In Fig. 12, the second thickness Tc of the second optical auxiliary body 160C needs to be increased by the amount that the thickness T1 of the first hole transport layer 201 is reduced.

[0185] The second thickness Tc in Fig. 11 is about 1480 Å, and the second thickness Tc in Fig. 12 is about 1780 Å. Therefore, the second thickness Tc in Fig. 11 is increased by about 300 Å. Considering that the optical refractive index of the optical auxiliary layer is about 1.5 and the optical refractive index of the first hole transport layer 201 at about 460 nm is about 1.9, the above-mentioned reduction amount of the thickness T1 of the first hole transport layer 201 and the above-mentioned increase amount of the second thickness Tc generally satisfy the above-mentioned Equation 1.

[0186] As a result of the numerical limitations on the thickness, the display device according to the embodiment of the present invention may implement a more efficient resonant structure than the display device according to the comparative example described below, and thus a display device with high light efficiency may be provided.

[0187] 13 and 14 are cross-sectional views each showing an example of a cross section corresponding to a stacked structure of a pixel electrode, an optical auxiliary layer, an intermediate layer, a capping layer, and a color filter layer in FIG. 3 in a display device according to a comparative example.

[0188] As shown in Fig. 13, the display device according to the comparative example has a problem that the light efficiency is excessively reduced because the thickness of the second connection layer 203 is thicker than the thickness of the first connection layer 202 and the thickness of the intermediate layer 200 is significantly thicker than the thickness of the intermediate layer 200 of Figs. 6, 10, 11, and 12 according to the exemplary embodiments of the present invention. In addition, the structure of Fig. 13 has a problem that the first thickness Ta is thicker than the second thickness Tc, and the arrangement of such optical auxiliary bodies is less favorable in terms of the resonant structure than the arrangement of the optical auxiliary bodies of Figs. 6, 10, 11, and 12 according to the exemplary embodiments of the present invention.

[0189] As shown in Fig. 14, in the display device according to another comparative example, the green light emitting layer and the red light emitting layer are not disposed between the blue light emitting layers. In that case, the characteristics of the blue visible light are greatly deteriorated, and the output of the blue visible light must be increased, which causes a problem of shortening the life of the organic material emitting the blue visible light. In addition, the structure of Fig. 14 has a problem that the first thickness Ta is thicker than the second thickness Tc, and such an arrangement of the optical auxiliary body is less advantageous in terms of the resonant structure than the arrangements of the optical auxiliary bodies of Figs. 6, 10, 11 and 12 according to the embodiments of the present invention.

[0190] Although the present invention has been described based on the embodiments shown in the drawings, these are merely illustrative, and a person skilled in the art would understand that various modifications and equivalent embodiments are possible. Therefore, the true technical scope of the present invention should be determined by the technical ideas of the claims.

[0191] According to one preferred embodiment, the following is true:

[0192] The background and issues of this case are as follows (i) to (vi).

[0193] (i) Display panels with an array of organic light-emitting devices (OLEDs) are widely used in mobile devices such as smartphones, tablet PCs, and smart watches. (ii) OLED display panels are also used in large TVs and the like, and for this purpose a method called "WOLED (white OLED)" is also adopted.

[0194] (iii) WOLEDs are typically formed by stacking (tandem stacking) R, G, and B light-emitting layers on all pixel dots (pixel openings) in a display area so that white light is emitted from the entire surface, and then R, G, and B color filters are formed for each pixel dot by an inkjet method or the like (Patent Documents 1-4). (iv) By overlapping the R, G, and B light-emitting layers, it is possible to extend the brightness and lifespan. However, in order to improve the durability and reliability of blue light-emitting elements in particular, there were problems such as the thickness of the organic active layer between the upper and lower electrodes becoming too thick and the light-emitting efficiency decreasing.

[0195] (v) Patent Documents 2 and 4 disclose the formation of two overlapping blue active layers. Patent Document 3 discloses increasing the thickness of the blue light-emitting layer. (vi) On the other hand, Patent Document 4 also discloses that a first blue light-emitting layer, a yellow-green light-emitting layer, and a second blue light-emitting layer are stacked in this order from below on a lower electrode (reflective electrode), and the thickness ratio of layers related to these light-emitting layers is optimized.

[0196] According to a particularly preferred embodiment, the following A1 to A4 or A1 to A5 are provided.

[0197] A1 In all pixel dots, the R, G, and B light-emitting layers are overlapped with each other. In this case, between the lower electrode (pixel electrode 150) as a reflective electrode and the upper electrode (counter electrode 170) as a transparent electrode, from below, a first blue light-emitting layer (EML1), a stacked light-emitting film of a red light-emitting layer (EML2) and a green light-emitting layer (EML3), a second blue light-emitting layer (fourth light-emitting layer EML4), and the upper electrode (counter electrode 170) as a transparent electrode are arranged in this order.

[0198] A1-1 "Connecting layers" (202, 203) are disposed between the red and green light-emitting stacked films and the first and second blue light-emitting layers (EML1, EML4), respectively. These "connecting layers" (202, 203) are organic stacked films in which a hole transport layer, a charge generation layer, and an electron transport layer are stacked from below.

[0199] A1-2 In the above-mentioned stacked light-emitting film, either the red light-emitting layer (EML2) or the green light-emitting layer (EML3) may be the lower layer or the upper layer.

[0200] A1-3: A "first hole transport layer (201)" is disposed between the lower electrode (pixel electrode 150) and the first blue light-emitting layer (first light-emitting layer EML1), and a "third electron transport layer (204)" is disposed between the second blue light-emitting layer (fourth light-emitting layer EML4) and the upper electrode (counter electrode 170).

[0201] A2 Between the "first hole transport layer (201)" and the lower electrode (pixel electrode 150), a "first optical auxiliary body (160A)" is arranged at a location overlapping the red filter (CF1), and a "second optical auxiliary body (160C)" is arranged in the area overlapping the blue filter (CF3).

[0202] A2-1 These optical auxiliary bodies (160A, 160C) are made of an inorganic material such as silicon oxide, silicon nitride or silicon oxynitride, and preferably have a refractive index of 1.4 to 1.6.

[0203] A2-2 The refractive index of the "first hole transport layer (201)" made of an organic layer is, for example, 1.6 to 2.2.

[0204] A2-3 The thickness (Tc) of the "second optical auxiliary body (160C)" is greater than the thickness (Ta) of the "first optical auxiliary body (160A)".

[0205] A2-4 The difference between the thickness (Tc) of the "second optical auxiliary body (160C)" and the thickness (Ta) of the "first optical auxiliary body (160A)" is 8 nm or more, 10 nm or more, 12 nm or more, or 14 nm or more, and 22 nm or less, 20 nm or less, or 18 nm or less. For example, it is 12 to 18 nm or 15 to 17 nm.

[0206] A2-5 The thickness (Tc) of the "second optical auxiliary body (160C)" and the thickness (Ta) of the "first optical auxiliary body (160A)" are determined so as to offset the difference in "optical thickness" between the areas overlapping the red filter (CF1) to the blue filter (CF3), respectively. The “optical thickness” here is the sum of the refractive index of the “first hole transport layer (201)” multiplied by its thickness for each primary color (R, G, B) and the refractive index of the optical auxiliary layer multiplied by its thickness.

[0207] A3 The total thickness of the organic layer ("intermediate layer (200)") from the lower surface of the "first hole transport layer (201)" to the upper surface of the "third electron transport layer (204)" is preferably less than 300 nm, less than 290 nm, less than 280 nm, less than 270 nm or less than 260 nm, and is generally 180 nm or more, 200 nm or more, or 220 nm or more.

[0208] In the area overlapping with the A4 blue filter (CF2), the inorganic layer ("optical auxiliary layer") can be omitted between the organic layer ("intermediate layer (200)") and the lower electrode (pixel electrode 150) (FIG. 6 of the present application).

[0209] A4-1 In this case, the thickness (Ta) of the "first optical auxiliary body (160A)" is preferably 40 nm or more, 50 nm or more, 60 nm or more, or 65 nm or more, and 100 nm or less, 90 nm or less, or 80 nm or less. For example, it is 70 nm.

[0210] A4-2 The thickness (Tc) of the "second optical auxiliary body (160C)" is preferably 60 nm or more, 70 nm or more, 80 nm or more, or 90 nm or more, and 120 nm or less, 110 nm or less, or 100 nm or less. For example, it is 96 nm.

[0211] A4-3 Taking the lower surface of the "first hole transport layer (201)" or the upper surface of the "optical auxiliary layer" as a reference, the height to the lower surface of the first blue light-emitting layer (EML1) is T1, the height to the lower surface of the stacked light-emitting film of the red light-emitting layer (EML2) and the green light-emitting layer (EML3) is T2, and the height to the lower surface of the second blue light-emitting layer (EML4) is T4, the following can be determined. T1 (thickness of the first hole transport layer (201)) In one embodiment, 76 nm. Typically, 60-90 nm or 70-80 nm. T2 (first hole transport layer (201) + first blue light-emitting layer (EML1) + first connection layer (202)): In one embodiment, 161 nm. Typically, 140-180 nm or 150-170 nm. T4 (intermediate layer (200)-[second blue light-emitting layer (EML4)+third electron transport layer (204)]): In one embodiment 207.5 nm, typically 180-230 nm, 190-220 nm or 200-215 nm. Ta (thickness of the second optical auxiliary body (160C)) In one embodiment, 70 nm. Typically, 50-90 nm or 60-80 nm. Tc (thickness of the second optical auxiliary body (160A)) In one embodiment 96 nm, typically 80-120 nm, 85-110 nm or 90-100 nm.

[0212] In the area overlapping with the A5 blue filter (CF2), an inorganic layer ("third optical auxiliary body (160B)") having a smaller thickness than the "first optical auxiliary body (160A)" and made of the same inorganic material as the "first optical auxiliary body (160A)" can be disposed between the organic layer ("intermediate layer (200)") and the lower electrode (pixel electrode 150) (Figures 10-11 of the present application).

[0213] A5-1 The thickness (Tb) of the "third optical auxiliary body (160B)" can be appropriately set so that the difference between it and the thickness (Tc) of the second optical auxiliary body (160C) is within a range of 90 to 102 nm. A5-2 The thickness (Tb) of the third optical auxiliary body (160B) can be set so that the difference between it and the thickness (Tc) of the second optical auxiliary body (160C) is 6 times the difference in thickness between the first optical auxiliary body (160A) and the second optical auxiliary body (160C), and more generally can be set so that it is 5 to 7 times or 4 to 8 times. A5-3 The thickness (Tc) of the second optical auxiliary body (160C) can be set so that the difference in the first optical auxiliary body (160A) becomes the above A2-4.

[0214] A5-4 Specifically, the thickness (Tb) of the "third optical auxiliary body (160B)" is preferably 40 to 65 nm, for example 54 nm, the thickness (Ta) of the "first optical auxiliary body (160A)" is preferably 120 to 150 nm, for example 134 nm, and the thickness (Tc) of the second optical auxiliary body (160C) is preferably 13 to 16 nm, for example 14.8 nm.

[0215] A5-5 The thickness (T1) of the first hole transport layer (201) may be a value that starts from the value of A4-3 above (especially 76 nm in one embodiment) and decreases in proportion to the increase in the thickness of the second optical auxiliary body (160C) from the value of A4-2 or A4-3 above (especially 96 nm in one embodiment). <Formula 1> T1 decrease amount × n201 = Tc increase amount × n160 Here, n201 is the refractive index of the first hole transport layer (201), typically 1.5. n160 is the refractive index of the second optical auxiliary body (160C), typically in the range of 1.6 to 2.2.

[0216] A5-6 Specific examples of the thickness (T1) of the first hole transport layer (201) and the thickness (Tc) of the second optical auxiliary body (160C) are as follows. · Example 1 (Figure 10): T1 is 50 nm, Tc is 122 nm. -Specific example 2 (Figure 11): T1 is 30 nm, Tc is 14.8 nm. -Specific example 3 (Figure 12): T1 is 10 nm, Tc is 17.8 nm.

[0217] A6 The lower electrode (pixel electrode 150) as a reflective electrode is composed of a reflective layer (152) made of Ag, Al or an alloy containing these, and transparent electrode layers (151, 153) sandwiching it from above and below. The transparent electrode layers (151, 153) are typically made of ITO or IZO. A6-1 The thickness of the upper and lower transparent electrode layers (151, 153) is smaller than the thickness of the reflective layer (152). A6-2 The thickness of the upper and lower transparent electrode layers (151, 153) is 7 nm in one specific example, for example, 4 to 10 nm. A6-3 The thickness of the reflective layer (152) is, in one specific example, 8.5 nm, for example, 7 to 10 nm. [Explanation of symbols]

[0218] 100 Substrates 150 pixel electrode 160 Optical auxiliary layer 200 Middle Class 170 Counter Electrode CPL Capping Layer CFL color filter layer

Claims

1. a circuit layer disposed on the substrate and including at least one thin film transistor; a pixel electrode disposed on the circuit layer; an intermediate layer disposed on the pixel electrode, the intermediate layer including a first light-emitting layer that emits light in a first wavelength band, a second light-emitting layer that emits light in a second wavelength band, a third light-emitting layer that emits light in a third wavelength band, and a fourth light-emitting layer that emits light in the first wavelength band, the first light-emitting layer to the fourth light-emitting layer overlapping each other in a planar view; a counter electrode disposed on the intermediate layer; a color filter layer disposed on the counter electrode, the color filter layer including: a first color filter that transmits light of the second wavelength band; a second color filter disposed alongside the first color filter and that transmits light of the third wavelength band; and a third color filter disposed alongside the second color filter and that transmits light of the first wavelength band; an optical auxiliary layer disposed between the pixel electrode and the intermediate layer, the optical auxiliary layer including a first optical auxiliary body having a first thickness, and a second optical auxiliary body disposed next to the first optical auxiliary body and having a second thickness greater than the first thickness, the first optical auxiliary body and the first color filter overlapping each other in a plan view, and the second optical auxiliary body and the third color filter overlapping each other in a plan view; A display device comprising:

2. The display device of claim 1 , wherein the intermediate layer further comprises a first hole transport layer disposed between the pixel electrode and the first light emitting layer.

3. 3. The display device of claim 2, wherein the sum of the optical thickness of the first hole transport layer in the first wavelength band and the optical thickness of the second optical auxiliary body in the first wavelength band is equal to the sum of the optical thickness of the first hole transport layer in the second wavelength band and the optical thickness of the first optical auxiliary body in the second wavelength band.

4. 3. The display device of claim 2, wherein an optical thickness of the first hole transport layer in the first wavelength band is inversely proportional to an optical thickness of the second optical auxiliary body in the first wavelength band.

5. 3. The display device of claim 2, wherein a portion of the first hole transport layer in the first wavelength band is replaceable by a portion of the second optical auxiliary body in the first wavelength band.

6. 6. The display device of claim 5, wherein an optical thickness of a portion of the first hole transport layer in the first wavelength band matches an optical thickness of a portion of the second optical auxiliary body in the first wavelength band.

7. the pixel electrode includes a reflective layer disposed on the substrate and a first transparent conductive layer disposed on the reflective layer; The display device of claim 1 , wherein the optical assist layer is disposed between the first transparent conductive layer and the intermediate layer.

8. The display device of claim 7 , wherein the pixel electrode further comprises a second transparent conductive layer disposed below the reflective layer, and an upper surface of the second transparent conductive layer and a lower surface of the reflective layer are in contact with each other.

9. The display device of claim 1 , wherein the difference between the second thickness and the first thickness is greater than a thickness of the first light-emitting layer.

10. 10. The display device of claim 9, wherein a thickness of the first light-emitting layer matches a thickness of the fourth light-emitting layer.

11. 2. The display device of claim 1, wherein the first wavelength band is a blue visible light region, the second wavelength band is a red visible light region, and the third wavelength band is a green visible light region.

12. The display device of claim 1 , wherein a first connection layer is disposed between the first light-emitting layer and the second light-emitting layer, and a second connection layer is disposed between the third light-emitting layer and the fourth light-emitting layer.

13. The display device of claim 12 , wherein the first and second connection layers have a thickness greater than a thickness of the first light emitting layer.

14. 13. The display device of claim 12, wherein the first connecting layer comprises a first electron transport layer disposed on the first light-emitting layer, a first charge generation layer disposed on the first electron transport layer, and a second hole transport layer disposed on the first charge generation layer.

15. 15. The display device of claim 14, wherein the second connecting layer comprises a second electron transport layer disposed on the third light-emitting layer, a second charge generation layer disposed on the second electron transport layer, and a third hole transport layer disposed on the second charge generation layer.

16. The display device of claim 12 , wherein an upper surface of the second light-emitting layer and a lower surface of the third light-emitting layer are in contact with each other.

17. 10. The display device of claim 1, further comprising a capping layer disposed between the counter electrode and the color filter layer.

18. The display device of claim 1 , wherein the difference between the second thickness and the first thickness is 120 Å to 180 Å.

19. 10. The display device of claim 1, wherein the optical assist layer further comprises a third optical assist body having a third thickness and disposed alongside the first optical assist body and the second optical assist body.

20. 20. The display device of claim 19, wherein the third thickness is less than the first thickness and the second thickness.

21. 21. The display device of claim 20, wherein the difference between the third thickness and the second thickness is 900 Å to 1020 Å.

22. 21. The display device of claim 20, wherein the difference between the second thickness and the third thickness is six times the difference between the first thickness and the second thickness.

23. The display device according to claim 19 , wherein the third optical auxiliary body overlaps with the second color filter in a plan view.

24. 2. The display device of claim 1, wherein the intermediate layer has a thickness of 2200 Å or more and 2800 Å or less.

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