Light emitting device and display device including the same

Abstract

Provided are a light emitting device and a display device including a phase shift mirror. The light emitting device includes a first electrode, a light emitting structure, a second electrode and a phase shift mirror. The phase shift mirror has a plurality of patterns arranged in a periodic manner, with intervals between adjacent patterns. Each pattern has a top surface and a side surface between the top surface of the corresponding pattern and the top surface of the first electrode. A first width of a bottom of a corresponding pattern directly adjacent to the top surface of the first electrode is greater than a second width of the top surface of the corresponding pattern, and the first width and the second width are less than a wavelength of light generated in the light emitting structure.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the priority of Korean Patent Application No. 10-2018-0096826 filed on August 20, 2018 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates to a light emitting device and a display device including the light emitting device, and more particularly, to an organic light emitting device having a phase shift mirror and an organic light emitting display device. Background Art

[0004] An organic light emitting device (OLED) is a display device that forms an image by light emission according to a combination of holes supplied from an anode in an organic emission layer and electrons supplied from a cathode. OLED has excellent display characteristics such as a wide viewing angle, a fast response speed, a thin thickness, a low manufacturing cost, and a high contrast ratio.

[0005] In addition, OLED can emit the desired color by selecting appropriate materials as the materials of the organic emission layer. According to this principle, a color display device can be manufactured by using OLED. For example, the organic emission layer of the blue pixel may include an organic material that generates blue light, the organic emission layer of the green pixel may include an organic material that generates green light, and the organic emission layer of the red pixel may include an organic material that generates red light. Alternatively, a white OLED can be manufactured by arranging a plurality of organic materials that respectively generate blue light, green light, and red light in one organic emission layer or by arranging two or more pairs of organic materials that are complementary to each other. Summary of the invention

[0006] According to one aspect of the present disclosure, a light-emitting device is provided, comprising: a first electrode; a light-emitting structure disposed on the first electrode; a second electrode disposed on the light-emitting structure; and a phase shifter formed on the top surface of the first electrode, the phase shifter comprising a plurality of patterns arranged in a periodic manner with intervals between adjacent patterns, wherein each of the plurality of patterns comprises a top surface and a side surface between the top surface of the corresponding pattern and the top surface of the first electrode, wherein a first width of a bottom portion of a corresponding pattern directly adjacent to the top surface of the first electrode is greater than a second width of the top surface of the corresponding pattern, and wherein the first width and the second width are less than a wavelength of light generated in the light-emitting structure.

[0007] The phase shift mirror and the second electrode may constitute a resonator having a resonant wavelength, and the resonant wavelength of the resonator may be determined according to at least one of the first width, the second width, a depth of each of the plurality of patterns, and an arrangement period of the plurality of patterns.

[0008] When the resonant wavelength of the resonator is λ, at least one of the following can be selected so that the optical length of the resonator satisfies nλ / 2: the first width, the second width, the depth of each of the multiple periodic patterns, and the arrangement period of the multiple periodic patterns, where n is a natural number.

[0009] The second electrode may be a transflective electrode that reflects a portion of light and transmits another portion of light.

[0010] A side surface of each of the plurality of patterns may be an inclined surface.

[0011] Each of the plurality of patterns may have a rod shape extending in a first direction, and the plurality of patterns may be arranged along a second direction perpendicular to the first direction.

[0012] Each of the plurality of patterns may have a truncated cone shape or a truncated polygonal pyramid shape, and the plurality of patterns may be two-dimensionally arranged.

[0013] The first electrode may include a reflective metal material, and the phase shift mirror may include the same reflective metal material as the first electrode.

[0014] The first electrode may include a reflective metal material, and the phase shift mirror may include a reflective metal material different from that of the first electrode.

[0015] A sum of the first width and the second width may be smaller than a wavelength of light generated in the light emitting structure.

[0016] A sum of the first width and the second width may be less than 1 / 3 of a wavelength of light generated in the light emitting structure.

[0017] The light emitting structure may include: a hole injection layer disposed on the first electrode; a hole transport layer disposed on the hole injection layer; an organic emission layer disposed on the hole transport layer; an electron transport layer disposed on the organic emission layer; and an electron injection layer disposed on the electron transport layer.

[0018] The light emitting device may further include: a dielectric layer formed between the plurality of patterns of the phase shift mirror.

[0019] The dielectric layer may be configured to completely cover top surfaces of the plurality of patterns, and the light emitting device may further include: a transparent electrode disposed between the dielectric layer and the light emitting structure.

[0020] The light emitting device may further include: a wiring configured to electrically connect the first electrode to the transparent electrode.

[0021] The light emitting device may further include: a transparent electrode disposed between the phase shift mirror and the light emitting structure.

[0022] According to another aspect of the present disclosure, a display device is provided, comprising: a first pixel configured to emit light of a first wavelength; and a second pixel configured to emit light of a second wavelength different from the first wavelength, wherein the first pixel comprises: a first electrode; a first light-emitting structure disposed on the first electrode; a second electrode disposed on the first light-emitting structure; and a first phase shifter formed on a top surface of the first electrode, the first phase shifter comprising a plurality of patterns arranged in a periodic manner, wherein each of the plurality of patterns comprises a top surface and a side surface between the top surface of the corresponding pattern and the top surface of the first electrode, wherein a first width of a bottom portion of a corresponding pattern directly adjacent to the top surface of the first electrode is greater than a second width of the top surface of the corresponding pattern, and wherein the first width and the second width are less than the wavelength of light generated in the first light-emitting structure.

[0023] The first phase shift mirror and the second electrode may constitute a first resonator having a resonant wavelength, and a distance between the second electrode and a top surface of each of the plurality of patterns, the first width of each of the plurality of patterns, the second width of each of the plurality of patterns, and a depth of each of the plurality of patterns may be selected so that the resonant wavelength of the first resonator is the same as the first wavelength.

[0024] The second pixel may include: a third electrode; a second light emitting structure disposed on the third electrode; and a fourth electrode disposed on the second light emitting structure.

[0025] The third electrode and the fourth electrode may constitute a second resonator having a resonance wavelength, and a distance between the third electrode and the fourth electrode may be selected such that the resonance wavelength of the second resonator is the same as the second wavelength.

[0026] A distance between the second electrode and a top surface of each of the plurality of patterns and a distance between the third electrode and the fourth electrode may be the same.

[0027] The first light emitting structure and the second light emitting structure may each be configured to emit white visible light.

[0028] The display device may further include: a third pixel configured to emit light of a third wavelength different from the first wavelength and the second wavelength, wherein the third pixel may include: a fifth electrode; a third light emitting structure disposed on the fifth electrode; a sixth electrode disposed on the light emitting structure; and a second phase shifter formed on a top surface of the fifth electrode, the second phase shifter including a plurality of patterns arranged in a periodic manner, wherein each of the plurality of patterns of the third pixel includes a top surface and a side surface between the top surface of the corresponding pattern and the top surface of the fifth electrode, wherein a third width of a bottom portion of a corresponding pattern of each of the plurality of patterns of the third pixel directly adjacent to the top surface of the fifth electrode is greater than a fourth width of the corresponding pattern of each of the plurality of patterns of the third pixel, and wherein the third width of the third pixel and the fourth width of the third pixel are less than the wavelength of light generated in the third light emitting structure.

[0029] The second phase shift mirror and the sixth electrode of the third pixel may constitute a third resonator having a resonant wavelength, and the distance between the sixth electrode of the third pixel and the top surface of each of the multiple patterns, the third width of each of the multiple patterns of the third pixel, the fourth width of each of the multiple patterns of the third pixel, and the depth of each of the multiple patterns of the third pixel may be selected so that the resonant wavelength of the third resonator is the same as the third wavelength.

[0030] The distance between the sixth electrode of the third pixel and the top surface of each of the multiple patterns and the distance between the second electrode of the first pixel and the top surface of each of the multiple patterns may be the same, and the depth of each of the multiple patterns of the third pixel may be different from the depth of each of the multiple patterns of the first pixel.

[0031] According to another aspect of the present disclosure, a light-emitting device is provided, comprising: a first electrode; a phase shifter formed on a top surface of the first electrode; a light-emitting structure disposed above the first electrode and the phase shifter; and a second electrode disposed on the light-emitting structure, wherein the phase shifter comprises a plurality of patterns with intervals between adjacent patterns, and wherein a size of each of the plurality of patterns is configured based on a wavelength of light generated in the light-emitting structure.

[0032] The light emitting device may further include: a dielectric layer formed between the plurality of patterns of the phase shift mirror.

[0033] A first width of a bottom of a pattern directly adjacent to the top surface of the first electrode among the plurality of patterns may be greater than a second width of a top surface of the pattern.

[0034] The first electrode and the phase shift mirror may be integrally formed as a single structure.

[0035] The first electrode and the phase shift mirror may be formed as separate structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] These and / or other aspects will become clear and more easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0037] Figure 1 is a sectional view showing the structure of a light emitting device according to an embodiment;

[0038] Figure 2 According to the embodiment Figure 1 An enlarged cross-sectional view of a phase shift mirror of a light emitting device;

[0039] FIG. 3A to FIG. 3C is a perspective view showing various shapes of a plurality of patterns of a phase shift mirror according to an embodiment;

[0040] Figure 4 is a graph comparing spectrum of reflected light according to a pattern shape in a phase shift mirror configured to reflect light in a green wavelength band according to an embodiment;

[0041] Figure 5 is a graph comparing spectrum of reflected light according to a pattern shape in a phase shift mirror configured to reflect light in a red wavelength band according to an embodiment;

[0042] Figure 6 is a diagram showing simulation results regarding a relationship between a depth of a pattern and a wavelength of light emitted from a light emitting device according to an embodiment;

[0043] Figure 7 is a graph showing a relationship between a depth of a pattern and a spectrum of light emitted from a light emitting device according to an embodiment;

[0044] Figure 8 is a cross-sectional view schematically showing the structure of a light emitting device according to another embodiment;

[0045] Fig. 9 is a cross-sectional view schematically showing the structure of a light emitting device according to an embodiment;

[0046] Fig.10is a cross-sectional view schematically showing the structure of a light emitting device according to an embodiment;

[0047] Fig.11 is a cross-sectional view schematically showing a structure of a display device according to an embodiment;

[0048] Fig.12 is a cross-sectional view schematically showing a structure of a display device according to another embodiment; and

[0049] Fig.13 is a cross-sectional view schematically showing the structure of a display device according to another embodiment. DETAILED DESCRIPTION

[0050] Hereinafter, with reference to the accompanying drawings, an organic light-emitting device and an organic light-emitting display device having a phase shift mirror will be described in detail. The same reference numerals always represent the same elements, and in the accompanying drawings, the size of the elements may be exaggerated for the sake of clarity and ease of explanation. The embodiments described below are merely exemplary and may be variously modified according to the embodiments. In the layer structure described below, the expression "above" or "on" may include not only "directly on in contact" but also "on in a non-contact manner".

[0051] Figure 1 is a cross-sectional view showing the structure of a light emitting device 100 according to an embodiment. Figure 1 According to the embodiment, the light emitting device 100 may include a first electrode 10, a light emitting structure 20 disposed on the first electrode 10, and a second electrode 18 disposed on the light emitting structure 20. The light emitting device 100 may further include a phase shift mirror 11 having a plurality of patterns on a surface of the first electrode 10 opposite to the second electrode 18. According to the embodiment, the plurality of patterns are arranged in a periodic manner.

[0052] The light emitting device 100 may be an organic light emitting diode (OLED). According to an embodiment, the light emitting structure 20 may include: a hole injection layer 13; a hole transport layer 14 disposed on the hole injection layer 13; an organic emission layer 15 disposed on the hole transport layer 14; an electron transport layer 16 disposed on the organic emission layer 15; and an electron injection layer 17 disposed on the electron transport layer 16. Figure 1, but the light emitting structure 20 may include various additional layers as needed. According to an embodiment, the light emitting structure 20 may further include an electron blocking layer between the hole transport layer 14 and the organic emission layer 15, and may further include a hole blocking layer between the organic emission layer 15 and the electron transport layer 16. In this structure, holes provided by the hole injection layer 13 and the hole transport layer 14 and electrons provided by the electron injection layer 17 and the electron transport layer 16 may be combined in the organic emission layer 15, thereby generating light. The wavelength of the generated light may be determined according to the energy band gap of the light emitting material of the organic emission layer 15.

[0053] The structure of the above-mentioned OLED is only an example of the light emitting device 100, and the light emitting device 100 is not limited to the OLED. Therefore, the structure and principle of the light emitting device 100 according to the embodiment of the present disclosure can be applied to an inorganic light emitting diode. Hereinafter, it is assumed that the light emitting device 100 is an OLED.

[0054] According to an embodiment, the first electrode 10 disposed at the lower portion of the light emitting structure 20 may be a reflective electrode that reflects light (e.g., visible light) and may be used as an anode for providing holes. The second electrode 18 disposed at the upper portion of the light emitting structure 20 may be a semi-transmissive and semi-reflective electrode that reflects a portion of the light and transmits another portion of the light, and may be used as a cathode for providing electrons. According to an embodiment, the first electrode 10 may include a metal material having excellent reflectivity and conductivity, such as silver (Ag) or aluminum (Al), and the second electrode 18 may include a reflective metal having a very thin thickness. According to an embodiment, the second electrode 18 may be a mixed layer of aluminum (Al), silver (Ag), and magnesium (Mg) or a mixed layer of aluminum (Al) and lithium (Li), and the entire thickness of the second electrode 18 may be about 5 nm to about 20 nm. Although the second electrode 18 includes a metal, since the thickness of the second electrode 18 is very thin, a portion of the light passes through the second electrode 18 and another portion of the light is reflected.

[0055] According to an embodiment, the phase shift mirror 11 may include the same conductive material as the first electrode 10, and may be a part of the first electrode 10. That is, the phase shift mirror 11 may be formed integrally with the first electrode 10. In an embodiment, the flat upper surface of the first electrode 10 may be etched to form the phase shift mirror 11. Since the phase shift mirror 11 has a plurality of nanometer-scale patterns 11a, the phase of the reflected light reflected by the phase shift mirror 11 may be changed.

[0056] The light emitting device 100 may further include a dielectric layer 12 formed of a dielectric material filled between the plurality of patterns 11a of the phase shift mirror 11. In an embodiment, the dielectric layer 12 may include a material that is transparent and insulating to visible light, such as SiO 2 、SiN x 、Al2 O 3 , HfO 2 The phase of the reflected light can also be adjusted according to the refractive index of the dielectric layer 12. In addition, the dielectric layer 12 can be used as a planarization layer for forming the light emitting structure 20 on the first electrode 10. To this end, the dielectric layer 12 can completely cover the upper surface of the pattern 11a, and the upper surface of the dielectric layer 12 can be flat.

[0057] The light emitting device 100 may further include a transparent electrode 10a disposed between the dielectric layer 12 and the light emitting structure 20, and a wiring 10b electrically connecting the transparent electrode 10a and the first electrode 10. According to an embodiment, when the dielectric layer 12 completely covers the upper surface of the pattern 11a of the phase shift mirror 11, current may not flow from the first electrode 10 to the light emitting structure 20. The transparent electrode 10a and the wiring 10b may be used to electrically connect the light emitting structure 20 to the first electrode 10. The transparent electrode 10a may include a transparent conductive oxide, such as ITO (indium tin oxide), IZO (indium zinc oxide), or AZO (aluminum zinc oxide).

[0058] Figure 2 According to the embodiment Figure 1 FIG. 1 is an enlarged cross-sectional view of the phase shift mirror 11 of the light emitting device 100 shown in FIG. Figure 2 , the phase shift mirror 11 may include a plurality of nanoscale patterns 11a arranged at regular intervals. Figure 2 Only four patterns 11a are shown in the figure, but actually many patterns 11a can be arranged in the phase shift mirror 11. Each pattern 11a of the phase shift mirror 11 may include a bottom surface 11b, a top surface 11t opposite to the bottom surface 11b, and a side surface 11s between the bottom surface 11b and the top surface 11t. The arrangement period of the pattern 11a can be considered as the sum of the width g of the interval 11g between two adjacent patterns 11a and the width ba of the bottom surface 11b of each pattern 11a.

[0059] According to the embodiment, Figure 2 As shown, the width ba of the bottom surface 11b may be greater than the width ta of the top surface 11t, and the side surface 11s may be an inclined surface. Therefore, the cross section of each pattern 11a may have a trapezoidal shape. Thus, light may easily penetrate into the interval 11g between the patterns 11a and then be reflected.

[0060] For example, a portion L1 of the incident light incident on the phase shift mirror 11 may be reflected by the top surface 11t of the pattern 11a, while another portion L2 may be reflected internally by the interval 11g between the patterns 11a. Therefore, there may be a phase difference between the light L1 reflected by the top surface 11t of the pattern 11a and the light L2 reflected internally by the interval 11g between the patterns 11a. As described above, the phase shift mirror 11 may change the phase of the reflected light. When the width ta of the top surface 11t is equal to or greater than the width ba of the bottom surface 11b, since the light may not sufficiently enter the interval 11g between the patterns 11a, it may be difficult for the phase shift mirror 11 to accurately change the phase of the reflected light as desired.

[0061] The phase shift of the reflected light reflected by the phase shift mirror 11 can be determined according to at least one of the following: the width ba of the bottom surface 11b, the width ta of the top surface 11t, the arrangement period of the pattern 11a, and the depth d of the pattern 11a. The size of the pattern 11a can be smaller than the wavelength of the incident light (for example, the light generated in the light emitting structure 20) to achieve a uniform and accurate phase shift. When the light emitting structure 20 emits light in the visible light region, the size of the pattern 11a can be smaller than the visible light. For example, the sum of the width ba of the bottom surface 11b and the width ta of the top surface 11t can be smaller than the wavelength of the light generated in the light emitting structure 20. Alternatively, the sum of the width ba of the bottom surface 11b and the width ta of the top surface 11t can be less than 1 / 3 of the wavelength of the light generated in the light emitting structure 20.

[0062] The plurality of patterns 11 a of the phase shift mirror 11 may have a one-dimensional (1D) array structure or a two-dimensional (2D) array structure. FIG. 3A to FIG. 3C 1 is a perspective view showing various shapes of a plurality of patterns 11 a of the phase shift mirror 11 according to the embodiment.

[0063] Figure 3A FIG. 1 shows a plurality of patterns 11a of a one-dimensional arrangement of the phase shift mirror 11. Referring to FIG. Figure 3A , each pattern 11a may have a rod shape elongated in a first direction, and a plurality of patterns 11a may be arranged in a second direction perpendicular to the first direction. In this case, the width ba of the bottom surface 11b of each pattern 11a may be, for example, about 30 nm to about 300 nm. In addition, the ratio r obtained by dividing the width ta of the top surface 11t by the width ba of the bottom surface 11b may be, for example, greater than 0 and less than 1 (0<r<1), and the period p of the pattern 11a may satisfy the relationship of (width ba of the bottom surface 11b+10 nm)≤p≤(wavelength of light generated in the light emitting structure 20).

[0064] also, Figure 3B and Figure 3C 2 shows a plurality of patterns 11a of a two-dimensional arrangement of the phase shift mirrors 11. Figure 3B, each pattern 11a may have, for example, a truncated cone shape, and a plurality of patterns 11a may be arranged two-dimensionally. Figure 3C Each pattern 11a may have a truncated rectangular pyramid shape. In addition to the truncated rectangular pyramid shape, each pattern 11a may have various truncated polygonal pyramid shapes. Figure 3B and Figure 3C In the embodiment, a plurality of patterns 11a are arranged two-dimensionally in a first direction and in a second direction perpendicular to the first direction to form a rectangular arrangement, but the plurality of patterns 11a may be arranged two-dimensionally to form a triangular or hexagonal arrangement. When the plurality of patterns 11a are arranged two-dimensionally, the width ba of the bottom surface 11b of each pattern 11a may be, for example, about 30nm to about 300nm. In addition, the ratio r obtained by dividing the width ta of the top surface 11t by the width ba of the bottom surface 11b may be, for example, greater than 0 and less than 1 (0<r<1), and the period p of the pattern 11a may satisfy the relationship of (width ba of the bottom surface 11b+10nm)≤p≤(wavelength of light generated in the light emitting structure 20).

[0065] Refer again Figure 1 , the phase shift mirror 11 may form a resonator L together with the second electrode 18. That is, the resonator L may be formed between the phase shift mirror 11 and the second electrode 18 of the light emitting device 100. Therefore, the light generated in the light emitting structure 20 may reciprocate and resonate between the phase shift mirror 11 and the second electrode 18, and then the light corresponding to the resonant wavelength of the resonator L may be emitted to the outside through the second electrode 18.

[0066] The resonant wavelength of the resonator L may be determined according to the optical length of the resonator L. For example, when the resonant wavelength of the resonator L is λ, the optical length of the resonator L may be nλ / 2 (n is a natural number). The optical length of the resonator L may be determined as the sum of the optical thickness of the light emitting structure 20, the optical thickness of the transparent electrode 10a, the optical thickness between the upper surface of the dielectric layer 12 and the top surface 11t of the pattern 11a, the phase shift caused by the second electrode 18, and the phase shift caused by the phase shift mirror 11. Here, the optical thickness of the light emitting structure 20, the optical thickness of the transparent electrode 10a, and the optical thickness between the upper surface of the dielectric layer 12 and the top surface 11t of the pattern 11a may not only be physical thicknesses, but may be thicknesses that take into account the refractive indexes of all materials between the second electrode 18 and the top surface 11t of each pattern 11a of the phase shift mirror 11. According to an embodiment, the optical length or resonant wavelength of the resonator L can be determined by adjusting only the phase shift caused by the phase shift mirror 11 while fixing the optical thickness of the light emitting structure 20, the optical thickness of the transparent electrode 10a, the optical thickness between the upper surface of the dielectric layer 12 and the top surface 11t of the pattern 11a, and the phase shift caused by the second electrode 18.

[0067] As described above, the phase shift caused by the phase shift mirror 11 can be determined according to at least one of the width ba of the bottom surface 11b of each pattern 11a, the width ta of the top surface 11t, the arrangement period of the pattern 11a, and the depth d of the pattern 11a. Therefore, the resonance wavelength of the resonator L formed between the phase shift mirror 11 and the second electrode 18 can be determined according to at least one of the width ba of the bottom surface 11b of each pattern 11a of the phase shift mirror 11, the width ta of the top surface 11t, the arrangement period of the pattern 11a, and the depth d of the pattern 11a. In other words, when the resonant wavelength of the resonator L is λ and the optical thickness of the light emitting structure 20, the optical thickness of the transparent electrode 10a, the optical thickness between the upper surface of the dielectric layer 12 and the top surface 11t of the pattern 11a, and the phase shift caused by the second electrode 18 are fixed, at least one of the following may be selected so that the optical length of the resonator L is nλ / 2 (n is a natural number): the width ba of the bottom surface 11b of each pattern 11a of the phase shift mirror 11, the width ta of the top surface 11t, the arrangement period of the pattern 11a, and the depth d of the pattern 11a. Therefore, the phase shift mirror 11 may be appropriately configured to easily match the resonant wavelength of the resonator L in the light emitting device 100 with the light emission wavelength of the light emitting device 100.

[0068] Figure 4 4 is a graph comparing spectrum of reflected light according to a pattern shape in the phase shift mirror 11 configured to reflect light in the green wavelength band according to an embodiment. Figure 4 The graph indicated by the solid line shows the spectrum of reflected light when the shape of the cross section of each pattern 11a is a trapezoid as in the embodiment, and as a comparative example, the graph indicated by the dotted line shows the spectrum of reflected light when the shape of the cross section of each pattern is a rectangle. In the case where each pattern 11a has a trapezoidal cross section, the width ba of the bottom surface 11b of each pattern 11a may be 100nm, the width ta of the top surface 11t may be 50nm, the width g of the interval 11g between the two patterns 11a may be 250nm, and the depth d of the pattern 11a may be 36nm. In the comparative example, the width of the top surface may be equal to the width of the bottom surface, and the depth of the pattern may be 21nm. Reference Figure 4 , it can be seen that the peak value of the solid line in the green wavelength region is much greater than the peak value of the dotted line. It can also be seen that the peak value of the dotted line in the blue wavelength region is only slightly less than the peak value of the dotted line in the green wavelength region, but the peak value of the solid line in the blue wavelength region is greatly suppressed. Therefore, the color purity of the light emitted from the light emitting device 100 can be improved.

[0069] Figure 5 is a graph comparing spectrum of reflected light according to a pattern shape in the phase shift mirror 11 configured to reflect light in the red wavelength band according to an embodiment. Figure 5 The graph indicated by the solid line shows the spectrum of reflected light when the shape of the cross section of each pattern 11a is a trapezoid as in the embodiment, and as a comparative example, the graph indicated by the dotted line shows the spectrum of reflected light when the shape of the cross section of each pattern is a rectangle. In the case where each pattern 11a has a trapezoidal cross section, the width ba of the bottom surface 11b of each pattern 11a may be 100nm, the width ta of the top surface 11t may be 50nm, the width g of the interval 11g between the two patterns 11a may be 250nm, and the depth d of the pattern 11a may be 96nm. In the comparative example, the width of the top surface may be equal to the width of the bottom surface, and the depth of the pattern may be 71nm. Reference Figure 5 , it can be seen that the peak of the solid line in the red wavelength region is greater than the peak of the dotted line. It can also be seen that the small peak of the dotted line graph appears in the blue wavelength region, but the small peak of the solid line graph is closer to the ultraviolet region.

[0070] Figure 6 The simulation results of the relationship between the depth 11a of the pattern and the wavelength of light emitted from the light emitting device 100 according to the embodiment are shown. For example, the simulation is performed by fixing the optical thickness of the light emitting structure 20 to an integral multiple of 1 / 2 of the blue wavelength, fixing the width ba of the bottom surface 11b of the pattern 11a to 100nm, fixing the width ta of the pattern 11a to 200nm, fixing the width g of the interval 11g between the two patterns 11a to 200nm, and changing the depth d of the pattern 11a from 0nm to 100nm. It is assumed that white light is emitted from the light emitting structure 20. Referring to Figure 6 When the depth d of the pattern 11a is small, since the influence of the phase shift mirror 11 is reduced, light of a blue wavelength may be emitted from the light emitting device 100. As the depth d of the pattern 11a becomes deeper, the wavelength of light emitted from the light emitting device 100 may shift in the long wavelength direction. When the depth d of the pattern 11a reaches about 90nm, the light emitting device 100 may emit light of a red wavelength.

[0071] Figure 7 is a graph showing a relationship between a depth d of the pattern 11a and a spectrum of light emitted from the light emitting device 100, and shows a relationship between the depth d of the pattern 11a and the spectrum of light emitted from the light emitting device 100 according to the embodiment. Figure 6 The simulation results are under the same conditions as in . Figure 7 When the depth d of the pattern 11a is 1 nm, a spectrum about blue wavelengths can be obtained, when the depth d of the pattern 11a is 31 nm, a spectrum about green wavelengths can be obtained, and when the depth d of the pattern 11a is 91 nm, a spectrum about red wavelengths can be obtained.

[0072] Therefore, it can be seen that the resonance wavelength of the resonator L of the light emitting device 100 can be adjusted by adjusting only the depth d of the pattern 11a of the phase shift mirror 11. In other words, by changing only the depth d of the pattern 11a while fixing the optical thickness of the light emitting structure 20, the optical thickness of the transparent electrode 10a, the optical thickness between the upper surface of the dielectric layer 12 and the top surface 11t of the pattern 11a, the width ba of the bottom surface 11b of the pattern 11a of the phase shift mirror 11, the width ta of the top surface 11t, and the arrangement period of the pattern 11a at appropriate values, the light emitting device 100 can easily match the resonance wavelength of the resonator L with the emission wavelength or emission color of the light emitting device 100. Therefore, the color purity of the light emitted from the light emitting device 100 can be easily improved. The depth d of the pattern 11a may vary depending on the optical thickness of the light emitting structure 20, the optical thickness of the transparent electrode 10a, the optical thickness between the upper surface of the dielectric layer 12 and the top surface 11t of the pattern 11a, the width ba of the bottom surface 11b of the pattern 11a of the phase shift mirror 11, the width ta of the top surface 11t and the arrangement period of the pattern 11a, but may be selected to be between about 0nm and about 250nm.

[0073] For example, when the light emitting device 100 is a red light emitting device, the width ba of the bottom surface 11b of each pattern 11a of the phase shift mirror 11, the width ta of the top surface 11t, the arrangement period of the pattern 11a, and the depth d of the pattern 11a can be selected so that the resonant frequency of the resonator L corresponds to the red band. The organic emission layer 15 can include only red light emitting materials. On the contrary, the organic emission layer 15 can include all blue light emitting materials, green light emitting materials, and red light emitting materials. The light emission wavelength of the light emitting device 100 can be determined only by the size of the pattern 11a of the phase shift mirror 11.

[0074] Figure 8 2 is a cross-sectional view schematically showing the structure of a light emitting device 110 according to another embodiment. Figure 8 , the light emitting device 110 may include a dielectric layer 12 filled only between the plurality of patterns 11a of the phase shift mirror 11. For example, the upper surface of the dielectric layer 12 may be coplanar with the top surface of the pattern 11a. In this case, the transparent electrode 10a may be electrically connected to the first electrode 10 without additional wiring. Figure 8 The remaining configuration of the light emitting device 110 shown in FIG. Figure 1 The configuration of the light emitting device 100 shown in FIG. 1 is the same.

[0075] Although the phase shift mirror 11 is integrally formed with the first electrode 10 as described above, the phase shift mirror 11 and the first electrode 10 may be formed separately. Fig. 9 2 is a cross-sectional view schematically showing the structure of a light emitting device 120 according to another embodiment. Fig. 9, the light emitting device 120 may include a first electrode 10 having a flat upper surface and a phase shift mirror 11 stacked on the upper surface of the first electrode 10. The phase shift mirror 11 may be additionally formed on the previously formed flat first electrode 10. In this case, the phase shift mirror 11 may include the same reflective metal material as the first electrode 10, or may include a reflective metal material different from the first electrode 10.

[0076] also, Fig.10 is a cross-sectional view schematically showing the structure of a light emitting device 130 according to another embodiment. Fig.10 The light emitting device 130 shown in the figure may not include a separate dielectric layer, and the transparent electrode 10a may be directly disposed on the phase shift mirror 11. The transparent electrode 10a may be disposed between the phase shift mirror 11 and the light emitting structure 20 to serve as a planarization layer for forming the light emitting structure 20. To this end, the transparent electrode 10a may be configured to fill between the plurality of patterns 11a of the phase shift mirror 11 and completely cover the top surface of the pattern 11a. In addition, the upper surface of the transparent electrode 10a may be configured to be flat. In this case, the transparent electrode 10a may be electrically connected to the first electrode 10 without additional wiring.

[0077] The above-mentioned light emitting devices 100, 110, 120 and 130 can be applied to display devices because they can adjust the resonant wavelength of the resonator in the visible light band according to the structure of the phase shift mirror 11. For example, Fig.11 2 is a cross-sectional view schematically showing the structure of a display device 200 according to an embodiment. Fig.11 , the display device 200 according to the embodiment may include a substrate 201 and a first pixel 100B, a second pixel 100G, and a third pixel 100R arranged in a row on the substrate 201. Fig.11 The first to third pixels 100B, 100G, and 100R shown in FIG. Figure 1 The light emitting device 100 shown in FIG. 1 has the same structure, but the first to third pixels 100B, 100G and 100R may have the same Figures 8 to 10 The emitting devices 110, 120 and 130 shown in FIG. 1 have the same structure. Fig.11 Only one of the first to third pixels 100B, 100G, and 100R is shown in FIG. 1 , but a large number of the first to third pixels 100B, 100G, and 100R may be repeatedly arranged in practice.

[0078] For example, each of the first to third pixels 100B, 100G, and 100R may include: a first electrode 10 disposed on the substrate 201 and including a phase shift mirror 11; a dielectric layer 12 disposed on the phase shift mirror 11; a transparent electrode 10a disposed on the dielectric layer 12; a light emitting structure 20 disposed on the transparent electrode 10a; and a second electrode 18 disposed on the light emitting structure 20. When the display device 200 is an OLED device, the light emitting structure 20 of each of the first to third pixels 100B, 100G, and 100R may include: a hole injection layer 13 disposed on the transparent electrode 10a; a hole transport layer 14 disposed on the hole injection layer 13; an organic emission layer 15 disposed on the hole transport layer 14; an electron transport layer 16 disposed on the organic emission layer 15; and an electron injection layer 17 disposed on the electron transport layer 16.

[0079] The first to third pixels 100B, 100G, and 100R may be configured to emit light of different wavelengths. For example, the first pixel 100B may be configured to emit light of the first wavelength band λ which is a blue wavelength band. 1 The second pixel 100G may be configured to emit the second wavelength band λ which is a green wavelength band. 2 The third pixel 100R may be configured to emit the third wavelength band λ which is a red wavelength band. 3 light R. To this end, the optical lengths of the resonators of the first to third pixels 100B, 100G and 100R may be configured to be different from each other. As described above, the optical length of the resonator may be determined to be the sum of the optical thickness of the light emitting structure 20, the optical thickness of the transparent electrode 10a, the optical thickness of the dielectric layer 12, the phase shift caused by the second electrode 18, and the phase shift caused by the phase shift mirror 11. According to an embodiment, the optical length or resonant wavelength of the resonator may be determined by adjusting only the phase shift caused by the phase shift mirror 11 while fixing the optical thickness of the light emitting structure 20, the optical thickness of the transparent electrode 10a, the optical thickness of the dielectric layer 12, and the phase shift caused by the second electrode 18. For example, the phase shift φ of the first pixel 100B caused by the phase shift mirror 11 1 , the phase shift φ of the second pixel 100G caused by the phase shift mirror 11 2 and the phase shift φ of the third pixel 100R caused by the phase shift mirror 11 3 can be configured differently from each other.

[0080] In other words, the width ba of the bottom surface 11b of each pattern 11a of the phase shift mirror 11 of the first pixel 100B, the width ta of the top surface 11t of each pattern 11a of the phase shift mirror 11 of the first pixel 100B, the arrangement period of the patterns 11a of the phase shift mirror 11 of the first pixel 100B, and the depth d of the patterns 11a of the phase shift mirror 11 of the first pixel 100B may be selected so that the resonant wavelength of the resonator of the first pixel 100B corresponds to the first wavelength band λ. 1 , a width ba of a bottom surface 11b of each pattern 11a of the phase shift mirror 11 of the second pixel 100G, a width ta of a top surface 11t of each pattern 11a of the phase shift mirror 11 of the second pixel 100G, an arrangement period of the patterns 11a of the phase shift mirror 11 of the second pixel 100G, and a depth d of the patterns 11a of the phase shift mirror 11 of the second pixel 100G may be selected so that the resonant wavelength of the resonator of the second pixel 100G corresponds to the second wavelength band λ 2 , and a width ba of a bottom surface 11b of each pattern 11a of the phase shift mirror 11 of the third pixel 100R, a width ta of a top surface 11t of each pattern 11a of the phase shift mirror 11 of the third pixel 100R, an arrangement period of the patterns 11a of the phase shift mirror 11 of the third pixel 100R, and a depth d of the patterns 11a of the phase shift mirror 11 of the third pixel 100R may be selected so that the resonant wavelength of the resonator of the third pixel 100R corresponds to the third wavelength band λ 3 .

[0081] More specifically, the width ba of the bottom surface 11b of each pattern 11a of the phase shift mirror 11 in the first pixel 100B, the width ta of the top surface 11t, the arrangement period of the pattern 11a, and the depth d of the pattern 11a may be selected so that the optical length of the resonator of the first pixel 100B is nλ 1 / 2, the width ba of the bottom surface 11b of each pattern 11a of the phase shift mirror 11 in the second pixel 100G, the width ta of the top surface 11t, the arrangement period of the pattern 11a, and the depth d of the pattern 11a can be selected so that the optical length of the resonator of the second pixel 100G is nλ 2 / 2, and the width ba of the bottom surface 11b of each pattern 11a of the phase shift mirror 11 in the third pixel 100R, the width ta of the top surface 11t, the arrangement period of the pattern 11a, and the depth d of the pattern 11a may be selected so that the optical length of the resonator of the third pixel 100R is nλ 3 / 2. Here, n can be a natural number.

[0082] As described above, the optical length of the resonator can be adjusted according to the width ba of the bottom surface 11b of each pattern 11a of the phase shift mirror 11, the width ta of the top surface 11t, the arrangement period of the pattern 11a, and the depth d of the pattern 11a. Figure 6 and Figure 7 As described above, the resonant wavelength in the visible light region of the resonator can be fully adjusted by adjusting only the depth d of the pattern 11a while fixing the width ba of the bottom surface 11b of each pattern 11a of the phase shift mirror 11, the width ta of the top surface 11t, and the arrangement period of the pattern 11a to specific values.

[0083] Therefore, since it is not necessary to adjust the thickness of each of the first to third pixels 100B, 100G, and 100R to adjust the optical length of each of the resonators of the first to third pixels 100B, 100G, and 100R, the display device 200 can configure the thickness of the first to third pixels 100B, 100G, and 100R to be the same. For example, the optical length between the second electrode 18 and the first electrode 10 in the first to third pixels 100B, 100G, and 100R can be the same. Therefore, the manufacturing process of the display device 200 can be simplified, so the display device 200 can easily have a large area. In addition, since the resonant wavelength of each of the resonators of the first to third pixels 100B, 100G, and 100R can be accurately adjusted, the color purity of the display device 200 can be improved.

[0084] For example, in Fig.11 In the case of the display device 200 shown, the depth d of the pattern 11a of the phase shift mirror 11 in the first pixel 100B may be 0 nm. In other words, the first electrode 10 may have a flat upper surface. In this case, it can be seen that the phase shift mirror 11 is not formed in the first pixel 100B. The second pixel 100G and the third pixel 100R may include a second phase shift mirror 11G and a third phase shift mirror 11R having patterns 11a of different depths d, respectively. For example, the depth d of the pattern 11a of the second phase shift mirror 11G may be about 30 nm, and the depth d of the pattern 11a of the third phase shift mirror 11R may be about 90 nm. Except for the depth d of the pattern 11a, the configurations of the first to third pixels 100B, 100G, and 100R may be exactly the same.

[0085] At the same time, the organic emission layers 15 of the first to third pixels 100B, 100G, and 100R may be configured differently. For example, the organic emission layer 15 of the first pixel 100B may include a light-emitting material that emits blue light, the organic emission layer 15 of the second pixel 100G may include a light-emitting material that emits green light, and the organic emission layer 15 of the third pixel 100R may include a light-emitting material that emits red light. However, since the light-emitting characteristics of the first to third pixels 100B, 100G, and 100R can be determined only by the structure of the phase shift mirror 11, the organic emission layers 15 of the first to third pixels 100B, 100G, and 100R may be configured to be the same as each other. For example, the organic emission layers 15 of the first to third pixels 100B, 100G, and 100R may all be configured to emit white visible light. When the organic emission layers 15 of the first to third pixels 100B, 100G, and 100R are the same, the manufacturing process of the display device 200 can be further simplified.

[0086] Not present Fig.11 The phase shift mirror 11 is formed in the first pixel 100B in the display device 200 shown, but the phase shift mirror 11 may be formed in the first pixel 100B according to the size of the pattern 11a. Fig.12 is a cross-sectional view schematically showing a structure of a display device 210 according to another embodiment. Fig.12 The first pixel 100B of the display device 210 shown in FIG. 2 may include a first phase shift mirror 11B, the second pixel 100G may include a second phase shift mirror 11G, and the third pixel 100R may include a third phase shift mirror 11R. In this case, the depth d of the pattern 11a of the second phase shift mirror 11G may be greater than the depth d of the pattern 11a of the first phase shift mirror 11B, and the depth d of the pattern 11a of the third phase shift mirror 11R may be greater than the depth d of the pattern 11a of the second phase shift mirror 11G.

[0087] In addition, since the light emitting characteristics of the first to third pixels 100B, 100G, and 100R can be determined only by the structure of the phase shift mirror 11, the display devices 200 and 210 may not include a separate color filter. However, in order to further improve the color purity of the display devices 200 and 210, a color filter may be provided as needed. For example, Fig.13 2 is a cross-sectional view schematically showing a structure of a display device 220 according to another embodiment. Fig.13 , the display device 220 may include a first color filter 30B disposed on the first pixel 100B, a second color filter 30G disposed on the second pixel 100G, and a third color filter 30R disposed on the third pixel 100R. For example, the first color filter 30B may be configured to emit only the first wavelength band λ which is a blue wavelength band. 1The second color filter 30G may be configured to emit only the second wavelength band λ which is a green wavelength band. 2 The third color filter 30R may be configured to emit only the third wavelength band λ which is a red wavelength band. 3 The remaining structure of the display device 220 can be the same as Fig.11 The display device 200 shown in Fig.12 The display device 210 shown in FIG.

[0088] Although the light emitting device and the display device including the light emitting device have been shown and described in conjunction with the embodiments shown in the accompanying drawings, it should be understood by those skilled in the art that various modifications and equivalent embodiments may be made therefrom. Therefore, the disclosed embodiments should be considered illustrative rather than restrictive. The scope of the embodiments will be in the appended claims, and it should be understood that all differences within their equivalent ranges are included in the embodiments.

Claims

1. A light emitting device, include: a first electrode; A light emitting structure, disposed on the first electrode; A second electrode is disposed on the light emitting structure; a phase shift mirror formed on a top surface of the first electrode, the phase shift mirror comprising a plurality of patterns arranged in a periodic manner with spaces between adjacent patterns; a dielectric layer formed between the plurality of patterns of the phase shift mirror, wherein the dielectric layer is configured to completely cover top surfaces of the plurality of patterns; and a transparent electrode disposed between the dielectric layer and the light emitting structure, wherein each of the plurality of patterns comprises a top surface and a side surface between the top surface of the pattern and a top surface of the first electrode, wherein a first width of a bottom portion of the pattern directly adjacent to a top surface of the first electrode is greater than a second width of a top surface of the pattern, and The first width and the second width are smaller than a wavelength of light generated in the light emitting structure.

2. The light emitting device according to claim 1, in, The phase shift mirror and the second electrode constitute a resonator having a resonance wavelength, and The resonant wavelength of the resonator is determined according to at least one of the following: the first width, the second width, and a depth of each of the plurality of patterns and an arrangement period of the plurality of patterns.

3. The light emitting device according to claim 2, in, When the resonant wavelength of the resonator is λ, at least one of the following is selected so that the optical length of the resonator satisfies nλ / 2: the first width, the second width, the depth of each of the multiple patterns, and an arrangement period of the multiple patterns, where n is a natural number.

4. The light emitting device according to claim 1, in, The second electrode is a semi-transmissive and semi-reflective electrode that reflects a portion of light and transmits another portion of light.

5. The light emitting device according to claim 1, in, A side surface of each of the plurality of patterns is an inclined surface.

6. The light emitting device according to claim 1, in, Each of the plurality of patterns has a rod shape extending in a first direction, and the plurality of patterns are arranged along a second direction perpendicular to the first direction.

7. The light emitting device according to claim 1, in, Each of the plurality of patterns has a truncated cone shape or a truncated polygonal pyramid shape, and the plurality of patterns are two-dimensionally arranged.

8. The light emitting device according to claim 1, in, The first electrode comprises a reflective metal material, and Wherein, the phase shift mirror comprises the same reflective metal material as the first electrode.

9. The light emitting device according to claim 1, in, The first electrode comprises a reflective metal material, and Wherein, the phase shift mirror comprises a reflective metal material different from that of the first electrode.

10. The light emitting device according to claim 1, in, A sum of the first width and the second width is smaller than a wavelength of light generated in the light emitting structure.

11. The light emitting device according to claim 1, in, A sum of the first width and the second width is less than 1 / 3 of a wavelength of light generated in the light emitting structure.

12. The light emitting device according to claim 1, in, The light emitting structure comprises: A hole injection layer is disposed on the first electrode; A hole transport layer, disposed on the hole injection layer; an organic emission layer, disposed on the hole transport layer; an electron transport layer, disposed on the organic emission layer; and The electron injection layer is arranged on the electron transport layer.

13. The light emitting device according to claim 1, further comprising: include: A wiring is configured to electrically connect the first electrode to the transparent electrode.

14. A display device, include: a first pixel configured to emit light of a first wavelength; as well as a second pixel configured to emit light of a second wavelength different from the first wavelength, Wherein, the first pixel comprises: a first electrode; A first light emitting structure is disposed on the first electrode; A second electrode, disposed on the first light emitting structure; a first phase shift mirror formed on a top surface of the first electrode, the first phase shift mirror comprising a plurality of patterns arranged in a periodic manner; a dielectric layer formed between the plurality of patterns of the first phase shift mirror, wherein the dielectric layer is configured to completely cover top surfaces of the plurality of patterns; and a transparent electrode, disposed between the dielectric layer and the first light emitting structure, wherein each of the plurality of patterns comprises a top surface and a side surface between the top surface of the pattern and a top surface of the first electrode, wherein a first width of a bottom portion of the pattern directly adjacent to a top surface of the first electrode is greater than a second width of a top surface of the pattern, and The first width and the second width are smaller than a wavelength of light generated in the first light emitting structure.

15. The display device according to claim 14, in, The first phase shift mirror and the second electrode constitute a first resonator having a resonance wavelength, and wherein a distance between the second electrode and a top surface of each of the plurality of patterns, the first width of each of the plurality of patterns, the second width of each of the plurality of patterns, and a depth of each of the plurality of patterns are selected so that a resonant wavelength of the first resonator is the same as the first wavelength.

16. The display device according to claim 15, in, The second pixel comprises: a third electrode; A second light emitting structure is disposed on the third electrode; and The fourth electrode is arranged on the second light emitting structure.

17. The display device according to claim 16, in, The third electrode and the fourth electrode constitute a second resonator having a resonance wavelength, and The distance between the third electrode and the fourth electrode is selected so that the resonant wavelength of the second resonator is the same as the second wavelength.

18. The display device according to claim 17, in, A distance between the second electrode and a top surface of each of the plurality of patterns and a distance between the third electrode and the fourth electrode are the same.

19. The display device according to claim 16, in, The first light emitting structure and the second light emitting structure are both configured to emit white visible light.

20. The display device according to claim 15, further comprising: include: a third pixel configured to emit light of a third wavelength different from the first wavelength and the second wavelength, Wherein, the third pixel comprises: a fifth electrode; A third light emitting structure is arranged on the fifth electrode; a sixth electrode, disposed on the light emitting structure; and a second phase shift mirror formed on a top surface of the fifth electrode, the second phase shift mirror comprising a plurality of patterns arranged in a periodic manner, wherein each of the plurality of patterns of the third pixel includes a top surface and a side surface between the top surface of the pattern and the top surface of the fifth electrode, wherein a third width of a bottom portion of the pattern directly adjacent to the top surface of the fifth electrode is greater than a fourth width of the top surface of the pattern, and The third width and the fourth width are smaller than a wavelength of light generated in the third light emitting structure.

21. The display device according to claim 20, in, The second phase shift mirror and the sixth electrode of the third pixel constitute a third resonator having a resonance wavelength, and wherein a distance between the sixth electrode of the third pixel and a top surface of each of the plurality of patterns, the third width of each of the plurality of patterns of the third pixel, the fourth width of each of the plurality of patterns of the third pixel, and a depth of each of the plurality of patterns of the third pixel are selected so that a resonant wavelength of the third resonator is the same as the third wavelength.

22. The display device according to claim 21, in, A distance between the sixth electrode of the third pixel and a top surface of each of the plurality of patterns and a distance between the second electrode of the first pixel and a top surface of each of the plurality of patterns are the same, and The depth of each of the plurality of patterns of the third pixel is different from the depth of each of the plurality of patterns of the first pixel.

23. A light emitting device, include: a first electrode; A phase shift mirror formed on a top surface of the first electrode, wherein the phase shift mirror includes a plurality of patterns with spaces between adjacent patterns; A light emitting structure, arranged above the first electrode and the phase shift mirror; A second electrode is disposed on the light emitting structure; a dielectric layer formed between the plurality of patterns of the phase shift mirror, wherein the dielectric layer is configured to completely cover top surfaces of the plurality of patterns; and a transparent electrode disposed between the dielectric layer and the light emitting structure, wherein the size of each of the plurality of patterns is configured based on the wavelength of light generated in the light emitting structure, and Among the plurality of patterns, a first width of a bottom portion of a pattern directly adjacent to the top surface of the first electrode is greater than a second width of a top surface of the pattern.

24. The light emitting device according to claim 23, in, The first electrode and the phase shift mirror are integrally formed as a single structure.

25. The light emitting device according to claim 23, in, The first electrode and the phase shift mirror are formed as separate structures.

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