Electroluminescent element and display device using the same

Abstract

The present invention discloses an electroluminescent element and a display device using the same, wherein the electroluminescent element includes a first electrical semiconductor layer, a second electrical semiconductor layer, an active layer, a first electrode, a second electrode and an optical conversion material. The active layer is located between the first electrical semiconductor layer and the second electrical semiconductor layer, and is in electrical contact with both. The first electrical semiconductor layer has a light-emitting surface, which is located on the opposite side of the active layer, and the first electrical semiconductor layer includes a plurality of regularly arranged three-dimensional structures, which together define at least one cavity, extending from the light-emitting surface to the active layer. The depth of the at least one cavity is substantially greater than 70% of the thickness of the first electrical semiconductor layer. The first electrode is in electrical contact with the first electrical semiconductor layer. The second electrode is in electrical contact with the second electrical semiconductor layer. The optical conversion material is filled in the at least one cavity.

Description

Technical Field

[0001] The present invention relates to a light emitting element and a display device using the light emitting element, and in particular to an electroluminescent element and a display device using the electroluminescent element. Background Art

[0002] Electroluminescent elements, such as light emitting diodes (LEDs), are semiconductor elements that can emit light. They have been widely used in various commercially available electronic products due to their advantages such as short response time, low heat generation, vibration resistance, low power consumption, low heat radiation, and long service life.

[0003] Micro Light Emitting Diode (μLED) displays are composed of multiple discretely packaged miniaturized light-emitting diodes that are combined with thin-film transistor circuits through flip-chip bonding technology to form an active drive architecture with single-point addressing electrical connections, making micro-LED displays self-luminous. Due to its advantages over organic light-emitting diode displays (OLED), such as higher material stability, longer service life, higher brightness, nanosecond-level high-speed response, faster modulation and signal carrying, it has gradually become the mainstream of the new generation of displays.

[0004] In order to make the micro LED display have full color effect, color conversion technology must be used to make the monochromatic light emitted by the LED bare chip pass through optical conversion materials (such as photoluminescence phosphor, quantum dot (QD) material, luminescent dye or a combination of the above) to produce different colors of light as three primary colors of self-luminous display sub-pixels. The current mainstream method in the market is to use blue light LED bare chips with quantum dot materials for packaging, so that the blue light emitted by the blue light LED bare chips of each sub-pixel is converted into different colors of light.

[0005] However, the light conversion efficiency of optical conversion materials has its limits. In order to improve the absorption / conversion efficiency of blue light, the concentration of quantum dots in the optical conversion material must be increased or the thickness of the optical conversion material layer must be increased. This not only increases the manufacturing cost but is also not conducive to the miniaturization of micro-LED components and limits the thinning of micro-LED displays.

[0006] Therefore, there is a need to provide an advanced electroluminescent element and a display device using the electroluminescent element to solve the problems faced by the prior art. Summary of the invention

[0007] One embodiment of the present specification discloses an electroluminescent element, comprising: a first electrical semiconductor layer, a second electrical semiconductor layer, an active layer, a first electrode, a second electrode, and an optical conversion material. The active layer is located between the first electrical semiconductor layer and the second electrical semiconductor layer, and is in electrical contact with the first electrical semiconductor layer and the second electrical semiconductor layer. The first electrical semiconductor layer has a light-emitting surface, which is located on the opposite side of the active layer, and the first electrical semiconductor layer includes a plurality of regularly arranged three-dimensional structures, which together define at least one cavity extending from the light-emitting surface to the active layer. The depth of the at least one cavity is substantially greater than 70% of the thickness of the first electrical semiconductor layer. The first electrode is in electrical contact with the first electrical semiconductor layer. The second electrode is in electrical contact with the second electrical semiconductor layer. The optical conversion material is filled in the at least one cavity.

[0008] A display device includes: a circuit substrate, at least one reflective baffle (reflect bank), a first light-emitting unit, a second light-emitting unit and a third light-emitting unit. The reflective baffle is located on the circuit substrate and defines a plurality of accommodating spaces together with the circuit substrate. The first light-emitting unit and the second light-emitting unit have the same structure as the above-mentioned electroluminescent element, the first light-emitting unit is located in the first of the plurality of accommodating spaces and emits red light; the second light-emitting unit is located in the second of the plurality of accommodating spaces and emits green light; the third light-emitting unit is located in the third of the plurality of accommodating spaces and emits blue light.

[0009] According to the above embodiments, this specification provides an electroluminescent element and a display device using the same. In the electroluminescent element, a plurality of three-dimensional structures are regularly arranged in the semiconductor layer on the light-emitting surface side to jointly define at least one cavity extending from the light-emitting surface to the active layer, so that the depth of the cavity is substantially greater than 70% of the thickness of the first electrical semiconductor layer, and an optical conversion material is filled in the cavity.

[0010] By filling the cavity in the semiconductor layer with the optical conversion material, the reaction probability between the light emitted by the active layer of the electroluminescent element and the optical conversion material can be increased without increasing the overall thickness of the optical conversion material or increasing the concentration of quantum dots contained in the optical conversion material, thereby improving the light absorption / conversion efficiency and effectively reducing the manufacturing cost. At the same time, the miniaturization of the electroluminescent element is taken into account and the demand for thinning the display device using the electroluminescent element is met. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to better understand the above and other aspects of this specification, the following embodiments are specifically cited and described in detail with reference to the attached drawings as follows:

[0012] Figure 1A A top view of the structure of an electroluminescent element according to an embodiment of the present specification;

[0013] Figure 1B For along Figure 1A A schematic cross-sectional structure diagram of an electroluminescent element depicted by a tangent line S1;

[0014] Figure 2A A top view of the structure of an electroluminescent element according to another embodiment of the present specification;

[0015] Figure 2B For along Figure 2A A schematic cross-sectional structure diagram of an electroluminescent element depicted by a tangent line S2;

[0016] Figure 3 A schematic cross-sectional structure diagram of an electroluminescent element according to another embodiment of the present specification;

[0017] Figure 4 A schematic cross-sectional structure diagram of an electroluminescent element according to yet another embodiment of the present specification;

[0018] Figure 5 is a schematic cross-sectional structure diagram of an electroluminescent element according to yet another embodiment of the present specification;

[0019] Figure 6 A schematic cross-sectional structure diagram of an electroluminescent element according to yet another embodiment of the present specification;

[0020] Figure 7 A schematic cross-sectional structure diagram of a display device according to an embodiment of the present specification;

[0021] Figure 8 A cross-sectional structural diagram of a display device is shown for another embodiment of the present specification; and

[0022] Fig. 9 A cross-sectional structural schematic diagram of a display device is shown as another embodiment of the present specification.

[0023] Explanation of symbols

[0024] 70: Display device

[0025] 71: Circuit board

[0026] 71a: Base material

[0027] 71b: Line layer

[0028] 71s: Surface of circuit board

[0029] 72: Reflective retaining wall

[0030] 72s: Sidewall

[0031] 73: first light emitting unit

[0032] 74: Second light emitting unit

[0033] 75: third light emitting unit

[0034] 76a: Accommodation space

[0035] 76b: Accommodation space

[0036] 76c: Accommodation space

[0037] 77R: Red optical conversion material

[0038] 77G: Green Optical Conversion Materials

[0039] 78: Translucent material

[0040] 79: Transparent passivation protective layer

[0041] 80: Display device

[0042] 82: Reflective retaining wall

[0043] 82s: Sidewall

[0044] 90: Display device

[0045] 93: first light emitting unit

[0046] 94: Second light emitting unit

[0047] 99: UV filter layer

[0048] 100:Electroluminescent element

[0049] 101: first electrical semiconductor layer

[0050] 101a: Light emitting surface

[0051] 102: second electrical type semiconductor layer

[0052] 103: Active layer

[0053] 104: first electrode

[0054] 105: Second electrode

[0055] 106: Optical conversion materials

[0056] 107: Boss

[0057] 107a: axis of the boss

[0058] 107U: Arrangement Unit

[0059] 108: Chamber

[0060] 108a: bottom surface

[0061] 200:Electroluminescent element

[0062] 201: first electrical semiconductor layer

[0063] 201a: light-emitting surface

[0064] 206: Optical conversion materials

[0065] 207: Alcove

[0066] 207a: Central axis

[0067] 208: Chamber

[0068] 300:Electroluminescent element

[0069] 306: Optical conversion materials

[0070] 309:Metal reflective layer

[0071] 309a:Through hole

[0072] 400:Electroluminescent element

[0073] 401: first electrical semiconductor layer

[0074] 401a: light-emitting surface

[0075] 406: Optical conversion materials

[0076] 407: Alcove

[0077] 408: Chamber

[0078] 409:Metal reflective layer

[0079] 409a:Through hole

[0080] 500:Electroluminescent element

[0081] 501: first electrical semiconductor layer

[0082] 501a: light-emitting surface

[0083] 506: Optical conversion materials

[0084] 507: Alcove

[0085] 508: Chamber

[0086] 509:Metal reflective layer

[0087] 509a:Through hole

[0088] 600:Electroluminescent element

[0089] 601: first electrical semiconductor layer

[0090] 601a: light emitting surface

[0091] 602: Second electrical type semiconductor layer

[0092] 603: Active layer

[0093] 604: first electrode

[0094] 605: second electrode

[0095] 606: Optical conversion materials

[0096] 607: Alcove

[0097] 608: Chamber

[0098] 609:Metal reflective layer

[0099] 609a:Through hole

[0100] D: Depth of the chamber

[0101] d: Diameter of the boss

[0102] F: Stacking direction

[0103] h: distance

[0104] T: thickness of the first electrical semiconductor layer

[0105] P: Spacing

[0106] S1: Tangent

[0107] S2: Tangent

[0108] δ: Angle DETAILED DESCRIPTION

[0109] This specification provides an electroluminescent element and a display device using the same, which can improve the absorption / conversion efficiency of light in its optical conversion material, effectively reduce the manufacturing cost, facilitate the miniaturization of the electroluminescent element, and meet the demand for thin display devices. In order to make the above-mentioned embodiments and other purposes, features and advantages of this specification more clearly understandable, the following specifically cites a number of preferred embodiments and describes them in detail with the attached drawings.

[0110] However, it must be noted that these specific implementation cases and methods are not intended to limit the present invention. The present invention may still be implemented using other features, components, methods and parameters. The preferred embodiments are only intended to illustrate the technical features of the present invention and are not intended to limit the claims of the present invention. A person of ordinary skill in the art will be able to make equal modifications and changes based on the description of the following specification without departing from the spirit of the present invention. In different embodiments and drawings, the same components will be represented by the same component symbols.

[0111] Please refer to Figure 1A and Figure 1B , Figure 1A is a top view of an electroluminescent element 100 according to an embodiment of the present specification; Figure 1B It is along Figure 1A The cross-sectional structure diagram of the electroluminescent element 100 is shown by the tangent line S1. Figure 1B The electroluminescent element 100 includes a first electrical type semiconductor layer 101 , a second electrical type semiconductor layer 102 , an active layer 103 , a first electrode 104 , a second electrode 105 and an optical conversion material 106 .

[0112] The active layer 103 is located between the first electrical semiconductor layer 101 and the second electrical semiconductor layer 102, and is in electrical contact with the first electrical semiconductor layer 101 and the second electrical semiconductor layer 102. The first electrical semiconductor layer 101, the second electrical semiconductor layer 102 and the active layer 103 may be an epitaxial stack structure formed by a deposition technique, such as an organic metal chemical vapor deposition technique.

[0113] For example, in some embodiments of the present specification, the first electrical semiconductor layer 101 and the second electrical semiconductor layer 102 can be an n-type semiconductor layer and a p-type semiconductor layer, respectively; the active layer 103 can be a multiple quantum well structure including multiple semiconductor nanostructures, such as semiconductor nanotubes, nanorods, and nano-particles.

[0114] The materials constituting such an epitaxial stack structure include: aluminum indium gallium nitride (AlGaInN) or gallium nitride (GaN). In this embodiment, the first electrical semiconductor layer 101 may include an n-type electrical gallium nitride layer; the second electrical semiconductor layer 102 may include a p-type electrical gallium nitride layer; and the active layer 103 is a multiple quantum well structure having gallium nitride.

[0115] The first electrical semiconductor layer 101 has a light emitting surface 101a and includes a plurality of regularly arranged three-dimensional structures, which together define at least one chamber (e.g., a plurality of chambers 108) extending from the light emitting surface 101a toward the active layer 103, and a depth D of each chamber 108 is substantially greater than 70% of a thickness T of the first electrical semiconductor layer 101.

[0116] In some embodiments of the present specification, the plurality of three-dimensional structures include a plurality of regularly arranged protrusions 107 of substantially the same size and shape, and a spacing P is provided between two adjacent protrusions 107 , and the spacing P is substantially 1.5 to 5 times the diameter d of the protrusions 107 .

[0117] For example, in this embodiment, Figure 1A As shown, the plurality of convex pillars 107 are arranged in a honeycomb pattern, with seven convex pillars 107 forming an arrangement unit 107U, and the axes of the convex pillars 107 are arranged at the center and six vertices of a hexagonal pattern to form an arrangement unit 107U; and the plurality of arrangement units 107U are then packed in a two-dimensional hexagonal pattern in the same manner, thereby defining a plurality of regularly arranged cavities 108 on the light-emitting surface 101a of the first electrical semiconductor layer 101. For example, the cavity 108 may be a space defined by (surrounded by) the six vertices of each arrangement unit 107U and the central convex pillar 107.

[0118] The diameter d of the protrusion 107 is between about 0.5 micrometers (μm) and 2 micrometers. The spacing P between the axes 107a of two adjacent protrusions 107 is 2 to 3 times the diameter d of the protrusion 107. Each cavity 108 defined by a plurality of three-dimensional structures (e.g., two adjacent protrusions 107) has a bottom surface 108a, and a distance h substantially less than 1 micrometer is between the bottom surface 108a and the active layer 103, so that the depth D of each cavity 108 is substantially between 2 micrometers and 3 micrometers.

[0119] In addition, each of the protrusions 107 has a circular cross section (eg, Figure 1A As shown), and a rectangular (long strip) longitudinal section parallel to the stacking direction F, each chamber 108 has a rectangular (long strip) longitudinal section parallel to the stacking direction F (as shown Figure 1B shown).

[0120] However, it is worth noting that the shape and arrangement of the three-dimensional structure (e.g., multiple convex pillars 107) are not limited to this, and any three-dimensional structure that can define multiple regularly arranged cavities 108 on the light-emitting surface 101a of the first electrical semiconductor layer 101 does not deviate from the spirit of this specification. For other forms of three-dimensional structures, please refer to the following embodiments.

[0121] The first electrode 104 is in electrical contact with the first electrical semiconductor layer 101. The second electrode 105 is in electrical contact with the second electrical semiconductor layer 102. In some embodiments of the present specification, one end of the first electrode 104 is located on the side of the second electrical semiconductor layer 102 away from the active layer 103; the other end passes through the second electrical semiconductor layer 102 and the active layer 103 to be in electrical contact with the first electrical semiconductor layer 101, but is electrically isolated from the second electrical semiconductor layer 102 and the active layer 103. The second electrode 105 is also located on the side of the second electrical semiconductor layer 102 away from the active layer 103, and is directly in electrical contact with the second electrical semiconductor layer 102.

[0122] The materials constituting the first electrode 104 and the second electrode 105 may be the same or different. In some embodiments, the materials constituting the first electrode 104 and the second electrode 105 may be selected from the group consisting of indium (In), aluminum (Al), titanium (Ti), gold (Au), tungsten (W), aluminum (Al), neodymium (Nd), palladium (Pd), platinum (pt), zirconium (Zr), nickel / silicon (Ni / Si), indium tin (InSn), titanium nitride (TiN), tungsten silicide (WSi), platinum indium (PtIn2), zirconium nitride ( / ZrN) and combinations thereof.

[0123] The optical conversion material 106 is filled in each cavity 108. In some embodiments of the present specification, the optical conversion material 106 can be a photoluminescent fluorescent material, a quantum dot material, a luminescent dye, or a combination thereof. For example, in one embodiment, the light emitted by the active layer 103 can be converted into a red light R having a wavelength substantially between about 570 nanometers (nm) and 750 nanometers after passing through the optical conversion material 106. In another embodiment, the light emitted by the active layer 103 can be converted into a green light (not shown) having a wavelength substantially between about 495 nanometers (nm) and 570 nanometers after passing through the optical conversion material 106.

[0124] In this embodiment, the optical conversion material 106 fills the cavity 108 (the gap between two adjacent protrusions 107) defined by a plurality of three-dimensional structures, and extends beyond the light-emitting surface 101a of the first electrical semiconductor layer 101, thereby entirely covering the first electrical semiconductor layer 101, the active layer 103 and the second electrical semiconductor layer 102.

[0125] By filling the optical conversion material 106 in each cavity 108, the reaction probability between the light emitted by the active layer 103 and the optical conversion material 106 can be increased without increasing the overall thickness of the optical conversion material 106 in the electroluminescent element 100 or increasing the concentration of quantum dots in the optical conversion material 106, thereby improving the light absorption / conversion efficiency, effectively reducing the manufacturing cost, and facilitating the miniaturization and thinning of the electroluminescent element 100.

[0126] Please refer to Figure 2A and Figure 2B , Figure 2A is a top view of an electroluminescent element 200 according to another embodiment of the present specification; Figure 2B It is along Figure 2A The cross-sectional structure diagram of the electroluminescent device 200 is shown along the cut line S2. The structure of the electroluminescent device 200 is substantially similar to that of the electroluminescent device 100, and the main difference is that the three-dimensional structure of the first electrical semiconductor layer 201 is configured differently.

[0127] In some embodiments of the present specification, the three-dimensional structure of the first electrical semiconductor layer 201 includes a plurality of regularly arranged concave chambers 207 of substantially the same size and shape, and a spacing P is provided between the central axes 207a of adjacent concave chambers 207, and the spacing P is substantially 1.5 to 5 times the diameter d of the concave chamber 207. In the present embodiment, the diameter d of the concave chamber 207 is between about 0.5 micrometers and 2 micrometers. The spacing P between the axes 207a of two adjacent concave chambers 207 is 2 to 3 times the diameter d of the concave chamber 207.

[0128] like Figure 2A As shown, each recess 207 has a polygonal cross section (e.g., a hexagonal cross section, but not limited thereto) perpendicular to the stacking direction F of the active layer 103, the first electrical type semiconductor layer 201, and the second electrical type semiconductor layer 102, and a rectangular longitudinal cross section (e.g., a long strip longitudinal cross section, but not limited thereto) parallel to the stacking direction F, so that each recess 207 defines a chamber 208 (e.g., Figure 2B shown).

[0129] The optical conversion material 206 is not only filled in the recessed chamber 207 (cavity 208), but also extends to cover the light emitting surface 201a of the first electrical semiconductor layer 201, but does not entirely cover the first electrical semiconductor layer 201, the active layer 103, and the second electrical semiconductor layer 102. By filling the optical conversion material 206 in each cavity 208, the reaction probability of the light emitted by the active layer 103 and the optical conversion material 206 can be increased without increasing the overall thickness of the optical conversion material 206 in the electroluminescent element 200 or increasing the concentration of quantum dots in the optical conversion material 206, thereby improving the absorption / conversion efficiency of the light, effectively reducing the manufacturing cost, and facilitating the miniaturization and thinning of the electroluminescent element 200.

[0130] Please refer to Figure 3 , Figure 3 FIG. 2 is a schematic cross-sectional view of an electroluminescent element 300 according to another embodiment of the present specification. The structure of the electroluminescent element 300 is substantially similar to that of the electroluminescent element 200 , with the main difference being that the electroluminescent element 300 may optionally include a metal reflective layer 309 .

[0131] In this embodiment, the metal reflective layer 309 is located outside the light emitting surface 201a of the first electrical semiconductor layer 201, and is used to reflect the external ambient light incident from the outside of the light emitting surface 201a to the inside of the first electrical semiconductor layer 201, and reflect a portion of the light emitted by the active layer 103. The metal reflective layer 309 has at least one (in this embodiment, multiple) through holes 309a, and each through hole 309a is aligned with a corresponding cavity 208. The optical conversion material 306 is only filled in the recess 207 (cavity 208), and does not extend beyond the through hole 309a of the metal reflective layer 309.

[0132] After passing through the optical conversion material 306, most of the light (e.g., blue light) emitted by the active layer 103 can be converted into green light having a wavelength substantially between about 495 nanometers (nm) and 570 nanometers. Part of the green light and part of the unconverted blue light are emitted to the outside of the light-emitting surface 301a through the through hole 309a at a divergence angle of, for example, less than 5°; another part of the unconverted blue light and another part of the green light are reflected by the metal reflective layer 309 and return to the optical conversion material 306 and the first electrical semiconductor layer 201, and can still be emitted to the outside of the light-emitting surface 201a through the through hole 309a after multiple reflections. Through the reflection of the metal reflective layer 309, the reaction probability of the light emitted by the active layer 103 and the optical conversion material 306 can be increased, thereby improving the conversion efficiency of the green light.

[0133] Please refer to Figure 4 , Figure 4 1 is a schematic cross-sectional view of an electroluminescent element 400 according to another embodiment of the present specification. The structure of the electroluminescent element 400 is similar to that of the electroluminescent element 300, and the main difference is that the three-dimensional structure of the first electrical semiconductor layer 401 is different.

[0134] In this embodiment, the three-dimensional structure of the first electrical semiconductor layer 401 includes a plurality of recessed chambers 407 of substantially the same size and shape and arranged regularly, each recessed chamber 407 has a stacking direction F parallel to the active layer 103, the first electrical semiconductor layer 401, and the second electrical semiconductor layer 102, and extends downward from the light-emitting surface 401a of the first electrical semiconductor layer 401, and has a wedge-shaped longitudinal cross section that is wide at the top and narrow at the bottom, so that each recessed chamber 407 defines a cavity 408 accordingly. The optical conversion material 406 is only filled in the recessed chamber 407 (cavity 408) and does not extend beyond the through hole 409a of the metal reflective layer 409.

[0135] Please refer to Figure 5 , Figure 5 1 is a schematic cross-sectional view of an electroluminescent element 500 according to another embodiment of the present specification. The structure of the electroluminescent element 500 is similar to that of the electroluminescent element 300, and the main difference is that the three-dimensional structure of the first electrical semiconductor layer 501 is different.

[0136] In this embodiment, the three-dimensional structure of the first electrical semiconductor layer 501 also includes a plurality of recessed chambers 507 of substantially the same size and shape and arranged regularly, each recessed chamber 507 having a stacking direction F parallel to the active layer 103, the first electrical semiconductor layer 301 and the second electrical semiconductor layer 102, and having an arc-shaped longitudinal section extending downward from the light-emitting surface 501a of the first electrical semiconductor layer 501, so that each recessed chamber 507 correspondingly defines a cavity 508. The optical conversion material 506 is only filled in the recessed chamber 507 (cavity 508) and does not extend beyond the through hole 509a of the metal reflective layer 509.

[0137] Please refer to Figure 6 , Figure 6 2 is a schematic cross-sectional view of an electroluminescent element 600 according to yet another embodiment of the present specification. The structure of the electroluminescent element 600 is similar to that of the electroluminescent element 200, with the main difference being that the structure of the cavity 608 for filling the optical conversion material 606, the first electrode 60 active layer 603 and the second electrical semiconductor layer 602 are different.

[0138] In this embodiment, the three-dimensional structure of the first electrical semiconductor layer 601 includes a plurality of recessed chambers 607 of substantially the same size and shape and arranged regularly, each recessed chamber 607 has a stacking direction F parallel to the active layer 603, the first electrical semiconductor layer 601 and the second electrical semiconductor layer 602, and extends downward from the light-emitting surface 601a of the first electrical semiconductor layer 601, through the first electrical semiconductor layer 601 and the active layer 603, and partially extends into the second electrical semiconductor layer 602 (but does not penetrate the second electrical semiconductor layer 602), so that each recessed chamber 607 defines a cavity 608 accordingly. The optical conversion material 606 is only filled in the recessed chamber 607 (cavity 608) and does not extend beyond the through hole 609a of the metal reflective layer 609.

[0139] The first electrode 604 is disposed on a side of the metal reflective layer 609 away from the light emitting surface 601a of the first electrical semiconductor layer 601, and is in electrical contact with the first electrical semiconductor layer 601 through the metal reflective layer 609. The second electrode 605 is disposed on a side of the second electrical semiconductor layer 602 away from the active layer 603, and is in direct contact with the second electrical semiconductor layer 602. In this embodiment, the first electrode 601 may be a transparent electrode layer including indium tin oxide (ITO). The second electrode 605 may be a metal reflective layer.

[0140] The electroluminescent element 100, 200, 300, 400, 500 or 600 described above may be a light emitting diode element and may be applied to the manufacture of the display device 70. For example, please refer to Figure 7 , Figure 7 FIG. 1 is a schematic cross-sectional view of a display device 70 according to an embodiment of the present specification. In the present embodiment, the display device 70 is a device that uses a plurality of Figure 2A and Figure 2B The electroluminescent element 200 is made of light-emitting units (for example, the first light-emitting unit 73 and the second light-emitting unit 74) with the same structure.

[0141] The display device 70 includes a circuit substrate 71, at least one reflective baffle (e.g., multiple reflective baffles 72), a first light-emitting unit 73, a second light-emitting unit 74, and a third light-emitting unit 75. The circuit substrate 71 includes a substrate 71a and a circuit layer 71b located thereon. The reflective baffles 72 are located on the circuit substrate 71, and each reflective baffle 72 has at least one side wall 72s that is substantially perpendicular to the surface 71s of the circuit substrate 71, and together with the surface 71s of the circuit substrate 71, defines multiple accommodation spaces (e.g., accommodation spaces 76a, 76b, and 76c).

[0142] The first light-emitting unit 73 and the second light-emitting unit 74 have the same structure as the above-mentioned electroluminescent element 200. The first light-emitting unit 73 is located in the accommodation space 76a; the second light-emitting unit 74 is located in the accommodation space 76b; the third light-emitting unit 705 is located in the accommodation space 76c, and the first light-emitting unit 73, the second light-emitting unit 74, and the third light-emitting unit 75 are respectively electrically connected to the circuit layer 71b located above the base material 71b of the circuit substrate 71.

[0143] The light emitted by the active layer 103 in the first light emitting unit 73 and the second light emitting unit 74 is blue light. The optical conversion material filled in the cavity 208 of the first light emitting unit 73 is a red optical conversion material 77R that can convert blue light into red light; the optical conversion material filled in the cavity 208 of the second light emitting unit 74 is a green optical conversion material 77G that can convert blue light into green light; the third light emitting unit 705 is a light emitting diode element that can emit blue light.

[0144] The accommodation spaces 76a, 76b and 76c are filled with a light-transmitting material 78, and cover the first light-emitting unit 73, the second light-emitting unit 74 and the third light-emitting unit 75. A transparent passivation protective layer 79 is also included on the light-transmitting material 78. The red light, green light and blue light emitted by the first light-emitting unit 73, the second light-emitting unit 74 and the third light-emitting unit 75 are emitted outward from the openings 76o of the accommodation spaces 76a, 76b and 76c respectively. The first light-emitting unit 73, the second light-emitting unit 74 and the third light-emitting unit 75 can constitute a pixel unit of the display device 70.

[0145] Please refer to Figure 8 , Figure 8 FIG. 8 is a cross-sectional view of a display device 80 according to another embodiment of the present specification. The structure of the display device 80 is similar to that of the display device 70, with the main difference being the shape of the reflective baffle 82 and the materials filled in the accommodating spaces 86a, 86b and 86c.

[0146] In this embodiment, each reflective baffle 82 of the display device 80 has at least one side wall 82s that forms an angle δ substantially between 45° and 60° with the surface 71s of the circuit substrate 71. The accommodation space 86a is filled with a red optical conversion material 77R and covers the first light-emitting unit 73; the accommodation space 86b is filled with a green optical conversion material 77G and covers the second light-emitting unit 74; and the accommodation space 86c is filled with a light-transmitting material 78 and covers the third light-emitting unit 75.

[0147] Please refer to Fig. 9 , Fig. 9FIG. 1 is a schematic diagram of a cross-sectional structure of a display device 90 according to another embodiment of the present specification. The structure of the display device 90 is roughly similar to that of the display device 80, with the main difference being that the light emitted by the active layer 103 in the first light-emitting unit 93 and the second light-emitting unit 94 is ultraviolet light. The accommodating spaces 76a, 76b, and 76c are filled with a light-transmitting material 78 covering the first light-emitting unit 93, the second light-emitting unit 94, and the third light-emitting unit 75. The light-transmitting material 78 also includes an ultraviolet light filter layer (VU cut) 99 for filtering a portion of the light (ultraviolet light) that is not converted into red light and green light by the red optical conversion material 77R and the green optical conversion material 77G.

[0148] According to the above embodiments, this specification provides an electroluminescent element and a display device using the same. In the electroluminescent element, a plurality of three-dimensional structures are regularly arranged in the semiconductor layer on the light-emitting surface side to jointly define at least one cavity extending from the light-emitting surface to the active layer, so that the depth of the cavity is substantially greater than 70% of the thickness of the first electrical semiconductor layer, and an optical conversion material is filled in the cavity.

[0149] By filling the cavity in the semiconductor layer with the optical conversion material, the reaction probability between the light emitted by the active layer of the electroluminescent element and the optical conversion material can be increased without increasing the overall thickness of the optical conversion material or increasing the concentration of quantum dots contained in the optical conversion material, thereby improving the light absorption / conversion efficiency and effectively reducing the manufacturing cost. At the same time, the miniaturization of the electroluminescent element is taken into account and the demand for thinning the display device using the electroluminescent element is met.

[0150] Although the present invention is disclosed in conjunction with the above preferred embodiments, they are not intended to limit the present invention. Any ordinary technician in the technical field may make slight changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the attached claims.

Claims

1. An electroluminescent element, comprising: A first electrical semiconductor layer; A second electrical type semiconductor layer; An active layer, located between the first electrical type semiconductor layer and the second electrical type semiconductor layer, and electrically contacting the first electrical type semiconductor layer and the second electrical type semiconductor layer; The first electrical semiconductor layer has a light-emitting surface located on the opposite side of the active layer, and the first electrical semiconductor layer includes a continuous bottom and a plurality of three-dimensional structures regularly arranged on the bottom, which together define at least one cavity extending from the light-emitting surface toward the active layer, and the at least one cavity has a depth substantially greater than 70% of the thickness of the first electrical semiconductor layer; A first electrode electrically contacting the first electrical type semiconductor layer; A second electrode electrically contacting the second electrical type semiconductor layer; as well as An optical conversion material is filled in the at least one cavity, wherein the multiple three-dimensional structures include a first three-dimensional structure and a second three-dimensional structure that are spaced apart from each other, the side walls of the first three-dimensional structure and the second three-dimensional structure that are close to each other and the side walls that are far away from each other are covered by the optical conversion material, and the light emitted by the active layer is converted into light of the same color after passing through the optical conversion material.

2. The electroluminescent device as claimed in claim 1, wherein the first electrical semiconductor layer comprises an n-type electrical gallium nitride (GaN) layer; the second electrical semiconductor layer comprises a p-type electrical gallium nitride layer; and the active layer comprises a multiple-quantum well (MQW) structure.

3. The electroluminescent element as claimed in claim 1, wherein the plurality of three-dimensional structures comprise a plurality of convex columns or a plurality of concave chambers which are substantially the same in size and regularly arranged; and the at least one chamber is located between the plurality of convex columns or is at least one of the plurality of concave chambers. 4 . The electroluminescent element as claimed in claim 3 , wherein there is a distance between two adjacent ones of the plurality of convex pillars or the plurality of concave chambers, and the distance is substantially 1.5 to 5 times of the diameter of the plurality of convex pillars or the plurality of concave chambers. 5 . The electroluminescent device as claimed in claim 3 , wherein the plurality of protrusions or the plurality of recesses are arranged in a honeycomb pattern. 6 . The electroluminescent device as claimed in claim 1 , wherein the at least one cavity has a longitudinal section parallel to a stacking direction of the active layer, the first electrical semiconductor layer and the second electrical semiconductor layer, and the longitudinal section is strip-shaped, wedge-shaped or arc-shaped. 7 . The electroluminescent device as claimed in claim 1 , wherein the at least one cavity has a bottom surface, a distance between the bottom surface and the active layer is substantially less than 1 μm, and the depth is substantially between 2 μm and 3 μm. 8 . The electroluminescent device as claimed in claim 1 , wherein the at least one cavity passes through the active layer and the first electrical semiconductor layer, and extends into the second electrical semiconductor layer. 9 . The electroluminescent device as claimed in claim 1 , further comprising a metal reflective layer located on the light emitting surface, and the metal reflective layer has at least one through hole aligned with the at least one cavity.

10. A display device comprising: Circuit board; At least one reflective bank is located on the circuit substrate and defines a plurality of accommodation spaces together with the circuit substrate; A first light emitting unit having the same structure as the electroluminescent element as claimed in any one of claims 1 to 9, and located in a first of the plurality of accommodating spaces, and emitting red light; A second light emitting unit has the same structure and is located in a second one of the plurality of accommodating spaces and emits green light; as well as The third light emitting unit is located in a third one of the plurality of accommodating spaces and emits blue light.

11. The display device as claimed in claim 10, wherein the first, the second and the third of the plurality of accommodating spaces are filled with a light-transmitting material, and the sidewall of the at least one reflective baffle wall and the surface of the circuit substrate used to jointly define the plurality of accommodating spaces are substantially perpendicular to each other. 12 . The display device as claimed in claim 10 , wherein a side wall of the at least one reflective baffle wall for jointly defining the plurality of accommodating spaces forms an angle substantially between 45° and 60° with the surface of the circuit substrate.

13. The display device according to claim 12, wherein: The first of the plurality of accommodating spaces is filled with a red optical conversion material; The second one of the plurality of accommodating spaces is filled with a green optical conversion material; and The third one of the plurality of accommodating spaces is filled with a light-transmitting material. 14 . The display device as claimed in claim 10 , wherein the first active layer of the first light emitting unit and the second active layer of the second light emitting unit emit ultraviolet light respectively.

15. The display device as claimed in claim 13, further comprising an ultraviolet filter layer (VU cut).

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