TWI893118B - Light-emitting device and display device having the same - Google Patents

Abstract

A light-emitting device includes: a semiconductor stack; and a filter on the semiconductor stack, wherein the filter includes a first surface facing the semiconductor stack and a second surface opposite to the first surface; wherein: the light-emitting device emits a light; the light includes a first light within a first direction, and the first light has a first full width at half maximum (FWHM); and a second light within a second direction, and the second light has a second FWHM; the angle between the first direction and a normal vector of the second surface is between 45-90 degrees and the angle between the second direction and the a normal vector of the second surface is between 0-30 degrees; and the second FWHM is smaller than the first FWHM.

Description

Light-emitting element and display device

The present invention relates to a light-emitting element and a display device, and in particular to a light-emitting element having a filter layer and a display device having the light-emitting element.

Light-emitting diodes (LEDs), a type of solid-state light-emitting device, offer advantages such as low power consumption, high brightness, excellent color rendering, and a compact size, making them widely used in various lighting and display devices. For example, as pixels in display devices, LEDs can replace traditional liquid crystal displays (LCDs) and achieve higher-quality displays. When LEDs are used in display devices, maintaining their photoelectric properties while improving the display quality is one of the research and development goals of researchers in this field.

A light-emitting element comprises: a semiconductor stack; and a filter layer disposed on the semiconductor stack, comprising a first surface facing the semiconductor stack and a second surface opposite the first surface. The light-emitting element emits light; the light includes light in a first direction having a first half-height width (WHM); and light in a second direction having a second half-height width (WHM). The angle between the first direction and a normal to the second surface is between 45 and 90 degrees, and the angle between the second direction and the normal to the second surface is between 0 and 30 degrees. The second half-height width (WHM) is smaller than the first half-height width (WHM).

A light-emitting element comprises: a semiconductor stack emitting a first light ray; and a filter layer disposed on the semiconductor stack, comprising a first surface facing the semiconductor stack and a second surface opposite the first surface. The first light ray passes through the filter layer to produce a second light ray. The first light ray has a first half-height width (WWHM), and the second light ray has a second half-height width (WWHM). The second half-height width (WWHM) is smaller than the first half-height width (WWHM), and/or the second light ray has a half-height width (WWHM) of less than or equal to 25 nm.

A light-emitting device comprises: a semiconductor stack that emits a first light ray; and a filter layer disposed on the semiconductor stack, comprising a first surface facing the semiconductor stack and a second surface opposite the first surface; wherein: the filter layer comprises a first dielectric material layer and a second dielectric material layer alternately stacked; the first light ray passes through the filter layer to obtain a second light ray; and the light-emitting device has a divergence angle ranging from 50 degrees to 110 degrees.

1, 2, 3, 4, 5, 9: Light-emitting elements

6, 6': Light-emitting element package

8a, 8b: Circuit bonding pads

10:Substrate

10a: First surface of substrate

10b: Second surface of substrate

11a, 11b: Light-emitting unit

101: Display device

201: Sensing module

110: Circuit layer

130: Data line driver circuit

140: Scanning line drive circuit

12: Semiconductor stacking

121: First semiconductor layer

121a: First surface

121b: Second surface

122: Second semiconductor layer

122a: Surface of the second semiconductor layer

123: Active layer

16: Reflective Structure

18:Transparent conductive layer

20, 20’, 20”: First electrode

30, 30’, 30”: Second electrode

26: Protective layer

261, 262: Protective layer opening

36: Insulating layer

40: Light sensor element

50, 50': Filter layer

50a: First sublayer

50b: Second sublayer

50c: Third sublayer

50d: Fourth sublayer

50e, 50e’: Filter surface

501, 502: Openings

60: Connecting electrodes

80: Light blocking element

81, 83: Electrode

90: Packaging materials

200: Display substrate

210: Display area

220: Non-display area

400: Carrier board

PX: Pixel

PX_A, PX_B, PX_C: sub-pixels

P1, P2: Light path

Figure 1 shows the light-emitting element 1 according to the first embodiment of this application.

Figures 2A and 2B show a partially enlarged cross-sectional view of a filter layer in a light-emitting element according to an embodiment of this application.

[Figure 3] shows the experimental results simulated according to an embodiment of this application.

Figure 4 shows the light-emitting element 2 according to the second embodiment of this application.

Figure 5 shows the light-emitting element 3 according to the third embodiment of this application.

[Figure 6] shows the light-emitting element 4 according to the fourth embodiment of this application.

Figures 7A and 7B show the light-emitting element 5 according to the fifth embodiment of this application.

Figures 8A to 8C show experimental comparisons of the light-emitting device 3 according to the third embodiment of this application and a comparative light-emitting device.

Figure 9 shows the wavelength and light intensity measured at different angles by the light-emitting element 3 according to the third embodiment of this application.

Figure 10A shows a schematic top view of a display device 101 according to an embodiment of the present application.

Figure 10B shows a schematic cross-sectional view of a pixel PX according to an embodiment of this application.

[Figure 10C] shows a schematic cross-sectional view of a light-emitting device package according to an embodiment of this application.

Figure 11 shows the light-emitting element 9 according to the sixth embodiment of this application.

Figure 12 shows a schematic diagram of the optical path of the light-emitting element 9 according to the sixth embodiment of this application.

Figure 13 shows the light intensity distribution of the light-emitting element 9 of the sixth embodiment and the light-emitting element of the comparative example.

Figure 14 shows a schematic cross-sectional view of a sensing module according to an embodiment of this application.

Below, exemplary embodiments of the present invention are described in detail with reference to the accompanying diagrams, enabling those skilled in the art to fully understand the spirit of the present invention. The present invention is not limited to the following embodiments and may be implemented in other forms. Throughout this specification, identical symbols denote components having identical or similar structures, functions, and principles, which can be inferred by those skilled in the art based on the teachings of this specification. For the sake of brevity, components with identical symbols will not be repeated.

Figure 1 shows a cross-sectional view of a light-emitting device 1 according to the first embodiment of this application. As shown in Figure 1 , the light-emitting device 1 comprises a substrate 10, a semiconductor stack 12 disposed on a first surface 10a of the substrate, and a first semiconductor layer 121, an active layer 123, and a second semiconductor layer 122, sequentially formed on the first surface 10a. The first semiconductor layer 121 has a first surface 121a uncovered by the active layer 123 and the second semiconductor layer 122. A transparent conductive layer 18 is disposed on the second semiconductor layer 122, a first electrode 20 is disposed on the first surface 121a of the first semiconductor layer, and a second electrode 30 is disposed on the transparent conductive layer 18. The filter layer 50 is located on the semiconductor stack 12. A reflective structure 16 is provided on the second surface 10b of the substrate 10, which is opposite to the first surface 10a.

Substrate 10 can be a growth substrate, including a gallium arsenide (GaAs) substrate and a gallium phosphide (GaP) substrate for growing gallium indium phosphide (AlGaInP), or a sapphire ( _Al2O3 ) substrate, a gallium nitride (GaN) substrate, a silicon carbide (SiC) substrate, and an aluminum nitride (AlN) substrate for growing indium gallium nitride ( _InGaN ) or aluminum gallium nitride (AlGaN). Substrate 10 can be a patterned substrate, i.e., substrate 10 has a patterned structure (not shown) on its first surface 10a. In one embodiment, light emitted from semiconductor stack 12 can be refracted by the patterned structure of substrate 10, thereby increasing the brightness of the light-emitting device. In addition, the patterned structure reduces or suppresses the misalignment between the substrate 10 and the semiconductor stack 12 caused by lattice mismatch, thereby improving the epitaxial quality of the semiconductor stack 12.

In one embodiment of the present application, the method for forming the semiconductor stack 12 on the substrate 10 includes metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), hydrogenated vapor phase epitaxy (HVPE), or ion plating, such as sputtering or evaporation.

The semiconductor stack 12 further includes a buffer structure (not shown) between the substrate first surface 10a and the first semiconductor layer 121. The buffer structure, the first semiconductor layer 121, the active layer 123, and the second semiconductor layer 122 constitute the semiconductor stack 12. The buffer structure can reduce the aforementioned lattice mismatch and suppress dislocation, thereby improving epitaxial quality. The buffer layer is made of GaN, AlGaN, or AlN. In one embodiment, the buffer structure includes multiple sublayers (not shown). The sublayers may comprise the same material or different materials. In one embodiment, the buffer structure includes two sublayers, wherein the first sublayer is grown by sputtering, and the second sublayer is grown by MOCVD. In one embodiment, the buffer layer further includes a third sublayer. The third sublayer is grown by MOCVD, and the second sublayer is grown at a temperature higher or lower than the third sublayer. In one embodiment, the first, second, and third sublayers comprise the same material, such as AlN, or different materials, such as An, GaN, or AlGaN. In one embodiment of the present application, a first semiconductor layer 121 and a second semiconductor layer 122, such as cladding layers or confinement layers, have different conductivity types, electrical properties, polarities, or doping elements that provide electrons or holes. For example, the first semiconductor layer 121 is an n-type semiconductor, and the second semiconductor layer 122 is a p-type semiconductor. An active layer 123 is formed between the first and second semiconductor layers 121, 122. Electrons and holes combine in the active layer 123 under current drive, converting electrical energy into light energy, resulting in luminescence. The wavelength of light emitted by the light-emitting element 1 or the semiconductor stack 12 can be adjusted by changing the physical properties and chemical composition of one or more layers in the semiconductor stack 12.

The material of the semiconductor stack 12 includes a III-V semiconductor material _{of AlxInyGa (1-xy)} N or _{AlxInyGa (1-xy) P} , wherein 0 x,y 1; x + y 1. Depending on the material of the active layer, when the material of the semiconductor stack 12 is AlInGaP series, red light with a wavelength between 570nm and 780nm or yellow light with a wavelength between 550nm and 570nm can be emitted. When the material of the semiconductor stack 12 is InGaN series, blue light or deep blue light with a wavelength between 380nm and 490nm or green light with a wavelength between 490nm and 550nm can be emitted. The active layer 123 can be a single heterostructure (SH), a double heterostructure (DH), a double-side double heterostructure (DDH), or a multi-quantum well (MQW). The material of the active layer 123 can be an i-type, p-type, or n-type semiconductor.

The transparent conductive layer 18 is in electrical contact with the second semiconductor layer 122 to disperse current laterally. In another embodiment, the transparent conductive layer 18 may include an opening (not shown) below the second electrode 30, exposing the second semiconductor layer 122. The second electrode 30 may contact the second semiconductor layer 122 through the opening in the transparent conductive layer 18. The transparent conductive layer 18 may be a metal or a transparent conductive material. The metal may be selected from a thin, light-transmitting metal layer. The transparent conductive material is transparent to light emitted by the active layer 123 and includes materials such as graphene, indium tin oxide (ITO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), zinc oxide (ZnO), or indium zinc oxide (IZO).

The first electrode 20 is located on the first surface 121a of the first semiconductor layer and is electrically connected to the first semiconductor layer 121. The second electrode 30 is electrically connected to the second semiconductor layer 122. The first electrode 20 and the second electrode 30 each include a pad electrode. In FIG1 , the pad electrodes of the first electrode 20 and the second electrode 30 are shown for exemplary purposes only. In another embodiment, the first electrode 20 and/or the second electrode 30 further include finger electrodes (not shown) extending from the pad electrodes. The pad electrodes of the first electrode 20 and the second electrode 30 are used for wire bonding or soldering to electrically connect the light-emitting element 1 to an external power source or external electronic component. The materials of the first electrode 20 and the second electrode 30 include metals, such as chromium (Cr), titanium (Ti), gold (Au), aluminum (Al), copper (Cu), silver (Ag), tin (Sn), nickel (Ni), rhodium (Rh), or platinum (Pt), or alloys or stacks of the above materials.

In one embodiment, the light-emitting element 1 may further include a current blocking layer (not shown) located between the transparent conductive layer 18 and the second semiconductor layer 122, and/or between the first electrode 20 and the first semiconductor layer 121.

The filter layer 50 includes openings 501 and 502. In this embodiment, as shown in FIG1 , the filter layer 50 covers the semiconductor stack 12, the transparent conductive layer 18, and portions of the first electrode 20 and the second electrode 30. The filter layer 50 also exposes the first electrode 20 and the second electrode 30 through the openings 501 and 502, respectively. More specifically, the bonding pads of the first electrode 20 and the second electrode 30 are exposed. In another embodiment (not shown), the filter layer 50 does not cover the first electrode 20 and the second electrode 30. In another embodiment (not shown), the filter layer 50 covers the semiconductor stack 12 and the transparent conductive layer 18 and extends to partially below the first electrode 20 and the second electrode 30. The first electrode 20 and the second electrode 30 are electrically connected to the semiconductor stack 12 through openings 501 and 502 thereunder, respectively.

The filter layer 50 is formed by stacking one or more pairs of alternating layers of materials with different refractive indices, providing a filtering function for light within a specific wavelength range. When the light-emitting element 1 emits a single color, the filter layer 50 filters the light within the specific wavelength range, purifying the single-color light emitted by the light-emitting element 1. Furthermore, in one embodiment, the filter layer 50 also serves as a protective structure, protecting the light-emitting element by, for example, preventing moisture from entering the light-emitting element. In one embodiment, the selection of dielectric materials with different refractive indices and their thickness design create an interference effect, allowing light emitted by the light-emitting element to be selectively transmitted or reflected by the filter layer 50. Only light within the specific wavelength range can pass through the filter layer 50, achieving the filtering effect. The filter layer 50 can have a bandpass filtering function, a low-pass filtering function, or a high-pass filtering function.

Figure 2A shows a partially enlarged cross-sectional view of the filter layer 50. In this embodiment, as shown in Figure 2A, the filter layer 50 includes a first set of material stacks, which are composed of a first sublayer 50a and a second sublayer 50b stacked together. The first set of material stacks, for example, includes a dielectric material, with a first sublayer 50a and a second sublayer 50b forming a dielectric material pair. The first sublayer 50a has a higher refractive index than the second sublayer 50b. By selecting materials with different refractive indices and designing their thicknesses, light within a specific wavelength range is filtered. In one embodiment, the first sublayer 50a has a smaller thickness than the second sublayer 50b. Dielectric materials include, for example, silicon oxide, silicon nitride, silicon oxynitride, niobium oxide, niobium oxide, titanium oxide, magnesium fluoride, aluminum oxide, etc. In one embodiment, the filter layer 50 is, for example, a distributed Bragg reflector (DBR).

In one embodiment, the filter layer 50 may include layers other than the first sublayer 50a and the second sublayer 50b. For example, the filter layer 50 may further include a base layer (not shown) positioned between the first sublayer 50a (and/or the second sublayer 50b) and the semiconductor stack 12. In other words, the base layer is formed on the semiconductor stack 12 first, followed by the first sublayer 50a and the second sublayer 50b. In one embodiment, the base layer comprises a dielectric material and has a thickness greater than that of the first sublayer 50a and the second sublayer 50b. In one embodiment, the base layer is formed differently from the first sublayer 50a and the second sublayer 50b. For example, the base layer is formed by chemical vapor deposition (CVD), more preferably, by plasma enhanced chemical vapor deposition (PECVD). The first sublayer 50a and the second sublayer 50b are formed by sputtering. In one embodiment, the base layer may provide protection for the light-emitting element or the semiconductor stack, for example, by preventing moisture from entering the light-emitting element.

In another embodiment, as shown in FIG2B , the filter layer 50 includes multiple sets of material stacks. The first set of material stacks is composed of a first sublayer 50a and a second sublayer 50b stacked together, and the second set of material stacks is composed of a third sublayer 50c and a fourth sublayer 50d stacked together. The second set of material stacks may include, for example, a dielectric material, with the third sublayer 50c and the fourth sublayer 50d forming a dielectric material pair. The third sublayer 50c has a higher refractive index than the fourth sublayer 50d. In one embodiment, the third sublayer 50c is thinner than the fourth sublayer 50d. The third sublayer 50c has a different thickness than the first sublayer 50a. The third sublayer 50c and the first sublayer 50a can be made of the same material or different materials. The fourth sublayer 50d has a different thickness than the second sublayer 50b. The fourth sublayer 50d and the second sublayer 50b can be made of the same material or different materials.

In another embodiment, the filter layer 50 may further include an upper layer (not shown) located on the first sublayer 50a (and/or the second sublayer 50b) on the other side of the second semiconductor layer 122. In other words, the first sublayer 50a and the second sublayer 50b are first formed on the semiconductor stack 12, and then the upper layer is formed. The upper layer includes a dielectric material and has a thickness greater than that of the first sublayer 50a and the second sublayer 50b. In one embodiment, the upper layer is formed differently from the first sublayer 50a and the second sublayer 50b. For example, the upper layer is formed by chemical vapor deposition (CVD), more preferably, by plasma-assisted chemical vapor deposition (PECVD). The first sublayer 50a and the second sublayer 50b are formed by sputtering. In one embodiment, the upper layer can increase the strength of the entire filter layer 50. For example, when the filter layer 50 is subjected to external forces, the upper layer can prevent the filter layer 50 from being broken or damaged.

In another embodiment, the filter layer 50 includes a plurality of sets of material stacks and a bottom layer and/or an upper layer.

In another embodiment, before forming the filter layer 50, a dense layer (not shown) is formed on the surfaces of the transparent conductive layer 18 and the semiconductor stack 12 by atomic deposition to directly cover the semiconductor stack 12. The dense layer is made of silicon oxide, aluminum oxide, einsteinium oxide, tantalum oxide, zirconium oxide, yttrium oxide, tantalum oxide, silicon nitride, aluminum nitride, or silicon oxynitride. In this embodiment, the interface between the dense layer and the semiconductor stack 12 contains a metal element and oxygen, wherein the metal element includes aluminum, einsteinium, tantalum, zirconium, yttrium, tantalum, or tantalum. The dense layer has a thickness ranging from 50Å to 2000Å, preferably from 100Å to 1500Å. In one embodiment, the dense layer can be conformally formed on the semiconductor stack 12. Its film properties can provide better protection for the semiconductor stack 12, such as preventing moisture from entering the semiconductor stack 12 and facilitating adhesion between the filter layer 50 and the semiconductor stack 12.

In one embodiment, the filter layer 50 includes at least 4 and no more than 30 dielectric material pairs. When the number of dielectric material pairs is less than 4, the filtering effect is poor. When the number of dielectric material pairs is greater than 30, the manufacturing cost increases. Preferably, the filter layer 50 includes at least 8 and no more than 20 dielectric material pairs. Taking a filter layer 50 with a low-pass filtering function as an example, the filter layer 50 has a transmittance of more than 95% for light with a wavelength less than λ _on and a transmittance of less than 5% for light with a wavelength greater than λ _off . For wavelengths between λ _on and λ _off , the transmittance varies dramatically depending on the number of dielectric material pairs in the filter layer 50. In one embodiment, when the filter layer 50 includes eight or more dielectric material pairs, the difference between λ _off and λ _on can be less than or equal to 31 nm. When the filter layer 50 includes twelve or more dielectric material pairs, the difference between λ _off and λ _on can be less than or equal to 11 nm. In other words, a filter layer 50 containing twelve or more dielectric material pairs can have a narrower light transition band, thereby achieving more effective light filtering and purification. The low-pass filtering function of the filter layer 50 can filter out light emitted by the light-emitting element 1 within a specific wavelength range greater than λ _off , further achieving a light purification effect. Similarly, when the filter layer 50 has a high-pass filtering function, it has a transmittance of greater than 95% for light with a wavelength greater than λ _on and a transmittance of less than 5% for light with a wavelength less than λ _off . When the filter layer 50 has a bandpass filtering function, it has a transmittance of greater than 95% for light with a wavelength between λ _on1 and λ _on2 , a transmittance of less than 5% for light with a wavelength less than λ _off1 , and a transmittance of less than 5% for light with a wavelength greater than λ _off2 , where λ _off1 <λ _on1 <λ _on2 <λ _off2 .

The reflective structure 16 is located on the second surface 10b of the substrate to reflect the light emitted by the semiconductor stack 12, so that the light is mainly extracted through the upper surface of the light-emitting element 1 (i.e., the surface where the filter layer 50 is located). In one embodiment, the reflective structure 16 includes a metal reflective layer, wherein the metal material can be selected from materials with high reflectivity for the light emitted by the semiconductor stack 12, such as aluminum, silver, etc. In another embodiment, the reflective structure 16 may include a stacked structure, wherein the stacked structure includes a pair or a plurality of pairs of sub-layers with different refractive indices stacked alternately. The material of each sub-layer of the stacked structure includes a light-transmitting material, such as a conductive material or an insulating material. Conductive materials include metal oxides such as indium tin oxide (ITO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), zinc oxide (ZnO), or indium zinc oxide (IZO). Insulating materials include organic or inorganic materials, with inorganic materials including silica gel, glass, or dielectric materials. By selecting materials with different refractive indices and adjusting their thicknesses, the reflective structure 16 provides a reflective function for light within a specific wavelength range. In one embodiment, the reflective structure 16 is, for example, a distributed Bragg reflector (DBR). In another embodiment, the reflective structure 16 includes a dielectric material stack and a metal layer (not shown) to form an omnidirectional reflector (ODR). In another embodiment, the reflective structure 16 may be omitted.

The light emitted by the semiconductor stack 12, such as a first light, is a single-color light, such as blue, green, blue-green, yellow, or red. It passes through the filter layer 50 to obtain a second light having the same color as the first light. The second light is extracted from the top surface of the light-emitting element 1. The second light has a smaller full width at half maximum (FWHM) than the first light. In one embodiment, the second light obtained after passing through the filter layer 50 has the same color as the first light, and its peak wavelength is consistent with or similar to the peak wavelength of the first light, or the wavelength ranges of the first light and the second light overlap, and the second light has a smaller full width at half maximum (FWHM) than the first light. In one embodiment, a portion of the first light emitted by the semiconductor stack 12 passes through the filter layer 50 and is extracted from the top surface, i.e., the second light. Another portion of the first light is extracted from the side of the light-emitting element 1 without passing through the filter layer 50. The peak wavelength and half-height width of the light extracted from the side of the light-emitting element 1 without passing through the filter layer 50 are consistent with or similar to those of the first light. In one embodiment, for light with a peak wavelength of _λp nm, the filter layer 50 has a transmittance of greater than 80% at _λp nm, and more preferably, a transmittance of greater than 90%. The transmittance of the filter layer 50 is less than 50% for light with a wavelength greater than ( _λp + Δλ) nm, and/or less than 50% for light with a wavelength less than ( _λp - Δλ) nm. The Δλ can be determined based on the user's requirements for filtering effect and light intensity of the light-emitting element, and the filter layer 50 can be designed by selecting sub-layer materials with different refractive indices and their thicknesses.

Figure 3 shows the experimental results simulated according to an embodiment of the present application. In Figure 3, curve L1 represents the wavelength spectrum of the light actually emitted by semiconductor stack 12, which is the first light; curve F1 represents the transmittance of filter layer 50 for light of different wavelengths; and curve L2 represents the simulated wavelength spectrum obtained by combining semiconductor stack 12 with filter layer 50, that is, the simulated wavelength spectrum of the second light obtained after the first light passes through filter layer 50. In this experiment, the first light emitted by semiconductor stack 12 is green light with a peak wavelength of 532 nm. The filter layer 50 includes a plurality of dielectric material pairs composed of _SiO2 and _TiO2 , including three groups of dielectric material stacks. The first group of dielectric material stacks is closer to the semiconductor stack 12, the second group of dielectric material stacks is farther away from the semiconductor stack 12, and the third group of dielectric material stacks is located between the first and second groups of dielectric material stacks. The optical thickness of the first group of _SiO2 and _TiO2 dielectric material pairs is greater than the optical thickness of the third group of _SiO2 and _TiO2 dielectric material pairs; and the optical thickness of the second group of _SiO2 and _TiO2 dielectric material pairs is greater than and/or less than the optical thickness of the third group of _SiO2 and _TiO2 dielectric material pairs. The first set of _SiO2 and _TiO2 dielectric material pairs may include an integer or non-integer number of pairs, the second set of _SiO2 and _TiO2 dielectric material pairs may include an integer or non-integer number of pairs, and the third set of _SiO2 and _TiO2 dielectric material pairs may include an integer or non-integer number of pairs. The number of dielectric material pairs in the third set of dielectric material stacks is greater than the number of dielectric material pairs in the first and second sets of dielectric material stacks, respectively. By adjusting the thickness of the first and second sets of dielectric material stacks, the reduction in transmittance in certain wavelength ranges due to interference can be reduced.

As shown in Figure 3, filter layer 50 has a transmittance of over 80% at this peak wavelength; more preferably, filter layer 50 has a transmittance of over 90% at this peak wavelength. Filter layer 50 has a transmittance of less than 50% for light with a wavelength above 550nm and a transmittance of greater than or equal to 80% for light with a wavelength below 535nm. Furthermore, the first light passes through filter layer 50 to produce a second light. This second light is also green, but has a smaller half-height width than the first light. Filter layer 50 filters out light from the first light in a specific wavelength range. In this experiment, the filter layer 50, due to its low transmittance for the first light above 550 nm, filters out most of the light above 550 nm. This makes the wavelength spectrum of the second light symmetrical with that of the first light, resulting in a smaller half-width (WWHM) than that of the first light. In one embodiment, the WWHM of the second light is less than or equal to 25 nm. More preferably, the WWHM of the second light is less than or equal to 20 nm. This improves the color purity of the light emitted by the light-emitting element 1.

In another embodiment, filter layer 50 has a bandpass filter function for light with a peak wavelength of _λp nm, such as 532 nm green light. It has a transmittance of over 80% for this peak wavelength, less than 50% for light with a wavelength above 550 nm, and less than 50% for light with a wavelength below 510 nm. Filter layer 50 filters out most of the light with a wavelength above 550 nm and the light with a wavelength below 510 nm.

Figure 4 shows a cross-sectional view of a light-emitting element 2 according to the second embodiment of this application. Unlike light-emitting element 1, light-emitting element 2 includes a plurality of light-emitting units electrically connected in series. This embodiment uses a light-emitting element 2 having two light-emitting units 11a and 11b as an example. Light-emitting units 11a and 11b are separated from each other and located on a first surface 10a of a substrate. Light-emitting units 11a and 11b each include a semiconductor stack 12 and a transparent conductive layer 18. An insulating layer 36 is located between light-emitting units 11a and 11b, covering the first surface 10a of the substrate, the sidewalls of the first semiconductor layer 121 of light-emitting unit 11a, the sidewalls of the semiconductor stack 12 of light-emitting unit 11b, and a portion of the upper surface of the second semiconductor layer 122. Connecting electrode 60 is located on insulating layer 36. One end of the connecting electrode contacts the first semiconductor layer 121 of light-emitting cell 11a, and the other end contacts the transparent conductive layer 18 of light-emitting cell 11b. This electrically connects light-emitting cells 11a and 11b in series. In another embodiment, connecting electrode 60 electrically connects the first semiconductor layer 121 of light-emitting cells 11a and 11b, and/or the second semiconductor layer 122 of light-emitting cells 11a and 11b, allowing light-emitting cells 11a and 11b to form different light-emitting cell arrays, such as parallel, series, or a combination of series and parallel.

The first electrode 20 is located on the first semiconductor layer 121 of the light-emitting cell 11b, and the second electrode 30 is located on the second semiconductor layer 122 of the light-emitting cell 11a. The filter layer 50 covers the light-emitting cells 11a and 11b, the connecting electrode 60, and the first surface 10a of the substrate between the light-emitting cells 11a and 11b. Similar to the light-emitting element 1 of the first embodiment, the filter layer 50 of the light-emitting element 2 has openings 501 and 502, respectively, exposing the first electrode 20 and the second electrode 30. The function, structure, and materials of the filter layer 50 are as described above and will not be elaborated here. The first light emitted by the semiconductor stack 12 in the light-emitting element 2 passes through the filter layer 50 to produce the second light, which is then extracted from the top surface of the light-emitting element 2 (i.e., the surface where the filter layer 50 is located). The second light has the same color as the first light and a smaller half-height width than the first light. This improves the color purity of the light emitted by the light-emitting element 2. In one embodiment, the second light is green, and its half-height width is less than or equal to 25 nm. More preferably, the half-height width of the second light is less than or equal to 20 nm.

Figure 5 shows a cross-sectional view of a light-emitting device 3 according to the third embodiment of this application. Unlike light-emitting devices 1 and 2, light-emitting device 3 is a flip-chip device. Its first electrode 20' and second electrode 30' are connected to a carrier (not shown) via a flip-chip method. This allows light-emitting device 3 to interface with circuitry on the carrier (not shown) to facilitate connection to external electronic components or an external power source. Furthermore, unlike light-emitting devices 1 and 2, light-emitting device 3 has a filter layer 50 formed on the semiconductor stack 12 and located on the second surface 10b of the substrate. The function, structure, and materials of filter layer 50 are similar to those of the previous embodiments and will not be further described here.

The light-emitting element 3 includes a reflective structure 28 covering the transparent conductive layer 18. The reflective structure 28 may include a metal reflective layer, such as a single metal layer or a stack of multiple metal layers. In one embodiment, the reflective structure 28 includes a barrier layer (not shown) and a reflective layer (not shown). The barrier layer is formed overlying the reflective layer to prevent the migration, diffusion, or oxidation of the metal elements in the reflective layer. The reflective layer comprises a metal material with high reflectivity for light emitted by the semiconductor stack 12, such as silver (Ag), gold (Au), aluminum (Al), titanium (Ti), chromium (Cr), copper (Cu), nickel (Ni), platinum (Pt), ruthenium (Ru), or alloys or stacks of these materials. The barrier layer comprises chromium (Cr), platinum (Pt), titanium (Ti), tungsten (W), zinc (Zn), or alloys or stacks of these materials. Light emitted by the semiconductor stack 12 is reflected by the reflective structure 28 and extracted from the top surface of the light-emitting element 3 (i.e., the surface where the filter layer 50 is located), thereby increasing the brightness of the light-emitting element 3.

The light-emitting element 3 includes a protective layer 26 covering the semiconductor stack 12 and the sidewalls of the semiconductor stack 12. In one embodiment, the protective layer 26 may further cover the first surface 10a of the substrate. The protective layer 26 includes openings 261 and 262 that expose the first semiconductor layer 121 and the reflective structure 28, respectively. The material of the protective layer 26 is a non-conductive material, including organic materials such as Su8, benzocyclobutene (BCB), perfluorocyclobutane (PFCB), epoxy resin, acrylic resin, cycloolefin copolymer (COC), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polycarbonate (PC), polyetherimide or fluorocarbon polymer, or inorganic materials such as silicone, glass or dielectric materials, such as silicon oxide ( _SiOx ), silicon nitride (SiNx), silicon oxynitride ( _SiOxNy ), _niobium oxide _{( Nb2O5} ), ferrous oxide ( _HfO2 ), titanium oxide ( _{TiOx )} , etc. ), magnesium fluoride (MgF ₂ ), aluminum oxide (Al ₂ O ₃ ), etc. In one embodiment, the protective layer 26 is formed by alternating a stack of one or more pairs of materials with different refractive indices. By selecting materials with different refractive indices and designing their thicknesses, the protective layer 26 forms a reflective structure that reflects light within a specific wavelength range, such as a distributed Bragg reflector. When the protective layer 26 forms a reflective structure, light emitted from the semiconductor stack 12 is reflected by the protective layer 26 and removed from the top surface of the light-emitting element 3 (i.e., the surface where the filter layer 50 is located), thereby increasing the brightness of the light-emitting element 3.

In one embodiment, when the protective layer 26 is a reflective structure, the reflective structure 28 can be omitted.

The light-emitting element 3 includes a first electrode 20' and a second electrode 30'. The first electrode 20' is electrically connected to the first semiconductor layer 121 via an opening 261, and the second electrode 30' is electrically connected to the reflective structure 28, the transparent conductive layer 18, and the second semiconductor layer 122 via an opening 262. The first electrode 20' and the second electrode 30' comprise a metal material, such as chromium (Cr), titanium (Ti), tungsten (W), gold (Au), aluminum (Al), indium (In), tin (Sn), nickel (Ni), rhodium (Rh), platinum (Pt), or a stack or alloy of these materials. The first electrode 20' and the second electrode 30' can be composed of a single layer or multiple layers. For example, the first electrode 20' and the second electrode 30' may include Ti/Au, Ti/Pt/Au, Cr/Au, Cr/Pt/Au, Ni/Au, Ni/Pt/Au, or Cr/Al/Cr/Ni/Au, etc.

In another embodiment, the light-emitting element 3 may include a plurality of light-emitting units formed on a substrate 10. Similar to the light-emitting element 2, an insulating layer is formed between adjacent light-emitting units to electrically connect the plurality of light-emitting units via connecting electrodes. Subsequently, a protective layer 26, a first electrode 20', and a second electrode 30' are formed.

The first light emitted by the semiconductor stack 12 in the light-emitting element 3 passes through the substrate 10 and the filter layer 50, resulting in the second light, which is then extracted from the top surface of the light-emitting element 3 (i.e., the surface where the filter layer 50 is located). The second light has the same color as the first light and a smaller half-height width than the first light. This improves the color purity of the light emitted by the light-emitting element 3. In one embodiment, the second light is green, and its half-height width is less than or equal to 25 nm. More preferably, the half-height width of the second light is less than or equal to 20 nm.

Figure 6 shows a cross-sectional view of a light-emitting element 4 according to the fourth embodiment of this application. Light-emitting element 4 is similar to light-emitting element 3, except that it lacks a substrate 10. Instead, a filter layer 50 is located on the second surface 121b of the first semiconductor layer 121, with the second surface 121b opposing the first surface 121a. The function, structure, and materials of the filter layer 50 are similar to those of the previous embodiments and will not be further described here. The first light emitted by the semiconductor stack 12 in light-emitting element 4 passes through the filter layer 50 to produce the second light, which is then extracted from the top surface of light-emitting element 4 (i.e., the surface where the filter layer 50 is located). The second light has a smaller half-height width than the first light. This improves the color purity of the light emitted by light-emitting element 4. In one embodiment, the second light is green light, and its half-width is less than or equal to 25 nm. More preferably, the half-width of the second light is less than or equal to 20 nm.

FIG7A shows a cross-sectional view of a light-emitting element 5 according to the fifth embodiment of the present application. The light-emitting element 5 includes a first electrode 20″ and a second electrode 30″ disposed on two opposing surfaces 121b and 122a of the semiconductor stack 12, respectively, and electrically connected to the first semiconductor layer 121 and the second semiconductor layer 122, respectively. The filter layer 50 covers the side surfaces of the semiconductor stack 12 and the second surface 121b of the first semiconductor layer, and includes an opening 501 exposing the first electrode 20". In another embodiment (not shown), the filter layer 50 further covers the side surfaces of the first electrode 20", and the opening 501 exposes the top surface of the first electrode 20". In another embodiment, the first electrode 20" is located in the opening 501 and covers a portion of the surface 50e of the filter layer 50. In one embodiment, the light-emitting element 5 further includes a conductive contact layer and/or a conductive substrate (not shown) located between the second semiconductor layer 122 and the second electrode 30", and the semiconductor stack 12 is bonded to the conductive substrate using the conductive contact layer. In another embodiment, as shown in Figure 7B, the order of the semiconductor stack 12 is opposite to that of Figure 7A. The filter layer 50 covers the side surface of the semiconductor stack 12 and the second semiconductor layer surface 122a, and includes an opening 501 exposing the second electrode 30". The first light emitted by the semiconductor stack 12 in the light-emitting element 5 passes through the filter layer 50 to obtain the second light, which is extracted from the upper surface and side surface of the light-emitting element 5 (that is, the surface where the filter layer 50 is located). The second light has the same color as the first light and has a smaller half-height width than the first light. In this way, the color purity of the light emitted by the light-emitting element 5 can be improved. In one embodiment, the second light is green light, and its half-height width is less than or equal to 25nm. More preferably, the half-height width of the second light is less than or equal to 20nm. In another embodiment (not shown), the filter layer 50 covers the surface 121b or 122a of the semiconductor stack 12, but does not cover the side of the semiconductor stack 12. In one embodiment, when measuring the light-emitting devices of the aforementioned embodiments, to avoid interference from light that does not pass through the filter layer 50, such as light picked up by the side of the light-emitting device not covered by the filter layer 50, an optical measurement sleeve can be used to collect and measure the second light picked up by the filter layer 50.

In this technical field, the wavelength with the highest light intensity in the wavelength spectrum of a light-emitting element is defined as the peak wavelength. When measuring the color characteristics of a light ray, especially the color characteristics of visible light, the dominant wavelength (dominant wavelength) or chromaticity coordinates of the color light can be used to define it. Those skilled in the art can understand that light rays with the same peak wavelength do not necessarily have the same dominant wavelength, that is, they do not necessarily have the same color characteristics. The closer the dominant wavelength and the peak wavelength of a color light are, the higher the color purity of the color light. Compared to the prior art, the light-emitting element according to any embodiment of the present application has a dominant wavelength and a peak wavelength that are closer. For example, the difference between the dominant wavelength and the peak wavelength of the light emitted by the light-emitting element is less than 3nm, and more preferably, less than 2nm. Figures 8A to 8C show experimental comparisons between the light-emitting element 3 according to the third embodiment of this application and a comparative light-emitting element. The difference between light-emitting element 3 and the comparative light-emitting element is that the comparative light-emitting element does not include a filter layer 50. In this experiment, the filter layer 50 includes a stacked structure similar to that used in the simulation experiment shown in Figure 3. As shown in Figure 8A, both the comparative light-emitting element and light-emitting element 3 emit green light with similar peak wavelengths. However, the light emitted by light-emitting element 3 according to the third embodiment has a smaller half-height width than that of the comparative light-emitting element. Furthermore, the difference between the main wavelength and peak wavelength of the light emitted by light-emitting element 3 is 2.46 nm, which is smaller than the 8.63 nm difference between the main wavelength and peak wavelength of the light-emitting element in the comparative example. In other words, the color purity of the light emitted by light-emitting element 3 is higher.

Figure 8B shows the color gamut distribution of the BT.2020 (also known as Rec. 2020) color gamut standard on the CIE 1931 chromaticity coordinates, as well as the distribution of forward light from the comparative example light-emitting element and Light-emitting Element 3 on the CIE 1931 chromaticity coordinates. In Figures 8B and 8C, the light from the comparative example light-emitting element and Light-emitting Element 3 was collected and measured using an optical measuring tube. To clearly illustrate the measured chromaticity coordinate values, Figure 8C shows a partial magnification of area R in Figure 8B. Referring to Figure 8B, the BT.2020 color gamut standard defines the CIE 1931 chromaticity coordinates as follows: pure red is located at (0.708, 0.292), pure green is located at (0.17, 0.797), and pure blue is located at (0.131, 0.046). Compared to conventional technology, the light-emitting element according to any embodiment of the present application emits light with higher color purity, that is, closer to the pure color point coordinates in the aforementioned color gamut specification. Generally speaking, the closer a measured light source is to the color gamut boundary on the chromaticity coordinates (i.e., as shown by the horseshoe-shaped spectral trajectory in Figure 8B), the higher the color purity. Color purity can be expressed as a percentage, defined as the percentage of the straight line distance between the chromaticity coordinates of the measured light source and the white point light source (energy white point) on the CIE chromaticity coordinates to the chromaticity coordinate distance of the spectral trajectory of the main wavelength of the measured light source. Taking green light emitted by a light-emitting element in any embodiment of the present application with a peak wavelength between 525nm and 535nm as an example, this green light has a chromaticity coordinate value (X1, Y1) based on the CIE 1931 chromaticity coordinates, where X1 ≤ 0.2 and Y1 ≥ 0.75. Referring to FIG8C , Group_Ref_1 represents the data points measured for a comparative example light-emitting element emitting light with a peak wavelength of 530nm, Group_Ref_2 represents the data points measured for a comparative example light-emitting element emitting light with a peak wavelength of 532nm, Group_Exp_1 represents the data points measured for light-emitting element 3 emitting light with a peak wavelength of 530nm, and Group_Exp_2 represents the data points measured for light-emitting element 3 emitting light with a peak wavelength of 532nm. Compared to a comparative light-emitting element with the same peak wavelength, the green light emitted by the light-emitting element 3 according to the third embodiment is closer to the pure green coordinates (0.17, 0.797), exhibiting higher color purity. For example, for green light emitted by the light-emitting element of any embodiment of this application with a peak wavelength between 525nm and 535nm, the color purity is greater than or equal to 92%. More preferably, it is greater than or equal to 93%.

Figure 9 shows the wavelength and light intensity measured at different angles for the light-emitting element 3 according to the third embodiment of this application. In this experiment, the light-emitting element 3, as described in the aforementioned embodiment, has a filter layer 50 located on the second surface 10b of the substrate. The light emitted by the light-emitting element 3 includes both forward and side light. The forward light has a higher intensity than the side light, and the half-width at half-height of the forward light is smaller than the half-width at half-height of the side light. The light emitted by the light-emitting element 3 includes light emitted in a first direction, including light emitted via the side light, having a first half-width at half-height and a first intensity. The light emitted by the light-emitting element 3 includes light emitted in a second direction, including light emitted via the forward light, having a second half-width at half-height and a second intensity. In one embodiment, since the filter layer 50 is located on the second surface 10b of the substrate, the sidewall between the second surface 10b and the first surface 10a of the substrate is not covered with the filter layer 50. Therefore, the first-directional light rays measured when the angle between the first direction and the normal direction of the light extraction surface is in the range of 45-90 degrees includes light rays that are not extracted from the side surface of the light-emitting element 3 (e.g., the substrate sidewall) through the filter layer 50. The second-directional light rays measured when the angle between the second direction and the normal direction of the light extraction surface is in the range of 0-30 degrees include light rays that are emitted in the forward direction. In this experiment, relative to the first-directional light rays, the second half-height width of the second-directional light rays is less than the first half-height width and less than or equal to 25nm, and the second light intensity is greater than the first light intensity. The light extraction surface here refers to surface 50e of the filter layer 50 facing the semiconductor stack 12. The above experiments used a green light-emitting device as an example. However, the semiconductor stack of the light-emitting device according to any embodiment of this application can emit red, yellow, blue, or blue-green light. By designing the stack structure of the filter layer 50 according to these colors, purified red, yellow, blue, or blue-green light can be obtained, achieving the same effect as described above. Improving the color purity of the light from the light-emitting device, especially in the forward direction, through the filter layer 50 can be beneficial for specific product applications. For example, using a light-emitting device according to any embodiment of this application in a display device can achieve high color saturation, high contrast, and a wide color gamut.

The light emitted in the forward direction is the light extracted by the filter layer 50, which purifies the light generated by the semiconductor stack 12 by the filtering properties of the filter layer 50. In this embodiment, the light emitted in the side direction, for example, the light in the first direction includes the light not extracted by the filter layer 50, for example, the light extracted from the side of the light-emitting element, and has characteristics close to those of the light generated by the original semiconductor stack 12, for example, having a half-height width close to that of the light generated by the original semiconductor stack 12. However, the present application is not limited to this. In order to further reduce the impact of the side light not extracted by the filter layer 50 on light purification, in one embodiment, a modulation structure (not shown) can also be formed on the side of the light-emitting element according to any embodiment of the present application. In one embodiment, the modulation structure includes a reflective layer that reflects or redirects light directed toward the sides of the light-emitting element, converting it into forward-emitting light. In another embodiment, the modulation structure includes a light-absorbing layer that absorbs light directed toward the sides of the light-emitting element. In another embodiment, the modulation structure includes a filter layer, which functions similarly to filter layer 50 by allowing only light within a specific wavelength band to pass through. In another embodiment, the modulation structure includes a light-blocking layer that blocks light from exiting the sides of the light-emitting element. In one embodiment, the modulation structure can be used in conjunction with a back-end packaging module application. For example, the modulation structure can be disposed on the side of the light-emitting element in the package. The structure of the light-emitting element package will be described in detail below.

Figure 10A is a top view schematic diagram of a display device 101 according to an embodiment of the present application. As shown in Figure 10 , the display device 101 includes a display substrate 200, wherein the display substrate 200 includes a display area 210 and a non-display area 220. A plurality of pixels PX are arranged in the display area 210 of the display substrate 200, each pixel PX including a first sub-pixel PX_A, a second sub-pixel PX_B, and a third sub-pixel PX_C. A data line driver circuit 130 and a scan line driver circuit 140 are disposed in the non-display area 220. The data line driver circuit 130 is connected to a data line (not shown) of each pixel PX to transmit a data signal to each pixel PX. The scan line driver circuit 140 connects to the scan lines (not shown) of each pixel PX to transmit a scan signal to each pixel PX. The pixel PX includes a light-emitting element according to any of the aforementioned embodiments, with the surface 50e of the filter layer 50 facing the semiconductor stack 12 serving as the primary light extraction surface. In one embodiment, to achieve a high-resolution display device, small, densely packed pixels are typically required. Therefore, the diagonal length of the light-emitting element in any sub-pixel is less than 300 μm.

Each subpixel emits light of a different color. In one embodiment, the first subpixel PX_A, the second subpixel PX_B, and the third subpixel PX_C are, for example, red, green, and blue, respectively. Light-emitting elements emitting light of different wavelengths can be used as subpixels to enable each subpixel to display a different color. The combination of red, green, and blue light emitted by each subpixel enables the display device 101 to produce a full-color image. Referring again to Figure 8B , the closer the color coordinates of the light emitted by the light-emitting elements in each subpixel are to the pure color point coordinates defined by the color gamut specification, the wider the color gamut the pixel can display, thus achieving a wide color gamut display device. In conventional display devices, achieving high color saturation, high contrast, or a wide color gamut requires the installation of filters or wavelength converters in addition to the light-emitting elements within the pixels. This can increase the overall display device's manufacturing process complexity, production costs, and structural complexity. Furthermore, the use of filters or wavelength converters can compromise the brightness or light intensity of the light-emitting elements. Display devices fabricated using the light-emitting elements of any embodiment of this application can alleviate these issues.

The number, area, and arrangement of sub-pixels in a single pixel PX in this embodiment are not limited thereto, and may be implemented in different ways based on the user's different requirements for color and resolution. According to a display device (not shown) in another embodiment of this application, the pixel PX further includes a fourth sub-pixel, and the fourth sub-pixel includes a light-emitting element according to any of the aforementioned embodiments. The light wavelength of the light-emitting element included in the fourth sub-pixel is different from that of the light-emitting elements in the first to third sub-pixels. For example, the fourth sub-pixel is a blue-green sub-pixel, and the peak wavelength of the light emitted by the light-emitting element in the fourth sub-pixel is between 495nm and 520nm. More preferably, it is between 500nm and 510nm. Similarly, the light-emitting element in the fourth sub-pixel uses the filter layer 50 to purify the blue-green light emitted by the semiconductor stack to obtain blue-green light with higher color purity, thereby improving the color rendering capability of the display device.

In one embodiment, Figure 10B is a schematic cross-sectional view of a pixel PX in Figure 10A . Each sub-pixel includes a light-emitting device package 6, which encapsulates the light-emitting device 3 of the third embodiment or the light-emitting device 4 of the fourth embodiment. The light-emitting device package 6 is bonded to a display substrate 200. A circuit layer 110 and circuit bonding pads 8a and 8b are provided on the display substrate 200. The circuit layer 110 is electrically connected to the circuit bonding pads and may include active electronic components, such as transistors. Electrodes 81 and 83 of the light-emitting device package 6 are bonded to circuit bonding pads 8a and 8b, respectively, for example, by soldering. These electrodes are then electrically connected to the display driver circuits (i.e., data line driver circuit 130 and scan line driver circuit 140) via circuit layer 110. In this way, the light-emitting device in the pixel PX can be controlled by the data line driver circuit 130, scan line driver circuit 140, and circuit layer 110.

FIG10C illustrates a light-emitting device package 6 according to an embodiment of the present application. As described above, the light-emitting device package 6 encapsulates the light-emitting device 3 of the third embodiment. The light-emitting device package 6 includes a packaging material 90 covering the side surfaces of the light-emitting device 3. In one embodiment, the packaging material 90 includes a matrix, such as silicone, epoxy, acrylic, or a mixture thereof. In another embodiment, the packaging material 90 includes a matrix and other materials to form the aforementioned modulation structure. For example, the packaging material 90 includes a matrix and a light-absorbing material to form a light-absorbing layer, wherein the light-absorbing material includes a black material, such as carbon black. For example, encapsulation material 90 includes a substrate and a reflective material to form a reflective layer, wherein the reflective material includes titanium oxide (TiO _x ), silicon oxide (SiO _x ), or a mixture thereof. In another embodiment, encapsulation material 90 includes multiple modulation structures with different functions. For example, encapsulation material 90 includes a reflective layer covering a light-emitting element and a light-absorbing layer covering the reflective layer.

In another embodiment (not shown), the pixel PX includes a light-emitting device package 6. Multiple light-emitting devices are encapsulated within a single light-emitting device package 6, each of which constitutes a sub-pixel. In one embodiment, the encapsulation material 90 of the light-emitting device package 6 forms a modulation structure and fills the spaces between the multiple light-emitting devices. Figure 10B exemplarily illustrates a flip-chip light-emitting device encapsulated within the light-emitting device package 6 according to one embodiment of the present application, but the light-emitting device package of the present application is not limited thereto. In other embodiments (not shown), each sub-pixel includes a light-emitting element according to any embodiment of the present application. The first electrode 20 (20' or 20") and the second electrode 30 (30' or 30") of the light-emitting element are electrically connected to circuit bonding pads 8a and 8b on the display substrate 200, respectively, using wire bonding, soldering, or die bonding methods appropriate for the light-emitting element of the respective embodiment.

Figure 11 is a cross-sectional view of a light-emitting element 9 according to the sixth embodiment of this application. The light-emitting element 9 in Figure 11 is merely an example of a light-emitting element similar to the light-emitting element 1 in Figure 1 . The primary structure of light-emitting element 9 is similar to that of light-emitting element 1, differing only in the filter layer 50'. However, the primary structure of light-emitting element 9 can be the same as that of any of the light-emitting elements in the aforementioned embodiments. Light-emitting element 9 includes a filter layer 50' formed by alternating stacks of one or more pairs of material layers having different refractive indices. Filter layer 50' has a similar structure to the aforementioned filter layer 50. By selecting dielectric materials with different refractive indices as the first and second sublayers (not shown) within filter layer 50' and adjusting their thicknesses, an interference effect is created, allowing light emitted by light-emitting element 9 to selectively pass through or reflect through filter layer 50'. The difference lies in that filter layer 50' filters light within a specific angle range, meaning that only light within that specific angle range can pass through filter layer 50'. Specifically, in the light-emitting element 9 shown in Figure 11, semiconductor stack 12 emits light with a specific peak wavelength that is incident on filter layer 50'. Filter layer 50' allows most of the light incident at low angles to pass through, while reflecting most of the light incident at high angles. In another embodiment, the structure of the light-emitting element 9 is similar to the light-emitting element 3 in the aforementioned embodiment. The light emitted by the semiconductor stack 12 passes through the substrate 10 and is incident on the filter layer 50'. The filter layer 50e' allows most of the small-angle incident light to pass through and reflects most of the large-angle incident light. The angle of the incident light here refers to the angle between the direction of the incident light and the normal direction of the incident surface. In one embodiment, Figure 12 shows a schematic diagram of the light path of the light-emitting element 9. The light path of the small-angle incident light is the same as P1. The light emitted from the active layer 123 passes through the filter layer 50' and is extracted from the filter layer surface 50e'. The optical path of high-angle incident light is similar to that of P2. Light emitted from active layer 123 undergoes total internal reflection at the interface between semiconductor stack 12 and filter layer 50', traveling toward substrate 10. There, it undergoes refraction and/or scattering at the patterned structure (not shown) on substrate first surface 10a, changing its direction. Light incident at the interface between semiconductor stack 12 and filter layer 50' forms low-angle incident light, which is then extracted from filter layer surface 50e'. In this way, filter layer 50' converges the light output angle of light emitted by light-emitting element 9, achieving a converged light output angle effect.

The light emitted by the light-emitting element 9 includes forward light and side light, with the intensity of the forward light being greater than the intensity of the side light. In one embodiment, the filter layer 50' has a light transmittance greater than 90% for light with an incident angle less than 10 degrees and less than 10% for light with an incident angle greater than 20 degrees. According to the sixth embodiment, the light-emitting element 9 has a divergence angle (also known as a beam angle) of less than or equal to 120 degrees. In another embodiment, the divergence angle of the light-emitting element 9 is less than or equal to 110 degrees. In another embodiment, the divergence angle of the light-emitting element 9 is between 50 and 110 degrees. In another embodiment, the divergence angle of the light-emitting element 9 is between 50 and 100 degrees. The divergence angle refers to the angle formed by the point in the light distribution curve of a light source, that is, the spatial distribution of the light intensity of the light-emitting element at various angles, where the light intensity reaches half of the light intensity in the direction normal to the light-emitting surface.

Figure 13 shows the spatial distribution of luminous intensity at various angles for the sixth embodiment of light-emitting element 9 and the comparative example light-emitting element. The structure of light-emitting element 9 of the sixth embodiment is similar to that of light-emitting element 1. Filter layers 50 and 50' are formed by alternating stacks of one or more pairs of first and second sublayers made of materials with different refractive indices. Filter layer 50', similar to filter layer 50, can selectively reflect and transmit specific incident light. The refractive indices and thicknesses of the first and second sublayers within filter layer 50 are set to allow light within a specific wavelength range to pass through, providing a filtering function. At the same time, at small incident angles, the light intensity is higher than at larger angles. The refractive index and thickness of the first and second sublayers within filter layer 50' are designed to allow light to penetrate within a specific range of incident angles. Light incident at shallow angles of incidence has a higher intensity than light incident at high angles. In one embodiment, light transmittance reaches over 90% at angles of incidence less than 10 degrees, while transmittance is less than 10% (or reflectivity reaches over 80%) at angles of incidence greater than 20 degrees. In one embodiment, the filter layer 50' includes a plurality of dielectric material pairs composed of _SiO2 and _TiO2 , including three groups of dielectric material stacks: a first group of dielectric material stacks is closer to the semiconductor stack 12, a second group of dielectric material stacks is farther from the semiconductor stack 12, and a third group of dielectric material stacks is located between the first and second groups of dielectric material stacks. The optical thickness of the first group of _SiO2 and _TiO2 dielectric material pairs is greater than the optical thickness of the third group of _SiO2 and _TiO2 dielectric material pairs; and the optical thickness of the second group of _SiO2 and _TiO2 dielectric material pairs is greater than and/or less than the optical thickness of the third group of _SiO2 and _TiO2 dielectric material pairs. The first set of _SiO2 and _TiO2 dielectric material pairs includes an integer or non-integer number of pairs, the second set of _SiO2 and _TiO2 dielectric material pairs includes an integer or non-integer number of pairs, and the third set of _SiO2 and _TiO2 dielectric material pairs includes an integer or non-integer number of pairs. The number of dielectric material pairs in the third set of dielectric material stacks is greater than the number of dielectric material pairs in the first and second sets of dielectric material stacks, respectively. By adjusting the thickness of the first and second sets of dielectric material stacks, the decrease in transmittance in certain angular ranges due to interference can be reduced. The comparative example light-emitting element structure is similar to light-emitting element 9, except that it does not include filter layer 50'. As shown in Figure 13 , compared to the comparative example, the sixth embodiment light-emitting element 9 exhibits higher light intensity at angles between 60 and 120 degrees, resulting in higher forward light. Specifically, within approximately 30 degrees from the normal to the filter surface 50e', the sixth embodiment light-emitting element 9 exhibits higher light intensity and can concentrate light in the forward direction. Furthermore, the sixth embodiment light-emitting element 9 exhibits a divergence angle of 101 degrees, which is smaller than the 139 degrees divergence angle of the comparative example light-emitting element.

As in the previous embodiment, in another embodiment, a modulation structure (not shown) may also be formed on the side of the light-emitting element 9 of the sixth embodiment. In one embodiment, the modulation structure includes a reflective layer to reflect or redirect light directed toward the side of the light-emitting element into forward-emitting light. In another embodiment, the modulation structure includes a light-absorbing layer to absorb light directed toward the side of the light-emitting element. In another embodiment, the modulation structure includes a filter layer, which functions similarly to the filter layer 50' by only allowing light at a specific angle to pass through. In another embodiment, the modulation structure includes a light-blocking layer to prevent light from escaping from the side of the light-emitting element.

FIG14 is a schematic diagram of a sensing module 201. As shown in FIG14 , the sensing module 201 includes a carrier 400, a light-emitting element package 6′ encapsulating a light-emitting element 9 according to any embodiment of the present application, and a light-sensing element 40 located on the surface of the carrier 400. The light-emitting element 9 and the light-sensing element 40 are electrically connected to a circuit (not shown) on the carrier 400. The structure of the light-emitting element package 6′ is similar to the light-emitting element package 6 described above and will not be described in detail here. The light-emitting element package 6′ and the light-emitting element 9 in FIG14 are flip-chip bonded to the carrier 400 in a structure similar to the light-emitting element 3 as an example. However, different wire bonding methods, soldering methods, or die bonding methods can be selected according to different embodiments of the light-emitting element to secure the light-emitting element 9 to the carrier 400 and electrically connect it to the circuit on the carrier 400. The light-sensing element 40 includes a photodiode. A light-blocking element 80 may be placed between the light-sensing element 40 and the light-emitting element package 6' or the light-emitting element 9 to prevent interference between the two, for example, preventing light emitted by the light-emitting element 9 from being directly received by the light-sensing element 40.

The sensing module 201 is applied to a physiological sensing device. For example, the light emitted by the light-emitting element 9 is irradiated on the user's body and generates a reflection signal. The light-sensing element 40 receives the reflection signal and obtains a measurement signal. Then, through circuit calculation, the user's physiological information is obtained, such as heart rate, blood oxygen, blood pressure, blood sugar, water content, or sweat. In order to measure accurate physiological information, the light emitted by the light-emitting element 9 is preferably concentrated and has a certain light intensity. According to the sensing module 201 of the embodiment of the present application, a light-emitting element 9 with a filter layer 50' is used. Since the filter layer 50' can converge the light output angle of the light-emitting element, a more concentrated light source can be obtained without the assistance of additional optical elements such as lenses. Furthermore, the lack of additional optical components also makes the sensing module 201 thinner and lighter, making it more suitable for users to wear.

In another embodiment, the light-emitting element 9 can also be used in the display device 101 shown in FIG10A and the pixel PX shown in FIG10B . By using the filter layer 50' to converge the light emission angle of the light-emitting element, the light emission angles of the light-emitting elements in the plurality of pixels PX of the entire display device 101 are made uniform, thereby improving the uniformity of the image on the display device 101.

The above embodiments are intended only to illustrate the principles and effects of this application and are not intended to limit this application. Anyone with ordinary skill in the art to which this application relates may modify and alter the above embodiments without departing from the technical principles and spirit of this application. All equivalent variations and modifications based on the shape, structure, features, and spirit of this application are intended to be included within the scope of this application.

3: Light-emitting element

10:Substrate

10a: First surface

10b: Second surface

12: Semiconductor stacking

121: First semiconductor layer

122: Second semiconductor layer

123: Active layer

18:Transparent conductive layer

26: Protective layer

261, 262: Openings

28: Reflective Structure

20’: First electrode

30’: Second electrode

50: Filter layer

50e: Filter surface

Claims (15)

A light-emitting device comprises: a semiconductor stack; and a filter layer located on the semiconductor stack, comprising a first surface facing the semiconductor stack and a second surface opposite the first surface, wherein the filter layer comprises a first dielectric material layer and a second dielectric material layer alternately stacked. The light-emitting device emits light; the light comprises a first directional light having a first half-height width (WHM) and a second directional light having a second half-height width (WHM). The first directional light forms an angle between 45 and 90 degrees and a normal to the second surface, and the second directional light forms an angle between 0 and 30 degrees and the normal to the second surface. The second half-height width (WHM) is smaller than the first half-height width (WHM). The light-emitting element of claim 1, wherein the light has a main wavelength and a peak wavelength, and the difference between the main wavelength and the peak wavelength is less than 3 nm. The light-emitting element of claim 1, wherein the light has a peak wavelength between 525 nm and 535 nm, and the light has a chromaticity coordinate value (X1, Y1) based on the CIE 1931 chromaticity coordinates, wherein X1≦0.2 and Y1≧0.75. The light-emitting element of claim 1, wherein the filter layer has a transmittance of more than 80% for a peak wavelength of the light. The light-emitting device of claim 1, wherein the second half-height width is less than or equal to 25 nm. The light-emitting element of claim 1, wherein the light intensity of the light in the second direction is greater than the light intensity of the light in the first direction. The light-emitting device of claim 1, wherein the light has a peak wavelength between 525 nm and 535 nm, and the light has a color purity greater than or equal to 92%. A light-emitting element comprises: a semiconductor stack emitting a first light ray having a peak wavelength; and a filter layer disposed on the semiconductor stack, comprising a first surface facing the semiconductor stack and a second surface opposite the first surface, wherein the filter layer comprises alternating stacks of a first dielectric material layer and a second dielectric material layer; wherein: the first light ray passes through the filter layer to produce a second light ray; the first light ray has a first half-height width (HWHM) and the second light ray has a second half-height width (HWHM); the second half-height width (HWHM) is smaller than the first half-height width (HWHM), and/or the second light ray has a half-height width (HWHM) of less than or equal to 25 nm; and the filter layer has a transmittance of greater than 80% at the peak wavelength. A light-emitting device comprises: a semiconductor stack that emits a first light ray; and a filter layer disposed on the semiconductor stack, comprising a first surface facing the semiconductor stack and a second surface opposite the first surface; wherein: the filter layer comprises a first dielectric material layer and a second dielectric material layer alternately stacked; the first light ray passes through the filter layer to obtain a second light ray; the light-emitting device has a divergence angle between 50 degrees and 110 degrees; wherein the filter layer has a light transmittance greater than 90% for the first light ray at an incident angle of less than 10 degrees. The light-emitting device of claim 1, 8, or 9 further comprises a substrate located between the semiconductor stack and the first surface, wherein the first surface faces the substrate. The light-emitting device of claim 1, 8, or 9 further comprises: a reflective structure covering the semiconductor stack, wherein the semiconductor stack is located between the reflective structure and the filter layer; and an electrode located on the reflective structure. The light-emitting element of claim 11, wherein the reflective structure comprises a metal reflective layer, and the electrode is electrically connected to the metal reflective layer. The light-emitting device of claim 11, wherein the reflective structure comprises a non-conductive material, the reflective structure comprises an opening, and the electrode is electrically connected to the semiconductor stack through the opening. The light-emitting device of claim 1, 8, or 9 further comprises: a substrate, wherein the semiconductor stack is located between the substrate and the filter layer; and an electrode located on the semiconductor stack; wherein the filter layer includes an opening exposing the electrode. A light-emitting element as claimed in claim 1, 8 or 9, wherein a diagonal length of the light-emitting element is less than 300 μm.