Quantum dot composite material, method of forming the same and light-emitting device

Abstract

A quantum dot composite material is provided, which including: a carrier core; a plurality of quantum dot particles attached to the carrier core; and a composite protective layer covering the carrier core and the quantum dot particles, wherein the composite protective layer includes a cladding layer and a porous light-diffusion layer. The cladding layer and the porous light-diffusion layer are light-transmissive materials. The cladding layer is formed conformably on the carrier core and the quantum dot particles, the porous light-diffusion layer is formed on the cladding layer and has an irregular surface.

Description

Technical Field

[0001] This disclosure relates to quantum dot composite materials and methods for their formation, particularly to quantum dot composite materials with a light-diffusing layer and methods for their formation. Prior Technology

[0002] Due to the quantum confinement effect, the emission spectrum of quantum dots can be tuned by particle size, and the emission spectrum has a narrow full width at half maximum (FWHM) characteristic, which can provide high-purity colored light. Quantum dots have a wide range of applications, such as light-emitting diodes, lighting, solar cells, biolabeling, and displays.

[0003] However, quantum dots are often affected by moisture and / or oxygen in the environment, which reduces their stability and thus their luminescence. Therefore, although existing quantum dots and their formation methods have gradually met their intended applications, they are not yet completely satisfactory in all aspects. Thus, there are still some problems to be overcome regarding quantum dots and their formation methods. Summary of the Invention

[0004] According to some embodiments, this disclosure provides a quantum dot composite material, comprising: a carrier core; a plurality of quantum dot particles attached to the carrier core; and a composite protective layer covering the carrier core and the quantum dot particles, wherein the composite protective layer comprises a coating layer and a porous light-diffusing layer, the coating layer and the porous light-diffusing layer are light-transmitting materials, the coating layer is compliantly formed on the carrier core and the quantum dot particles, and the porous light-diffusing layer is formed on the coating layer and has an irregular surface.

[0005] According to other embodiments, this disclosure provides a method for forming a quantum dot composite material, comprising: dispersing and attaching a plurality of quantum dot particles to a carrier core; conformally forming a coating layer on the quantum dot particles and the carrier core; and forming a porous light-diffusing layer with an irregular surface on the coating layer. Simple Explanation of the Diagram

[0006] The embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be noted that, in accordance with industry standard practice, the various features are not drawn to scale and are only used for illustrative purposes. In fact, the dimensions of the components can be arbitrarily enlarged or reduced to clearly demonstrate the features of the embodiments of this disclosure. Figure 1A illustrates a schematic diagram of a quantum dot composite material according to some embodiments. Figure 1B is a partially enlarged schematic diagram of the quantum dot composite material shown in Figure 1A. Figure 1C is a partially enlarged schematic diagram of the quantum dot composite material shown in Figure 1A. Figure 2A is a schematic diagram illustrating the carrier core of the quantum dot composite material according to some other embodiments. Figure 2B illustrates a schematic diagram of a quantum dot composite material having a carrier core as shown in Figure 2A. Figure 3 shows the FTIR images of quantum dot composite materials in some embodiments. Figure 4A shows a SEM image of the quantum dot composite material after the coating layer is formed in some embodiments. Figure 4B shows a SEM image of the quantum dot composite material after the formation of the porous light-diffusing layer in some embodiments. Figure 5A illustrates a schematic diagram of a light-emitting diode chip according to some embodiments. Figure 5B illustrates a schematic diagram of a light-emitting diode chip according to some embodiments. Figure 6A illustrates a schematic diagram of a light-emitting diode device according to some embodiments. Figure 6B illustrates a schematic diagram of a light-emitting diode device according to some embodiments. Figure 6C illustrates a schematic diagram of a light-emitting diode device according to some embodiments. Figure 7 illustrates a schematic diagram of a quantum dot light-emitting diode (QLED) according to some embodiments. Figures 8A-8C show the results of the high-temperature and high-humidity storage test disclosed herein. Implementation

[0007] The following disclosure provides numerous embodiments or examples for implementing different elements of the provided subject matter. Specific examples of each element and its configuration are described below to simplify the description of the embodiments disclosed herein. Of course, these are merely examples and are not intended to limit the embodiments disclosed herein. For example, if the description mentions a first element formed on a second element, it may include embodiments where the first and second elements are in direct contact, or embodiments where an additional element is formed between the first and second elements such that they are not in direct contact. Furthermore, reference values ​​and / or letters may be repeated in various examples of the embodiments disclosed herein. Such repetition is for the purpose of brevity and clarity, and is not intended to indicate a relationship between the different embodiments and / or configurations discussed.

[0008] Furthermore, spatially relative terms may be used, such as "below," "below," "lower," "above," "higher," etc., to facilitate the description of the relationship between one or more components or features in the diagram. Spatially relative terms are used to include different orientations of the device in use or operation, as well as the orientations described in the diagram. When the device is turned to different orientations (rotated 90 degrees or other orientations), the spatially relative adjectives used will also be interpreted according to the orientation after the turn.

[0009] Furthermore, when using terms such as "approximately" or "around" to describe a number or range of numbers, this terminology is intended to cover numbers within a reasonable range, taking into account the inherent variations in the manufacturing process as understood by those skilled in the art. For example, based on known manufacturing tolerances for manufacturing parts with characteristics related to that number, the number or range of numbers covers a reasonable range including, for example, within + / - 10% of the number. Moreover, in this specification, the term "X~Y" indicating a range means "above X and below Y".

[0010] Referring to Figures 1A-1C, Figure 1A shows a schematic diagram of the quantum dot composite material 100 disclosed herein, Figure 1B is a partially enlarged schematic diagram of region A1 in Figure 1A, and Figure 1C is a partially enlarged schematic diagram of region A2 in Figure 1A. The quantum dot composite material 100 disclosed herein includes a carrier core 110, complex quantum dot particles 120, and a composite protective layer 130.

[0011] The carrier core 110 disclosed herein is used to disperse quantum dot particles 120, allowing the quantum dot particles 120 to adhere to its surface. This reduces the self-absorption of the quantum dot particles 120 during luminescence and decreases the amount of quantum dot particles used. In some embodiments, the carrier core 110 may be an unactivated crystalline material, a metal oxide, or a combination thereof. An unactivated crystalline material refers to an inorganic light emitter without an activator, i.e., a host lattice material without an emission center, such as unactivated crystalline nitrides, oxynitrides, or SiAlON; unactivated crystalline aluminates, gallates, and aluminosilicates; or unactivated crystalline silicates or halosilicates. Metal oxides include SiO₂, TiO₂, ZrO₂, Al₂O₃, MgO, CaO, SrO, and BaO. The diameter of the carrier core 110 may be, for example, 2 nm to 40 nm, to evenly disperse the quantum dot particles 120 without affecting the luminescence efficiency of the quantum dot particles 120.

[0012] The unactivated crystalline material is an unactivated crystalline nitride, oxynitride, or SiAlON, selected from the group consisting of: M3+N, M2+Si2O2N2, M2+2Si5N8, M3+3Si6N11, M2+AlSiN3, α-silicon aluminum oxynitride (sialon), and β-silicon aluminum oxynitride; wherein M2+ is Zn, Fe, Co, Ni, Cd, Cu, and / or one or more alkaline earth metals; and M3+ is Al, Ga, Sc, Y, La, and / or one or more rare earth metals selected from the group consisting of: Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

[0013] Unactivated crystalline materials are unactivated crystalline aluminates, gallates, or aluminum silicates, selected from the group consisting of the following: M + AlO 2, M 3 + AlO 3, M 2 + M 3 + AlO 4, M 2 + Al 2O 4, M 2 + Al 4O 7, M + Al 5O 8, M 3 + 4Al 2O 9, M 3 + 3Al 5O 12, M + Al 11O 17, M 2 + 2Al 10O 17, M 3 + 3Al 5O 12, M 3 + 3(Al,Ga) 5O 12, M 3 + 3Sc 2Al 3O 12, M 2 + 2Al 6O 11, M 2 + Al 8O 13, M 2 + M 3 + Al 11O 19, M 2 + Al 12O 19, M 2+ 4Al 14O 25, M 2+ 3Al 16O 27, M 2+Ga 2O 4, M 2+Ga 4O 7, M 3+ 3Ga 5O 12, M +Ga 11O 17, M 2+Ga 12O 19, M + 2M 2+ 3Al 2Si 2O 10 and M 2+ 3Al 2Si 3O 12; wherein M+ is one or more alkali metals; M 2+ is Zn, Fe, Co, Ni, Cd, Cu and / or one or more alkaline earth metals; M The 3+ series Al, Sc, Y, La and / or one or more rare earth metals selected from the following: Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu; and the X series one or more halogens.

[0014] Unactivated crystalline materials are unactivated crystalline silicates or halosilates, selected from the following groups of compositions: M²⁺SiO₃, M²⁺ 2SiO₄, M²⁺ 2(Si,Ge)O₄, M²⁺ 3SiO₅, M³⁺ 2SiO₅, M³⁺M⁺SiO₄, M²⁺Si₂O₅, M²⁺ 2Si₂O₆, M²⁺ 3Si₂O₇, M²⁺ 2M⁺ 2Si₂O₇, M³⁺ 2Si₂O₇, M²⁺ 4Si₂O₈, M²⁺ 2Si₃O₈, M²⁺ 3M³⁺ 2Si₃O₇, M⁺ + M³⁺M²⁺ 4Si₄O₇, M⁺ + M²⁺ 4M³⁺Si⁺ 4O 14, M 2+ 3M 3+ 2Si 6O 18, M 3+SiO 3X, M 2+ 3SiO 4X 2, M 2+ 5SiO 4X 6, M + 2M 2+ 2Si 4O 10X 2, M 2+ 5Si 4O 10X 6, M + 2SiX 6, M 2+ 3SiO 3X 4 and M 2+ 9(SiO 4) 4X 2; wherein M+ is one or more alkali metals; M 2+ is Zn, Fe, Co, Ni, Cd, Cu and / or one or more alkaline earth metals; M The 3+ series Al, Sc, Y, La and / or one or more rare earth metals selected from the following: Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu; and the X series one or more halogens.

[0015] The complex quantum dot particles 120 disclosed herein are not particularly limited and can be appropriately selected according to requirements. For example, they can be II-VI group semiconductors such as CdSe and CdS; III-V group semiconductors such as AlP, InP, GaP, AlAs, InAs, GaAs, AlN, InN, and GaNd; IV-VI group semiconductors such as PbSe and PbS; or combinations thereof. They can also be core-shell structures containing the above-mentioned compounds, such as CdSe / ZnS and InP / ZnS. The complex quantum dot particles 120 can be uniformly dispersed and attached to the surface of the support core 110 by methods such as spin coating, spray coating, dip coating, physical adsorption, chemical solution growth, epitaxial growth, or electric field confinement.

[0016] In some embodiments, the quantum dot particle 120 may give off longer wavelength (low energy) light after being excited by short wavelength (high energy) blue light or UV light. In some embodiments, blue light may be provided by a blue light-emitting diode and UV light may be provided by a UV light-emitting diode. In some embodiments, quantum dot 120 emits wavelength greater than that of blue or UV light under excitation of blue or UV light. For example, quantum dot particles 120 may be yellow, red, or green quantum dot particles that, when excited by blue or UV light, may emit yellow, red, or green light. In some embodiments, the diameter r1 of the complex quantum dot particle 120 may be suitably selected depending on the wavelength to be emitted, the larger the size of the quantum dot particle has a longer (redshift) of luminescence wavelength closer to the red light, and the smaller the size of the quantum dot particle with a shorter (blue shift) to the blue end of the spectrum. For example, larger quantum dots above 5-6 nm in diameter emit longer wavelengths, emitting orange or red light, while smaller 2-3 nm diameters emit shorter wavelengths, emitting blue or green light. In some embodiments, the quantum dot particle 120 may be a core-shell type quantum dot particle. The mantle can improve the quantum yield and also make the quantum dots more robust and durable, therefore, the mantle thickness can be selected based on the desired physical properties (e.g., photoconversion efficiency, heat resistance, etc.).

[0017] Then, a composite protective layer 130 coated with the carrier core 110 and the quantum dot particle 120 was formed. The composite protective layer 130 comprises a cladding layer 132 and a pore diffuser layer 134 . This disclosure reveals that by means of the cladding layer 132 , the impact of the quantum dot composite 100 by water vapor and / or oxygen in the environment can be reduced, while improving the light resistance of the quantum dot composite 100 by uniformly dispersing the excitation light (e.g., blue or UV light) incident to the quantum dot composite 100 by using the pores of the pore diffuser layer 134 .

[0018] BET Specific Surface Area is the abbreviation of BET Specific Surface Area Testing Method, BET is the acronym for three scientists (Brunauer, Emmett and Teller). The total surface area occupied by 1g of solid is the specific surface area S (specific surface area, m 2 / g) of the substance. In some embodiments, the BET specific surface area of ​​the composite protective layer 130 is from 0.5 to 50 m2 / g, such as from about 1 to 45 m2 / g, from about 3 to 40 m2 / g, from about 5 to 35 m2 / g, from about 8 to 30 m2 / g, from about 10 to 25 m2 / g, from about 15 to 20 m2, etc. By setting the BET specific surface area of ​​the composite protective layer 130 in the range described above, the excitation light incident to the quantum dot composite 100 can be uniformly dispersed, and the luminescence efficiency of the quantum dot particles 120 is maintained.

[0019] The coating layer 132 is made of a light-transmitting material, which reduces the impact of the environment on the quantum dot particles 120 without affecting the luminescence of the quantum dot particles 120. In some embodiments, the coating layer 132 may contain metal oxides, such as SiO2, TiO2, ZrO2, Al2O3, MgO, CaO, SrO, BaO, or combinations thereof. The coating layer 132 may be a single layer or multiple layers, each layer may contain the same or different materials, and the thickness of each layer may be the same or different.

[0020] In some embodiments, the coating layer 132 may be formed conformally to the carrier core 110 and quantum dot particles 120 by atomic layer deposition (ALD), thus the surface shape of the coating layer 132 corresponds to the surface shape of the underlying quantum dot particles 120 and carrier core 110. In some embodiments, the reaction temperature of the atomic layer deposition process may be greater than or equal to 60°C to less than or equal to 180°C. For example, the reaction temperature of atomic layer deposition may be 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, or a value or range between the aforementioned values, but this disclosure is not limited thereto.

[0021] In some embodiments, as shown in Figure 1B, the thickness d1 of the coating layer 132 is defined as the distance between the quantum dot particle 120 and the adjacent surface of the coating layer 132, and d1 is about 1 nm to 10 nm, such as about 2 nm to 9 nm, about 3 nm to 8 nm, about 4 nm to 7 nm, about 5 nm to 6 nm, etc. In some embodiments, the ratio (r1:d1) of the diameter r1 of the quantum dot particle 120 to the thickness d1 of the coating layer 132 is about 1:0.2 to about 1:0.5, such as about 1:0.25 to about 1:0.48, about 1:0.28 to about 1:0.45, about 1:0.3 to about 1:0.43, about 1:0.33 to about 1:0.4, about 1:0.35 to about 1:0.38, etc. By controlling the thickness d1 of the coating layer 132 and its ratio (r1:d1) to the quantum dot particles within the above range, the luminous efficiency of the quantum dot particles 120 can be maintained while protecting the quantum dot particles 120 from degradation caused by environmental factors.

[0022] The porous light-diffusing layer 134 is also a light-transmitting material and has an irregular surface, used to disperse the light incident on the quantum dot particles 120. In some embodiments, as shown in Figure 1C, the thickness d2 of the porous light-diffusing layer 134 is defined as the distance between the surface of the coating layer 132 and the surface of the porous light-diffusing layer 134, and the thickness d2 is 100nm-1μm, for example, about 150nm to 950nm, about 200nm to 900nm, about 250nm to 850nm, about 300nm to 800nm, about 350nm to 750nm, about 400nm to 700nm, about 450nm to 650nm, about 500nm to 600nm, about 550nm to 580nm, etc. In some embodiments, the ratio (r1:d2) of the diameter r1 of the quantum dot particles 120 to the thickness d2 of the porous light-diffusing layer is about 1:5 to about 1:50, for example, about 1:10 to about 1:45, about 1:15 to about 1:40, about 1:20 to about 1:35, about 1:25 to about 1:30, etc. By controlling the thickness of the porous light-diffusing layer 134 and the ratio (r1:d2) to the diameter of the quantum dot particles 120 within the above range, the lightfastness of the quantum dot particles 120 can be improved while maintaining the luminous efficiency of the quantum dot particles 120.

[0023] In some embodiments, the ratio (d1:d2) of the thickness d1 of the coating layer 132 to the thickness d2 of the porous light-diffusing layer 134 is about 1:10 to about 1:250, for example, about 1:30 to about 1:230, about 1:50 to about 1:210, about 1:70 to about 1:200, about 1:90 to about 1:180, about 1:100 to about 1:160, about 1:120 to about 1:150, about 1:130 to about 1:140, etc. By controlling the ratio (d1:d2) of the thickness of the coating layer 132 to the thickness of the porous light-diffusing layer 134 within the above range, the lightfastness of the quantum dot particles 120 can be improved while maintaining the luminous efficiency of the quantum dot particles 120.

[0024] The porous light-diffusing layer 134 contains a plurality of pores 134p for dispersing the light path. In some embodiments, the volume of the pores 134p is about 0.01 to 0.5 cm³ / g, for example, about 0.03 to 0.45 cm³ / g, about 0.05 to 0.4 cm³ / g, about 0.1 to 0.35 cm³ / g, about 0.15 to 0.3 cm³ / g, about 0.2 to 0.3 cm³ / g, etc. By keeping the volume of the pores 134p in the porous light-diffusing layer 134 within the above range, light can be effectively dispersed without affecting the luminous efficiency of the quantum dot.

[0025] In some embodiments, the porous light-diffusing layer 134 comprises an inorganic compound, an organic compound, or a combination thereof. Examples of inorganic compounds include SiOR, SiO2, Si(OR)4 or Si(OMe)3C3H6S, other silica materials; metal oxides such as Al2O3; metal nitrides such as Si3N3; or combinations thereof, wherein each of the Rs independently represents a C1 to C20 alkyl group. Examples of organic compounds include polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polystyrene (PS), polyethylene (PP), polyamide (PA), polycarbonate (PC), polyimide (PI), epoxy resin, polydimethylsiloxane (PDMS), silicone, or combinations thereof.

[0026] In some embodiments, the pore-expanding layer 134 can be formed by a sol-gel method. For example, quantum dot particles 120 dispersed in the support core 110 and coated by the coating layer 132 are placed in 400 ml to 600 ml of a solvent such as methanol or ethanol, and about 10 ml to 30 ml of a precursor and optionally the aforementioned organic compound are added, and the mixture is stirred at about 15 to 80 °C for about 45 to 80 minutes. Then, 3 to 10 ml of a catalyst (e.g., acidic HCl, H₂SO₄ and HNO₃, and alkaline NaOH and NH₄OH, etc.) is added to the reaction flask, and the mixture is stirred at about 15 to 80 °C for 1 to 6 hours. This material is washed several times with n-hexane and dried at about 50 to 80 °C for 3 to 5 hours to obtain the quantum dot composite material disclosed herein.

[0027] Examples of metal alkoxides that serve as precursors include monometallic alkoxides such as Si(OCH 3) 4, Si(OC 2H 5) 4, Ti(OCH 3) 4, Ti(OC 2H 5) 4, Zr(OCH 3) 4, Zr(OC 2H 5) 4, Al(OCH 3) 3, Al(OC 2H 5) 3; and bimetallic alkoxides such as La[Al(iso-OC 3H 7) 4] 3, Mg[Al(iso-OC 3H 7) 4] 2, Ni[Al(iso-OC 3H 7) 4] 2, (C 3H 7O) 2Zr[Al(OC 3H 7) 4] 2, and Ba[Zr(OC 2H 5) 9] 2. Examples of metal salts that serve as precursors include nitrates, sulfates, acetates, sulfides, and chlorides of metals such as aluminum, hafnium, silicon, zirconium, titanium, lanthanum, germanium, and tantalum.

[0028] When the pore light-diffusing layer 134 contains only organic compounds, the pore light-diffusing layer 134 can be formed by, but not limited to, chemical solution growth and sol-gel methods.

[0029] Referring next to Figures 2A and 2B, Figure 2A is a schematic diagram illustrating the carrier core of the quantum dot composite material according to some other embodiments. Figure 2B illustrates a schematic diagram of the quantum dot composite material having the carrier core shown in Figure 2A. In some embodiments, the quantum dot composite material 100 may also use a porous substrate as the carrier core 110', i.e., the outer surface of the carrier core 110' includes a plurality of recesses 110p for embedding quantum dot particles 120. The size of the recesses 110p can be rationally designed according to the particle size of the quantum dot particles 120, for example, the size of the recesses 110p is larger than or substantially equal to the particle size of the quantum dot particles 120, so as to accommodate the quantum dot particles 120 therein. In some embodiments, the size of the recess 110p is about 1 nm to 100 nm, such as about 5 nm to 95 nm, about 10 nm to 90 nm, about 15 nm to 85 nm, about 20 nm to 80 nm, about 30 nm to 75 nm, about 35 nm to 70 nm, about 40 nm to 65 nm, about 45 nm to 60 nm, about 50 nm to 55 nm, etc. In some embodiments, the material of the carrier core 110' may include materials with high light transmittance such as silica or glass, which will not reduce the light extraction efficiency from the quantum dot particles 120.

[0030] Because the carrier core 110' has a high specific surface area, it can strongly adsorb quantum dot particles 120, which can enter the pores through physical adsorption. For example, in some embodiments, the quantum dot particles 120 can be dissolved in a solvent such as hexane, and then the carrier core 110' can be added to the quantum dot particle 120 solution. After mixing in a ratio of approximately 1:8 to 1:15 between the total quantum dot particles 120 and the carrier core 110', the mixture is stirred for about one hour. Then, after centrifugation at 2000-5000 rpm for 5-15 minutes, the powder of quantum dot particles 120 contained in the carrier core 110' can be obtained. Next, a coating layer 132 and a pore light-diffusing layer 134 are formed. The materials, thicknesses, and formation methods of the coating layer 132 and the pore light-diffusing layer 134 can be referred to the embodiments described above in Figures 1A-1C, and will not be repeated here.

[0031] Next, referring to Figure 3, which shows the FTIR images of the quantum dot composite material in some embodiments. The quantum dot composite material 100 disclosed herein, when measured by FTIR, clearly shows the Al-O peak of the coating layer 132 and the Si-O peak of the porous light-diffusing layer 134, indicating that the quantum dot composite material 100 indeed simultaneously possesses the coating layer 132 and the porous light-diffusing layer 134 formed thereon.

[0032] Referring to Figures 4A and 4B, Figure 4A is a SEM image of the quantum dot composite material 100 after forming a coating layer 132 in one embodiment, and Figure 4B is a SEM image of the porous light-diffusing layer 134 formed on the coating layer 132. It can be clearly seen that the coating layer 132 has a relatively dense structure, while the porous light-diffusing layer 134 has a relatively loose structure and an irregular surface. In this embodiment, the BET specific surface area of ​​the coating layer 132 is 0.4 m² / g, and the BET specific surface area after forming the porous light-diffusing layer 134 is 7.9 m² / g.

[0033] The quantum dot composite material 100 disclosed herein can be applied to various light-emitting devices, such as lighting-related applications, automotive lighting, or display applications, such as light-emitting modules (front light modules, back light modules) of displays for mobile phone screens, television screens, automotive dashboards, etc., and panel pixels or sub-pixels of displays.

[0034] For example, the quantum dot composite material 100 disclosed herein can be used as a wavelength conversion material for light-emitting devices, such as being contained in a wavelength conversion layer and / or doped in a light-transmitting substrate. In some embodiments, the wavelength conversion material may be coated on the light-emitting surface of a light-emitting diode wafer. The LED light-emitting devices in some embodiments of this disclosure are described below with reference to Figures 5A-5B and 6A-6C.

[0035] Figure 5A illustrates a diode chip 200 in a light-emitting device according to some embodiments. The light-emitting diode chip 200 includes a substrate 202, an epitaxial structure 204, a first electrode 214, and a second electrode 216. The epitaxial structure 204 includes a first-type semiconductor layer 206, an active layer 208, and a second-type semiconductor layer 210 stacked sequentially from the substrate 202. The first electrode 214 and the second electrode 216 are respectively connected to the first-type semiconductor layer 206 and the second-type semiconductor layer 210. The substrate 202 may include an insulating material (e.g., sapphire) or a semiconductor material. The first-type semiconductor layer 206 and the second-type semiconductor layer 210 have opposite conductivity types. For example, the first-type semiconductor layer 206 has an N-type semiconductor layer, while the second-type semiconductor layer 210 has a P-type semiconductor layer, wherein the first electrode 214 is an N-type electrode and the second electrode 216 is a P-type electrode. For example, the first type semiconductor layer 206 has a P-type semiconductor layer, while the second type semiconductor layer 210 has an N-type semiconductor layer, wherein the first electrode 214 is a P-electrode and the second electrode 216 is an N-electrode. The LED chip 200 can be mounted using either a face-up mount or a flip-chip mount. In the flip-chip mounting implementation, the LED chip 200 is inverted so that the first electrode 214 and the second electrode 216 face the substrate, such as a circuit board, and are electrically connected to the contact pads via solder.

[0036] Figure 5B illustrates a vertically oriented light-emitting diode (LED) chip 300 in a light-emitting device, according to another embodiment. The LED chip 300 includes a substrate 302 and an epitaxial structure 204. The epitaxial structure 204 includes a first-type semiconductor layer 206, an active layer 208, and a second-type semiconductor layer 210 stacked sequentially from the substrate 302. A first electrode 314 and a second electrode 316 are respectively connected to the substrate 302 and the second-type semiconductor layer 210. The material of the substrate 302 is selected from metals, alloys, conductors, semiconductors, and combinations thereof. The substrate 302 may include a semiconductor material with the same conductivity as the first-type semiconductor layer 206, or a conductive material, such as a metal, that can form an ohmic contact with the first-type semiconductor layer 206. For example, the first-type semiconductor layer 206 has an N-type semiconductor layer, and the second-type semiconductor layer 210 has a P-type semiconductor layer, wherein the first electrode 314 is an N-type electrode and the second electrode 316 is a P-type electrode. For example, the first type semiconductor layer 206 has a P-type semiconductor layer, while the second type semiconductor layer 210 has an N-type semiconductor layer, wherein the first electrode 314 is a P-electrode and the second electrode 316 is an N-electrode.

[0037] In some embodiments, the P-type semiconductor layer may be a P-type GaN material, and the N-type semiconductor layer may be an N-type GaN material. In one embodiment, the P-type semiconductor layer may be a P-type AlGaN material, and the N-type semiconductor layer may be an N-type AlGaN material. The active layer 208 is a multiple quantum well structure.

[0038] In some embodiments, the wavelength of the first light emitted by the light-emitting diode chips 200 and 300 is from 220 nm to 480 nm. In some embodiments, the light-emitting diode chips 200 and 300 may be ultraviolet light-emitting diode chips, emitting the first light with a wavelength from 200 nm to 400 nm. In some embodiments, the light-emitting diode chips 200 and 300 may be blue light-emitting diode chips, emitting the first light with a wavelength from 430 nm to 480 nm.

[0039] Figure 6A illustrates a schematic diagram of a light-emitting diode (LED) device according to some embodiments. In some embodiments, the LED device 400 includes a base 410, an LED chip 420, a wavelength conversion layer 430, and a reflective wall 440. The base 410 has a positive electrode 410a and a negative electrode 410b, and a die-bonding region 410s is provided on the upper surface of the base 410. The reflective wall 440 is located on the base 410, surrounds the die-bonding region 410s, and defines an accommodating space 412. The LED chip 420 may be an LED chip 200 or 300 as described above, and is disposed in the accommodating space 412 and fixed on the die-bonding region 410s of the base 410. The LED chip 420 may emit blue light or UV light. Furthermore, the LED chip 420 may be a small-sized LED chip, such as a sub-millimeter LED chip or a micro LED chip. The light-emitting diode chip 420 can be mounted face-up as shown in Figure 6A, or it can be mounted in other flip-chip configurations as needed. A wavelength conversion layer 430 is disposed on the light-emitting surface of the light-emitting diode chip 420, and the wavelength conversion layer 430 includes a transparent adhesive and a quantum dot composite material 100 as disclosed in Figures 1A-1C or 2A-2B. Transparent adhesive materials may include, for example, one or a combination of two or more of the following: polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polystyrene (PS), polyethylene (PP), polyamide (PA), polycarbonate (PC), polyimide (PI), polydimethylsiloxane (PDMS), epoxy resin, and silicone.

[0040] According to some embodiments of this disclosure, the wavelength conversion layer 430, in addition to the quantum dot composite material 100 disclosed herein, may also be mixed with other phosphors or with quantum dot composite materials 100 that emit different colors, depending on color requirements. For example, if the light-emitting diode device 400 emits white light, the light-emitting diode chip 420 emits blue light, and the wavelength conversion layer 430 includes green quantum dot composite material 100 and red quantum dot composite material 100. Alternatively, if the light-emitting diode device 400 emits white light, the light-emitting diode chip 420 emits UV light, and the wavelength conversion layer 430 includes blue quantum dot composite material 100, green quantum dot composite material 100, and red quantum dot composite material 100. The amount of powder used in the wavelength conversion layer 430 is not particularly limited. For example, in some embodiments, the amount of powder used in the wavelength conversion layer 430 may be 50wt% to 80wt%, meaning the transparent adhesive 432 contains a total of 50wt% to 80wt% of quantum dot composite material 100 and other phosphors.

[0041] Figure 6B illustrates a schematic diagram of another light-emitting diode (LED) device 405 according to some other embodiments, which includes an LED wafer 420, a base 410, a cup wall 445, a wavelength conversion layer 435, and a reflective wall 446. The base 410 has a positive electrode 410a and a negative electrode 410b. A die-bonding region 410s is located on the upper surface of the base 410, and the cup wall 445 is located on the base 410, surrounding the die-bonding region 410s and defining an accommodating space 412. The LED wafer 420 is disposed in the accommodating space 412 and fixed to the die-bonding region 410s of the base 410. The wavelength conversion layer 435 is located on the light-emitting side of the LED wafer 420 and on the top surface of the cup wall 445. The reflective wall 446 may be disposed around the outer wall of the wavelength conversion layer 435 and is located on the top surface of the cup wall 445. The reflective wall 446 is a material with light-reflective properties and low light leakage, such as reflective glass, quartz, light-reflective patches, polymer plastics, or other suitable materials. The polymer plastic can be one or a combination of two or more materials, such as polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polystyrene (PS), polyethylene (PP), nylon (PA), polycarbonate (PC), epoxy resin, and silicone. The light-reflective capability of the reflective wall 446 can be altered by adding other filler particles. These filler particles can be composite materials with different particle sizes or materials. The filler particle materials can be, for example, titanium dioxide (TiO₂), silicon dioxide (SiO₂), aluminum oxide (Al₂O₃), boron nitride (BN), and zinc oxide (ZnO). In this example, the light-emitting diode chip 420 and the wavelength conversion layer 435 are separated from each other by the air gap in the accommodating space 412 defined by the cup wall 445. In other words, the accommodating space 412 may not be filled with other substances that come into contact with the light-emitting diode chip 420, that is, the accommodating space 412 is air.

[0042] The wavelength conversion layer 435 includes a transparent adhesive and a quantum dot composite material 100 as shown in Figures 1A-1C or 2A-2B. The material of the transparent adhesive can be referenced from that of the transparent adhesive of the wavelength conversion layer 430, and will not be described again here. In some embodiments, the wavelength conversion layer 435 and the light-emitting diode chip 420 are separated from each other (in this example, by the accommodating space 412). This avoids the wavelength conversion layer 435 from being too close to the light-emitting diode chip 420, which could affect its thermal and chemical stability, thereby improving the lifetime of the wavelength conversion layer 435 and enhancing the reliability of the light-emitting diode packaging structure product. In some other embodiments, the air gap in the accommodating space 412 defined by the cup wall 445 can also be filled with a transparent encapsulating colloid (not shown). The transparent encapsulating colloid can be one or a combination of two or more materials, such as polymethyl methacrylate, polyethylene terephthalate, polystyrene, polyethylene, nylon, polycarbonate, polyimide, polydimethylsiloxane, epoxy resin, and silicone. In some embodiments, this transparent encapsulating colloid may be doped with one or more wavelength conversion materials. In other variations, one or more wavelength conversion materials may be coated on the light-emitting surface of the light-emitting diode chip 420. Therefore, in addition to the wavelength conversion layer 435, the light-emitting properties of the light-emitting diode device 405 can be adjusted through the encapsulating (transparent) colloid containing wavelength conversion material and / or the coating containing wavelength conversion material on the surface of the light-emitting diode chip 420. The types of wavelength conversion materials in the wavelength conversion layer 435, the encapsulating colloid, and / or the coating can be appropriately adjusted according to the actual needs of the product.

[0043] Figure 6C illustrates a schematic diagram of another light-emitting diode (LED) device according to some other embodiments. The LED device 500 includes an LED chip 520 and a wavelength conversion layer 530. The LED chip 520 is a flip-chip type, and the wavelength conversion layer 530 includes a quantum dot composite material 100 and a transparent adhesive material. The wavelength conversion layer 530 conformally covers the upper surface and sidewalls of the LED chip 520. The material of the transparent adhesive material can be referred to as that of the transparent adhesive material of the wavelength conversion layer 430, and will not be described again here.

[0044] The light-emitting diode (LED) device can take many forms and is not limited to the LED devices shown in Figures 6A-6C. Furthermore, the quantum dot composite material 100 disclosed herein can also be used in quantum dot LEDs (QLEDs). The following description of quantum dot LEDs is based on the accompanying diagrams.

[0045] Figure 7 illustrates a schematic diagram of a quantum dot light-emitting diode (QLED) according to some embodiments. The quantum dot light-emitting diode 600 includes an anode 610, a hole injection layer 620, a light-emitting layer 630, an electron injection layer 640, and a cathode 650 stacked sequentially. The light-emitting layer 630 contains a quantum dot composite material 100, such as red quantum dot composite material 100, green quantum dot composite material 100, blue quantum dot composite material 100, or combinations thereof. The anode 610 and cathode 650 may include transparent conductors such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide, titanium nitride, and polyaniline; and opaque conductors such as aluminum, lithium aluminum alloy, silver, magnesium-silver alloy, and lithium fluoride-aluminum (LiF:Al). The hole injection layer 620 includes, for example, PEDOT:PSS, HATNA-F6, and MeO-Spiro-TPD, and the electron injection layer 640 includes, for example, NTCDA, BCP, and 3TPYMB.

[0046] To make the above-described contents and other objects, features and advantages of this disclosure more apparent and understandable, embodiments are described below in conjunction with the accompanying drawings for detailed explanation.

[0047] [Experimental Example 1]

[0048] CdSe quantum dot particles were dissolved in hexane. Then, silicate, serving as the support core, was added to the quantum dot particle solution, mixing at a ratio of approximately 1:0.03 (total quantum dot particles to support core). The mixture was stirred for about one hour. After centrifugation at 9000 rpm for one minute, a powder containing quantum dot particles embedded in the support core was obtained. Next, alumina was deposited onto the support core and quantum dot particles via atomic layer deposition to form a coating layer.

[0049] Next, the powder obtained above was placed in 500 ml of ethanol, and 20 mL of tetraethoxysilane was added as a Si- precursor. The mixture was stirred at 60 °C for about 60 minutes. Then, 5 mL of ammonia water as a catalyst was added to the reaction flask, and the mixture was kept at 60 °C for 6 hours. This composite material was washed several times with n-hexane and dried at 60 °C for 4 hours to form a porous light-diffusing layer, thus obtaining the composite material structure disclosed herein.

[0050] The quantum dot composite material described above is mixed with an organosiloxane resin, and then coated onto a blue light-emitting diode wafer with a wavelength of about 450~460nm, an optical power of about 34.6 mW, and a wafer size of about 0.35*0.70 mm to obtain a light-emitting device as shown in Figure 6A. The powder loading of the light-emitting device is 75wt%, that is, the wavelength conversion layer of the light-emitting device contains 75wt% quantum dot composite material and 25wt% organosiloxane resin.

[0051] [Comparative Example 1]

[0052] Except for forming only the coating layer described in Experimental Example 1 as a protective layer for the quantum dot composite material, the light-emitting device was manufactured in the same manner as in Experimental Example 1.

[0053] [Comparative Example 2]

[0054] Except for forming only the porous light-diffusing layer described in Experimental Example 1 as a protective layer for the quantum dot composite material, the light-emitting device is manufactured in the same manner as in Experimental Example 1.

[0055] High Temperature and High Humidity Storage Test

[0056] The manufactured light-emitting devices underwent a high-temperature and high-humidity storage test to verify the heat aging resistance of the encapsulation material. Different currents were applied to the manufactured light-emitting devices to induce emission, and the chromaticity (Cy) and luminous intensity (IV) of each device according to the HHO6090 standard were measured using a luminance meter (Vimin Enterprise / 6122). Subsequently, the light-emitting devices in their luminous state were placed in a test furnace at 60°C and 90% humidity, and the chromaticity (Cy) and luminous intensity were measured at 1, 24, and 96 hours after the high-temperature and high-humidity test. Then, starting from the 168th hour, the manufactured light-emitting devices were removed from the test furnace and measured every 168 hours until the 840th hour, i.e., data from the 168th, 336th, 504th, 672nd, and 840th hours were measured. Using the luminous intensity and chromaticity before being placed in the test furnace as a benchmark, the degree of luminous intensity decay and chromaticity deviation of the light-emitting devices over time were calculated.

[0057] The degree of chromaticity decay over time and the calculation method for chromaticity deviation are as follows: The degree of luminescence intensity degradation after n hours of high temperature and high humidity is: Luminescence intensity at n hours after high temperature and high humidity / Luminescence intensity before high temperature and high humidity * 100% The chromaticity deviation at n hours after high temperature and high humidity is: Chromaticity at n hours after high temperature and high humidity - Chromaticity before high temperature and high humidity.

[0058] The high temperature and high humidity storage tests were carried out on Example 1 and Comparative Examples 1-2 at currents of 10 mA, 15 mA, or 20 mA respectively. The results are shown in Figures 8A-8C respectively. It can be seen from the experimental results that regardless of whether the current is 10 mA, 15 mA, or 20 mA, the attenuation degree of luminescence intensity and chromaticity deviation of both Comparative Example 1 with only the coating layer as the protective layer and Comparative Example 2 with only the pore light-diffusing layer as the protective layer are significantly greater than those of Example 1 with both the coating layer and the pore light-diffusing layer as the protective layer.

[0059] <BET specific surface area measurement>

[0060] The BET specific surface area of the composite material structures manufactured in Example 1 and Comparative Examples 1-2 was measured using an instrument with the brand Micromeritics - model ASAP 2020.

[0061] <Luminous flux measurement>

[0062] The luminous flux of the light-emitting devices manufactured in Example 1 and Comparative Example 1-B2 was measured using an integrating sphere (IS) instrument. Specifically, a current was applied to the light-emitting device to make it emit light, and the luminous flux (lm) was measured. The results are shown in Table 1.

[0063] Next, by the method of the above high temperature and high humidity storage test, the degree of decline of the luminescence intensity of the device at 10 mA current at the 840th hour after high temperature and high humidity, that is, HHO6090 IV%-840H-10mA, and the chromaticity deviation, that is, HHO6090△y-840H-10mA and RTO△y-840H-10mA, were obtained. The results are shown in Table 1.

[0064] [Table 1] <00002*16> # Comparative Example 1 Example 1 Comparative Example 2 <00002*20> Protective layer <00002*21> Coating layer Composite protective layer Pore light-diffusing layer Note: There seems to be a formatting issue in the original text where some tags like and have an asterisk in them which might be a mistake. I've translated them as is while keeping the asterisk in the translation. If these are meant to be something else, please correct the original text for a more accurate translation. Powder dosage (wt%) 75 75 75 BET specific surface area (m² / g) 0.004 25 150 Luminous flux (lm) 8.93 7.73 5.97 HHO6090 IV%-840H-10mA 81% 87% 77% HHO6090 △y-840H-10mA -0.029 -0.02 -0.033 RTO△y-840H-10mA -0.023 -0.01 -0.018

[0065] As can be seen from Table 1, although Comparative Example 1, which uses only the coating layer as the protective layer, has a higher luminous flux, its chromaticity deviation is larger, and its heat aging resistance is not as good as that of Example 1, which uses a composite protective layer. In addition, Comparative Example 2, which uses only the porous light-diffusing layer as the protective layer, not only has a lower luminous flux, but also a larger chromaticity deviation, and its heat aging resistance is also lower than that of Example 1.

[0066] In summary, the quantum dot composite material disclosed herein can be used in various light-emitting devices and has heat aging resistance. Therefore, its application in various device products can improve the stability of performance and service life.

[0067] The components of several embodiments are summarized above to facilitate a better understanding of the views expressed in the embodiments of this disclosure by those skilled in the art. Those skilled in the art should understand that they can design or modify other processes and structures based on the embodiments of this disclosure to achieve the same purpose and / or advantages as the embodiments described herein. Those skilled in the art should also understand that such equivalent processes and structures do not depart from the spirit and scope of this disclosure, and that they can make various changes, substitutions, and replacements without departing from the spirit and scope of this disclosure.

[0068] 100: Quantum dot composite materials 110: Vector Core 110': Vector Core 110p: Recessed hole 120: Quantum Dot Particles 130: Composite protective layer 132: Covering layer 134: Pore light-diffusing layer 134p: Complex porosity 200: Light Emitting Diode Chip 202: Base 204: Epitaxial structure 206: Type I semiconductor layer 208: Active Layer 208 210: Type II semiconductor layer 214: First electrode 214 216: Second electrode 216 300: Light Emitting Diode Chip 302: Base 314: First electrode 316: Second electrode 400: Light Emitting Diode Device 405: Light Emitting Diode Device 410: Base 410a: Positive electrode 410b: Negative electrode 410s: Die-bonding region 412: Storage space 420: Light Emitting Diode Chip 430: Wavelength Conversion 435: Wavelength Conversion 440: Reflective Wall 445: Cup wall 446: Reflective Wall 500: Light Emitting Diode Device 520: Light Emitting Diode Chip 530: Wavelength conversion layer 600: Quantum Dot Light Emitting Diode 610: Anode 620: Hole Injection Layer 630: Emissive layer 640: Electron Injection Layer 650: Cathode A1: District A2: District d1: Thickness d2: thickness r1: diameter

Claims

1. A quantum dot composite material, comprising: One carrier core; Multiple quantum point particles are attached to the carrier core; And a composite protective layer covering the carrier core and the quantum dot particles, wherein the composite protective layer includes a coating layer and a porous light-diffusing layer, the coating layer and the porous light-diffusing layer are light-transmitting materials, the coating layer is compliantly formed on the carrier core and the quantum dot particles, and the porous light-diffusing layer is formed on the coating layer and has an irregular surface.

2. The quantum dot composite material as claimed in claim 1, wherein the thickness of the porous light-diffusing layer is 100 nm to 1 μm, and the thickness of the coating layer is more than 1 nm and less than 10 nm.

3. The quantum dot composite material as described in claim 1, wherein the BET specific surface area of ​​the composite protective layer is 0.5~50 m2 / g.

4. The quantum dot composite material as claimed in claim 1 or 3, wherein the porous light-diffusing layer contains a plurality of pores, the volume of which is 0.01 to 0.5 cm3 / g.

5. The quantum dot composite material as claimed in claim 1, wherein the porous light-diffusing layer comprises an inorganic compound, an organic compound, or a combination thereof.

6. The quantum dot composite material as claimed in claim 1, wherein the coating layer comprises a metal oxide.

7. The quantum dot composite material as claimed in claim 1, wherein the ratio of the diameter of the quantum dot particles to the thickness of the coating layer is 1:0.2 to 1:0.

5.

8. The quantum dot composite material as claimed in claim 1 or 7, wherein the ratio of the diameter of the quantum dot particles to the thickness of the porous light-diffusing layer is 1:5 to 1:

50.

9. The quantum dot composite material as described in claim 1 or 7, wherein the ratio of the thickness of the coating layer to the thickness of the porous light-diffusing layer is 1:10 to 1:

250.

10. The quantum dot composite material as claimed in claim 1, wherein the carrier core comprises an inorganic light emitter, a metal oxide, or a combination thereof without an activator.

11. The quantum dot composite material as claimed in claim 1, wherein the outer surface of the carrier core includes a plurality of recesses for accommodating the quantum dot particles.

12. The quantum dot composite material as described in claim 1, wherein the quantum dot particles are core-shell quantum dot particles.

13. A method for forming a quantum dot composite material, comprising: dispersing and attaching a plurality of quantum dot particles to a carrier core; conformally forming a coating layer on the quantum dot particles and the carrier core; and forming a porous light-diffusing layer having an irregular surface on the coating layer.

14. A method for forming a quantum dot composite material as described in claim 13, wherein the coating layer is formed by atomic layer deposition.

15. A method for forming a quantum dot composite material as described in claim 13, wherein the porous light-diffusing layer is formed by a sol-gel method.

16. A light-emitting device comprising the quantum dot composite material described in claims 1 to 12.

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