Quantum dot particles with passivation layers and their fabrication methods

Abstract

This invention relates to a quantum dot particle with a passivation layer and a method for fabricating the same. The invention mainly includes at least one quantum dot particle, at least one first passivation layer, and at least one second passivation layer. The first passivation layer is disposed on the surface of the quantum dot particle, and the second passivation layer is disposed on the surface of the first passivation layer. The precursor for forming the first passivation layer does not contain water, thus preventing the powder from becoming damp during deposition. The second passivation layer is formed on the surface of the first passivation layer. The precursor for the second passivation layer includes trimethylaluminum and water, and the density of the second passivation layer is higher than that of the first passivation layer. The precursor for the second passivation layer is isolated by the first passivation layer, preventing the powder from coming into contact with water and becoming damp and deteriorating. This improves the process yield and lifespan of the quantum dot particles.

Description

Technical Field

[0001] This invention relates to a quantum dot particle with a passivation layer and a method for manufacturing the same, which can effectively protect the quantum dot particle and improve the process yield and lifespan of the quantum dot particle. Background Technology

[0002] Nanoparticles are generally defined as particles smaller than 100 nanometers in at least one dimension. Their physical and chemical properties differ significantly from those of macroscopic matter. While the physical properties of macroscopic matter are generally independent of its size, this is not the case for nanoparticles. Nanoparticles have potential applications in biomedicine, optics, and electronics.

[0003] Quantum dot particles are nanoparticles of semiconductors. Currently, the semiconductor materials being studied are II-VI materials, such as ZnS, CdS, and CdSe, with CdSe attracting the most attention. The size of quantum dot particles typically ranges from 2 to 50 nanometers. When quantum dot particles are irradiated with ultraviolet light, the electrons within them absorb energy and transition from the valence band to the conduction band. When the excited electrons return from the conduction band to the valence band, they release energy through luminescence.

[0004] The band gap of quantum dot particles is related to their size. Larger quantum dot particles have smaller band gaps and emit longer wavelengths of light when illuminated. Conversely, smaller quantum dot particles have larger band gaps and emit shorter wavelengths of light when illuminated. For example, 5 to 6 nanometer quantum dot particles emit orange or red light, while 2 to 3 nanometer quantum dot particles emit blue or green light. Of course, the color of the light depends on the material composition of the quantum dot particles.

[0005] Light emitted by light-emitting diodes (LEDs) using quantum dot particles can produce light with a near-continuous spectrum and high color rendering index, which is beneficial for improving the luminous quality of LEDs. Furthermore, the wavelength of the emitted light can be adjusted by changing the size of the quantum dot particles, making quantum dot particles a key focus of development for next-generation light-emitting devices and displays.

[0006] While quantum dot particles possess the aforementioned advantages and properties, they are prone to aggregation during the manufacturing process. Furthermore, quantum dot particles exhibit high surface activity and readily react with air and moisture, thereby shortening their lifespan.

[0007] Specifically, during the process of fabricating quantum dot particles into the sealant for light-emitting diodes (LEDs), an aggregation effect may occur, reducing the optical performance of the quantum dot particles. Furthermore, after the quantum dot particles are used as the sealant for LEDs, external oxygen or moisture may still penetrate the sealant and contact the surface of the quantum dot particles, leading to oxidation and shortening the performance or lifespan of both the quantum dot particles and the LED. In addition, surface defects and dangling bonds in the quantum dot particles may also cause nonradiative recombination.

[0008] Currently, the industry uses atomic layer deposition (ALD) to form a nanometer-thick thin film on the surface of quantum dot particles to protect them. However, the protective effect of the currently used films on quantum dot particles is still limited, and they cannot effectively extend the lifespan of quantum dot particles. Summary of the Invention

[0009] To address the problems of the prior art, this invention proposes a quantum dot particle with a passivation layer, wherein a first passivation layer and a second passivation layer are sequentially formed on the surface of the quantum dot particle. The precursor of the first passivation layer does not contain water, thus preventing the quantum dot particle from coming into contact with water during the manufacturing process and deteriorating.

[0010] One object of the present invention is to provide a quantum dot particle with a passivation layer, mainly comprising at least one quantum dot particle, at least one first passivation layer, and at least one second passivation layer, wherein the first passivation layer and the second passivation layer are sequentially disposed on the surface of the quantum dot particle. The precursor of the first passivation layer does not contain water, which can prevent contact with water during the process of setting the first passivation layer on the quantum dot particle, thus preventing moisture-induced deterioration.

[0011] Before the formation of the second passivation layer, a first passivation layer is formed on the surface of the quantum dot particles. The first passivation layer can be used to isolate the precursors used when setting the second passivation layer, such as water and trimethylaluminum, to prevent the quantum dot particles from directly contacting the precursors of the second passivation layer and causing the quantum dot particles to become damp and deteriorate.

[0012] One objective of this invention is to provide a quantum dot particle with a passivation layer, mainly comprising at least one quantum dot particle, at least one first passivation layer, and at least one second passivation layer, wherein the first passivation layer and the second passivation layer are sequentially disposed on the quantum dot particle. The first passivation layer in contact with the quantum dot particle has a relatively loose density, mainly to prevent the quantum dot particle from contacting moisture and becoming damp. The second passivation layer disposed on the surface of the first passivation layer has a relatively dense density, mainly to provide stronger protection for the quantum dot particle, thereby extending the lifespan of the quantum dot particle.

[0013] The precursors used in the first passivation layer include trimethylaluminum and alcohols, resulting in a high carbon content in the first passivation layer. The precursors used in the second passivation layer include trimethylaluminum and water, resulting in a low carbon content in the second passivation layer.

[0014] One objective of this invention is to provide a method for fabricating quantum dot particles with a passivation layer, comprising forming a first passivation layer on the surface of the quantum dot particles by an atomic layer deposition process, wherein the precursor for forming the first passivation layer does not contain water, so as to prevent contact with water during the process of setting the first passivation layer on the quantum dot particles and thus prevent moisture-induced deterioration.

[0015] After the second passivation layer is applied, the quantum dot particles can be inspected for discoloration due to moisture to assess the success of the atomic layer deposition. For example, quantum dot particles with a passivation layer can be mixed with silicone and coated onto a light-emitting diode (LED) stage. The LED stage can then be observed for blackening. If the LED stage exhibits blackening, it indicates that the passivation layer did not completely coat the quantum dot particles, resulting in a reaction between the sulfur (ZnS) on the quantum dot particle surface and the silver on the LED stage.

[0016] To achieve the above objectives, the present invention proposes a quantum dot particle with a passivation layer, comprising: at least one quantum dot particle; a first passivation layer disposed on a surface of the quantum dot particle; and a second passivation layer disposed on a surface of the first passivation layer, wherein the density of the second passivation layer is greater than that of the first passivation layer.

[0017] The present invention provides a method for fabricating quantum dot particles with a passivation layer, comprising: providing at least one quantum dot particle; performing a first atomic layer deposition on the quantum dot particle to form a first passivation layer on the surface of the quantum dot particle; and performing a second atomic layer deposition on the quantum dot particle to form a second passivation layer on the surface of the first passivation layer, wherein a precursor of the second atomic layer deposition comprises trimethylaluminum and water.

[0018] The present invention also provides a method for fabricating quantum dot particles with a passivation layer, comprising: providing at least one quantum dot particle; performing a molecular layer deposition on the quantum dot particle and forming a first passivation layer on the surface of the quantum dot particle; and performing an atomic layer deposition on the quantum dot particle and forming a second passivation layer on the surface of the first passivation layer, wherein a precursor for the atomic layer deposition includes trimethylaluminum and water.

[0019] The quantum dot particles with passivation layers, wherein the first passivation layer is an organic-inorganic hybrid layer, the carbon content of the second passivation layer is less than 10%, and the carbon content of the first passivation layer is greater than or equal to 10%.

[0020] The quantum dot particles with passivation layers, wherein the thickness of the first passivation layer is greater than 0.5 nm.

[0021] The quantum dot particles with passivation layers, wherein the thickness of the second passivation layer is greater than or equal to that of the first passivation layer.

[0022] The method for fabricating quantum dot particles with a passivation layer, wherein a precursor used for the deposition of the first atomic layer includes trimethylaluminum and alcohols.

[0023] The method for fabricating quantum dot particles with a passivation layer, wherein a precursor used for the deposition of the first atomic layer does not include water.

[0024] The beneficial effects of this invention are: it provides a quantum dot particle with a passivation layer, mainly by sequentially forming a first passivation layer and a second passivation layer on the surface of the quantum dot particle. The precursor of the first passivation layer does not contain water, which can prevent the quantum dot particle from coming into contact with water during the manufacturing process and thus deteriorating. Attached Figure Description

[0025] Figure 1 This is a cross-sectional schematic diagram of an embodiment of the quantum dot particles with a passivation layer of the present invention.

[0026] Figure 2 This is a flowchart illustrating the steps of an embodiment of the method for fabricating quantum dot particles with a passivation layer according to the present invention.

[0027] Figure 3 A graph showing the temperature and etching rate of the first passivation layer of quantum dot particles with a passivation layer, using 5% potassium hydroxide.

[0028] Figure 4 A graph showing the temperature and etching rate of the second passivation layer of quantum dot particles with a passivation layer, using 0.08% potassium hydroxide.

[0029] Explanation of reference numerals in the attached figures: 10 - quantum dot particle with passivation layer; 11 - quantum dot particle; 13 - first passivation layer; 15 - second passivation layer. Detailed Implementation

[0030] Please see Figure 1 This is a cross-sectional schematic diagram of an embodiment of the quantum dot particle with a passivation layer according to the present invention. The quantum dot particle 10 with a passivation layer includes at least one quantum dot 11, at least one first passivation layer 13 and at least one second passivation layer 15, wherein the first passivation layer 13 is disposed on the surface of the quantum dot particle 11, and the second passivation layer 15 is disposed on the surface of the first passivation layer 13.

[0031] The quantum dot particles 11 can be II-VI semiconductor materials such as ZnS, CdS, and CdSe, wherein the size of the quantum dot particles 11 is typically less than 100 nm, and the first passivation layer 13 and the second passivation layer 15 formed on the quantum dot particles 11 include, but are not limited to, aluminum oxide (Al2O3).

[0032] In practical applications, a first passivation layer 13 can be formed on the surface of the quantum dot particles 11 through a first atomic layer deposition process. The precursor for forming the first passivation layer 13 does not include water. For example, the precursor for forming the first passivation layer 13 can be trimethylaluminum and alcohols. Therefore, during the first atomic layer deposition process on the surface of the quantum dot particles 11, the quantum dot particles 11 will not come into contact with water, thus preventing the quantum dot particles 11 from becoming damp and deteriorating.

[0033] After the first passivation layer 13 is formed on the surface of the quantum dot particles 11, a second atomic layer deposition can be performed on the quantum dot particles 11 to form a second passivation layer 15 on the surface of the first passivation layer 13. Before forming the second passivation layer 15, the first passivation layer 13 has been formed on the surface of the quantum dot particles 11, which serves to isolate the quantum dot particles 11 from the precursor used for the second atomic layer deposition. Therefore, there is no need to limit the precursor used for the second atomic layer deposition, where a precursor capable of forming a high-density second passivation layer 15 is preferred; for example, the precursor for forming the second passivation layer 15 could be trimethylaluminum and water.

[0034] Generally, if the precursor used for the first atomic layer deposition does not contain water, such as trimethylaluminum and alcohols, the quantum dot particles 11 can be prevented from contacting water and deteriorating. However, the resulting first passivation layer 13 has a low density, which is not conducive to extending the lifespan of the quantum dot particles 11. In contrast, the precursor used for the second atomic layer deposition is not limited, and can be, for example, trimethylaluminum and water, which can form a higher density second passivation layer 15 and is beneficial to extending the lifespan of the quantum dot particles 11.

[0035] To this end, the present invention proposes to pre-form a first passivation layer 13 on the surface of the quantum dot particles 11, and then form a second passivation layer 15 on the surface of the first passivation layer 13. Although the precursor used to form the second passivation layer 15 includes water, since the first passivation layer 13 has been pre-formed on the surface of the quantum dot particles 11, the water in the precursor used for the second atomic layer deposition can be effectively prevented from contacting the quantum dot particles 11.

[0036] Specifically, the precursors used in the first atomic layer deposition and the second atomic layer deposition of the present invention are different, which makes the first passivation layer 13 and the second passivation layer 15 formed on the surface of the quantum dot particles 11 have different characteristics and effects, and can effectively prevent the quantum dot particles 11 from getting damp and deteriorating, while improving the protection of the quantum dot particles 11.

[0037] The different precursors used in the first and second atomic layer depositions result in differences in the composition of the first passivation layer 13 and the second passivation layer 15. Specifically, the precursors used in the second atomic layer deposition, such as trimethylaluminum and water, result in a lower carbon content in the second passivation layer 15 compared to the first passivation layer 13. For example, the carbon content of the second passivation layer 15 is less than 10%, while the carbon content of the first passivation layer 13 is greater than or equal to 10%.

[0038] In one embodiment of the present invention, the first passivation layer 13 may be an organic-inorganic hybrid layer. Furthermore, the first passivation layer 13 primarily isolates moisture in the atomic layer deposition process, while the second passivation layer 15 provides primary protection for the quantum dot particles 11. Therefore, the thickness of the second passivation layer 15 is typically greater than or equal to that of the first passivation layer 13 to enhance the protection of the quantum dot particles 11. After numerous experiments, when the thickness of the first passivation layer 13 is greater than 0.5 nm, it can effectively isolate the quantum dot particles 11 from the water-containing precursors used in the second atomic layer deposition process and prevent the quantum dot particles 11 from becoming damp and deteriorating.

[0039] exist Figure 1 The illustration mainly uses the first passivation layer 13 and the second passivation layer 15 to cover a single quantum dot particle 11. However, in practical applications, the first passivation layer 13 and the second passivation layer 15 can cover multiple quantum dot particles 11.

[0040] Please see Figure 2 This is a flowchart illustrating the fabrication process of the quantum dot particles with a passivation layer according to the present invention. Please refer to the accompanying documentation. Figure 1First, at least one quantum dot particle 11 is provided, as shown in step 21. The quantum dot particle 11 can be made of II-VI semiconductor materials such as ZnS, CdS, and CdSe, wherein the size of the quantum dot particle 11 is typically less than 100 nm. The manufacturing methods of quantum dot particles can be broadly classified into three categories, including chemical solution growth, epitaxial growth, and electric field confinement. The manufacturing method of quantum dot particle 11 is not a major technical feature of this invention and will not be described in detail here.

[0041] A first atomic layer deposition is performed on the quantum dot particles 11 to form a first passivation layer 13 on the surface of the quantum dot particles 11, as shown in step 23. In one embodiment of the present invention, the precursor used for the first atomic layer deposition does not include water. For example, the precursor used for the first atomic layer deposition includes, but is not limited to, trimethylaluminum and alcohols, to avoid the quantum dot particles 11 from coming into contact with moisture and becoming damp during the first atomic layer deposition process. The fact that water is not used as a precursor in the first atomic layer deposition also avoids the aggregation of individual quantum dot particles 11. In another embodiment of the present invention, the first passivation layer 13 can also be formed on the surface of the quantum dot particles 11 by molecular layer deposition, wherein the precursor used for molecular layer deposition does not include water, and includes, for example, trimethylaluminum and alcohols.

[0042] Then, a second atomic layer deposition is performed on the quantum dot particles 11, and a second passivation layer 15 is formed on the surface of the first passivation layer 13 of the quantum dot particles 11. The precursors used for the second atomic layer deposition include trimethylaluminum and water, as shown in step 25. The density of the second passivation layer 15 formed by the second atomic layer deposition is higher than that of the first passivation layer 13, which is beneficial to increasing the lifetime of the quantum dot particles 11.

[0043] Please refer to the following: Figure 3 and Figure 4 , Figure 3 The graph shows the temperature and etching rate of the first passivation layer 13 with 0.08% potassium hydroxide (KOH). Figure 4 The graph shows the temperature and etching rate of the second passivation layer 15 when 5% potassium hydroxide is applied. Figure 3 and Figure 4 It can be clearly seen that the etching rate of the second passivation layer 15 with 5% potassium hydroxide is less than the etching rate of the first passivation layer 13 with 0.08% potassium hydroxide, indicating that the density of the second passivation layer 15 is higher than that of the first passivation layer 13. Furthermore, if the first passivation layer 13 is etched using 5% potassium hydroxide, the thickness can be reduced to [a certain value] in less than one second. The first passivation layer 13 formed by aluminum oxide was completely etched away.

[0044] The precursors used in the first atomic layer deposition do not contain water, such as trimethylaluminum and alcohols, which prevents the quantum dot particles 11 from coming into contact with water and deteriorating. However, the resulting first passivation layer 13 has a low density, which is not conducive to extending the lifespan of the quantum dot particles 11. In contrast, the precursors used in the second atomic layer deposition are not limited, such as trimethylaluminum and water, and the resulting second passivation layer 15 can have a higher density, which is beneficial for extending the lifespan of the quantum dot particles 11.

[0045] Advantages of this invention:

[0046] A quantum dot particle with a passivation layer is proposed, mainly by sequentially forming a first passivation layer and a second passivation layer on the surface of the quantum dot particle. The precursor of the first passivation layer does not contain water, which can prevent the quantum dot particle from coming into contact with water during the manufacturing process and thus deteriorating.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. All equivalent variations and modifications made in accordance with the shape, structure, features and spirit described in the claims of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A quantum dot particle with a passivation layer, characterized in that, include: At least one quantum dot particle; A first passivation layer is disposed on one surface of the quantum dot particle; and A second passivation layer is disposed on a surface of the first passivation layer, such that the density of the second passivation layer is greater than that of the first passivation layer. The preparation method of the second passivation layer includes: Provide at least one quantum dot particle; A one-molecular-layer deposition is performed on the quantum dot particle, and the first passivation layer is formed on the surface of the quantum dot particle; and An atomic layer is deposited on the quantum dot particle, and a second passivation layer is formed on the surface of the first passivation layer, wherein a precursor for the atomic layer deposition is trimethylaluminum and water; One of the precursors used in this molecular layer deposition is trimethylaluminum and alcohols.

2. The quantum dot particle with a passivation layer according to claim 1, characterized in that, The first passivation layer is an organic-inorganic mixed layer, the second passivation layer has a carbon content of less than 10%, and the first passivation layer has a carbon content of greater than or equal to 10%.

3. The quantum dot particle with a passivation layer according to claim 1, characterized in that, The thickness of the first passivation layer is greater than 0.5 nm.

4. The quantum dot particle with a passivation layer according to claim 1, characterized in that, The thickness of the second passivation layer is greater than or equal to that of the first passivation layer.

5. A method for fabricating quantum dot particles with a passivation layer, characterized in that, include: Provide at least one quantum dot particle; A molecular layer is deposited on the quantum dot particle, and a first passivation layer is formed on the surface of the quantum dot particle. and An atomic layer is deposited on the quantum dot particle, and a second passivation layer is formed on the surface of the first passivation layer, wherein a precursor for the atomic layer deposition is trimethylaluminum and water; One of the precursors used in this molecular layer deposition is trimethylaluminum and alcohols.

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