Structure, method for producing a structure, method for adjusting a water content of a structure

Abstract

A structure is specified. According to one embodiment, the structure includes a nanocrystal configured to convert primary radiation to secondary radiation and an encapsulation at least partially surrounding the nanocrystal, where the encapsulation includes a humectant. The invention further relates to a method for producing a structure, to a method for adjusting the moisture content of a structure, and to an optoelectronic device, in particular comprising a micro-LED.

Description

[0001] A structure, a method for producing the structure, a method for adjusting the water content of the structure, and an optoelectronic device are specified.

[0002] It is an object to provide a structure with improved efficiency. It is a further object to provide a simple method for producing such a structure. It is additionally an object to provide a simple method for adjusting the water content of such a structure. It is furthermore an object to provide an optoelectronic device with improved efficiency.

[0003] A structure is specified. The structure can comprise different elements, components or parts with specific, in particular different, properties.

[0004] According to embodiments, the structure comprises nanocrystals configured to convert primary radiation into secondary radiation. In other words, the nanocrystals convert electromagnetic radiation of a first wavelength range (primary radiation) into electromagnetic radiation of a second wavelength range (secondary radiation). In particular, the nanocrystals absorb electromagnetic radiation of the first wavelength range, convert the electromagnetic radiation of the first wavelength range into electromagnetic radiation of the second wavelength range, and emit the electromagnetic radiation of the second wavelength range. For example, the second wavelength range is in the visible or IR wavelength range. For example, the second wavelength range is between 400 nm and 2000 nm, including both 400 nm and 2000 nm. In particular, the second wavelength range is between 500 nm and 1000 nm, including both 500 nm and 1000 nm.

[0005] In particular, the nanocrystals are particles with a diameter between 1 nm and 100 nm, including both 1 nm and 100 nm, for example between 2 nm and 20 nm, including both 2 nm and 20 nm. Due to their size, the nanocrystals have different properties than bulk material formed of the same material. For example, the nanocrystals are spherical, rod-shaped or cubic. The surface of the nanocrystals can be uniform or non-uniform.

[0006] For example, the nanocrystals comprise or consist of a semiconductor material. The semiconductor material is for example a III-V compound semiconductor material, a II-VI compound semiconductor material or a II-III-V compound semiconductor material.

[0007] III-V compound semiconductor materials contain at least one element from Group 13 of the periodic table (e.g., B, Al, Ga, In) and at least one element from Group 15 of the periodic table (e.g., N, P, As). II-VI compound semiconductor materials contain at least one element from Group 2 or Group 12 of the periodic table (e.g., Zn, Cd, Mg) and at least one element from Group 16 of the periodic table (e.g., O, S, Se, Te). II-III-V compound semiconductor materials contain at least one element from Group 2 or Group 12 of the periodic table, at least one element from Group 13 of the periodic table, and at least one element from Group 15 of the periodic table. For example, nanocrystals contain or are composed of sulfides, selenides, nitrides, or phosphides.

[0008] According to at least one embodiment, the structure includes an encapsulation that at least partially surrounds the nanocrystal. The encapsulation may include different layers and / or elements. The encapsulation may be configured or designed as a passivation layer for electronic passivation and / or a protective layer for protecting structural components (e.g., the nanocrystal) from degradation. Specifically, the encapsulation completely surrounds the nanocrystal. The encapsulation may be in direct contact with the nanocrystal. Alternatively, additional layers may be disposed between the nanocrystal and the encapsulation.

[0009] According to at least one embodiment, the encapsulation includes a humectant. Specifically, the humectant is a molecular mechanism that attracts, absorbs, retains, preserves, and releases moisture or water. In other words, the humectant is a moisture or water-regulating substance. For example, the humectant is configured to regulate the water content of a structure. Specifically, the humectant is a hygroscopic or water-absorbing substance used to maintain a specific water content within the structure. For example, the humectant balances or buffers the water content within the structure by attracting, absorbing, retaining, preserving, and releasing moisture or water.

[0010] According to at least one embodiment, the structure includes a nanocrystal configured to convert primary radiation into secondary radiation and an encapsulation at least partially surrounding the nanocrystal, wherein the encapsulation includes a humectant.

[0011] The concept of this application is to provide a structure that provides an ideal environment for highly luminescent and stable nanocrystals due to the incorporation of a humectant within the encapsulation. The availability of water near the nanocrystals helps maintain strong luminescence over time. However, excessive water content can lead to corrosion of the nanocrystals. Using a humectant within the encapsulation allows for the controllable adjustment of the amount of water captured and absorbed by controlling its transport and storage within the encapsulation and therefore within the structure. This, in turn, imparts more stable properties to the nanocrystals, such as color as a function of temperature and lifetime, and greater durability during operation and storage due to less corrosion.

[0012] According to at least one embodiment, a nanocrystal includes a core and at least one shell. Specifically, the nanocrystal is a quantum dot including a core and at least one shell. The core and / or shell may comprise at least one semiconductor material. In particular, the core comprises a semiconductor material different from the shell. For example, at least one shell is epitaxially grown onto the core. The nanocrystal may include additional shells and / or layers. For example, the nanocrystal includes a quantum well structure. For example, the nanoparticle is a core-shell quantum dot or a core-shell-shell quantum dot.

[0013] According to at least one embodiment, a humectant is configured to balance the presence of water. Specifically, the humectant balances the moisture content within the structure by attracting, absorbing, retaining, storing, and releasing moisture or water. For example, the humectant acts as a buffer to ensure that the structure will withstand changes in humidity by releasing or absorbing moisture. A humectant configured to balance the presence of water advantageously protects the nanocrystals from corrosion by limiting excessive moisture content, while maintaining the luminescence of the nanocrystals over time by retaining available water within the structure.

[0014] According to at least one embodiment, the humectant is at least one of salt, small molecule, polymer, degel, and clay mineral. In particular, each type of humectant has a specific water-binding strength. For example, the structure may include exactly one type of humectant. Alternatively, the structure may include more than one type of humectant.

[0015] A salt is a chemical compound composed of a collection of positively charged cations and negatively charged anions, and carries no net charge. Salts can bind with water and thus retain water. Salts can include simple salts and complex salts.

[0016] In particular, simple salts contain ingredients selected from Li + Na + K + NH4 + and Mg 2+ At least one of the cations and selected from Cl - H3CCOO - NO3 2- and SO4 2- An anion of at least one of the following. For example, a simple salt is at least one of lithium chloride (LiCl) or lithium acetate (H3CCOOLi).

[0017] Complex salts, especially polyatomic salts. For example, complex salts contain components selected from Li. + and Na +The complex salt comprises at least one cation and at least one anion selected from oleate, metaphosphate such as hexametaphosphate, and polyphosphate. Herein and hereinafter, the term polyphosphate includes all polymer ions formed from phosphates, such as oligomers with ten or fewer phosphate groups and polymers with more than ten phosphate groups. For example, the complex salt is at least one of lithium oleate, lithium polyphosphate, or sodium hexametaphosphate.

[0018] Small molecules, especially those containing at least one hydrophilic group such as a hydroxyl group, can retain water through the formation of hydrogen bonds. For example, a small molecule is glycerol. Glycerol is also known as glycerol or propane-1,2,3-triol and contains three hydroxyl groups.

[0019] Polymers are macromolecules composed of multiple repeating subunits. Polymers may contain several hydrophilic groups (such as hydroxyl groups), which can retain water through hydrogen bonding. For example, polymers are polysaccharides or polyalkylene glycols, such as polyethylene glycol (PEG) or polypropylene glycol (PPG).

[0020] Dry gel is a solid formed by drying a gel under unimpeded shrinkage. Specifically, dry gel has a porosity of 15% to 50% (inclusive) and a density of 150 μm. 2 / g to 900 m 2 / g (including 150 m) 2 / g and 900 m 2 A dry gel has a surface area of ​​1 nm to 10 nm (inclusive) and a pore size of 1 nm to 10 nm (inclusive). Dry gels can retain water due to their high porosity and high surface area. For example, a dry gel is silica gel.

[0021] Clay minerals are layered silicates, such as hydrated layered aluminum silicate. In other words, clay minerals are platy silicates, such as hydrated aluminum platy silicate. Clay minerals retain water between the platy layers due to their platy structure. Examples of clay minerals include kaolinite or montmorillonite. The chemical formula of kaolinite is Al₂Si₂O₅(OH)₄. In ceramic applications, the molecular formula of kaolinite is written in oxide form, therefore the molecular formula is Al₂O₃. 2SiO2 2H2O. Kaolinite is a layered silicate material in which a silica tetrahedron is linked to an alumina octahedron via oxygen atoms. Montmorillonite is a mineral mixture of various layered silicates with a three-layer structure—two silica tetrahedrons cross-linked via a layer of Al2O3 or Fe2O3 octahedra.

[0022] According to at least one embodiment, the encapsulation includes a passivation layer that at least partially, and particularly completely, surrounds the nanocrystals. The diameter of the nanocrystals surrounded by the passivation layer can be less than 1 μm, particularly between 1 nm and 500 nm and including 1 nm and 500 nm, or between 1 nm and 100 nm and including 1 nm and 100 nm. In particular, the passivation layer comprises or is composed of a metal oxide, such as silicon dioxide, aluminum oxide, zirconium oxide, hafnium oxide, strontium oxide, or tin oxide. For example, the passivation layer comprises or is composed of silicon dioxide. The metal oxide, particularly silicon dioxide, can advantageously be uniformly deposited around the nanocrystals, for example, using wet or dry chemical deposition methods. The passivation layer surrounding the nanocrystals advantageously increases the robustness of the nanocrystals.

[0023] According to at least one embodiment, the passivation layer includes a humectant. Specifically, the humectant is disposed within the passivation layer. In other words, the passivation layer at least partially, and particularly completely, surrounds the humectant. Specifically, the humectant exists in the passivation layer in the form of humectant molecules or humectant particles. The diameter of the humectant particles can be less than 1 μm, for example, between 1 nm and 500 nm and including 1 nm and 500 nm, or between 1 nm and 100 nm and including 1 nm and 100 nm. The humectant can have a gradient within the passivation layer. For example, the concentration of the humectant decreases with increasing distance from the nanocrystals, or the concentration of the humectant increases with increasing distance from the nanocrystals. The passivation layer including the humectant advantageously allows for close contact and improved interaction between the nanocrystals and the humectant.

[0024] According to at least one embodiment, the humectant is embedded in the passivation layer. In particular, each type of humectant described herein can be embedded in the passivation layer. For example, the humectant is a simple salt, a complex salt, a small molecule, a polymer, a degel, a clay mineral, or a combination thereof. Embedding the humectant in the passivation layer allows for close contact and improved interaction between the nanocrystals and the humectant.

[0025] According to at least one embodiment, a simple salt is embedded in the passivation layer, and the concentration of the simple salt in the passivation layer is from 1 wt.-% (weight %) to 30 wt.-% (including 1 wt.-% and 30 wt.-%), particularly from 3 wt.-% to 10 wt.-% (including 3 wt.-% and 10 wt.-%).

[0026] According to at least one embodiment, lithium chloride is embedded in the passivation layer. Embedding lithium chloride in the passivation layer of the metal oxide creates a lithium chloride and lithium-metal oxide complex within the oxide network of the passivation layer, both of which act as humectants.

[0027] According to at least one embodiment, the humectant is covalently bonded to the material of the passivation layer. In other words, the humectant contains covalent bonds with the material of the passivation layer. In particular, the humectant is polyethylene glycol (PEG) or polypropylene glycol (PPG). Both PEG and PPG can be covalently bonded to the oxide network of the passivation layer of the metal oxide during the formation of the passivation layer. The humectant covalently bonded to the passivation layer is advantageously incorporated into the passivation layer through strong chemical interactions.

[0028] According to at least one embodiment, the passivation layer is made of a humectant. Specifically, the passivation layer is formed of a humectant. For example, the passivation layer consists of a humectant. Alternatively, the passivation layer may comprise other materials, such as metal oxides that are not humectants. Specifically, the passivation layer comprises 1% to 100% humectant (inclusive). For example, the humectant is ammonium silicate or an alkali metal silicate, such as sodium silicate or lithium silicate. Using a humectant as the material of the passivation layer, the nanocrystals are protected by a dual-purpose passivation and humectant layer. This dual-purpose layer advantageously facilitates the use of a high-load humectant.

[0029] According to at least one embodiment, an additional humectant is embedded in the passivation layer of a material having a humectant as a passivation layer. In other words, the passivation layer comprises two different humectants, wherein one humectant is embedded in the passivation layer, and the other humectant is the material forming the passivation layer. The additional humectant is, for example, a complexed salt or a clay mineral. In a structure with two different humectants, the strength of water binding can be advantageously adjusted for a specific application.

[0030] According to at least one embodiment, the two materials of the passivation layer are humectants. Specifically, the passivation layer is formed from two humectants. The concentrations of the two humectants in the resulting passivation layer can be the same or different. In other words, the concentrations of the two humectants can be varied in the passivation layer. For example, the humectants are sodium silicate and lithium silicate. Because the two materials of the passivation layer are humectants, it is advantageous to obtain a passivation layer with finely regulated composition, which can be adjusted for specific conditions.

[0031] According to at least one embodiment, an encapsulation includes a humectant layer adjacent to a passivation layer, wherein the humectant layer comprises or is composed of a humectant. In other words, the humectant layer is arranged directly adjacent to the passivation layer. Specifically, the humectant layer comprises a humectant and a matrix material, such as silica, silicone resin, or organic polymer. The humectant may be embedded in the matrix material. For example, the humectant is a complex salt such as a polyphosphate, a polymer, or a clay mineral such as montmorillonite or kaolinite. For example, small clay mineral particles may be embedded in silica. Alternatively, complex salt grains may be incorporated into silica, silicone resin, or organic polymer. Alternatively, the humectant layer may be composed of a humectant. In particular, the humectant layer is formed of a humectant. The humectant layer adjacent to the passivation layer advantageously places less demand on the compatibility of the respective components while allowing them to be in close contact.

[0032] According to at least one embodiment, a humectant layer is at least partially, and particularly completely, disposed between the nanocrystals and the passivation layer. Specifically, the humectant layer is in direct contact with both the nanocrystals and the passivation layer. For example, the humectant layer comprises or is composed of polyphosphates disposed on the surface of the nanocrystals prior to the addition of the passivation layer. The humectant layer between the nanocrystals and the passivation layer allows for close contact and improved interaction between the nanocrystals and the humectant in the humectant layer.

[0033] According to at least one embodiment, the humectant layer at least partially, and particularly completely, surrounds the passivation layer. Specifically, the humectant layer is in direct contact with the passivation layer on the side of the passivation layer facing away from the nanocrystals. For example, the humectant layer comprises or is composed of a simple salt or polyphosphate, which is disposed on the surface of the passivation layer facing away from the nanocrystals after the nanocrystals are surrounded by the passivation layer. Advantageously, after the passivation layer is disposed on the nanocrystals, the humectant layer surrounding the passivation layer can be added independently of the formation of the passivation layer.

[0034] According to at least one embodiment, the package includes a plurality of passivation layers and humectant layers arranged in an alternating manner. In other words, the package includes a sequential structure of a plurality of passivation layers and a plurality of humectant layers. Specifically, the package includes at least two, particularly at most ten, passivation layers and at least two, particularly at most ten humectant layers arranged in an alternating manner. The material of the plurality of passivation layers can be the same for all passivation layers, while the humectant layers can include the same humectant or different humectants. For example, the passivation layer is a silica layer, and the humectant layers include clay minerals such as montmorillonite or kaolinite. Alternatively, the passivation layer can be a silica layer, and one or more humectant layers include one humectant, such as a clay mineral, and one or more humectant layers include different humectants, such as different clay minerals or salts. The alternating arrangement of the passivation layers and humectant layers can increase the advantageous effect of incorporating humectants into the structure. By having different humectants in different humectant layers, the strength of water binding can be advantageously adjusted according to the specific application.

[0035] According to at least one embodiment, the structure further includes a barrier layer that at least partially, and particularly completely, surrounds the package. Specifically, the barrier layer is configured to mitigate or prevent water from diffusing into and out of the package. For example, the barrier layer is the outermost layer of the structure. The barrier layer is advantageous for applications with elevated operating temperatures, where structures without a barrier layer become dehydrated due to water evaporation.

[0036] According to at least one embodiment, the barrier layer is hermetically sealed. In other words, the barrier layer is an impermeable barrier layer. Specifically, the barrier layer is waterproof, allowing little or no water to enter or leave the structure. For example, the water vapor transmission rate of the barrier layer ranges from 10. -2 g / m 2 / day to 10 -6 g / m 2 / day, including 10 -2 g / m 2 / Tianhe10 -6 g / m 2 / day. The thickness of the barrier layer can be between 10 nm and 100 nm, including both. For example, the barrier layer is ethylene cellulose (EC) or atomic layer deposition (ALD) layer, such as an ALD layer of alumina. The hermetically sealed barrier layer advantageously prevents any water from leaving the structure, while protecting the nanocrystals from water entering the structure from the outside.

[0037] According to at least one embodiment, the barrier layer is a semi-permeable layer. A semi-permeable layer has the property of partial permeability. In other words, the semi-permeable layer allows only specific compounds or molecules to pass through while retaining other compounds or molecules. Specifically, the semi-permeable layer is partially permeable to water molecules. In other words, the semi-permeable layer allows only a portion of the water located within the structure to leave the structure. Furthermore, the semi-permeable layer allows only a portion of the water existing outside the structure to enter the structure through the semi-permeable layer. For example, the water vapor permeability of the barrier layer ranges from 10. -2 g / m 2 / day to 10 -6 g / m 2 / day, including 10 -2 g / m 2 / Tianhe10 -6 g / m 2 / day. The thickness of the barrier layer can be between 10 nm and 100 nm, or both. For example, the barrier layer is an organic polymer. The semi-permeable layer advantageously slows down the diffusion of water into and out of the structure.

[0038] According to at least one embodiment, the barrier layer comprises a semi-permeable layer and a water-sealing layer. Specifically, the semi-permeable barrier layer is disposed on the encapsulation, and the water-sealing layer is disposed on the semi-permeable barrier layer. For example, the water-sealing layer is an ALD layer. In this case, water can diffuse through the semi-permeable barrier layer into the humectant, and advantageously, a small amount of water can be trapped by the humectant in the passivation layer, while the water-sealing layer prevents the structure from dehydrating.

[0039] According to at least one embodiment, the encapsulation includes a first matrix material, wherein a humectant and nanocrystals are embedded in the first matrix material. In this embodiment, a passivation layer at least partially, and particularly completely, surrounds the nanocrystals. The nanocrystals and the humectant are arranged in the same matrix material but are physically separated from each other. In particular, the humectant is present in the form of humectant particles. For example, the diameter of the humectant particles is less than 1 μm, particularly between 1 nm and 500 nm and including 1 nm and 500 nm, or between 1 nm and 100 nm and including 1 nm and 100 nm. For example, the humectant particles are degelatinized particles such as silica gel particles, complexed salts such as polyphosphates, or clay minerals such as montmorillonite or kaolinite. In particular, multiple nanocrystals and multiple humectant particles are embedded in the first matrix material. The first matrix material can be arranged in the form of a layer or a casting. For example, the first matrix material is silicone resin. Embedding the nanocrystals and the humectant in the first matrix material advantageously allows for complete freedom of the properties of the humectant.

[0040] Furthermore, a method for producing the structure is specified. In particular, the structure described herein is produced by the method for producing the structure. Therefore, the embodiments, features, and advantages described in connection with the structure also apply to the method for producing the structure, and vice versa.

[0041] According to at least one embodiment, the method includes: setting a nanocrystal configured to convert primary radiation into secondary radiation; and setting an encapsulation at least partially surrounding the nanocrystal, wherein the encapsulation includes a humectant.

[0042] Specifically, the method used to produce the structure is a method for producing multiple structures. In this case, multiple nanocrystals are provided, and each nanocrystal is at least partially surrounded by an encapsulation comprising a moisturizing agent.

[0043] Advantageously, this method is a simple and effective way to produce structures with an ideal environment for highly luminescent and stable nanocrystals by incorporating a humectant within the encapsulation of the structure.

[0044] According to at least one embodiment, providing an encapsulation includes forming a passivation layer that at least partially, and particularly completely, surrounds the nanocrystals. Specifically, the passivation layer is synthesized using an anti-micelle process. For example, the passivation layer is produced as follows: one or more nanocrystals are suspended in a nonpolar hydrophobic solvent to form a first solution. A surfactant is added to the first solution, followed by the addition of a metal oxide precursor, other reagents, and a catalyst to initiate the growth of a metal oxide on the surface of the nanocrystals.

[0045] According to at least one embodiment, the material of the passivation layer is a humectant. Specifically, the passivation layer is produced as described above, and a humectant precursor is added as a reagent to replace or supplement the metal oxide precursor. For example, the humectant precursor is a silica-based humectant such as an alkali metal silicate or ammonium silicate precursor. By using a humectant as the material of the passivation layer, a dual-purpose passivation and humectant layer with a high humectant load can be produced simply and efficiently in very few steps.

[0046] According to at least one embodiment, the two materials of the passivation layer are humectants. Specifically, the passivation layer is produced as described above, and two humectant precursors are added as reagents to replace or supplement the metal oxide precursor. For example, the two humectant precursors are added in different amounts. For example, the humectant precursors are sodium silicate and lithium silicate. Using two different humectant precursors as materials for the passivation layer advantageously allows for the simple production of passivation layers with finely regulated composition.

[0047] According to at least one embodiment, a humectant is applied to the surface of the nanocrystals before forming a passivation layer. Specifically, a humectant layer comprising the humectant is applied to the surface of the nanocrystals. For example, the surface of the nanocrystals is treated with a polyphosphate to create a charged nanocrystal surface, and subsequently, a passivation layer is produced on the charged nanocrystal surface. Applying the humectant to the surface of the nanocrystals before forming the passivation layer allows for close contact and improved interaction between the nanocrystals and the humectant, while placing less emphasis on the compatibility of the respective components.

[0048] According to at least one embodiment, a humectant is embedded in the passivation layer during its formation. Specifically, the humectant is added to the first solution simultaneously with the addition of a metal oxide precursor. The humectant can be pre-formed and then added to the first solution. This can improve the accuracy and yield of forming the target humectant and achieving the final chemical composition. Alternatively or additionally, the humectant precursor can be added to the first solution, and the humectant can be formed in situ. In-situ formation allows for close contact and greater interaction between the nanocrystals and the humectant. In particular, each of the types of humectants described above can be used in this method. For example, the humectant is a simple salt such as lithium chloride. The addition of lithium chloride will produce lithium chloride within the oxide network of the passivation layer and a lithium-metal oxide complex in the passivation layer, both of which act as humectants. For example, the humectant is polyethylene glycol or polypropylene glycol. Polyethylene glycol or polypropylene glycol can be covalently bound to the metal oxide network of the passivation layer during its formation. Embedding a humectant into the passivation layer during its formation advantageously combines the passivation process with minute changes to create a structure in the passivation layer that includes the humectant.

[0049] According to at least one embodiment, a humectant is added after the passivation layer is formed. Advantageously, adding the humectant after the passivation layer is formed allows the humectant to be incorporated into the structure, independent of the formation of the passivation layer.

[0050] According to at least one embodiment, a humectant layer comprising a humectant is disposed on the surface of a passivation layer. Specifically, nanocrystals are surrounded by a passivation layer as described above, and subsequently, a humectant layer is deposited on the surface of the passivation layer. For example, a simple salt or a complex salt such as a polyphosphate is deposited from a polar solution. Advantageously, after the passivation layer is disposed on the nanocrystals, the humectant layer surrounding the passivation layer can be added independently of the formation of the passivation layer.

[0051] According to at least one embodiment, a humectant is disposed on the surface of a passivation layer and diffuses into the passivation layer. Specifically, as described above, nanocrystals are surrounded by the passivation layer, and subsequently, the humectant is driven into the pre-formed oxide of the passivation layer. For example, after the formation of the passivation layer, a simple salt can be precipitated onto and into the passivation layer. For example, lithium chloride powder can be added after the formation of the passivation layer to generate a physically adsorbed but unabsorbed humectant substance. In particular, the humectant, such as a simple salt, is balanced throughout the passivation layer. Alternatively, a humectant, such as a clay mineral or molecule, tightly bound to the metal oxide of the passivation layer, forms a gradient within the passivation layer, such that the concentration of the humectant increases with increasing distance from the nanocrystals. This post-synthetic addition of the humectant can advantageously provide greater control over properties that can affect water absorption and desorption kinetics, such as grain size.

[0052] According to at least one embodiment, the amount of humectant in the passivation layer is controlled. Specifically, a certain amount of humectant or humectant precursor is added at the start of the reaction forming the passivation layer, and additional amounts of humectant or humectant precursor are added once or more during the entire reaction forming the passivation layer. For example, a syringe pump is used to increase the total amount of humectant or humectant precursor, and the dispensing is performed slowly during the reaction time. By controlling the amount of humectant in the passivation layer, a gradient of humectant can be included in the passivation layer. Controlling the amount and rate of the reagent entering the reaction mixture into the first solution can help avoid interfering with the reaction forming the passivation layer.

[0053] According to at least one embodiment, the passivation layer at least partially surrounds the nanocrystals, and the humectant and nanocrystals are embedded in a first matrix material. Specifically, multiple nanocrystals and multiple humectant particles are embedded in the first matrix material. Embedding the humectant and nanocrystals in the same matrix material advantageously allows for complete freedom in the properties of the humectant.

[0054] According to at least one embodiment, the method further includes adjusting the water content of the humectant. The water content of the humectant can be adjusted by exposing the structure to an environment with a specific humidity level. Specifically, the structure is exposed to the environment with a specific humidity level for a specific duration and at a specific temperature. For example, the temperature is selected between 0°C and 100°C. The water content can be adjusted in a humidity chamber. For example, the water content of the humectant can be decreased. Alternatively, the water content of the humectant can be increased. Adjusting the water content of the humectant advantageously allows a desired water content to be achieved in the structure.

[0055] According to at least one embodiment, the method further includes providing a barrier layer that at least partially, and particularly completely, surrounds the package. Specifically, providing the barrier layer includes hermetically sealing the package by forming an impermeable barrier layer. Alternatively, providing the barrier layer includes forming a semi-permeable barrier layer on the package. For example, a semi-permeable barrier layer is provided on the package, followed by the addition of water, and then a water-sealing agent layer, such as an ALD layer, is provided on the semi-permeable barrier layer. In this case, water can diffuse through the semi-permeable barrier layer into the humectant, and advantageously, a small amount of water can be trapped by the humectant in the passivation layer, while the water-sealing agent layer prevents the structure from dehydrating.

[0056] Furthermore, a method for adjusting the moisture content of a structure is specified. Specifically, the moisture content of the structure described herein is adjusted using this method. Therefore, the embodiments, features, and advantages described in conjunction with the structure and the method for producing the structure also apply to the method for adjusting the moisture content of the structure, and vice versa.

[0057] According to at least one embodiment, the method includes exposing the structure to an environment with a specific humidity level, wherein a humidifier releases or absorbs water. Specifically, the structure is exposed to the environment with the specific humidity level for a specific duration and at a specific temperature. For example, the temperature is selected between 0°C and 100°C. The water content can be adjusted in a humidity chamber. For example, the water content of the humidifier can be reduced by exposing the structure to a dry environment with a humidity level lower than that of the structure and / or by a high temperature. In this case, the humidifier releases water. Alternatively, the water content of the humidifier can be increased by exposing the structure to a humid environment with a humidity level higher than that of the structure. In this case, the humidifier absorbs water.

[0058] Specifically, the method used to adjust the moisture content of a structure is a method used to adjust the moisture content of multiple structures. In this case, multiple structures are exposed to an environment with a specific humidity, and each humectant reduces or absorbs water.

[0059] Advantageously, the method for adjusting the moisture content of the humectant allows for the achievement of a desired moisture content in the structure, wherein the humectant in the structure acts as a buffer to ensure that the structure will withstand further changes in humidity once removed from the humidity chamber. The method for adjusting the moisture content of the humectant can advantageously be used after the structure has been exposed to dry conditions and / or high-temperature conditions (e.g., assembly processes performed at high temperatures).

[0060] Furthermore, an optoelectronic device is specified. In particular, the optoelectronic device includes at least one structure described herein. Therefore, the embodiments, features, and advantages described in conjunction with the structure, the method for producing the structure, and the method for adjusting the moisture content of the structure also apply to the optoelectronic device, and vice versa.

[0061] According to one embodiment, the optoelectronic device includes a semiconductor chip configured to emit primary radiation. In other words, the semiconductor chip is configured to emit electromagnetic radiation in a first wavelength range. Specifically, the primary radiation includes wavelengths in the ultraviolet to blue spectral region.

[0062] According to at least one embodiment, the optoelectronic device includes a conversion element comprising at least one structure, and particularly multiple structures, as described herein. Specifically, the conversion element is configured to convert at least a portion of primary radiation into secondary radiation. In other words, the conversion element converts electromagnetic radiation in a first wavelength range into electromagnetic radiation in a second wavelength range. For example, the first wavelength range is at least partially different from the second wavelength range. For example, the second wavelength range includes wavelengths with lower energy compared to wavelengths in the first wavelength range. In particular, the ability of the conversion element to convert electromagnetic radiation is attributed to a structure comprising nanocrystals that convert primary radiation into secondary radiation.

[0063] According to at least one embodiment, the optoelectronic device includes a semiconductor chip configured to emit primary radiation and a conversion element including at least one structure disclosed herein.

[0064] Advantageously, due to the incorporation of a humectant into the structure, the optoelectronic device described herein exhibits improved efficiency, particularly increased operating life under corrosive conditions. In this way, the conversion element can maintain its conversion efficiency for a longer period compared to conversion elements comprising a structure without a humectant.

[0065] According to at least one embodiment, the semiconductor chip is a microLED. Herein and below, LED is an abbreviation for the term "light-emitting diode". MicroLEDs can have a width, length, thickness, and / or diameter of less than or equal to 100 micrometers, particularly less than or equal to 70 micrometers, for example, less than or equal to 50 micrometers. Specifically, the edge length of the light-emitting surface of a microLED (e.g., a rectangular microLED) (e.g., in a planar view of a stacked layer) is less than or equal to 70 micrometers, for example, less than or equal to 50 micrometers. For example, a microLED is a light-emitting diode in which a growth substrate is removed, such that the thickness of the microLED is, for example, between 1.5 micrometers and 10 micrometers, and includes both 1.5 micrometers and 10 micrometers. For example, a microLED is disposed on a wafer having a releasable retention structure. The microLED can be removed from the wafer in a non-destructive manner.

[0066] According to at least one embodiment, the conversion element includes a second matrix material, and at least one structure, particularly multiple structures, is embedded in the second matrix material. Specifically, the structure includes nanocrystals at least partially surrounded by a passivation layer, wherein a humectant is embedded in the passivation layer. Alternatively, the structure may include nanocrystals at least partially surrounded by a passivation layer, wherein the material of the passivation layer is a humectant. Alternatively, the structure may include nanocrystals at least partially surrounded by a passivation layer, wherein a humectant layer including the humectant is adjacent to the passivation layer. For example, the second matrix material is silicone, polysiloxane, or epoxy resin. In this case, the conversion element is formed as a layer or a casting.

[0067] According to at least one embodiment, the conversion element comprises a structure including nanocrystals at least partially surrounded by a passivation layer, wherein the humectant and the nanocrystals are embedded in a first matrix material. In this case, the conversion element is formed as a layer or a casting.

[0068] According to at least one embodiment, the optoelectronic device is used in augmented reality and / or virtual reality applications, automotive applications, and / or for lighting. Attached Figure Description

[0069] Advantageous embodiments and improvements to the structure, methods for producing the structure, methods for adjusting the moisture content of the structure, and optoelectronic devices will become apparent from the exemplary embodiments described below in conjunction with the accompanying drawings.

[0070] In the attached diagram:

[0071] Figure 1 A schematic diagram of a nanocrystal according to an exemplary embodiment is shown.

[0072] Figure 2 , Figure 3 and Figures 5 to 9 Each shows a schematic diagram of a structure according to a different exemplary embodiment.

[0073] Figure 4 The photoluminescence quantum yield of the structure according to the exemplary embodiment and comparative example is shown.

[0074] Figure 11 and Figure 12 Each illustration shows a schematic diagram of an optoelectronic device according to a different exemplary embodiment. Detailed Implementation

[0075] In the exemplary embodiments and drawings, components that function similarly or analogously are given the same reference numerals. The elements shown in the drawings and their dimensional relationships with each other should not be considered as true scale. Rather, for better representation and / or for better understanding, individual elements may be represented with enlarged dimensions.

[0076] Figure 1 A schematic diagram of nanocrystal 2 is shown. Nanocrystal 2 includes a core 21 and a shell 22. The core 21 and / or shell 22 includes at least one semiconductor material. The semiconductor material is, for example, a III-V compound semiconductor material, a II-VI compound semiconductor material, or a II-III-V compound semiconductor material. In particular, the core 21 includes a semiconductor material different from that of the shell 22. Nanocrystal 2 may include additional shells and / or layers.

[0077] Figure 2 A schematic diagram of structure 1 described herein according to a first exemplary embodiment is shown. Structure 1 includes nanocrystals 2 and an encapsulation 3. Encapsulation 3 is a passivation layer 31 surrounding the nanocrystals 2. For example, the passivation layer 31 is a silicon dioxide layer. A humectant 4 is embedded in the passivation layer 31. The humectant 4 may be at least one of a simple salt such as lithium chloride, a complex salt such as sodium hexametaphosphate, a small molecule such as glycerol, a polymer such as polyethylene glycol, polypropylene glycol or polysaccharides, a degel such as silica gel, and a clay mineral such as montmorillonite or kaolinite. Structure 1 also includes a barrier layer 5 surrounding the encapsulation 3. For example, the barrier layer 5 is a ethylene cellulose layer, an ALD layer made of alumina, or a semi-permeable barrier layer made of an organic polymer.

[0078] Structure 1 of the first exemplary embodiment can be produced as follows:

[0079] Nanocrystals 2, particularly multiple nanocrystals 2, are provided by suspending one or more nanocrystals 2 in a nonpolar hydrophobic solvent to form a first solution. A passivation layer 31 is synthesized using a reverse micelle process. Therefore, a surfactant and subsequently a metal oxide precursor, such as a silica precursor, other reagents, and a catalyst are added to the first solution to initiate the growth of the metal oxide on the surface of the nanocrystals 2.

[0080] Humectant 4 can be added during the synthesis of the metal oxide, prior to purification. Humectant 4 can be pre-formed and added subsequently. Alternatively or additionally, a humectant precursor can be added and humectant 4 can be formed in situ. For example, humectant 4 can be added in the form of a simple salt such as lithium chloride. The addition of a simple salt such as lithium chloride produces lithium chloride within the oxide network and a lithium-metal oxide complex such as a lithium-silicate complex, both of which act as humectant 4. Thus, lithium chloride acts both as a pre-formed humectant 4 in the form of lithium chloride within the oxide network and as a humectant precursor for the in-situ formation of humectant 4 in the form of a lithium-metal oxide complex.

[0081] The amount of humectant 4 in the passivation layer 31 can be controlled by adding a certain amount of humectant 4 or humectant precursor at the start of the reaction forming the passivation layer 31, and by injecting additional amounts of humectant 4 or humectant precursor once or more throughout the entire reaction forming the passivation layer 31. For example, an injection pump can be used to increase the total amount of humectant 4 or humectant precursor. With an injection pump, dispensing can be performed slowly during the reaction time.

[0082] As an alternative to adding humectant 4 during metal oxide synthesis, humectant 4 can be added to the metal oxide passivation layer 31 after metal oxide growth and diffuse into the passivation layer 31. For example, humectant 4 can be injected into the pre-formed metal oxide of the passivation layer 31 in the form of a simple salt such as lithium chloride. Adding lithium chloride powder to the pre-formed metal oxide of the passivation layer 31 produces physically adsorbed but unabsorbed humectant material.

[0083] Figure 3 A schematic diagram of structure 1 described herein according to a second exemplary embodiment is shown. The second exemplary embodiment substantially corresponds to... Figure 2 The first exemplary embodiment is shown. Compared to the first exemplary embodiment, the passivation layer 31 includes an increased amount of humectant 4. The structure 1 according to the second embodiment can be manufactured similarly to the structure 1 according to the first embodiment.

[0084] Figure 4 It is shown that, according to, Figure 2 The photoluminescence quantum yield of the first embodiment and the comparative example are shown. Figure 4 In the graphs, the photoluminescence quantum yield is plotted against operating time t in hours. Curve 4-1 shows the change in photoluminescence quantum yield over time for structure 1, which includes lithium acetate and potassium acetate as humectants. Curve 4-2 shows the change in photoluminescence quantum yield over time for a comparative example without humectants. Figure 4 It is evident that the luminescence of structure 1, including humectant 4 (curve 4-1), can be maintained for a longer period than the luminescence of the structure without humectant (curve 4-2). In the absence of humectant, the photoluminescence quantum yield decreases rapidly after a short time (curve 4-2), while the photoluminescence quantum yield of structure 1 with humectant 4 decreases only slightly over a significantly longer period (curve 4-1).

[0085] Figure 5 A schematic diagram of structure 1 described herein according to a third exemplary embodiment is shown. The third exemplary embodiment substantially corresponds to... Figure 2The first exemplary embodiment is shown. In contrast to the first exemplary embodiment, the material of the passivation layer 31 is a humectant 4. The passivation layer 31 is partially or entirely formed of the humectant 4. Specifically, the passivation layer 31 comprises 1% to 100% of the humectant 4 (including 1% and 100%). For example, the humectant 4 is ammonium silicate or an alkali metal silicate such as sodium silicate or lithium silicate.

[0086] Structure 1 according to the third embodiment can be manufactured in a manner substantially similar to that according to structure 1 according to the first embodiment. The difference in the method for manufacturing structure 1 according to the third embodiment lies in that: the passivation layer 31 is manufactured as described above, and a humectant precursor is added as a reagent to replace or supplement the metal oxide precursor. For example, the humectant precursor is a silica-based humectant such as an alkali metal silicate or ammonium silicate precursor.

[0087] Instead of adding one humectant precursor, two humectant precursors can be added as reagents to replace or supplement the metal oxide precursor. For example, two humectant precursors can be added in different amounts. For instance, the humectant precursors could be sodium silicate and lithium silicate.

[0088] Figure 6 A schematic diagram of structure 1 described herein according to a fourth exemplary embodiment is shown. The fourth exemplary embodiment substantially corresponds to... Figure 5 The third exemplary embodiment is shown. Compared to the third exemplary embodiment, the passivation layer 31 includes an increased amount of humectant 4. In particular, the passivation layer 31 is composed of humectant 4. The structure 1 according to the fourth embodiment can be manufactured similarly to the structure 1 according to the third exemplary embodiment.

[0089] Figure 7 A schematic diagram of structure 1 described herein according to a fifth exemplary embodiment is shown. The fifth exemplary embodiment substantially corresponds to... Figure 2 The first exemplary embodiment is shown. Compared to the first exemplary embodiment, the package 3 includes a passivation layer 31 and a humectant layer 32. Specifically, the passivation layer 31 may be free of humectant. The humectant layer 32 includes or is composed of humectant 4. Specifically, the humectant layer 32 includes humectant 4 and a matrix material. The humectant layer 32 is disposed between the nanocrystals 2 and the passivation layer 31, such that the humectant layer 32 is adjacent to both the nanocrystals 2 and the passivation layer 31.

[0090] According to structure 1 of the fifth exemplary embodiment, it is produced as follows:

[0091] The surface of nanocrystals 2 is treated with a humectant 4 (e.g., a complex salt or clay mineral) to produce a charged nanocrystal surface with a humectant layer 32. Subsequently, as described above... Figure 2 As described in the first embodiment, a passivation layer 31 is grown onto a humectant layer 32.

[0092] Figure 8 A schematic diagram of structure 1 described herein according to a sixth exemplary embodiment is shown. The sixth exemplary embodiment substantially corresponds to... Figure 7 The fifth exemplary embodiment is shown. Compared to the fifth exemplary embodiment, the humectant layer 32 is disposed on the surface of the passivation layer 32 facing away from the nanocrystals 2.

[0093] According to the sixth exemplary embodiment, structure 1 is produced as follows:

[0094] As mentioned above Figure 2 As described in the first embodiment, a passivation layer 31 is grown onto the surface of the nanocrystal 2. Subsequently, a humectant layer 32 comprising a humectant 4, such as a simple salt or a complex salt, is deposited from a polar solution onto the surface of the passivation layer 31 facing away from the nanocrystal 2.

[0095] Combination Figure 7 and Figure 8 The structure 1 described according to the fifth and sixth exemplary embodiments may include a plurality of passivation layers 31 and humectant layers 32 arranged in an alternating manner. Such a structure 1 therefore includes a sequential structure. Such a structure 1 can be produced by repeatedly providing humectant layers 32 and providing passivation layers 31.

[0096] Figure 9 A schematic diagram of structure 1 described herein according to a seventh exemplary embodiment is shown. Structure 1 includes nanocrystals 2 and encapsulation 3. Encapsulation 3 includes a passivation layer 31 surrounding the nanocrystals 2. For example, the passivation layer 31 is a silicon dioxide layer. Encapsulation 3 also includes a first matrix material 33, such as silicone resin. The nanocrystals 2 and a humectant 4 are embedded in the first matrix material 33. The humectant 4 is embedded in the first matrix material 33, specifically in the form of humectant particles. The diameter of the humectant particles may be less than 1 μm, for example, between 1 nm and 500 nm and including 1 nm and 500 nm, or between 1 nm and 100 nm and including 1 nm and 100 nm. The humectant 4 may be at least one of the following: a simple salt such as lithium chloride, a complex salt such as sodium hexametaphosphate, a small molecule such as glycerol, a polymer such as polyethylene glycol, polypropylene glycol or polysaccharides, a degel such as silica gel, and a clay mineral such as montmorillonite or kaolinite.

[0097] Figure 10 A schematic diagram of structure 1 described herein according to an eighth exemplary embodiment is shown. The eighth exemplary embodiment substantially corresponds to... Figure 9 The seventh exemplary embodiment is shown. Compared with the seventh exemplary embodiment, structure 1 includes a plurality of nanocrystals 2 and a plurality of humectant particles.

[0098] Such as combination Figure 2 , Figure 3 and Figures 5 to 10 The moisture content of any of the structures 1 shown can be adjusted by exposing structure 1 to an environment with a specific humidity level. Specifically, structure 1 is exposed to the environment with a specific humidity level for a specific duration and at a specific temperature. For example, the temperature is selected between 0°C and 100°C. For example, humectant 4 can release water, thus reducing the moisture content of structure 1. Alternatively, humectant 4 can absorb water, thus increasing the moisture content of structure 1.

[0099] Figure 11 A schematic diagram of the optoelectronic device 10 described herein according to a first exemplary embodiment is shown. The optoelectronic device includes a semiconductor chip 11 configured to emit primary radiation in a first wavelength range. The semiconductor chip may be a microLED. For example, the first wavelength range is in the blue spectrum region.

[0100] The conversion element 12 is disposed on the radiation emitting surface of the semiconductor chip 11. The conversion element 12 may be disposed directly on the radiation emitting surface or at a distance from the radiation emitting surface. The conversion element 12 may be in the form of a layer or a casting. The conversion element 12 converts primary radiation into secondary radiation in a second wavelength range. The conversion element includes or is composed of at least one structure 1 described herein.

[0101] For example, the conversion element 12 includes at least one structure 1, and in particular, includes multiple structures 1, such as in combination. Figure 2 , Figure 3 and Figures 5 to 9 As shown. In particular, at least one structure 1 may be embedded in a second matrix material such as silicone, polysiloxane or epoxy resin.

[0102] Figure 12 A schematic diagram of the optoelectronic device 10 described herein according to a second exemplary embodiment is shown. The second exemplary embodiment substantially corresponds to... Figure 11 The first exemplary embodiment is shown. Compared to the first exemplary embodiment, the semiconductor chip 11 and the conversion element 12 are arranged in a recess of the housing. The conversion element 12 includes a casting-like structure surrounding the semiconductor chip 11, such as a composite... Figure 10 Structure 1 is shown.

[0103] The features and exemplary embodiments described in conjunction with the accompanying drawings can be combined with each other according to other exemplary embodiments, even if not all combinations are explicitly described. Furthermore, the exemplary embodiments described in conjunction with the accompanying drawings may have alternative or additional features as described in the general section.

[0104] Based on the description of the exemplary embodiments, the present invention is not limited to the exemplary embodiments. Rather, the present invention covers any new features and any combination of features, even if the feature or combination itself is not expressly specified in the patent claims or exemplary embodiments. The present invention particularly includes any combination of features in the patent claims and any combination of features in the exemplary embodiments.

[0105] This patent application claims priority to U.S. Patent Application 63 / 508,912, the disclosure of which is incorporated herein by reference.

[0106] Figure Labels

[0107] 1. Structure

[0108] 2 nanocrystals

[0109] 21 cores

[0110] 22 shells

[0111] 3. Packaging

[0112] 31 Passivation layer

[0113] 32 Moisturizer Layers

[0114] 33 First matrix material

[0115] 4. Moisturizer

[0116] 5. Barrier layer

[0117] 10 Optoelectronic Devices

[0118] 11 Semiconductor chips

[0119] 12 Conversion Element

[0120] 4-1 Curve

[0121] 4-2 Curve

Claims

1. A structure (1) comprising: - a nanocrystal (2) configured to convert primary radiation into secondary radiation, and - an encapsulation (3) at least partially surrounding the nanocrystal (2), wherein the encapsulation comprises a humectant (4).

2. The structure (1) according to the preceding claim, wherein the nanocrystal (2) comprises a core (21) and at least one shell (22).

3. The structure (1) according to one of the preceding claims, wherein the humectant (4) is configured for balancing the presence of water.

4. The structure (1) according to one of the preceding claims, wherein the humectant (4) is at least one of a salt, a small molecule, a polymer, a xerogel and a clay mineral.

5. The structure (1) according to one of the preceding claims, wherein the encapsulation (3) comprises a passivation layer (31) at least partially surrounding the nanocrystal (2).

6. The structure (1) according to the preceding claim, wherein the passivation layer (31) comprises the humectant (4).

7. The structure (1) according to the preceding claim, wherein the humectant (4) is embedded in the passivation layer (31).

8. The structure (1) according to one of claims 6 or 7, wherein the humectant (4) is covalently bonded to a material of the passivation layer (31).

9. The structure (1) according to claim 6, wherein a material of the passivation layer (31) is the humectant (4).

10. The structure according to claim 5, wherein, the encapsulation comprises a humectant layer (32) adjoining the passivation layer (31), wherein the humectant layer (32) comprises the humectant (4).

11. The structure according to claim 10, wherein the humectant layer (32) is at least partially arranged between the nanocrystal (2) and the passivation layer (31).

12. The structure according to claim 10, wherein, the humectant layer (32) at least partially surrounds the passivation layer (31).

13. The structure according to one of claims 10 to 12, wherein the encapsulation (3) comprises a plurality of passivation layers (31) and humectant layers (31) arranged in an alternating manner.

14. The structure according to one of the preceding claims, further comprising: a barrier layer (5) at least partially surrounding the encapsulation (3).

15. The structure according to claim 5, wherein, the encapsulation (3) comprises a first matrix material (33), wherein the humectant (4) and the nanocrystal (2) are embedded in the first matrix material (33).

16. A method for producing a structure (1) comprising: providing a nanocrystal (2) configured to convert primary radiation into secondary radiation, providing an encapsulation (3) at least partially surrounding the nanocrystal (2), wherein the encapsulation comprises a humectant (4).

17. The method according to claim 16, wherein providing the encapsulation (3) comprises forming a passivation layer (31) at least partially surrounding the nanocrystal (2), wherein a material of the passivation layer (31) is the humectant (4), or wherein the humectant (4) is provided on the surface of the nanocrystal (2) before forming the passivation layer (31), or wherein the humectant (4) is embedded in the passivation layer (31) during forming the passivation layer (31), or wherein the humectant (4) is added after forming the passivation layer (31), or wherein the humectant (4) and the nanocrystal (2) are embedded in a first matrix material (33).

18. A method for adjusting the water content of a structure (1) according to one of claims 1 to 15, comprising: exposing the structure (1) to an environment of a certain humidity, wherein the humectant (4) releases or absorbs water.

19. An optoelectronic device (1), comprising: - a semiconductor chip (11), in particular a micro-LED, configured to emit primary radiation, and - a conversion element (12) comprising at least one structure (1) according to one of claims 1 to 15.

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