WO2025051607A1 - Method for producing a structure, structure and optoelectronic device - Google Patents

Method for producing a structure, structure and optoelectronic device Download PDF

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Publication number
WO2025051607A1
WO2025051607A1 PCT/EP2024/074049 EP2024074049W WO2025051607A1 WO 2025051607 A1 WO2025051607 A1 WO 2025051607A1 EP 2024074049 W EP2024074049 W EP 2024074049W WO 2025051607 A1 WO2025051607 A1 WO 2025051607A1
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Prior art keywords
encapsulation
nanocrystal
metal
coordination
complex
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French (fr)
Inventor
Katherine GRICE
Lars Erik Thomas Johansson
Brian THEOBALD
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Ams Osram International GmbH
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Ams Osram International GmbH
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Priority to CN202480041317.1A priority Critical patent/CN121368622A/en
Priority to DE112024001614.6T priority patent/DE112024001614T5/en
Publication of WO2025051607A1 publication Critical patent/WO2025051607A1/en
Anticipated expiration legal-status Critical
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent materials, e.g. electroluminescent or chemiluminescent
    • C09K11/02—Use of particular materials as binders, particle coatings or suspension media therefor
    • C09K11/025—Use of particular materials as binders, particle coatings or suspension media therefor non-luminescent particle coatings or suspension media
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent materials, e.g. electroluminescent or chemiluminescent
    • C09K11/08—Luminescent materials, e.g. electroluminescent or chemiluminescent containing inorganic luminescent materials
    • C09K11/70—Luminescent materials, e.g. electroluminescent or chemiluminescent containing inorganic luminescent materials containing phosphorus
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
    • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
    • H10H20/80—Constructional details
    • H10H20/85—Packages
    • H10H20/851—Wavelength conversion means
    • H10H20/8511—Wavelength conversion means characterised by their material, e.g. binder
    • H10H20/8512—Wavelength conversion materials

Definitions

  • a method for producing a structure, a structure and an optoelectronic device are specified.
  • the structure can comprise different elements, components or parts with specific, in particular different, properties.
  • the method for producing a structure comprises providing a nanocrystal configured to convert a primary radiation into a secondary radiation.
  • the nanocrystal converts electromagnetic radiation of a first wavelength range, the primary radiation, into electromagnetic radiation of a second wavelength range, the secondary radiation.
  • the nanocrystal absorbs the electromagnetic radiation of the first wavelength range, converts the electromagnetic radiation of the first wavelength range into the electromagnetic radiation of the second wavelength range and emits the electromagnetic of the second wavelength range.
  • the second wavelength range is in the visible or IR wavelength range.
  • the second wavelength range is between 500 nm and 2000 nm, both inclusive.
  • the second wavelength range is between 500 nm and 1000 nm, both inclusive.
  • the nanocrystal is a particle having a diameter of between and including 1 nm to 100 nm, for example between and including 2 nm and 20 nm. Due to their size, nanocrystals have different properties than a bulk material formed from the same material. For example, a nanocrystal is spherical, rod-shaped or cuboid. A surface of the nanocrystal can be uniform or uneven.
  • the nanocrystal comprises or consists of a nanoparticle, phosphor particle or quantum dot.
  • the nanoparticle is usually defined as a particle of matter that is between 1 and 100 nanometers in diameter.
  • the nanoparticle can be silver, silicon dioxide, zinc oxide, titanium dioxide, diamond, copper, cobalt oxide, boron nitride, zirconium dioxide, tungsten, aluminum oxide, boron, palladium, calcium carbonate and calcium sulfonate.
  • the phosphor can be a ceramic phosphor.
  • the phosphor can be in the form of phosphor particles.
  • the phosphor particles preferably comprise a crystalline, for example ceramic, host lattice into which foreign elements are introduced as activator elements.
  • the phosphor may be a ceramic material, for example.
  • the ceramic phosphor comprises a garnet phosphor.
  • the garnet phosphor is a YAG phosphor having the chemical formula Y 3 (Al, Ga) 5O12 : Ce or a LUAG phosphor having the chemical formula
  • the ceramic phosphor may also comprise a nitride and/or oxynitride phosphor.
  • the nitride or oxynitride phosphor may be, for example, an alkaline earth siliconoxynitride, an oxynitride, an aluminum oxynitride, a silicon nitride or a Sialon.
  • the nanocrystal comprises or consists 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.
  • a III-V compound semiconductor material comprises at least one element of group 13 of the periodic table, for example B, Al, Ga, In, and at least one element of group 15 of the periodic table, for example N, P, As.
  • a II-VI compound semiconductor material comprises at least one element of group 2 or 12 of the periodic table, for example Zn, Cd, Mg, and at least one element of group 16 of the periodic table, for example 0, S, Se, Te.
  • a II-III-V compound semiconductor material comprises at least one element of group 2 or 12 of the periodic table, at least one element of group 13 of the periodic table and at least one element of group 15 of the periodic table.
  • the nanocrystal comprises or consists of a sulfide, a selenide, a nitride or a phosphide.
  • the method comprises forming an encapsulation around the nanocrystal using a coordination-complex.
  • the encapsulation can comprise different layers and/or elements.
  • the encapsulation can be configured or designed as a passivation layer for electronic passivation and/or as a protection layer for protecting components, for example the nanocrystal of the structure, against degradation.
  • the encapsulation completely surrounds the nanocrystal.
  • the encapsulation can be in direct contact to the nanocrystal. Alternatively, further layers can be arranged between the nanocrystal and the encapsulation.
  • the coordination-complex is a catalyst and is a chemical compound consisting of a central atom or ion, which is usually metallic, and is called the coordination centre and a surrounding array of bound molecules or ions that are in turn known as ligands or complexing agents .
  • Many metal-containing compounds are coordination-complexes .
  • the coordination-complex utili zes catalyzing of a deposition on and around the nanocrystals to form the encapsulation .
  • the coordinationcomplex can act as both acid and base and therefore the coordination-complex can catalyze hydrolysis and polymeri zation .
  • the coordination-complex preferably, is added to the total reaction volume at a ratio between 0 . 05 w/w% and 8 . 5 w/w% , both inclusive .
  • the encapsulation comprises an oxide .
  • the oxide can be , for example , an inorganic oxide or preferably a metal oxide .
  • the coordination-complex may decompose in the reaction, allowing the central atom, so-called metal , to be incorporated into the encapsulation, leading to tunable mixed metal oxide stacks with reduced pin-hole defects .
  • the coordination-complex undergoes hydrolysis and can form the encapsulation leading to the possibility of making structures with preferably mixed-metal oxides and layered metal oxides .
  • the use of the coordination-complex acts to slow down the hydrolysis , therefore allowing conformal oxide growth around the nanocrystals .
  • the method for producing a structure comprises providing a nanocrystal configured to convert a primary radiation into a secondary radiation, forming an encapsulation around the nanocrystal using a coordination-complex, wherein the encapsulation comprises an oxide .
  • the structure comprises a nanocrystal which is encapsulated by a metal oxide encapsulant without signi ficantly harming the photoluminescence quantum yield (PLQY) of the nanocrystals .
  • the photoluminescence quantum yield - as one criterion for a success ful downconverter - is signi ficantly, and positively, af fected during oxide encapsulation using the here described method .
  • the encapsulation provides improved protection during stress testing when compared to unencapsulated nanocrystals . This can further improve the quality of the encapsulation by tuning its chemistry .
  • the method described herein slows the hydrolysis of the oxide , resulting in conformal encapsulation around the nanocrystals for optimal barrier protection .
  • the nanocrystal comprises or consists of a semiconductor material and the semiconductor material is a I I-VI or a I I I-V compound semiconductor material .
  • the nanocrystal is free of cadmium .
  • the nanocrystal comprises a core and at least one shell.
  • the nanocrystal is a quantum dot comprising a core and at least one shell.
  • the core and/or the shell may comprise at least one semiconductor material.
  • the core comprises a different semiconductor material than the shell.
  • the at least one shell is epitaxially grown onto the core.
  • the nanocrystal can comprise further shells and/or layers.
  • the nanocrystal comprises a quantum well structure.
  • the nanoparticle is a core-shell quantum dot or a core-shell-shell quantum dot.
  • the quantum dot is cadmium-free.
  • the quantum dot is a III-V compound semiconductor material.
  • a metal of the coordination-complex is selected from the following group: alkali metal, alkaline earth metal, transition metal or posttransition metal.
  • the post-transition metal is located in the periodic table between the transition metals to the left and the chemically weak non-metallic metalloids to their right. These metals are soft, have poor mechanical strength and usually have melting points lower than those of the transition metals.
  • the metal of the coordination-complex is selected from the following group: alkali metal, alkaline earth metal, transition metal and/or Al, Ga, In, Tl, Sn, Pb, Bi, Po .
  • the metal of the coordination-complex is selected from the group consisting of Al, Zr, Cu and Ti.
  • the coordination-complex comprises the metal which is coordinated by at least one ligand.
  • the ligands can differ from each other.
  • the metal of the coordination-complex can form the encapsulation as a metal oxide. In other words, the metal of the coordination-complex forms the oxide of the encapsulation.
  • the method for forming the encapsulation around the nanocrystal further comprises using an oxide precursor which is selected from the group consisting of: tetraethyl orthosilicate, tetramethyl orthosilicate, tetrabutyl orthosilicate or tetrapropyl orthosilicate, a silane with an amino, mercapto, phosphonic, isocyanate, aldehyde, or carboxylic headgroup and combinations thereof.
  • the silane with an amino, mercapto, phosphonic, isocyanate, aldehyde, or carboxylic headgroup can also be a silane containing ligand on the nanocrystal used for conformal encapsulation. That means that, on the surface, the nanocrystal comprises an intermediate layer which comprises a silane with an amino, mercapto, phosphonic, isocyanate, aldehyde, or carboxylic headgroup.
  • the Si-metal of the oxide precursor forms the oxide of the encapsulation.
  • the oxide precursor is tetraethyl orthosilicate and this oxide precursor forms a Si-oxide which encapsulates the nanocrystal.
  • the coordinationcomplex is a hydrolysis and polymerization catalyst for the formation of siloxanes.
  • the oxide is selected from the group consisting of: a mixed metal oxide and/or a metal oxide, wherein the metal is derived from the metal of the coordination-complex and/or the metal is derived from the oxide precursor.
  • the oxide is a metal oxide or a mixed metal oxide.
  • the mixed metal oxide can be obtained from the metal of the coordination-complex and the oxide precursor.
  • the mixed metal oxide can be obtained from at least two coordination-complexes which differ in their metal or from at least two oxide precursors which differ in their metal.
  • the mixed metal oxide can be aluminosilicate.
  • the metal of the oxide differs from the metal of the coordination-complex.
  • the oxide is selected from the group consisting of: silica (SiO 2 ) , alumina (A1 2 O 3 ) , titania (TiO 2 ) , zirconia (ZrO 2 ) , aluminosilicate and combinations thereof.
  • a ligand of the coordination-complex is selected from the group consisting of: alkoxide, acetylacetonate (acac) , ammine, diketone, hybride, hydrate, ethylacetoacetate, acetylacetonate derivates and combinations thereof.
  • the ligand is a bidentate ligand.
  • the coordination-complex comprises a metal and at least one ligand wherein the ligands can, for example, differ from each other.
  • the coordinationcomplex is a post-transition metal diketone.
  • the coordination-complex is a metal acetylacetonate .
  • the coordinationcomplex is Aluminum acetylacetonate (Al ( acac ) s ) .
  • the metal acetylacetonate utili zes catalyzing a deposition, for example a silica deposition, on and around the nanocrystal , for example quantum dot , to form the encapsulation .
  • a deposition for example a silica deposition
  • nanocrystal for example quantum dot
  • the current understanding of how metal acetylacetonates catalyze hydrolysis and polymeri zation relies on their ability to act as both acids and bases . This is di f ferent from other bases used to deposit the encapsulation, for example silica, on and around nanocrystals .
  • the metal acetylacetonate undergoes hydrolysis , or alcoholysis and forms the encapsulation comprising a metal oxide , leading to the possibility of making structures with preferably mixed-metal oxides and layered metal oxides .
  • the use of the metal acetylacetonate acts to slow down the hydrolysis , therefore allowing conformal metal oxide growth around the nanocrystals .
  • an intermediate layer is arranged between the encapsulation and the nanocrystal .
  • the intermediate layer is selected from the group consisting of : a silane terminated ligand, a hydroxide terminated ligand or combinations thereof .
  • the intermediate layer comprises a silane terminated ligand as well as a hydroxide terminated ligand .
  • the intermediate layer is used to functionali ze the surface of the nanocrystal for a more conformal encapsulation .
  • the headgroup of the material of the intermediate layer, which is linked to the nanocrystal surface can comprise an amino, mercapto, phosphonic, isocyanate, aldehyde or carboxylic acid.
  • the encapsulation individually encapsulates the nanocrystal. This means that each nanocrystal is covered by one encapsulation.
  • the encapsulation is preferably free of pinholes or paths.
  • the encapsulation almost completely surrounds the nanocrystal.
  • the encapsulation completely surrounds the nanocrystal.
  • Individually encapsulated nanocrystals can be obtained by adding a surfactant, such as AOT or Igepal, via a micelle formation.
  • the surfactant is, for example, added to the nanocrystal and to the coordination-complex.
  • the encapsulation comprises forming a plurality of sublayers which surrounds the nanocrystal.
  • the plurality of sublayers can comprise the same metal oxide.
  • the plurality of sublayers comprises different metal oxides and/or mixed metal oxides.
  • an oxide sublayer deposition can be done many times over, creating sublayers that are more effective barriers than single, thick layers. This includes, for example, that initial, coordination-complex catalyzed materials provide improved stability.
  • At least two adjacent sublayers comprise different oxides.
  • one sublayer comprises or consists of SiCy and the adjacent sublayer comprises or consists of a metal oxide, for example AI2O3.
  • one of the sublayers is formed from the oxide precursor and one of the sublayers is formed from the metal of the coordination-complex.
  • at least one sublayer of the encapsulation comprises silica. It is also possible that one sublayer comprises or consists of a mixed metal oxide , for example aluminosilicate .
  • one of the sublayers is formed from the coordination-complex and/or one of the sublayers is formed by the oxide precursor .
  • the oxide of the sublayer comprises the same metal as the metal of the coordination-complex and/or the metal of the oxide precursor .
  • the metal of the coordinationcomplex is aluminium and the oxide of the sublayer is aluminium oxide and/or the metal of the oxide precursor is Si and the oxide of the sublayer is SiCy .
  • this preferably, creates a path to make mixed-metal oxide sublayers as the coordination-complex themselves are susceptible to hydrolysis and subsequent incorporation into the oxide encapsulation .
  • various acac coordination-complexes with di f ferent acac ligands enables the formation of stacks for preventing pinholes , or paths through the encapsulation .
  • the encapsulation comprises a thickness in the range between 0 . 5 nm and 500 nm, both inclusive .
  • the encapsulation comprises a thickness in the range between 5 nm and 50 nm, both inclusive .
  • At least two nanocrystals are surrounded by the same encapsulation .
  • ratios of a solvent , of the coordination-complex and the nanocrystals can be tailored to give either a single nanocrystal or agglomerates (clusters of a plurality of nanocrystals) in the encapsulation.
  • forming the encapsulation around the nanocrystal further uses water.
  • the volume of water in a reaction mixture can vary anywhere from 0.001 to 20 w/w%, both inclusive. In a preferred embodiment, the volume of water is between 0.001 and 10 wt . % .
  • forming the encapsulation around the nanocrystal is initially anhydrous.
  • the initial catalytic reaction may not be a hydrolytic reaction (eg. alcoholysis) , but the initial reaction produces water as a by-product, which then can proceed as a hydrolytic reaction, resulting in increased water w/w% as the reaction progresses .
  • forming the encapsulation around the nanocrystal further uses a solvent in which the nanocrystal and the coordination-complex are soluble.
  • the solvent can be a solvent in which all reagents, that means the coordination-complex, the nanocrystal, optionally the water and optionally the oxide precursor, are fully soluble or of several mixed but miscible solvents of mixed polarity.
  • the solvents can include cyclohexane, acetone, toluene, acetonitrile, ethanol, isopropanol, methanol, butanol, tetrahydrofuran, or dimethylformamide.
  • the solvent can be selected from the group consisting of: cyclohexane, acetone, acetonitrile, an alcohol or combinations thereof.
  • the method takes place in atmosphere or it can be performed in an air-free atmosphere under a flowing or static inert gas environment , for example argon, nitrogen, etc .
  • the method can be run at elevated temperatures below the boiling point of the solvent system .
  • the method takes place at a temperature between 25 ° C and 100 ° C, both inclusive in an inert gas environment .
  • the method takes place at a temperature between 25 ° C and 45 ° C, both inclusive .
  • the method is run under inert atmosphere at a temperature of 35 ° C .
  • the encapsulation is produced as follows : The nanocrystal or the plurality of nanocrystals is suspended in the solvent and optionally in water, forming a first solution . A surfactant and subsequently, the coordinationcomplex and optionally an oxide precursor, are added to the first solution to initiate the oxide growth on a surface of the nanocrystal to form the encapsulation .
  • a structure is speci fied .
  • the method for producing a structure described herein produces the structure .
  • embodiments , features and advantages described in combination with the method for producing a structure also apply to the structure and vice versa .
  • the structure comprises a nanocrystal configured to convert a primary radiation into a secondary radiation, and an encapsulation at least partially surrounding the nanocrystal encapsulation comprises an oxide .
  • the structure comprises a good photoluminescence quantum yield and longevity under conditions like LED operating conditions is improved .
  • the encapsulation protects the nanocrystal during stress-testing .
  • the encapsulation comprises a plurality of sublayers .
  • the plurality of sublayers forms the encapsulation .
  • the plurality of sublayers can be , for example , a mixed metal oxide and/or a metal oxide .
  • a mixed metal oxide is , for example , aluminosilicate and a metal oxide is , for example SiCy or AI2O3.
  • Further oxides are alkali metal oxides , alkaline earth metal oxides , transition metal oxides or post-transition metal oxides or combinations thereof .
  • the mixed metal oxide can be obtained by the metal of the oxide precursor in combination with the metal of the coordination-complex .
  • the metal oxides can be obtained by the metal of the oxide precursor and/or by the metal of the coordination-complex .
  • At least two adj acent sublayers comprise di f ferent oxides . This means that each sublayer can have a di f ferent oxide .
  • the encapsulation comprises traces from a coordination-complex .
  • the traces can be detected with common analytical methods .
  • the coordination-complex slows down the hydrolysis of the metal oxide , which leads to a conformal encapsulation around the nanocrystal for the optimal barrier protection .
  • an optoelectronic device is speci fied .
  • the optoelectronic device comprises at least one structure described herein .
  • embodiments , features , and advantages described in combination with the structure and the method for producing a structure also apply to the optoelectronic device and vice versa .
  • the optoelectronic device comprises a semiconductor chip configured to emit a primary radiation .
  • the semiconductor chip is configured to emit electromagnetic radiation of a first wavelength range .
  • the primary radiation comprises wavelengths in the ultraviolet to blue spectral region .
  • the optoelectronic device comprises a conversion element comprising at least one structure , in particular a plurality of structures , described herein .
  • the conversion element is configured to convert at least a portion of the primary radiation into secondary radiation .
  • the conversion element converts the electromagnetic radiation of the first wavelength range into electromagnetic radiation of a second wavelength range .
  • the first wavelength range is at least partially di f ferent from the second wavelength range .
  • the second wavelength range comprises wavelengths having a lower energy compared to the wavelengths in the first wavelength range .
  • an ability of the conversion element to convert electromagnetic radiation is attributed to the structure , which comprises the nanocrystal , converting primary radiation into secondary radiation .
  • the optoelectronic device comprises a semiconductor chip configured to emit a primary radiation, and a conversion element comprising at least one structure disclosed herein .
  • the optoelectronic device described herein has improved ef ficiency, in particular, an increased operating li fetime in corrosive conditions due to the encapsulated nanocrystals .
  • the conversion element can maintain its conversion ef ficiency over a longer time compared to conversion elements comprising structures without an encapsulation .
  • the photoluminescence quantum yield of the encapsulated nanocrystals is advantageously not signi ficantly af fected .
  • the semiconductor chip is a micro-LED .
  • LED is an abbreviation for the term " light-emitting diode” .
  • Micro-LEDs may have a width, a length, a thickness and/or a diameter smaller than or equal to 100 micrometers , in particular smaller than or equal to 70 micrometers , for example smaller than or equal to 50 micrometers .
  • micro-LEDs for example rectangular micro-LEDs , have an edge length, for instance in plan view of layers of a layer stack, of a luminous surface smaller than or equal to 70 micrometers , for example smaller than or equal to 50 micrometers .
  • the micro-LED is a light-emitting diode wherein a growth substrate is removed, such that a thickness of the micro-LED is , for instance , between and including 1 . 5 micrometers and 10 micrometers .
  • the micro-LED is provided on a wafer having releasable retaining structures . The micro-LED can be detached from the wafer in a non-destructive manner .
  • the conversion element comprises a matrix material and the at least one structure , in particular the plurality of structures, is embedded in the matrix material.
  • the matrix material is silicone, polysiloxane, or epoxy.
  • the conversion element is formed as a layer or a casting.
  • the at least one structure is, preferably, homogenously distributed in the matrix material.
  • the conversion element consists of the structure comprising a nanocrystal and an encapsulation, wherein the structure is embedded in the matrix material.
  • the conversion element is formed as a layer or a casting.
  • the optoelectronic device is used in augmented reality and/or virtual reality applications, in automotive applications, in downconverters, in sensors, for illumination and/or in other applications.
  • FIG. 1 shows a schematic illustration of a method for producing a structure according to an exemplary embodiment
  • FIGS . 2 , 3 and 4 each show a schematic illustration of a method for producing a structure according to di f ferent exemplary embodiments ;
  • FIGS . 5 , 6 and 7 each show a schematic illustration of a structure according to di f ferent exemplary embodiments ;
  • FIGS . 8 and 9 each show a schematic illustration of an optoelectronic device according to di f ferent exemplary embodiments .
  • FIG . 10 shows the photoluminescent quantum yield of a structure according to an exemplary embodiment and a comparative example .
  • FIG . 1 shows a schematic illustration of the method for producing a structure 1 according to an exemplary embodiment .
  • a coordination-complex 4 and a nanocrystal 2 are provided and form a reaction mixture .
  • the nanocrystal 2 is configured to convert a primary radiation into a secondary radiation .
  • optionally water 9 , a solvent 13 and an oxide precursor 7 are part of the reaction mixture .
  • An encapsulation 3 is formed around the nanocrystal 2 , wherein the encapsulation 3 comprises an oxide .
  • the nanocrystal 2 can, for example, be a nanoparticle, a phosphor or a quantum dot.
  • the nanocrystal 2 comprises or consists of a semiconductor material and the semiconductor material is a II-VI or a III-V compound semiconductor material.
  • the semiconductor material is cadmium-free.
  • the coordination-complex 4 consists of at least one metal 5 and at least one ligand 6.
  • the metal 5 is selected from the following group: alkali metal, alkaline earth metal, transition metal or post-transition metal.
  • the ligand 6 of the coordination-complex 4 is selected from the group consisting of: alkoxide, acetylacetonate (acac) , ammine, diketone, hybride, hydrate, ethylacetoacetate, acetylacetonate derivatives and combinations thereof.
  • the coordination-complex 4 is a metal acetylacetonate.
  • the coordinationcomplex 4 is an aluminium acetylacetonate.
  • the oxide precursor 7 is selected from the group consisting of: tetraethyl orthosilicate, tetramethyl orthosilicate, tetrabutyl orthosilicate, tetrapropyl orthosilicate, a silane with an amino, mercapto, phosphonic, isocyanate, aldehyde, or carboxylic headgroup and combinations thereof.
  • the coordination-complex 4 is used as a catalyst to catalyse the formation of the structure 1.
  • the coordination-complex 4 will itself hydrolyse and form the encapsulation 3, which is a metal oxide.
  • the coordination-complex 4 forms a mixed metal oxide and layered metal oxides around the nanocrystal 2.
  • the oxide is selected from the group consisting of a mixed metal oxide and/or a metal oxide, wherein the metal is derived from the metal 5 of the coordination-complex 4 and/or the metal is derived from the oxide precursor 7.
  • An intermediate layer (not shown in the figures) can be formed between the nanocrystal 2 and the encapsulation 3.
  • the intermediate layer is selected from the group consisting of a silane terminated ligand, a hydroxide terminated ligand or combinations thereof.
  • the encapsulation 3 individually encapsulates one nanocrystal 2.
  • the encapsulation 3 comprises a thickness in the range between 0.5 nm and 500 nm, both inclusive. The method takes place at a temperature between 25 °C and 45 °C in an inert gas atmosphere .
  • FIG. 2 shows a schematic illustration of a method for producing a structure 1 according to an exemplary embodiment.
  • Water 9, tetraethyl orthosilicate as the oxide precursor 7, the nanocrystal 2 and metal acetylacetonate (M(acac) 3 ) as the coordination-complex 4 are mixed together.
  • the reaction occurs under an air-free method and a flowing or static inert gas environment (argon, nitrogen, etc.) . This can be run at elevated temperatures below the boiling point of the solvent system. In a preferred embodiment it is run under inert atmosphere at a temperature of 35°.
  • argon, nitrogen, etc. argon, nitrogen, etc.
  • a solvent 13 selected from the group consisting of cyclohexane, acetone, toluene, acetonitrile, ethanol, isopropanol, methanol, butanol, tetrahydrofuran, or dimethylformamide is added.
  • the coordination-complex 4 catalyses the reaction and an encapsulation 3 is formed around the nanocrystal 2.
  • the encapsulation 3 is SiO 3 or can be a mixed metal oxide, for example aluminosilicate. Between the nanocrystal 2 and the encapsulation 3 an intermediate layer can be formed (not shown here) .
  • the coordination-complex 4 comprises a metal 5 which is selected from the following group: alkali metal, alkaline earth metal, transition metal, or post-transition metal.
  • the coordination-complex 4 comprises a ligand 6 which is selected from the group consisting of: alkoxide, acetylacetonate (acac) , ammine, diketone, hybride, hydrate, ethylacetoacetate, acetylacetonate derivatives and combinations thereof.
  • the ligand in the exemplary embodiment of FIG. 2 is an acetylacetonate or diketone.
  • FIG. 3 shows a schematic illustration of a method for producing a structure 1 according to an exemplary embodiment.
  • FIG. 3 differs from FIG. 2 in that the encapsulation 3 covers three nanocrystals 2. In other words, at least two nanocrystals 2 are surrounded by the same encapsulation 3.
  • the encapsulation 3 can be SiCy.
  • FIG. 4 shows a schematic illustration of the method for producing a structure 1 according to an exemplary embodiment.
  • FIG. 4 differs from Figures 2 and 3 in that the structure 1 comprises a nanocrystal 2 and at least two sublayers 8.
  • the encapsulation 3 comprises forming a plurality of sublayers 8 which surrounds the nanocrystal 2. At least two adjacent sublayers 8 comprise different oxides.
  • One oxide of the sublayers 8 is formed from the metal 5 of the coordinationcomplex 4 and one oxide of the sublayers 8 is formed from the oxide precursor 7.
  • the nanocrystal 2, preferably quantum dot is surrounded by SiO2 so that the first sublayer 8 is SiO2, the second sublayer 8 is a metal oxide sublayer 8 and can be formed from the coordinationcomplex 4, and the third sublayer 8 is SiCy, a metal oxide or a mixed metal oxide.
  • FIG. 5 shows a schematic illustration of a structure 1 according to an exemplary embodiment.
  • the structure 1 comprises a nanocrystal 2 configured to convert a primary radiation into a secondary radiation and an encapsulation 3 at least partially surrounding the nanocrystal 2 and wherein the encapsulation 3 comprises an oxide.
  • the nanocrystal 2 can be a quantum dot and can comprise a core and a shell.
  • the core and/or the shell comprise at least one semiconductor material.
  • the semiconductor material is, for example, a III-V compound semiconductor material or a II-VI compound semiconductor material.
  • the core comprises a different semiconductor material than the shell.
  • the nanocrystal 2 can comprise further shells and/or layers.
  • the nanocrystal 2 comprises a semiconductor material which is cadmium-free and the encapsulation 3 is SiCy.
  • the SiCh encapsulation 3 is formed from the oxide precursor 7.
  • FIG. 6 shows a schematic illustration of a structure 1 according to an exemplary embodiment.
  • the structure 1 comprises a nanocrystal 2 and an encapsulation 3.
  • the encapsulation 3 is in contact with the nanocrystal 2 and covers the nanocrystal 2 almost completely.
  • the encapsulation 3 comprises a plurality of sublayers 8. At least two adjacent sublayers 8 comprise different oxides.
  • the first sublayer 8, which is closer to the nanocrystal 2, is SiCy
  • the second sublayer 8, which is between the first and the third sublayer 8 is a metal oxide, for example aluminium oxide
  • the third sublayer 8 is SiCy, a metal oxide or a mixed metal oxide, for example aluminosilicate.
  • the encapsulation 3 comprises a thickness in the range between 0.5 nm and 500 nm, both inclusive. The exact layering, order and number of layers is only an exemplary embodiment and many other combinations are possible.
  • FIG. 7 shows a schematic illustration of a structure 1 described herein according to an exemplary embodiment.
  • the structure 1 comprises a plurality of nanocrystals 2 and an encapsulation 3 which surrounds the plurality of nanocrystals 2 .
  • the encapsulation 3 is the same for the plurality of nanocrystals 2 .
  • the encapsulation 3 can be SiCy and the nanocrystals 2 are cadmium- free quantum dots .
  • I f the coordination-complex 4 is Al ( acac ) s, then the encapsulation 3 can be AI2O3 or aluminosilicate .
  • Figures 5 , 6 and 7 comprise SiCy as the encapsulation 3 or as a sublayer 8 , but other metal oxides are also possible , either as a homogenous mixture and as dispersed or as layered structures .
  • FIG . 8 shows a schematic illustration of an optoelectronic device 10 described herein according to a first exemplary embodiment .
  • the optoelectronic device 10 comprises a semiconductor chip 11 configured to emit the primary radiation of a first wavelength range .
  • the semiconductor chip 11 can be a microLED, for example the first wavelength range is in the blue spectral region .
  • a conversion element 12 is arranged on a radiation exit surface of the semiconductor chip 11 .
  • the conversion element 12 can be arranged directly on the radiation exit surface or at a distance to the radiation exit surface .
  • the conversion element 12 can be in the form of a layer or a casting .
  • the conversion element 12 converts the primary radiation into secondary radiation of the second wavelength range .
  • the conversion element 12 comprises or consists of at least one structure 1 described herein .
  • the conversion element 12 comprises at least one structure 1 , in particular a plurality of structures 1 as shown in conj unction with Figures 5 , 6 and 7 .
  • the at least one structure 1 may be embedded in a matrix material , such as silicon, polysiloxane or epoxy .
  • FIG . 9 shows a schematic illustration of an optoelectronic device 10 described herein according to a second exemplary embodiment .
  • the second exemplary embodiment corresponds substantially to the first exemplary embodiment shown in FIG . 8 .
  • the semiconductor chip 11 and the conversion element 12 are arranged in the recess of a housing .
  • the conversion element 12 comprises the structure 1 as shown in conj unction with FIG . 8 in the form of a casting around the semiconductor chip 11 .
  • FIG . 10 shows the photoluminescence quantum yield PLQY of a structure 1 according to the exemplary embodiment shown in FIG . 5 and a comparative example .
  • the comparative example describes a structure 1 without an encapsulation 3 .
  • the comparative example is a structure 1 comprising a quantum dot .
  • the photoluminescent quantum yield is plotted against the operating time t in minutes .
  • Curve 10- 1 shows the photoluminescent quantum yield as a function of time of a structure 1 comprising a quantum dot with an encapsulation 3 .
  • Curve 10-2 shows the photoluminescent quantum yield as a function of time of a comparative example of a structure without an encapsulation 3 .
  • the luminescence of the structure 1 comprising an encapsulation 3 can be maintained longer ( curve 10- 1 ) than the luminescence of a structure without an encapsulation 3 ( curve 10-2 ) .
  • the structure 1 of the exemplary embodiment comprises a nanocrystal 2 with an encapsulation 3 .
  • the coordination-complex 4 used for the synthesis is Al ( acach and the oxide of the encapsulation 3 is SiO x .
  • the structure 1 of the comparative example comprises a nanocrystal 2 and an SiO x encapsulation 3 , whereas the encapsulation 3 is obtained by a coordination-complex- free method .
  • the PLQY retention as well as the powder PLQY are much higher for the structure 1 of the exemplary embodiment compared to the structure 1 of the comparative example .
  • the structure 1 with one SiO x sublayer 8 according to an exemplary embodiment and a structure 1 with two SiO x sublayers 8 according to an exemplary embodiment show almost the same PLQY .
  • present disclosure is not restricted to the exemplary embodiments by the description on the basis of said exemplary embodiments. Rather, the present disclosure encompasses any new feature and also any combination of features, which in particular comprises any combination of features in the patent claims and any combination of features in the exemplary embodiments, even if this feature or this combination itself is not explicitly specified in the patent claims or exemplary embodiments.

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Abstract

A method for producing a structure is specified. According to one embodiment, the method comprises providing a nanocrystal configured to convert a primary radiation into a secondary radiation, and forming an encapsulation around the nanocrystal using a coordination-complex, wherein the encapsulation comprises an oxide. Furthermore, a structure and an optoelectronic device are specified.

Description

Description
METHOD FOR PRODUCING A STRUCTURE, STRUCTURE AND OPTOELECTRONIC DEVICE
A method for producing a structure, a structure and an optoelectronic device are specified.
It is an object to provide a method for producing a structure with a good quantum yield. It is a further object to provide a structure and an optoelectronic device with improved efficiency.
A method for producing a structure is specified. The structure can comprise different elements, components or parts with specific, in particular different, properties.
According to an embodiment, the method for producing a structure comprises providing a nanocrystal configured to convert a primary radiation into a secondary radiation. In other words, the nanocrystal converts electromagnetic radiation of a first wavelength range, the primary radiation, into electromagnetic radiation of a second wavelength range, the secondary radiation. In particular, the nanocrystal absorbs the electromagnetic radiation of the first wavelength range, converts the electromagnetic radiation of the first wavelength range into the electromagnetic radiation of the second wavelength range and emits the electromagnetic of the second wavelength range. For example, the second wavelength range is in the visible or IR wavelength range. For instance, the second wavelength range is between 500 nm and 2000 nm, both inclusive. In particular, the second wavelength range is between 500 nm and 1000 nm, both inclusive. In particular, the nanocrystal is a particle having a diameter of between and including 1 nm to 100 nm, for example between and including 2 nm and 20 nm. Due to their size, nanocrystals have different properties than a bulk material formed from the same material. For example, a nanocrystal is spherical, rod-shaped or cuboid. A surface of the nanocrystal can be uniform or uneven.
For example, the nanocrystal comprises or consists of a nanoparticle, phosphor particle or quantum dot. The nanoparticle is usually defined as a particle of matter that is between 1 and 100 nanometers in diameter. The nanoparticle can be silver, silicon dioxide, zinc oxide, titanium dioxide, diamond, copper, cobalt oxide, boron nitride, zirconium dioxide, tungsten, aluminum oxide, boron, palladium, calcium carbonate and calcium sulfonate.
The phosphor can be a ceramic phosphor. The phosphor can be in the form of phosphor particles. The phosphor particles preferably comprise a crystalline, for example ceramic, host lattice into which foreign elements are introduced as activator elements. The phosphor may be a ceramic material, for example. Preferably, the ceramic phosphor comprises a garnet phosphor. Particularly preferably, the garnet phosphor is a YAG phosphor having the chemical formula Y3 (Al, Ga) 5O12 : Ce or a LUAG phosphor having the chemical formula
Lua (Al, Ga) 5O12 : Ce . Furthermore, the ceramic phosphor may also comprise a nitride and/or oxynitride phosphor. The nitride or oxynitride phosphor may be, for example, an alkaline earth siliconoxynitride, an oxynitride, an aluminum oxynitride, a silicon nitride or a Sialon. Further, the nanocrystal comprises or consists 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. A III-V compound semiconductor material comprises at least one element of group 13 of the periodic table, for example B, Al, Ga, In, and at least one element of group 15 of the periodic table, for example N, P, As. A II-VI compound semiconductor material comprises at least one element of group 2 or 12 of the periodic table, for example Zn, Cd, Mg, and at least one element of group 16 of the periodic table, for example 0, S, Se, Te. A II-III-V compound semiconductor material comprises at least one element of group 2 or 12 of the periodic table, at least one element of group 13 of the periodic table and at least one element of group 15 of the periodic table. For instance, the nanocrystal comprises or consists of a sulfide, a selenide, a nitride or a phosphide.
According to at least one embodiment, the method comprises forming an encapsulation around the nanocrystal using a coordination-complex. The encapsulation can comprise different layers and/or elements. The encapsulation can be configured or designed as a passivation layer for electronic passivation and/or as a protection layer for protecting components, for example the nanocrystal of the structure, against degradation. In particular, the encapsulation completely surrounds the nanocrystal. The encapsulation can be in direct contact to the nanocrystal. Alternatively, further layers can be arranged between the nanocrystal and the encapsulation. The coordination-complex is a catalyst and is a chemical compound consisting of a central atom or ion, which is usually metallic, and is called the coordination centre and a surrounding array of bound molecules or ions that are in turn known as ligands or complexing agents . Many metal-containing compounds , especially those that include transition metals , are coordination-complexes . The coordination-complex utili zes catalyzing of a deposition on and around the nanocrystals to form the encapsulation . Advantageously, the coordinationcomplex can act as both acid and base and therefore the coordination-complex can catalyze hydrolysis and polymeri zation . The coordination-complex, preferably, is added to the total reaction volume at a ratio between 0 . 05 w/w% and 8 . 5 w/w% , both inclusive .
According to at least one embodiment , the encapsulation comprises an oxide . The oxide can be , for example , an inorganic oxide or preferably a metal oxide .
The coordination-complex may decompose in the reaction, allowing the central atom, so-called metal , to be incorporated into the encapsulation, leading to tunable mixed metal oxide stacks with reduced pin-hole defects . The coordination-complex undergoes hydrolysis and can form the encapsulation leading to the possibility of making structures with preferably mixed-metal oxides and layered metal oxides . Advantageously, the use of the coordination-complex acts to slow down the hydrolysis , therefore allowing conformal oxide growth around the nanocrystals .
According to at least one embodiment , the method for producing a structure comprises providing a nanocrystal configured to convert a primary radiation into a secondary radiation, forming an encapsulation around the nanocrystal using a coordination-complex, wherein the encapsulation comprises an oxide .
It is an idea of the present application to provide a method for producing a structure , wherein the structure comprises a nanocrystal which is encapsulated by a metal oxide encapsulant without signi ficantly harming the photoluminescence quantum yield ( PLQY) of the nanocrystals . The photoluminescence quantum yield - as one criterion for a success ful downconverter - is signi ficantly, and positively, af fected during oxide encapsulation using the here described method .
In addition, longevity under conditions like LED operating conditions is improved .
Further, the encapsulation provides improved protection during stress testing when compared to unencapsulated nanocrystals . This can further improve the quality of the encapsulation by tuning its chemistry .
Moreover, the method described herein slows the hydrolysis of the oxide , resulting in conformal encapsulation around the nanocrystals for optimal barrier protection .
According to at least one embodiment , the nanocrystal comprises or consists of a semiconductor material and the semiconductor material is a I I-VI or a I I I-V compound semiconductor material . Preferably, the nanocrystal is free of cadmium . According to at least one embodiment, the nanocrystal comprises a core and at least one shell. In particular, the nanocrystal is a quantum dot comprising a core and at least one shell. The core and/or the shell may comprise at least one semiconductor material. In particular, the core comprises a different semiconductor material than the shell. For instance, the at least one shell is epitaxially grown onto the core. The nanocrystal can comprise further shells and/or layers. For instance, the nanocrystal comprises a quantum well structure. For example, the nanoparticle is a core-shell quantum dot or a core-shell-shell quantum dot. Preferably, the quantum dot is cadmium-free.
In a preferred embodiment, the quantum dot is a III-V compound semiconductor material.
According to at least one embodiment, a metal of the coordination-complex is selected from the following group: alkali metal, alkaline earth metal, transition metal or posttransition metal. The post-transition metal is located in the periodic table between the transition metals to the left and the chemically weak non-metallic metalloids to their right. These metals are soft, have poor mechanical strength and usually have melting points lower than those of the transition metals. In other words, the metal of the coordination-complex is selected from the following group: alkali metal, alkaline earth metal, transition metal and/or Al, Ga, In, Tl, Sn, Pb, Bi, Po . Preferably, the metal of the coordination-complex is selected from the group consisting of Al, Zr, Cu and Ti. The coordination-complex comprises the metal which is coordinated by at least one ligand. The ligands can differ from each other. The metal of the coordination-complex can form the encapsulation as a metal oxide. In other words, the metal of the coordination-complex forms the oxide of the encapsulation.
According to a further embodiment, the method for forming the encapsulation around the nanocrystal further comprises using an oxide precursor which is selected from the group consisting of: tetraethyl orthosilicate, tetramethyl orthosilicate, tetrabutyl orthosilicate or tetrapropyl orthosilicate, a silane with an amino, mercapto, phosphonic, isocyanate, aldehyde, or carboxylic headgroup and combinations thereof. The silane with an amino, mercapto, phosphonic, isocyanate, aldehyde, or carboxylic headgroup, can also be a silane containing ligand on the nanocrystal used for conformal encapsulation. That means that, on the surface, the nanocrystal comprises an intermediate layer which comprises a silane with an amino, mercapto, phosphonic, isocyanate, aldehyde, or carboxylic headgroup.
Preferably, the Si-metal of the oxide precursor forms the oxide of the encapsulation. For example, the oxide precursor is tetraethyl orthosilicate and this oxide precursor forms a Si-oxide which encapsulates the nanocrystal.
According to at least one embodiment, the coordinationcomplex is a hydrolysis and polymerization catalyst for the formation of siloxanes. This enables the conversion of the oxide precursor, for example tetraethyl orthosilicate, into silica, while largely preserving the nanocrystal's photoluminescence quantum yield. Advantageously, only a few harmful interactions between the coordination-complex and the nanocrystal occur. According to a further embodiment, the oxide is selected from the group consisting of: a mixed metal oxide and/or a metal oxide, wherein the metal is derived from the metal of the coordination-complex and/or the metal is derived from the oxide precursor. This means, for example, that the oxide is a metal oxide or a mixed metal oxide. The mixed metal oxide can be obtained from the metal of the coordination-complex and the oxide precursor. Alternatively the mixed metal oxide can be obtained from at least two coordination-complexes which differ in their metal or from at least two oxide precursors which differ in their metal.
In other words, if the oxide precursor is, for example, tetraethyl orthosilicate and the coordination-complex is an aluminium complex, then the mixed metal oxide can be aluminosilicate. For example, the metal of the oxide differs from the metal of the coordination-complex. For example, the oxide is selected from the group consisting of: silica (SiO2) , alumina (A12O3) , titania (TiO2) , zirconia (ZrO2) , aluminosilicate and combinations thereof.
According to at least one embodiment, a ligand of the coordination-complex is selected from the group consisting of: alkoxide, acetylacetonate (acac) , ammine, diketone, hybride, hydrate, ethylacetoacetate, acetylacetonate derivates and combinations thereof. Preferably, the ligand is a bidentate ligand. For example, the coordination-complex comprises a metal and at least one ligand wherein the ligands can, for example, differ from each other.
According to at least one embodiment, the coordinationcomplex is a post-transition metal diketone. According to a preferred embodiment , the coordination-complex is a metal acetylacetonate . Preferably the coordinationcomplex is Aluminum acetylacetonate (Al ( acac ) s ) .
Advantageously the metal acetylacetonate utili zes catalyzing a deposition, for example a silica deposition, on and around the nanocrystal , for example quantum dot , to form the encapsulation . The current understanding of how metal acetylacetonates catalyze hydrolysis and polymeri zation relies on their ability to act as both acids and bases . This is di f ferent from other bases used to deposit the encapsulation, for example silica, on and around nanocrystals .
Additionally, the metal acetylacetonate undergoes hydrolysis , or alcoholysis and forms the encapsulation comprising a metal oxide , leading to the possibility of making structures with preferably mixed-metal oxides and layered metal oxides . Advantageously, the use of the metal acetylacetonate acts to slow down the hydrolysis , therefore allowing conformal metal oxide growth around the nanocrystals .
According to at least one embodiment , an intermediate layer is arranged between the encapsulation and the nanocrystal . The intermediate layer is selected from the group consisting of : a silane terminated ligand, a hydroxide terminated ligand or combinations thereof . In other words , the intermediate layer comprises a silane terminated ligand as well as a hydroxide terminated ligand . The intermediate layer is used to functionali ze the surface of the nanocrystal for a more conformal encapsulation . The headgroup of the material of the intermediate layer, which is linked to the nanocrystal surface, can comprise an amino, mercapto, phosphonic, isocyanate, aldehyde or carboxylic acid.
According to at least one embodiment, the encapsulation individually encapsulates the nanocrystal. This means that each nanocrystal is covered by one encapsulation. The encapsulation is preferably free of pinholes or paths. The encapsulation almost completely surrounds the nanocrystal. Preferably, the encapsulation completely surrounds the nanocrystal. Individually encapsulated nanocrystals can be obtained by adding a surfactant, such as AOT or Igepal, via a micelle formation. The surfactant is, for example, added to the nanocrystal and to the coordination-complex.
According to at least one embodiment, the encapsulation comprises forming a plurality of sublayers which surrounds the nanocrystal. The plurality of sublayers can comprise the same metal oxide. Preferably, the plurality of sublayers comprises different metal oxides and/or mixed metal oxides. In other words, an oxide sublayer deposition can be done many times over, creating sublayers that are more effective barriers than single, thick layers. This includes, for example, that initial, coordination-complex catalyzed materials provide improved stability.
According to a further embodiment, at least two adjacent sublayers comprise different oxides. For example, one sublayer comprises or consists of SiCy and the adjacent sublayer comprises or consists of a metal oxide, for example AI2O3. In other words, one of the sublayers is formed from the oxide precursor and one of the sublayers is formed from the metal of the coordination-complex. For example, at least one sublayer of the encapsulation comprises silica. It is also possible that one sublayer comprises or consists of a mixed metal oxide , for example aluminosilicate .
According to at least one embodiment , one of the sublayers is formed from the coordination-complex and/or one of the sublayers is formed by the oxide precursor . This means that the oxide of the sublayer comprises the same metal as the metal of the coordination-complex and/or the metal of the oxide precursor . For example , the metal of the coordinationcomplex is aluminium and the oxide of the sublayer is aluminium oxide and/or the metal of the oxide precursor is Si and the oxide of the sublayer is SiCy . Moreover, this preferably, creates a path to make mixed-metal oxide sublayers as the coordination-complex themselves are susceptible to hydrolysis and subsequent incorporation into the oxide encapsulation . The use of , for example , various acac coordination-complexes with di f ferent acac ligands , enables the formation of stacks for preventing pinholes , or paths through the encapsulation .
According to at least one embodiment , the encapsulation comprises a thickness in the range between 0 . 5 nm and 500 nm, both inclusive . Preferably, the encapsulation comprises a thickness in the range between 5 nm and 50 nm, both inclusive .
According to at least one embodiment , at least two nanocrystals are surrounded by the same encapsulation . This means that an aggregate of a few nanocrystals may be encapsulated by the same encapsulation . Then, the aggregate is , preferably, fully covered by the encapsulation . For example , ratios of a solvent , of the coordination-complex and the nanocrystals can be tailored to give either a single nanocrystal or agglomerates (clusters of a plurality of nanocrystals) in the encapsulation.
According to at least one embodiment, forming the encapsulation around the nanocrystal further uses water. The volume of water in a reaction mixture can vary anywhere from 0.001 to 20 w/w%, both inclusive. In a preferred embodiment, the volume of water is between 0.001 and 10 wt . % .
According to at least one embodiment, forming the encapsulation around the nanocrystal is initially anhydrous. The initial catalytic reaction may not be a hydrolytic reaction (eg. alcoholysis) , but the initial reaction produces water as a by-product, which then can proceed as a hydrolytic reaction, resulting in increased water w/w% as the reaction progresses .
According to at least one embodiment, forming the encapsulation around the nanocrystal further uses a solvent in which the nanocrystal and the coordination-complex are soluble. The solvent can be a solvent in which all reagents, that means the coordination-complex, the nanocrystal, optionally the water and optionally the oxide precursor, are fully soluble or of several mixed but miscible solvents of mixed polarity. The solvents can include cyclohexane, acetone, toluene, acetonitrile, ethanol, isopropanol, methanol, butanol, tetrahydrofuran, or dimethylformamide. In a preferred embodiment, the solvent can be selected from the group consisting of: cyclohexane, acetone, acetonitrile, an alcohol or combinations thereof.
According to at least one embodiment, the method takes place in atmosphere or it can be performed in an air-free atmosphere under a flowing or static inert gas environment , for example argon, nitrogen, etc . In addition, the method can be run at elevated temperatures below the boiling point of the solvent system .
According to at least one embodiment , the method takes place at a temperature between 25 ° C and 100 ° C, both inclusive in an inert gas environment . Preferably, the method takes place at a temperature between 25 ° C and 45 ° C, both inclusive . In a preferred embodiment , the method is run under inert atmosphere at a temperature of 35 ° C .
For example , the encapsulation is produced as follows : The nanocrystal or the plurality of nanocrystals is suspended in the solvent and optionally in water, forming a first solution . A surfactant and subsequently, the coordinationcomplex and optionally an oxide precursor, are added to the first solution to initiate the oxide growth on a surface of the nanocrystal to form the encapsulation .
Furthermore , a structure is speci fied . In particular, the method for producing a structure described herein produces the structure . Thus , embodiments , features and advantages described in combination with the method for producing a structure also apply to the structure and vice versa .
According to at least one embodiment , the structure comprises a nanocrystal configured to convert a primary radiation into a secondary radiation, and an encapsulation at least partially surrounding the nanocrystal encapsulation comprises an oxide . Advantageously, the structure comprises a good photoluminescence quantum yield and longevity under conditions like LED operating conditions is improved . The encapsulation protects the nanocrystal during stress-testing .
According to at least one embodiment , the encapsulation comprises a plurality of sublayers . In other words , the plurality of sublayers forms the encapsulation . The plurality of sublayers can be , for example , a mixed metal oxide and/or a metal oxide . A mixed metal oxide is , for example , aluminosilicate and a metal oxide is , for example SiCy or AI2O3. Further oxides are alkali metal oxides , alkaline earth metal oxides , transition metal oxides or post-transition metal oxides or combinations thereof . The mixed metal oxide can be obtained by the metal of the oxide precursor in combination with the metal of the coordination-complex . The metal oxides can be obtained by the metal of the oxide precursor and/or by the metal of the coordination-complex .
According to at least one embodiment , at least two adj acent sublayers comprise di f ferent oxides . This means that each sublayer can have a di f ferent oxide .
According to at least one embodiment , the encapsulation comprises traces from a coordination-complex . This means that the structure comprises traces from the coordination-complex . The traces can be detected with common analytical methods .
Advantageously, the coordination-complex slows down the hydrolysis of the metal oxide , which leads to a conformal encapsulation around the nanocrystal for the optimal barrier protection .
Furthermore , an optoelectronic device is speci fied . In particular, the optoelectronic device comprises at least one structure described herein . Thus , embodiments , features , and advantages described in combination with the structure and the method for producing a structure also apply to the optoelectronic device and vice versa .
According to an embodiment , the optoelectronic device comprises a semiconductor chip configured to emit a primary radiation . In other words , the semiconductor chip is configured to emit electromagnetic radiation of a first wavelength range . In particular, the primary radiation comprises wavelengths in the ultraviolet to blue spectral region .
According to at least one embodiment , the optoelectronic device comprises a conversion element comprising at least one structure , in particular a plurality of structures , described herein . In particular, the conversion element is configured to convert at least a portion of the primary radiation into secondary radiation . In other words , the conversion element converts the electromagnetic radiation of the first wavelength range into electromagnetic radiation of a second wavelength range . For example , the first wavelength range is at least partially di f ferent from the second wavelength range . For instance , the second wavelength range comprises wavelengths having a lower energy compared to the wavelengths in the first wavelength range . In particular, an ability of the conversion element to convert electromagnetic radiation is attributed to the structure , which comprises the nanocrystal , converting primary radiation into secondary radiation .
According to at least one embodiment , the optoelectronic device comprises a semiconductor chip configured to emit a primary radiation, and a conversion element comprising at least one structure disclosed herein .
Advantageously, the optoelectronic device described herein has improved ef ficiency, in particular, an increased operating li fetime in corrosive conditions due to the encapsulated nanocrystals . In this way, the conversion element can maintain its conversion ef ficiency over a longer time compared to conversion elements comprising structures without an encapsulation . In addition, the photoluminescence quantum yield of the encapsulated nanocrystals is advantageously not signi ficantly af fected .
According to at least one embodiment , the semiconductor chip is a micro-LED . Here and in the following, LED is an abbreviation for the term " light-emitting diode" . Micro-LEDs may have a width, a length, a thickness and/or a diameter smaller than or equal to 100 micrometers , in particular smaller than or equal to 70 micrometers , for example smaller than or equal to 50 micrometers . In particular, micro-LEDs , for example rectangular micro-LEDs , have an edge length, for instance in plan view of layers of a layer stack, of a luminous surface smaller than or equal to 70 micrometers , for example smaller than or equal to 50 micrometers . For example , the micro-LED is a light-emitting diode wherein a growth substrate is removed, such that a thickness of the micro-LED is , for instance , between and including 1 . 5 micrometers and 10 micrometers . For example , the micro-LED is provided on a wafer having releasable retaining structures . The micro-LED can be detached from the wafer in a non-destructive manner .
According to at least one embodiment , the conversion element comprises a matrix material and the at least one structure , in particular the plurality of structures, is embedded in the matrix material. For example, the matrix material is silicone, polysiloxane, or epoxy. In this instance, the conversion element is formed as a layer or a casting. The at least one structure is, preferably, homogenously distributed in the matrix material.
According to at least one embodiment, the conversion element consists of the structure comprising a nanocrystal and an encapsulation, wherein the structure is embedded in the matrix material. In this instance, the conversion element is formed as a layer or a casting.
According to at least one embodiment, the optoelectronic device is used in augmented reality and/or virtual reality applications, in automotive applications, in downconverters, in sensors, for illumination and/or in other applications.
Advantageous embodiments and developments of the method for producing a structure, of the structure and of the optoelectronic device will become apparent from the exemplary embodiments described below in conjunction with the figures.
In the drawings, like reference characters generally refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the disclosure. In the following description, various aspects of the disclosure are described with reference to the following drawings, in which:
FIG. 1 shows a schematic illustration of a method for producing a structure according to an exemplary embodiment; FIGS . 2 , 3 and 4 each show a schematic illustration of a method for producing a structure according to di f ferent exemplary embodiments ;
FIGS . 5 , 6 and 7 each show a schematic illustration of a structure according to di f ferent exemplary embodiments ;
FIGS . 8 and 9 each show a schematic illustration of an optoelectronic device according to di f ferent exemplary embodiments ; and
FIG . 10 shows the photoluminescent quantum yield of a structure according to an exemplary embodiment and a comparative example .
In the exemplary embodiments and figures , similar or similarly acting constituent parts are provided with the same reference signs . The elements illustrated in the figures and their si ze relationships among one another should not be regarded as true to scale . Rather, individual elements may be represented with an exaggerated si ze for the sake of better representability and/or for the sake of better understanding .
FIG . 1 shows a schematic illustration of the method for producing a structure 1 according to an exemplary embodiment . A coordination-complex 4 and a nanocrystal 2 are provided and form a reaction mixture . The nanocrystal 2 is configured to convert a primary radiation into a secondary radiation . In addition, optionally water 9 , a solvent 13 and an oxide precursor 7 are part of the reaction mixture . An encapsulation 3 is formed around the nanocrystal 2 , wherein the encapsulation 3 comprises an oxide . The nanocrystal 2 can, for example, be a nanoparticle, a phosphor or a quantum dot. Preferably, the nanocrystal 2 comprises or consists of a semiconductor material and the semiconductor material is a II-VI or a III-V compound semiconductor material. For example, the semiconductor material is cadmium-free. The coordination-complex 4 consists of at least one metal 5 and at least one ligand 6. The metal 5 is selected from the following group: alkali metal, alkaline earth metal, transition metal or post-transition metal. The ligand 6 of the coordination-complex 4 is selected from the group consisting of: alkoxide, acetylacetonate (acac) , ammine, diketone, hybride, hydrate, ethylacetoacetate, acetylacetonate derivatives and combinations thereof.
Preferably, the coordination-complex 4 is a metal acetylacetonate. Particularly preferably, the coordinationcomplex 4 is an aluminium acetylacetonate. The oxide precursor 7 is selected from the group consisting of: tetraethyl orthosilicate, tetramethyl orthosilicate, tetrabutyl orthosilicate, tetrapropyl orthosilicate, a silane with an amino, mercapto, phosphonic, isocyanate, aldehyde, or carboxylic headgroup and combinations thereof.
The coordination-complex 4 is used as a catalyst to catalyse the formation of the structure 1. The coordination-complex 4 will itself hydrolyse and form the encapsulation 3, which is a metal oxide. In addition, it is also possible that the coordination-complex 4 forms a mixed metal oxide and layered metal oxides around the nanocrystal 2. The oxide is selected from the group consisting of a mixed metal oxide and/or a metal oxide, wherein the metal is derived from the metal 5 of the coordination-complex 4 and/or the metal is derived from the oxide precursor 7. An intermediate layer (not shown in the figures) can be formed between the nanocrystal 2 and the encapsulation 3. The intermediate layer is selected from the group consisting of a silane terminated ligand, a hydroxide terminated ligand or combinations thereof. The encapsulation 3 individually encapsulates one nanocrystal 2. The encapsulation 3 comprises a thickness in the range between 0.5 nm and 500 nm, both inclusive. The method takes place at a temperature between 25 °C and 45 °C in an inert gas atmosphere .
FIG. 2 shows a schematic illustration of a method for producing a structure 1 according to an exemplary embodiment. Water 9, tetraethyl orthosilicate as the oxide precursor 7, the nanocrystal 2 and metal acetylacetonate (M(acac)3) as the coordination-complex 4 are mixed together. The reaction occurs under an air-free method and a flowing or static inert gas environment (argon, nitrogen, etc.) . This can be run at elevated temperatures below the boiling point of the solvent system. In a preferred embodiment it is run under inert atmosphere at a temperature of 35°. In addition, a solvent 13 selected from the group consisting of cyclohexane, acetone, toluene, acetonitrile, ethanol, isopropanol, methanol, butanol, tetrahydrofuran, or dimethylformamide is added. The coordination-complex 4 catalyses the reaction and an encapsulation 3 is formed around the nanocrystal 2. In this exemplary embodiment the encapsulation 3 is SiO3 or can be a mixed metal oxide, for example aluminosilicate. Between the nanocrystal 2 and the encapsulation 3 an intermediate layer can be formed (not shown here) .
The coordination-complex 4 comprises a metal 5 which is selected from the following group: alkali metal, alkaline earth metal, transition metal, or post-transition metal. In addition, the coordination-complex 4 comprises a ligand 6 which is selected from the group consisting of: alkoxide, acetylacetonate (acac) , ammine, diketone, hybride, hydrate, ethylacetoacetate, acetylacetonate derivatives and combinations thereof. The ligand in the exemplary embodiment of FIG. 2 is an acetylacetonate or diketone.
FIG. 3 shows a schematic illustration of a method for producing a structure 1 according to an exemplary embodiment. FIG. 3 differs from FIG. 2 in that the encapsulation 3 covers three nanocrystals 2. In other words, at least two nanocrystals 2 are surrounded by the same encapsulation 3. In this case the encapsulation 3 can be SiCy.
FIG. 4 shows a schematic illustration of the method for producing a structure 1 according to an exemplary embodiment. FIG. 4 differs from Figures 2 and 3 in that the structure 1 comprises a nanocrystal 2 and at least two sublayers 8. The encapsulation 3 comprises forming a plurality of sublayers 8 which surrounds the nanocrystal 2. At least two adjacent sublayers 8 comprise different oxides. One oxide of the sublayers 8 is formed from the metal 5 of the coordinationcomplex 4 and one oxide of the sublayers 8 is formed from the oxide precursor 7. In particular, the nanocrystal 2, preferably quantum dot, is surrounded by SiO2 so that the first sublayer 8 is SiO2, the second sublayer 8 is a metal oxide sublayer 8 and can be formed from the coordinationcomplex 4, and the third sublayer 8 is SiCy, a metal oxide or a mixed metal oxide.
FIG. 5 shows a schematic illustration of a structure 1 according to an exemplary embodiment. The structure 1 comprises a nanocrystal 2 configured to convert a primary radiation into a secondary radiation and an encapsulation 3 at least partially surrounding the nanocrystal 2 and wherein the encapsulation 3 comprises an oxide. The nanocrystal 2 can be a quantum dot and can comprise a core and a shell. The core and/or the shell comprise at least one semiconductor material. The semiconductor material is, for example, a III-V compound semiconductor material or a II-VI compound semiconductor material. In particular, the core comprises a different semiconductor material than the shell. The nanocrystal 2 can comprise further shells and/or layers. For example, the nanocrystal 2 comprises a semiconductor material which is cadmium-free and the encapsulation 3 is SiCy. The SiCh encapsulation 3 is formed from the oxide precursor 7.
FIG. 6 shows a schematic illustration of a structure 1 according to an exemplary embodiment. The structure 1 comprises a nanocrystal 2 and an encapsulation 3. The encapsulation 3 is in contact with the nanocrystal 2 and covers the nanocrystal 2 almost completely. The encapsulation 3 comprises a plurality of sublayers 8. At least two adjacent sublayers 8 comprise different oxides. The first sublayer 8, which is closer to the nanocrystal 2, is SiCy, the second sublayer 8, which is between the first and the third sublayer 8, is a metal oxide, for example aluminium oxide, and the third sublayer 8 is SiCy, a metal oxide or a mixed metal oxide, for example aluminosilicate. The encapsulation 3 comprises a thickness in the range between 0.5 nm and 500 nm, both inclusive. The exact layering, order and number of layers is only an exemplary embodiment and many other combinations are possible.
FIG. 7 shows a schematic illustration of a structure 1 described herein according to an exemplary embodiment. The structure 1 comprises a plurality of nanocrystals 2 and an encapsulation 3 which surrounds the plurality of nanocrystals 2 . The encapsulation 3 is the same for the plurality of nanocrystals 2 . The encapsulation 3 can be SiCy and the nanocrystals 2 are cadmium- free quantum dots . I f the coordination-complex 4 is Al ( acac ) s, then the encapsulation 3 can be AI2O3 or aluminosilicate .
Figures 5 , 6 and 7 comprise SiCy as the encapsulation 3 or as a sublayer 8 , but other metal oxides are also possible , either as a homogenous mixture and as dispersed or as layered structures .
FIG . 8 shows a schematic illustration of an optoelectronic device 10 described herein according to a first exemplary embodiment . The optoelectronic device 10 comprises a semiconductor chip 11 configured to emit the primary radiation of a first wavelength range . The semiconductor chip 11 can be a microLED, for example the first wavelength range is in the blue spectral region . A conversion element 12 is arranged on a radiation exit surface of the semiconductor chip 11 . The conversion element 12 can be arranged directly on the radiation exit surface or at a distance to the radiation exit surface . The conversion element 12 can be in the form of a layer or a casting . The conversion element 12 converts the primary radiation into secondary radiation of the second wavelength range . The conversion element 12 comprises or consists of at least one structure 1 described herein .
For example , the conversion element 12 comprises at least one structure 1 , in particular a plurality of structures 1 as shown in conj unction with Figures 5 , 6 and 7 . In particular the at least one structure 1 may be embedded in a matrix material , such as silicon, polysiloxane or epoxy .
FIG . 9 shows a schematic illustration of an optoelectronic device 10 described herein according to a second exemplary embodiment . The second exemplary embodiment corresponds substantially to the first exemplary embodiment shown in FIG . 8 . In contrast to the first exemplary embodiment , the semiconductor chip 11 and the conversion element 12 are arranged in the recess of a housing . The conversion element 12 comprises the structure 1 as shown in conj unction with FIG . 8 in the form of a casting around the semiconductor chip 11 .
FIG . 10 shows the photoluminescence quantum yield PLQY of a structure 1 according to the exemplary embodiment shown in FIG . 5 and a comparative example . The comparative example describes a structure 1 without an encapsulation 3 . In more detail , the comparative example is a structure 1 comprising a quantum dot .
In the diagram in FIG . 10 , the photoluminescent quantum yield is plotted against the operating time t in minutes . Curve 10- 1 shows the photoluminescent quantum yield as a function of time of a structure 1 comprising a quantum dot with an encapsulation 3 . Curve 10-2 shows the photoluminescent quantum yield as a function of time of a comparative example of a structure without an encapsulation 3 . As can be seen in FIG . 10 , the luminescence of the structure 1 comprising an encapsulation 3 can be maintained longer ( curve 10- 1 ) than the luminescence of a structure without an encapsulation 3 ( curve 10-2 ) . Without an encapsulation 3 the photoluminescent quantum yield decreases rapidly after a short amount of time ( curve 10-2 ) , whereas the photoluminescent quantum yield of the structure 1 with an encapsulation 3 only slightly decreases over a signi ficantly longer period of time ( curve 10- 1 ) . These measurements are obtained by blue light exposure 60 mW / cm2 .
In the table listed below, the initial photoluminescent quantum yield of an exemplary embodiment against a comparative example is shown . In addition, two di f ferent encapsulation methods are compared . The structure 1 of the exemplary embodiment comprises a nanocrystal 2 with an encapsulation 3 . The coordination-complex 4 used for the synthesis is Al ( acach and the oxide of the encapsulation 3 is SiOx . The structure 1 of the comparative example comprises a nanocrystal 2 and an SiOx encapsulation 3 , whereas the encapsulation 3 is obtained by a coordination-complex- free method . It can be shown that the PLQY retention as well as the powder PLQY are much higher for the structure 1 of the exemplary embodiment compared to the structure 1 of the comparative example . In addition, it can be seen that the structure 1 with one SiOx sublayer 8 according to an exemplary embodiment and a structure 1 with two SiOx sublayers 8 according to an exemplary embodiment show almost the same PLQY .
Figure imgf000026_0001
Figure imgf000027_0001
The features and exemplary embodiments described in connection with the figures can be combined with each other according to further exemplary embodiments, even if not all combinations are explicitly described. Furthermore, the exemplary embodiments described in connection with the figures may have alternative or additional features as described in the general part.
As used herein, unless otherwise specified the use of the ordinal adjectives "first", "second", "third" etc., to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner.
The present disclosure is not restricted to the exemplary embodiments by the description on the basis of said exemplary embodiments. Rather, the present disclosure encompasses any new feature and also any combination of features, which in particular comprises any combination of features in the patent claims and any combination of features in the exemplary embodiments, even if this feature or this combination itself is not explicitly specified in the patent claims or exemplary embodiments.
This patent application claims the priority of US patent application 63/580,716, the disclosure content of which is hereby incorporated by reference. References
1 structure
2 nanocrystal 3 encapsulation
4 coordination-complex
5 metal
6 ligand
7 oxide precursor 8 sublayer
9 water
10 optoelectronic device
11 semiconductor chip
12 conversion element 13 solvent
10- 1 curve comparative example
10-2 curve exemplary embodiment

Claims

Claims
1. A method for producing a structure (1) , comprising: providing a nanocrystal (2) configured to convert a primary radiation into a secondary radiation, forming an encapsulation (3) around the nanocrystal (2) using a coordination-complex (4) , wherein the encapsulation (3) comprises an oxide.
2. The method according to the preceding claim, wherein the nanocrystal (2) comprises or consists of a semiconductor material and the semiconductor material is a II-VI or a III-V compound semiconductor material.
3. The method according to one of the preceding claims, wherein a metal (5) of the coordination-complex (4) is selected from the following group: alkali metal, alkaline earth metal, transition metal, or post-transition metal.
4. The method according to one of the preceding claims, wherein forming the encapsulation (3) around the nanocrystal
(2) further comprises using an oxide precursor (7) which is selected from the group consisting of: tetraethyl orthosilicate, tetramethyl orthosilicate, tetrabutyl orthosilicate, tetrapropyl orthosilicate, a silane with an amino, mercapto, phosphonic, isocyanate, aldehyde, or carboxylic headgroup and combinations thereof.
5. The method according to one of the preceding claims, wherein the oxide is selected from the group consisting of: a mixed metal oxide and/or a metal oxide, wherein the metal is derived from the coordination-complex (4) and/or the metal is derived from the oxide precursor (7) .
6. The method according to one of the preceding claims, wherein a ligand (6) of the coordination-complex (4) is selected from the group consisting of: alkoxide, acetylacetonate (acac) , ammine, diketone, hybride, hydrate, ethylacetoacetate, acetylacetonate derivatives and combinations thereof.
7. The method according to one of the preceding claims, wherein the coordination-complex (4) is a metal acetylacetonate .
8. The method according to one of the preceding claims, wherein an intermediate layer is formed between the encapsulation (3) and the nanocrystal (2) , and the intermediate layer is selected from the group consisting of: a silane terminated ligand, a hydroxide terminated ligand or combinations thereof.
9. The method according to one of the preceding claims, wherein the encapsulation (3) individually encapsulates one nanocrystal ( 2 ) .
10. The method according to one of the preceding claims, wherein the encapsulation (3) comprises forming a plurality of sublayers (8) which surrounds the nanocrystal (2) .
11. The method according to the preceding claim, wherein at least two adjacent sublayers (8) comprise different oxides.
12. The method according to one of the preceding claims, wherein one of the sublayers (8) is formed from the coordination-complex (4) and/or one of the sublayers (8) is formed by the oxide precursor (7) .
13. The method according to one of the preceding claims, wherein at least two nanocrystals (2) are surrounded by the same encapsulation (3) .
14. The method according to one of the preceding claims, wherein forming the encapsulation (3) around the nanocrystal (2) further uses water (9) and/or a solvent (13) in which the nanocrystal (2) and the coordination-complex (4) are soluble.
15. The method according to one of the preceding claims, wherein the method takes place at a temperature between 25 °C and 100 °C in an inert gas atmosphere.
16. A structure (1) comprising
- a nanocrystal (2) configured to convert a primary radiation into a secondary radiation, and
- an encapsulation (3) at least partially surrounding the nanocrystal (2) , and wherein the encapsulation (3) comprises an oxide.
17. The structure (1) according to the preceding claim, wherein the encapsulation (3) comprises a plurality of sublayers ( 8 ) .
18. The structure (1) according to one of the preceding claims , wherein at least two adjacent sublayers (8) comprise different oxides .
19. The structure (1) according to one of the preceding claims, wherein the encapsulation (3) comprises at least traces from a coordination-complex (4) .
20. An optoelectronic device (10) comprising - a semiconductor chip (11) configured to emit a primary radiation, and
- a conversion element (12) comprising at least one structure (1) according to one of the claims 16 to 19.
PCT/EP2024/074049 2023-09-06 2024-08-28 Method for producing a structure, structure and optoelectronic device Pending WO2025051607A1 (en)

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Citations (3)

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Publication number Priority date Publication date Assignee Title
US20150011029A1 (en) * 2013-07-03 2015-01-08 Benjamin Daniel Mangum Network of semiconductor structures with fused insulator coating
US20160149091A1 (en) * 2013-06-25 2016-05-26 Konica Minolta, Inc. Light-emitting material, method for producing same, optical film, and light-emitting device
WO2023275498A1 (en) * 2021-06-30 2023-01-05 Aledia Protected and light-emitting nanoparticle, method for producing same and use thereof for optoelectronic device radiation converters

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20160149091A1 (en) * 2013-06-25 2016-05-26 Konica Minolta, Inc. Light-emitting material, method for producing same, optical film, and light-emitting device
US20150011029A1 (en) * 2013-07-03 2015-01-08 Benjamin Daniel Mangum Network of semiconductor structures with fused insulator coating
WO2023275498A1 (en) * 2021-06-30 2023-01-05 Aledia Protected and light-emitting nanoparticle, method for producing same and use thereof for optoelectronic device radiation converters
US20240287381A1 (en) * 2021-06-30 2024-08-29 Aledia Light-emitting and protected nanoparticle, a manufacturing method thereof and an application thereof for the optoelectronic device radiation converters

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