STRUCTURE, OPTOELECTRONIC DEVICE, AND METHOD FOR MANUFACTURING STRUCTURE

Abstract

A structure, an optoelectronic device, and a method of manufacturing the structure are disclosed. In an embodiment, the structure includes a first nanoparticle including at least one semiconductor material. The first nanoparticle is chromophore in a first wavelength range and emissive in a second wavelength range. The structure further includes a plurality of second nanoparticles. The second nanoparticle is non-chromophore in the first wavelength range and in the second wavelength range.

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE Structures, optoelectronic devices, and methods of manufacturing the structures are disclosed. [Background technology]

[0002] Structures with improved performance are desired. Optoelectronic devices with structures with improved performance are desired. Methods of manufacturing structures with improved performance are desired. Summary of the Invention

[0003] According to at least one embodiment, a structure is provided, which may include different elements, components or parts with particular properties, in particular different properties.

[0004] According to at least one embodiment, the structure includes first nanoparticles that include or consist of at least one semiconductor material, for example, the first nanoparticles include or consist of a material based on III-V or II-VI compound semiconductor materials.

[0005] In particular, the structure comprises exactly one first nanoparticle, or exactly two first nanoparticles, or a plurality of first nanoparticles, for example ten or more first nanoparticles.

[0006] According to at least one embodiment, the first nanoparticle is chromophore in a first wavelength range and emissive in a second wavelength range. Here and hereinafter, chromophore means that the first nanoparticle is electronically excitable in a certain wavelength range. In other words, the first nanoparticle is configured or designed to absorb electromagnetic radiation having a wavelength in the first wavelength range, in particular by exciting electrons from a ground state to an excited state. Here and hereinafter, emissive means that the first nanoparticle emits radiation in a certain wavelength range. In other words, the first nanoparticle is configured or designed to emit electromagnetic radiation having a wavelength in the second wavelength range, in particular by returning excited electrons from an excited state to a ground state.

[0007] In particular, the first nanoparticles have wavelength conversion properties. In other words, the first nanoparticles have the ability to absorb electromagnetic radiation in a first wavelength range and emit electromagnetic radiation in a second wavelength range. In a further embodiment, the second wavelength range is at least partially different from the first wavelength range. For example, the first nanoparticles are chromophores in a first wavelength range of 400 nm to 490 nm (inclusive), such as at 450 nm. For example, the first nanoparticles are emissive in a second wavelength range of 500 nm to 2000 nm (inclusive), such as at 500 nm to 700 nm (inclusive).

[0008] According to at least one embodiment, the structure includes a plurality of second nanoparticles. In other words, the structure includes two or more second nanoparticles, for example, 10 or more second nanoparticles. Each second nanoparticle of the plurality of second nanoparticles may be identical, similar, or different in at least one of size, composition, and shape compared to other second nanoparticles. In particular, the plurality of second nanoparticles may include different types of second nanoparticles, where the different types of second nanoparticles have, for example, different compositions.

[0009] It should be noted that the number of second nanoparticles in the structure may depend on the size of the second nanoparticles compared to the size of the first nanoparticles. The smaller the second nanoparticles are compared to the first nanoparticles, the more second nanoparticles need to be present in the structure. If the second nanoparticles are the same size as the first nanoparticles or larger than the first nanoparticles, there may be about the same amount of second nanoparticles in the structure compared to the first nanoparticles.

[0010] According to at least one embodiment, the second nanoparticles are non-chromophoric in the first and second wavelength ranges. Here and hereinafter, non-chromophoric means that the second nanoparticles are not electronically excitable in a particular wavelength range. Thus, the second nanoparticles absorb significantly less electromagnetic radiation in both the first and second wavelength ranges compared to particles that are chromophoric in at least one of the above wavelength ranges. In other words, the second nanoparticles absorb significantly less electromagnetic radiation in both the excitation and emission wavelength ranges of the first nanoparticles.

[0011] As defined herein, "absorb significantly less electromagnetic radiation" means that the second nanoparticles absorb less energy of electromagnetic radiation in a first wavelength range and a second wavelength range compared to a particle that is a chromophore in at least one of the first wavelength range and the second wavelength range. In particular, the second nanoparticles absorb at least 50%, at least 60%, at least 70%, at least 80%, or at least 90% less energy of electromagnetic radiation compared to the chromophore particle.

[0012] It should be noted that the second nanoparticles may be chromophoric at wavelength ranges different than the first and second wavelength ranges, for example, the second nanoparticles may be non-emissive and chromophoric in an ultraviolet (UV) wavelength range, such as 250 nm to 400 nm, but non-chromophoric in a first wavelength range of 400 nm to 490 nm (inclusive) and a second wavelength range of 500 nm to 2000 nm (inclusive).

[0013] In particular, the second nanoparticles are configured or designed to have equal or greater affinity for the decomposition species, for example, by exhibiting chemical reactivity to the decomposition species that are likely to decompose the first nanoparticles. In other words, the non-chromophore material of the second nanoparticles may block the decomposition species that would normally decompose the outermost surface of the first nanoparticles. Decomposition species include, but are not limited to, oxygen, water, high temperatures, and combinations thereof. In the presence of the decomposition species, the second nanoparticles may consume the decomposition species through chemical reactions before the decomposition species react with the first nanoparticles. Thus, the second nanoparticles may act as a protective screen between the first nanoparticles and the decomposition species. Alternatively, the material of the second nanoparticles may exhibit a physical affinity for species that are likely to decompose the first nanoparticles, for example, but not limited to, water, and absorb the decomposition species before they can reach the surface of the first nanoparticles.

[0014] For example, the second nanoparticles stabilize the dissolution of the outermost shell of a first nanoparticle, such as a multishell quantum dot, through one or more of the following mechanisms: The second nanoparticles can prevent or delay dissolution of the outermost shell by providing a constant level of dissolved ions of the same species as the outermost shell near the first nanoparticle. In addition, the second nanoparticles can also provide a source of monomers for the outermost shell to redeposit shell material on a partially eroded first nanoparticle. In addition, the second nanoparticles can also provide a reservoir of harmful redox equivalents photogenerated during material aging, such as photooxidation by the Auger process. In addition, the second nanoparticles can scavenge superoxide, hydroxyl radicals, and other reactive oxygen species.

[0015] In accordance with at least one embodiment, a structure includes a first nanoparticle including at least one semiconductor material. The first nanoparticle is chromophore in a first wavelength range and emissive in a second wavelength range. The structure further includes a plurality of second nanoparticles. The second nanoparticles are non-chromophore in the first wavelength range and in the second wavelength range.

[0016] In the structures described herein, the second nanoparticles provide a barrier to degradation of the first nanoparticles by having equal or greater affinity for degradative species likely to degrade the first nanoparticles, and the second nanoparticles intercept the degradative species by chemically reacting with or chemically absorbing the degradative species, thereby stabilizing the first nanoparticles under environmentally harsh conditions such as high humidity and high temperature.

[0017] According to at least one embodiment, the first nanoparticle comprises a core and at least one shell. The core and / or the shell comprises at least one semiconductor material. In a further embodiment, the core comprises a different semiconductor material than the shell. In particular, the at least one shell is epitaxially grown on the core. Furthermore, the first nanoparticle may comprise further shells and / or layers. For example, the first nanoparticle is a quantum dot, in particular a core-shell quantum dot.

[0018] According to at least one embodiment, the first nanoparticles include a core-shell-shell structure, for example, the first nanoparticles are CdSe / CdS / ZnS photoluminescent quantum dots.

[0019] According to at least one embodiment, the first nanoparticles have a diameter between 20 nm and 50 nm, inclusive.

[0020] According to at least one embodiment, the second nanoparticles have a diameter between 2 nm and 50 nm, inclusive. In particular, the second nanoparticles are smaller in size than the first nanoparticles or comparable in size to the first nanoparticles. In other words, the second nanoparticles are within the same order of magnitude compared to the first nanoparticles.

[0021] According to at least one embodiment, the second nanoparticles are at least one of metal particles, semiconductor particles, chalcogenide particles, pnictide particles, and combinations thereof. In particular, the second nanoparticles include or consist of Zn-containing particles.

[0022] The metallic particles include or consist of a metal, such as a d-block transition metal of the periodic table.

[0023] The semiconductor particles include or consist of a semiconductor material, such as a II-VI or III-V semiconductor.

[0024] Chalcogenide particles include or consist of a chalcogenide. A chalcogenide is a chemical compound that consists of at least one chalcogen anion of an element from group 16 of the periodic table and at least one or more electropositive elements, such as a metal. For example, chalcogenides can be oxides, sulfides, selenides, tellurides, and / or polonides.

[0025] For example, the chalcogenide particles may include or consist of zinc oxide, particularly nano-ZnO. A second nanoparticle formed from ZnO may have a band structure different from the outermost shell of a first nanoparticle, particularly one that includes a related material such as ZnS. The difference in band structure results in a difference in redox potential. A second nanoparticle having a different band structure, and thus a different redox potential than the outermost shell of the first nanoparticle, is particularly advantageous for providing a reservoir of damaging redox equivalents to capture reactive oxygen species in the vicinity of the first nanoparticle.

[0026] Alternatively, or in addition, the chalcogenide particles comprise or consist of zinc sulfide, particularly nano-ZnS. Second nanoparticles formed from ZnS are particularly advantageous for first nanoparticles that comprise an outermost shell of ZnS. In addition to providing a reservoir for damaging redox equivalents to scavenge reactive oxygen species, the second nanoparticles of ZnS may be provided in the vicinity of the first nanoparticles to retard dissolution of the outermost shell of the first nanoparticles. 2+ Ion and S 2-A level of dissolved ZnS in ionic form may be provided, and further, the second nanoparticles of ZnS may provide a source of ZnS monomers for redepositing onto the partially eroded first nanoparticles.

[0027] Pnictide particles include or consist of pnictides. Pnictides are chemical compounds consisting of at least one pnictogen anion of an element from group 15 of the periodic table and at least one or more electropositive elements, such as metals. For example, pnictides are nitrides, phosphides, arsenides, antimonides, and / or bismuthides.

[0028] According to at least one embodiment, the first nanoparticle and the second nanoparticle are arranged in close proximity within the structure. In other words, the first nanoparticle and the second nanoparticle are arranged very close or in close proximity to each other. In particular, the first nanoparticle and the second nanoparticle are separated from each other by less than 30 μm. For example, the distance between the first nanoparticle and the second nanoparticle is between 0 μm and 30 μm inclusive. In other words, the first nanoparticle and the second nanoparticle may be arranged in direct contact or may be spaced apart by up to 30 μm. The second nanoparticle arranged in close proximity to the first nanoparticle provides a barrier against decomposition species and enhances the stability of the first nanoparticle.

[0029] According to at least one embodiment, the first nanoparticles and the second nanoparticles are arranged at the same location in the structure. In other words, the first nanoparticles and the second nanoparticles are arranged to be in the same place or to be close to each other, for example, at the same location. In particular, the nanoparticles arranged at the same location have an inter-nanoparticle distance of 0 μm to 30 μm inclusive. The co-location of the first nanoparticles and the second nanoparticles increases the stability of the structure against decomposition species, in particular the stability of the first nanoparticles.

[0030] According to at least one embodiment, the structure further comprises an encapsulant. In particular, the encapsulant is provided to protect the first nanoparticles and / or the second nanoparticles from degradation. The encapsulant can at least partially or completely surround the first nanoparticles and / or the second nanoparticles. The first nanoparticles and / or the second nanoparticles may be surrounded by the encapsulant on all sides. In particular, the first nanoparticles and / or the second nanoparticles may be in direct contact with the encapsulant material.

[0031] According to at least one embodiment, the encapsulant comprises a material that includes or consists of metal oxides and mixtures thereof, for example, the encapsulant material includes or consists of silica.

[0032] According to at least one embodiment, the first nanoparticle and the second nanoparticle are co-encapsulated in an encapsulant. The co-encapsulated nanoparticles are co-located or co-encapsulated in the encapsulant material such that the encapsulant material at least partially or completely surrounds both the first nanoparticle and the second nanoparticle. In other words, the encapsulant forms a layer at least partially or completely around both the first nanoparticle and the second nanoparticle. In particular, the second nanoparticle is encapsulated in the encapsulant material in close proximity to the first nanoparticle such that the first nanoparticle and the second nanoparticle can move together in the encapsulant. In particular, structures containing co-encapsulated nanoparticles exhibit different properties than structures containing the first nanoparticle encapsulated in the encapsulant material that is subsequently treated with a chemical compound. Furthermore, the nanoscale size of the second nanoparticle may provide a means of encapsulating the second nanoparticle in the same vicinity as the first nanoparticle. This may be in contrast to ions or small molecules that are somewhat free to diffuse through the encapsulant material, such as silica.

[0033] According to at least one embodiment, the first nanoparticles and the second nanoparticles are spaced apart within the encapsulation. In particular, the first nanoparticles are not in direct contact with any of the second nanoparticles. The distance between the first nanoparticles and the second nanoparticles within the encapsulation is at most 30 μm. Thus, even if the first nanoparticles and the second nanoparticles are not in direct physical contact, the mere proximity of the second nanoparticles to the first nanoparticles is sufficient to create a preservative effect within the structure.

[0034] According to at least one embodiment, each second nanoparticle directly contacts at least one of the first nanoparticle and the further second nanoparticle of the plurality of second nanoparticles. The first nanoparticle and the second nanoparticle are in such close proximity that the surfaces of the first nanoparticle and the second nanoparticle are in contact. In other words, the first nanoparticle and the second nanoparticle form an aggregate. In particular, the aggregate may be formed by electrostatic attraction between the first nanoparticle and the second nanoparticle, or the aggregate may be formed by applying heat to the first nanoparticle and the second nanoparticle. In particular, the first nanoparticle and the second nanoparticle are in electronic contact with each other. The second nanoparticle in direct contact with the first nanoparticle can enhance the preservation effect of the second nanoparticle in the structure.

[0035] According to at least one embodiment, the second nanoparticles are bound to the first nanoparticles by at least one method, such as aggregation, non-covalent bonding, covalent bonding, melting, sintering, agglomeration, and combinations thereof. In particular, the second nanoparticles are bound to the first nanoparticles prior to encapsulation of the first nanoparticles and / or the second nanoparticles in an encapsulant material, where the first nanoparticles and the second nanoparticles form a pre-aggregate prior to encapsulation.

[0036] As described herein, agglomerating a first nanoparticle and a second nanoparticle means combining the first nanoparticle and the second nanoparticle such that the first nanoparticle and the second nanoparticle form an aggregate. The aggregate may be formed by aggregating the first nanoparticle and the second nanoparticle, for example into a cluster. In particular, agglomeration does not necessarily mean that the first nanoparticle and the second nanoparticle are combined in a stoichiometric manner.

[0037] As described herein, a non-covalent bond between a first nanoparticle and a second nanoparticle means that a physical and / or chemical interaction occurs between the first nanoparticle and the second nanoparticle, resulting in a non-covalent bond between the first nanoparticle and the second nanoparticle. A non-covalent bond can include any bond that is a non-covalent bond, such as a dative bond, an ionic bond, a hydrogen bond, a dipole-dipole interaction, an intercalation, and a van der Waals interaction.

[0038] For example, the first nanoparticles and the second nanoparticles can be prepared such that the two nanoparticle types are oppositely charged. The oppositely charged nanoparticles can aggregate to form heterostructures. In particular, the first nanoparticles and / or the second nanoparticles can include binding ligands, such as organic ligands, and charged ligands on the surface. The organic ligands can be positively or negatively charged. Alternatively, the first nanoparticles can include an encapsulant that surrounds the naturally negatively charged first nanoparticles. In this case, the negatively charged first nanoparticles can bind to the positively charged second nanoparticles due to non-covalent binding based on ionic bonds.

[0039] Alternatively, the first nanoparticle and the second nanoparticle may comprise ligands with long hydrophobic chains such that the first nanoparticle and the second nanoparticle can be non-covalently bound by inserting the hydrophobic ligand.

[0040] As described herein, the covalent bond between a first nanoparticle and a second nanoparticle means that a covalent bond is formed between the first nanoparticle and / or the second nanoparticle. In particular, the covalent bond is formed between the ligands of the first nanoparticle and / or the second nanoparticle. The covalent bond between the first nanoparticle and / or the second nanoparticle can be formed by any chemical reaction that bonds two ligands, such as photoreaction chemistry, peptide chemistry, methacrylate chemistry, polyester chemistry, etc. For example, ether or ester bonds, and carbon-carbon bonds, silicon-carbon bonds, sulfur-carbon bonds, phosphorus-carbon bonds, or nitrogen-carbon bonds can be used to link the ligands of the first nanoparticle and / or the second nanoparticle to each other.

[0041] As described herein, bonding a second nanoparticle to a first nanoparticle by melting means that the second nanoparticle adjacent to the first nanoparticle is at least partially melted such that the second nanoparticle is bonded to the surface of the first nanoparticle as an at least partially molten structure. In particular, the structural integrity of the first nanoparticle is not compromised by bonding the second nanoparticle to the first nanoparticle by melting.

[0042] As described herein, sintering of a first nanoparticle and a second nanoparticle means that the first nanoparticle and the second nanoparticle are compressed by heat or pressure to form a solid mass of material without melting the first nanoparticle and / or the second nanoparticle to a liquid point. The second nanoparticle can form a sintered structure on the surface of the first nanoparticle. In particular, the structural integrity of the first nanoparticle is not compromised by bonding the second nanoparticle to the first nanoparticle by sintering.

[0043] In particular, the first nanoparticles and the second nanoparticles are sintered or at least partially melted by applying a temperature between 90° C. and 400° C. inclusive.

[0044] In particular, by bonding the second nanoparticles to the first nanoparticles by melting or sintering, there is no organic mediator in the structure, particularly between the first nanoparticles and the second nanoparticles. In other words, there is no organic mediator in the structure.

[0045] As described herein, agglomeration should be understood as combining a first nanoparticle with a second nanoparticle. In other words, the first nanoparticle and the second nanoparticle form an agglomerate. In the agglomerate, the spatial morphology of the first nanoparticle and the second nanoparticle can be recognized. Thus, the spatial shape of the first nanoparticle and the second nanoparticle remains intact after agglomeration.

[0046] According to at least one embodiment, the surface of the first nanoparticles is partially covered by the second nanoparticles. The first nanoparticles may be at least partially surrounded by the second nanoparticles. In other words, the surface of the first nanoparticles is modified at least in places with the second nanoparticles. In particular, the surface of the first nanoparticles is in direct contact with the second nanoparticles at least in places.

[0047] According to at least one embodiment, the surface of the first nanoparticle is completely covered by the second nanoparticle, the first nanoparticle being surrounded by the second nanoparticle such that the entire surface of the first nanoparticle is modified with the second nanoparticle.

[0048] According to at least one embodiment, the second nanoparticles form a layer around the first nanoparticles. The layer of second nanoparticles may at least partially or completely surround the first nanoparticles. The layer of second nanoparticles may include aggregated second nanoparticles, agglomerated second nanoparticles, covalently bonded second nanoparticles, or non-covalently bonded second nanoparticles. In this case, the shape of the individual second nanoparticles remains discernible. Alternatively, the layer of second nanoparticles may include a fused and / or sintered structure.

[0049] In particular, the surface of the layer of second nanoparticles around the first nanoparticles is provided with a roughness, in particular the roughness of the layer of second nanoparticles is increased compared to the roughness of the surface of the first nanoparticles.

[0050] In particular, the surface of the layer of second nanoparticles around the first nanoparticles has an increased surface area compared to the surface area or roughness of the surface of the first nanoparticles, the increased surface area being advantageous for promoting surface reactions.

[0051] According to at least one embodiment, the layer of second nanoparticles has a thickness of 1 nm to 100 nm inclusive, in particular 1 nm to 20 nm inclusive, or 1 nm to 10 nm inclusive. The layer of second nanoparticles may comprise one monolayer of second nanoparticles, or two or more monolayers of second nanoparticles.

[0052] According to at least one embodiment, the second nanoparticle includes at least one surface moiety. The surface moiety can be organic or inorganic. The surface moiety can be configured or designed to have an affinity for species that are likely to degrade the first nanoparticle. In particular, the at least one surface moiety is directly or indirectly bonded to the surface of the second nanoparticle. For example, the surface moiety is polyethylene glycol. The polyethylene glycol modified second nanoparticles, due to their affinity for water, can increase the humidity of the environment near the first nanoparticle, thereby helping to prevent photodegradation of the first nanoparticle. Another class of surface moieties includes at least one of boranes, borohydrides, citrates, oxalates, reducing sugars, aldehydes, or reducing and oxidizing agents such as hydrazine iodide, sulfites, thiosulfates, and dithionates.

[0053] According to at least one embodiment, the second nanoparticles comprising at least one surface moiety are inert. In this case, the second nanoparticles can be more utilized due to the carrying capacity of their surface moieties. In other words, the second nanoparticles do not interact with species that are likely to degrade the first nanoparticles, and therefore have no affinity for such species. For example, the inert second nanoparticles are silica nanoparticles or polymer nanoparticles.

[0054] According to at least one embodiment, the second nanoparticles comprising at least one surface moiety are active. In other words, the second nanoparticles and the surface moiety interact with species that are likely to degrade the first nanoparticles. Thus, both the second nanoparticles and the surface moiety are beneficial to the protection of the first nanoparticles. For example, an active second nanoparticle is a second nanoparticle that is configured or designed to have equal or greater affinity to decomposition species that are likely to degrade the first nanoparticles, such as ZnS or ZnO nanoparticles.

[0055] According to at least one embodiment, at least one surface moiety is diffused into the encapsulant material surrounding the second nanoparticle and the first nanoparticle. In other words, the surface moiety can be bound to the second nanoparticle before encapsulation and can diffuse into the encapsulant material during or after encapsulation. In particular, the surface moiety is no longer in direct contact with the second nanoparticle during or after encapsulation.

[0056] According to at least one embodiment, the second nanoparticle comprises two surface moieties, the first surface moiety being bound to the second nanoparticle by the second surface moiety. The second surface moiety may be bound to the surface of the second nanoparticle by a non-covalent or covalent bond. The second surface moiety may be a polymeric or molecular species that has an affinity for the first surface moiety. The first surface moiety may be bound to the second nanoparticle by forming a non-covalent or covalent bond with the second surface moiety. This is particularly advantageous for a first surface moiety that has little or no binding affinity to the surface of the second nanoparticle.

[0057] According to at least one embodiment, the structure includes at least one internal payload species in proximity to the first nanoparticle, the internal payload species including, for example, ions such as copper (I), iron (II), and mercury, and the internal payload species in proximity to the first nanoparticle is configured or designed to have equal or greater affinity for decomposition species likely to degrade the first nanoparticle.

[0058] According to at least one embodiment, at least one internal payload species is inside the second nanoparticle. In other words, the internal payload species is not attached to the surface of the second nanoparticle, but is substitutionally or interstitially incorporated into the lattice of the second nanoparticle. The second nanoparticle may function as a buffer to provide an ion flow of the internal payload species in the vicinity of the first nanoparticle. It should be noted that the internal payload species exerts its effect when released in the vicinity of the first nanoparticle, not when bound on and / or within the second nanoparticle. In particular, the second nanoparticle functions as a carrier to bring the internal payload species in the vicinity of the first nanoparticle, which functions as a sustained release agent.

[0059] According to at least one embodiment, at least one of the second nanoparticles comprises a first internal payload species and at least one of the second nanoparticles comprises a second internal payload species. In particular, the first and second internal payload species differ from each other in at least one of composition and charge number. In this context, composition should be understood as comprising one or more elements, in particular one metal element. Two different internal payload species in close proximity to the first nanoparticle may increase the beneficial effect of the internal payload species on protection against degradation.

[0060] According to at least one embodiment, the first nanoparticle is encapsulated in a first encapsulant, the second nanoparticle is encapsulated in a second encapsulant, and the first encapsulant and the second encapsulant are in direct contact with each other. In other words, the encapsulated first nanoparticle and the encapsulated second nanoparticle form agglomerates or aggregates or are fused together such that the encapsulated nanoparticles are in close proximity to each other. The structure may therefore be an assembly of pre-encapsulated nanoparticles. In particular, the first nanoparticles may be individually encapsulated and a plurality of second nanoparticles may be encapsulated together in one encapsulant, or alternatively, each second nanoparticle may be individually encapsulated. In particular, at least one of the first encapsulant and the second encapsulant comprises or consists of an encapsulant material selected from the group consisting of metal oxides and mixtures thereof. In particular, the first nanoparticles and / or the second nanoparticles are homogeneously encapsulated.

[0061] According to at least one embodiment, the first encapsulant and the second encapsulant comprise the same encapsulant material. In particular, the encapsulant material of the first encapsulant and the second encapsulant is selected from the group consisting of metal oxides and mixtures thereof. For example, the encapsulant material of the first encapsulant and the second encapsulant is silica.

[0062] Another embodiment relates to an optoelectronic device. In a further embodiment, the optoelectronic device described herein comprises at least one structure as described above. Accordingly, features and embodiments of the optoelectronic device are also disclosed for the structure and vice versa.

[0063] According to at least one embodiment, an optoelectronic device comprises a semiconductor chip configured to emit a primary radiation and a conversion element configured to convert at least a portion of the primary radiation into a secondary radiation, the conversion element including at least one structure as described above.

[0064] The semiconductor chip may comprise an active layer stack including an active region that emits primary radiation during operation of the device. For example, the semiconductor chip is a light emitting diode chip or a laser diode chip. The primary radiation generated in the semiconductor chip may be emitted through a radiation emitting surface of the semiconductor chip. In particular, the semiconductor chip emits primary radiation in the visible wavelength range, such as wavelengths above 400 nm, during operation. For example, the semiconductor chip emits primary radiation in the wavelength range of 400 nm to 490 nm inclusive, such as 450 nm.

[0065] The structures in the conversion element are configured to convert the primary radiation at least partially or completely into secondary radiation. In particular, the secondary radiation has a wavelength range that is at least partially different or completely different from the wavelength range of the primary radiation. For example, the wavelength range of the secondary radiation is within the visible or infrared wavelength range, for example, within the wavelength range of 500 nm to 2000 nm inclusive.

[0066] The features of the structure have already been disclosed in relation to the structure and also apply to structures in optoelectronic devices.

[0067] Such optoelectronic devices can be used to emit white or colored light. The co-location of the non-chromophore second nanoparticles and the chromophore and emissive first nanoparticles in the conversion element provides the structure with improved stability in environmentally harsh conditions such as high humidity and high temperature. Thus, the optoelectronic devices described herein have an extended operating life under corrosive conditions.

[0068] Another embodiment relates to a method for manufacturing a structure. The methods described herein may be used to manufacture the above-mentioned structures, which may be used in the above-mentioned optoelectronic devices. Accordingly, features and embodiments of the methods are also disclosed for the structures and optoelectronic devices, and vice versa.

[0069] According to at least one embodiment, a method of fabricating a structure includes providing a first nanoparticle comprising at least one semiconductor material. The first nanoparticle is chromophore in a first wavelength range and emissive in a second wavelength range. The method further includes providing a plurality of second nanoparticles. The second nanoparticles are non-chromophore in the first wavelength range and in the second wavelength range. The method further includes disposing the first nanoparticle and the second nanoparticle in close proximity.

[0070] The steps of the methods of manufacturing the structures described herein are not limited to this order, however, according to further embodiments, the steps are performed in this order.

[0071] Such methods can produce structures in which a first nanoparticle is protected from a degradative species by bringing the first nanoparticle into close proximity with a second nanoparticle that has an equal or greater affinity for the degradative species likely to degrade the first nanoparticle.

[0072] According to at least one embodiment, the method further includes binding the second nanoparticles to the first nanoparticles by at least one method, such as aggregation, non-covalent bonding, covalent bonding, melting, sintering, agglomeration, and combinations thereof. In particular, the second nanoparticles at least partially or completely cover the surface of the first nanoparticles. The second nanoparticles can form a layer around the first nanoparticles by methods, such as aggregation, non-covalent bonding, covalent bonding, agglomeration, and combinations thereof. Alternatively, the second nanoparticles can form a layer around the first nanoparticles that includes a fused or sintered structure of the second nanoparticles.

[0073] According to at least one embodiment, the method further comprises applying an encapsulant. The encapsulant may be applied before, during or after placing the first nanoparticle and the second nanoparticle in close proximity. For example, the first nanoparticle and / or the second nanoparticle are encapsulated before placing the nanoparticles in close proximity. Alternatively, the first nanoparticle and the second nanoparticle are encapsulated together and thus placed in close proximity in the encapsulant. In this case, the first nanoparticle and the second nanoparticle are co-encapsulated. In particular, this co-encapsulation may include mixing the first nanoparticle and the second nanoparticle before forming the encapsulant around the nanoparticle. Such a method may be sufficient to provide a statistically distributed random co-encapsulation of the first nanoparticle and the second nanoparticle. Alternatively, the first nanoparticle and the second nanoparticle may be placed in close proximity, i.e. pre-assembled, for example by binding the second nanoparticle to the surface of the first nanoparticle before encapsulation.

[0074] According to at least one embodiment, the method further includes encapsulating the first nanoparticle in a first encapsulant, encapsulating the second nanoparticle in a second encapsulant, and placing the first encapsulant and the second encapsulant in direct contact, i.e., both the first nanoparticle and the second nanoparticle are encapsulated prior to placing the first nanoparticle and the second nanoparticle in close proximity.

[0075] Advantageous embodiments and developments of the structure, the optoelectronic device and the method for manufacturing the structure will become apparent from the exemplary embodiments described below in conjunction with the figures. [Brief description of the drawings]

[0076] [Figure 1] 1A-1D depict schematic diagrams of structures in accordance with different illustrative embodiments; [Diagram 2] 1-3 depict schematic illustrations of methods for manufacturing structures according to different illustrative embodiments; [Diagram 3]1 shows a transmission electron microscope (TEM) micrograph of a structure according to an example embodiment. [Figure 4A] 1A-1D depict schematic diagrams of structures in accordance with different illustrative embodiments; [Figure 4B] 1A-1D depict schematic diagrams of structures in accordance with different illustrative embodiments; [Figure 5A] 1-3 depict schematic illustrations of methods for manufacturing structures according to different illustrative embodiments; [Figure 5B] 1-3 depict schematic illustrations of methods for manufacturing structures according to different illustrative embodiments; [Figure 5C] 1-3 depict schematic illustrations of methods for manufacturing structures according to different illustrative embodiments; [Figure 6] 1A-1D depict schematic diagrams of structures in accordance with different illustrative embodiments; [Figure 7A] 1-3 depict schematic illustrations of methods for manufacturing structures according to different illustrative embodiments; [Figure 7B] 1-3 depict schematic illustrations of methods for manufacturing structures according to different illustrative embodiments; [Figure 8] 1A-1D depict schematic diagrams of structures in accordance with different illustrative embodiments; [Figure 9] 1-3 depict schematic illustrations of methods for manufacturing structures according to different illustrative embodiments; [Figure 10] 1A-1D depict schematic diagrams of structures in accordance with different illustrative embodiments; [Figure 11] 1-3 depict schematic illustrations of methods for manufacturing structures according to different illustrative embodiments; [Figure 12] 1A-1D depict schematic diagrams of structures in accordance with different illustrative embodiments; [Figure 13] 1-3 depict schematic illustrations of methods for manufacturing structures according to different illustrative embodiments; [Figure 14] 1 shows a schematic diagram of an optoelectronic device according to an exemplary embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0077] In the exemplary embodiments and figures, similar or similarly acting components are given the same reference numerals. The elements shown in the figures and their size relationships to one another should not be considered to be to scale. Rather, for better representation and / or for deeper understanding, individual elements may be represented with exaggerated dimensions.

[0078] FIG. 1 shows a schematic diagram of a structure 1. The structure 1 comprises a first nanoparticle 2. The first nanoparticle 2 comprises at least one semiconductor material. For example, the first nanoparticle is a photoluminescent quantum dot, such as a CdSe / CdS / ZnS core-shell-shell quantum dot. The first nanoparticle 2 is chromophore in a first wavelength range and emissive in a second wavelength range. In other words, the first nanoparticle 2 can absorb electromagnetic radiation in a first wavelength range and emit electromagnetic radiation in a second wavelength range. For example, the first wavelength range includes wavelengths between 400 nm and 490 nm inclusive, and the second wavelength range includes wavelengths between 500 nm and 2000 nm inclusive, in particular wavelengths between 500 nm and 700 nm inclusive.

[0079] The structure further includes a plurality of second nanoparticles 3. The second nanoparticles 3 are non-chromophoric in the first and second wavelength ranges. In other words, the second nanoparticles 3 do not absorb wavelengths in the first and second wavelength ranges. Alternatively, the second nanoparticles 3 absorb significantly less electromagnetic radiation in both the first and second wavelength ranges than particles that are chromophoric in the above wavelength ranges. For example, the second nanoparticles 3 are metal particles, semiconductor particles such as II-VI semiconductors, chalcogenide particles such as nano ZnS or nano ZnO, pnictide particles, and combinations thereof. The second nanoparticles 3 are located in the same position as the first nanoparticles 2 in the structure 1, which means that the second nanoparticles 3 are located in close proximity to the first nanoparticles 2. Specifically, the distance between the first nanoparticles 2 and the second nanoparticles 3 is 0 μm to 30 μm (inclusive). The second nanoparticles 3 have an equal or greater affinity for decomposition species that are likely to decompose the first nanoparticles 2 by blocking the decomposition species, chemically reacting with the decomposition species, and / or absorbing the decomposition species.

[0080] Optionally, the structure 1 may include an encapsulant 4 that at least partially or completely surrounds the first nanoparticle 2 and the second nanoparticle 3. In this case, the first nanoparticle 2 and the second nanoparticle 3 may be co-encapsulated within the encapsulant 4. The encapsulant 4 may include or consist of an encapsulant material that includes or consists of a metal oxide such as silica.

[0081] A structure 1 according to Figure 1 can be produced according to Figure 2 by mixing first nanoparticles 2 and second nanoparticles 3 before forming an encapsulation 4 around the nanoparticles, thereby providing a statistically well-distributed random co-encapsulation of the second nanoparticles 3 and the first nanoparticles 2.

[0082] In a further embodiment of the structure 1 according to FIG. 1, the first nanoparticles 2 are CdSe / CdS / ZnS photoluminescent quantum dots and the second nanoparticles 3 are nano-ZnS particles. Optionally, the first nanoparticles 2 and the second nanoparticles 3 are co-encapsulated within a silica encapsulant 4. In this case, the nano-ZnS stabilizes the decomposition of the ZnS layer of the multi-shell quantum dots through one or more of several mechanisms. The nano-ZnS provides a certain level of dissolved ZnS (Zn 2+ and S 2- ) and retard dissolution. Nano-ZnS can also provide a reservoir of harmful redox equivalents that are photogenerated during material aging, e.g., during photooxidation by the Auger process. Nano-ZnS can scavenge superoxide, hydroxyl radicals, and other reactive oxygen species. Nano-ZnS can further provide a source of ZnS monomers for redepositing onto partially corroded quantum dots.

[0083] Figure 3 shows a TEM micrograph of a structure 1 comprising CdSe / CdS / ZnS primary nanoparticles 2 co-encapsulated in a silica encapsulant 4 with nano-ZnS secondary nanoparticles 3. The mere proximity of the nano-ZnS secondary nanoparticles 3 is sufficient to produce a preservative effect on the CdSe / CdS / ZnS primary nanoparticles 2 composite system.

[0084] The structure 1 according to Fig. 4A and Fig. 4B differs from the structure according to Fig. 1 in that each second nanoparticle 3 is in direct contact with at least one of the first nanoparticle 2 and the further second nanoparticle 3. The first nanoparticle 2 and the second nanoparticle 3 form an aggregate. Optionally, this aggregate may be encapsulated in an encapsulant 4. The surface of the first nanoparticle 2 may be partially (Fig. 4A) or completely (Fig. 4B) covered with the second nanoparticles 3. In other words, the second nanoparticles 3 form a layer around the first nanoparticle 2. The layer of the second nanoparticles 3 may have a thickness of 1 nm to 100 nm inclusive, for example a thickness of 1 nm to 20 nm inclusive or a thickness of 1 nm to 10 nm inclusive.

[0085] The structure 1 according to Figures 4A and 4B can be produced by forming an aggregate of first nanoparticles 2 and second nanoparticles 3 according to Figures 5A and 5B and optionally encapsulating the aggregate with an encapsulant 4.

[0086] The assembly can be prepared such that the second nanoparticles 3 are bound to the first nanoparticles 2 by at least one of aggregation, non-covalent bonds, covalent bonds, and agglomeration. For example, the first nanoparticles 2 and the second nanoparticles 3 can be prepared such that the nanoparticles 2, 3 are oppositely charged, taking into account the binding and charged ligands. The oppositely charged nanoparticles 2, 3 can be aggregated into the structure 1. Alternatively, to achieve an even higher level of control, the first nanoparticles 2 and the second nanoparticles 3 can be covalently bound, for example, via organic ligands attached to the surfaces of the first nanoparticles 2 and the second nanoparticles 3 that chemically react with each other.

[0087] As shown in FIG. 5C, two different types of second nanoparticles 3, 3' may be provided to form an aggregate with the first nanoparticles 2. The two different types of second nanoparticles 3, 3' differ from each other in at least one of size, composition, and shape. For example, the second nanoparticles 3 have a different composition from the second nanoparticles 3'. In that case, the structure 1 comprises a mixed layer of the two types of second nanoparticles 3, 3' on the surface of the first nanoparticles 2.

[0088] Figure 6 shows a structure 1 which differs from the structure 1 according to figures 4A and 4B in that the second nanoparticles 3 are partially melted or lightly sintered relative to the first nanoparticles 2. The partially melted or lightly sintered second nanoparticles 3 form a molten or sintered structure 5 which at least partially or completely surrounds the first nanoparticles 2. The molten or sintered structure 5 may have the form of a layer surrounding the first nanoparticles 2, having a thickness of 1 nm to 100 nm inclusive, for example a thickness of 1 nm to 20 nm inclusive or a thickness of 1 nm to 10 nm inclusive.

[0089] A structure according to FIG. 6 may be fabricated according to FIG. 7A by providing a second nanoparticle 3 in close proximity to a first nanoparticle 2. For example, by applying a temperature between 90° C. and 400° C. (inclusive), the second nanoparticle 3 is melted and / or sintered to the surface of the first nanoparticle 2 to form a molten or sintered structure 5. Further application of temperature causes multiple sintering events to increase the coverage of the first nanoparticle 2 by the molten or sintered structure 5. In further embodiments, the surface of the first nanoparticle 2 is completely covered by the molten or sintered structure 5. Optionally, the first nanoparticle 2 and the second nanoparticle 3 may be co-encapsulated within the encapsulant 4 after various degrees of melting or sintering.

[0090] Instead of using one type of second nanoparticles 3, as shown in Figure 7B, two different types of second nanoparticles 3, 3' may be provided and fused and / or sintered to the first nanoparticles 2, thereby forming a fused or sintered structure 5' on the surface of the first nanoparticles 2. The fused or sintered structure 5' is a mixed layer of both types of second nanoparticles 3, 3'.

[0091] 8 shows a structure 1 comprising a first nanoparticle 2 encapsulated in a first encapsulant 6 and a second nanoparticle 3 encapsulated in a second encapsulant 7. The first encapsulant 6 and the second encapsulant 7 are in direct contact, thus bringing the first nanoparticle 2 and the second nanoparticle into close proximity. The first encapsulant 6 and the second encapsulant 7 may comprise the same encapsulant material, for example silica.

[0092] The structure 1 according to Fig. 8 can be produced by encapsulating first nanoparticles 2 in a first encapsulant 6, in particular uniformly, and encapsulating second nanoparticles 3 in a second encapsulant 7, in particular uniformly, according to Fig. 9. Each second nanoparticle 3 can be encapsulated individually, or multiple second nanoparticles 3 can be encapsulated together. The previously encapsulated nanoparticles 2, 3 are then mixed and agglomerated or aggregated or fused to form the structure 1.

[0093] FIG. 10 shows a structure 1 with an intermediate structure 10 of a second nanoparticle 3 comprising surface moieties 8, 9, the first surface moiety 8 being bound to the second nanoparticle 3 by a second surface moiety 9. The second surface moiety 9 may be a polymeric or molecular species that has an affinity to bind to the first surface moiety. The first surface moiety 8 may be an organic or inorganic molecule or species. The first surface moiety 8 is, for example, a polyethylene glycol, which, due to its affinity for water, can increase the humidity of the environment near the first nanoparticle 2. Alternatively, the first surface moiety 8 may be a reducing and oxidizing agent, such as a borane, borohydride, citrate, oxalate, reducing sugar, aldehyde, or hydrazine iodide, sulfite, thiosulfate, and dithionate.

[0094] In the exemplary embodiment of FIG. 10, the second nanoparticles 3 themselves may be inert, meaning that they do not have interactions with species that are likely to degrade the first nanoparticles 2. In this case, the second nanoparticles 3 are more utilized due to the loading capacity of their surface moieties. Alternatively, the second nanoparticles 3 may be active, meaning that they have interactions with species that are likely to degrade the first nanoparticles 2. In either case, the nanoscale size of the second nanoparticles 3 provides a means of encapsulating the second nanoparticles 3 with surface moieties 8, 9 in the same vicinity as the first nanoparticles 2. This is in contrast to ions or small molecules that may be somewhat free to diffuse through the surrounding medium, such as silica encapsulation.

[0095] A structure 1 according to Fig. 10 can be produced by preparing an intermediate structure 10 comprising a second nanoparticle 3 modified with surface moieties 8, 9 by bonding the second surface moiety 9 to the surface of the second nanoparticle 3 and by bonding the first surface moiety 8 to the second surface moiety 9 according to Fig. 11. The second nanoparticle 3 modified with surface moieties 8, 9 is then placed in proximity to the first nanoparticle 2 and optionally encapsulated together with the first nanoparticle 2 within an encapsulant 4.

[0096] FIG. 12 illustrates a structure 1 in which at least one of the second nanoparticles 3 includes an internal payload species A and at least one of the second nanoparticles 3 includes a second internal payload species B. The first internal payload species A and the second internal payload species B differ from each other in at least one of composition and charge number. Each internal payload species A, B is located inside the second nanoparticle 3 rather than attached to the surface of the second nanoparticle 3. Specifically, the internal payload species A, B are substitutionally or interstitially incorporated into the lattice of the second nanoparticle 3. The internal payload species A, B include, for example, copper (I), iron (II), mercury, and combinations thereof.

[0097] In the structure 1 of Figure 12, the second nanoparticle 3 can function as a buffer to provide a flow of ions of the internal payload species A, B in the vicinity of the first nanoparticle 2. It should be noted that the internal payload species A, B exert their effect when released in the vicinity of the first nanoparticle, not when bound on and / or in the second nanoparticle 3. In particular, the second nanoparticle 3 functions as a carrier to bring the internal payload species A, B in the vicinity of the first nanoparticle 2, which functions as a sustained release drug.

[0098] A structure 1 according to Figure 12 may be produced by mixing a first nanoparticle 2 with a second nanoparticle 3 containing internal payload species A, B, prior to forming an encapsulation 4 around the nanoparticles 2, 3 according to Figure 13. During and after encapsulation, the second nanoparticle 3 provides the internal payload species A, B in close proximity to the first nanoparticle 2.

[0099] Fig. 14 shows a schematic diagram of an optoelectronic device 100 comprising a semiconductor chip 101 having an active layer stack and an active region (not explicitly shown here). In operation, the semiconductor chip 101 emits primary radiation, for example from the radiation emission surface 102. In particular, the primary radiation is electromagnetic radiation in a first wavelength range. For example, the semiconductor chip 101 emits electromagnetic radiation in the visible wavelength range, in particular in the blue wavelength range, for example in the wavelength range of 400 nm to 490 nm inclusive, such as 450 nm.

[0100] The conversion element 103 is disposed on the radiation emitting surface 102 of the semiconductor chip 101. In particular, the conversion element is disposed in direct contact with the radiation emitting surface 102. The conversion element 103 is configured or designed to absorb the primary radiation and convert at least a part of the primary radiation into secondary radiation. The secondary radiation is electromagnetic radiation having a wavelength range that is at least partially or completely different from the primary radiation. In particular, the secondary radiation is electromagnetic radiation in a second wavelength range, for example having a wavelength between 500 nm and 2000 nm inclusive, such as between 500 nm and 700 nm inclusive.

[0101] The transduction element 103 includes or consists of at least one structure 1. For example, the transduction element 103 includes at least one structure 1, in particular a plurality of structures 1, as shown in relation to Figures 1, 3, 4A, 4B, 6, 8, 10, and 12. In particular, the at least one structure 1 may be embedded in a matrix material, such as silicone, polysiloxane, or epoxy.

[0102] The features and example embodiments described in connection with the figures can be combined with each other according to further example embodiments, even if not all combinations are explicitly described. Furthermore, the example embodiments described in connection with the figures can have alternative or additional features as described in the summary section.

[0103] The present invention is not limited to the exemplary embodiments described above, but rather includes any novel feature and includes any combination of features, and in particular includes any combination of features in the claims and in the exemplary embodiments, even if this feature or this combination itself is not explicitly set forth in the claims or in the exemplary embodiments.

[0104] This patent application claims priority to U.S. patent application 17 / 530,568, the disclosure of which is incorporated herein by reference. [Explanation of symbols]

[0105] 1 structure 2. The first nanoparticles 3, 3' Second nanoparticle 4. Encapsulation 5, 5' Fused or sintered structure 6. First Encapsulation 7 Secondary Encapsulation 8 First surface portion 9 Second Surface Part 10 Intermediate structure A First internal payload type B Second internal payload type 100 Optoelectronic Devices 101 Semiconductor Chip 102 Radiation emitting surface 103 Conversion Factor

Claims

1. 1. A structure (1), a first nanoparticle (2) comprising at least one semiconductor material, the first nanoparticle (2) being chromophore in a first wavelength range and emissive in a second wavelength range; a plurality of second nanoparticles (3, 3'), the second nanoparticles (3, 3') being non-chromophore in the first wavelength range and in the second wavelength range; A structure (1) comprising:

2. The structure (1) according to claim 1, wherein the first nanoparticle (2) comprises a core and at least one shell.

3. The structure (1) according to claim 1 or 2, wherein the second nanoparticles (3, 3') comprise particles selected from the group consisting of metal particles, semiconductor particles, chalcogenide particles, pnictide particles, and combinations thereof.

4. The structure (1) according to any one of claims 1 to 3, further comprising an encapsulant (4).

5. 5. The structure (1) according to claim 4, wherein the first nanoparticles (2) and the second nanoparticles (3, 3') are spaced apart within the encapsulant (4).

6. The structure (1) according to any one of claims 1 to 5, wherein each second nanoparticle (3, 3') of the plurality of second nanoparticles (3, 3') is in direct contact with the first nanoparticle (2) and with at least one further second nanoparticle (3, 3') of the plurality of second nanoparticles (3, 3').

7. The structure (1) according to any one of claims 1 to 6, wherein the second nanoparticles (3, 3') are bonded to the first nanoparticles (2) by at least one method selected from the group consisting of aggregation, non-covalent bonding, covalent bonding, melting, sintering, agglomeration, and combinations thereof.

8. The structure (1) according to any one of the preceding claims, wherein the surface of the first nanoparticles (2) is partially covered by the second nanoparticles (3, 3').

9. The structure (1) according to any one of the preceding claims, wherein the surface of the first nanoparticles (2) is completely covered by the second nanoparticles (3, 3').

10. The structure (1) according to any one of the preceding claims, wherein the second nanoparticles (3, 3') comprise at least one surface portion (8, 9).

11. 11. The structure (1) according to claim 10, wherein the second nanoparticle (3, 3') comprises a first surface portion (8) and a second surface portion (9), and the first surface portion (8) is bonded to the second nanoparticle (3, 3') by the second surface portion (9).

12. The structure (1) according to any one of the preceding claims, wherein the structure (1) comprises at least one internal payload species (A, B) in proximity to the first nanoparticle (2).

13. 13. The structure (1) according to claim 12, wherein said at least one internal payload species (A, B) is inside said second nanoparticle (3, 3').

14. The first nanoparticles (2) are encapsulated in a first encapsulant (6), said second nanoparticles (3, 3') being encapsulated in a second encapsulant (7); The structure (1) according to any one of the preceding claims, wherein the first encapsulation (6) and the second encapsulation (7) are in direct contact with each other.

15. 15. The structure (1) according to claim 14, wherein the first encapsulant (6) and the second encapsulant (7) comprise the same encapsulant material.

16. An optoelectronic device (100), comprising: a semiconductor chip (101) configured to emit primary radiation; a conversion element (103) configured to convert at least a portion of the primary radiation into secondary radiation, An optoelectronic device (100), wherein the conversion element (103) comprises at least one structure (1) according to any one of the preceding claims.

17. A method for producing a structure (1), comprising the steps of: Providing first nanoparticles (2) comprising at least one semiconductor material, the first nanoparticles (2) being chromophoric in a first wavelength range and emissive in a second wavelength range; Providing a plurality of second nanoparticles (3), the second nanoparticles (3, 3') being non-chromophore in the first wavelength range and in the second wavelength range; disposing said first nanoparticles (2) and said second nanoparticles (3, 3') in close proximity to each other; A method comprising:

18. 18. The method of claim 17, further comprising bonding the second nanoparticles (3, 3') to the first nanoparticles (2) by at least one method selected from the group comprising aggregation, non-covalent bonding, covalent bonding, melting, sintering, agglomeration, and combinations thereof.

19. 19. The method according to claim 17 or 18, further comprising applying an encapsulant (4).

20. Encapsulating said first nanoparticles (2) within a first encapsulant (6); encapsulating said second nanoparticles (3, 3') within a second encapsulant (7); placing said first encapsulation (6) and said second encapsulation (7) in direct contact with each other; The method of any one of claims 17 to 19, further comprising:

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