Photoluminescence nanocomposite material

Abstract

A photoluminescent nanocomposite material according to one aspect of the present invention includes a carrier matrix, a plurality of photoluminescence nanostructures distributed in the carrier matrix, and an additive including one or more coordination complexes having thiol and lipophilic properties.

Description

Photoluminescent nanocomposite materials

[0001] This application claims priority to U.S. Provisional Application No. 63 / 653,578, filed May 30, 2024, the contents of which are incorporated herein by reference.

[0002] The poor operational stability of quantum dots under optical excitation in humid environments can be improved by overlaying a so-called "barrier layer" on the quantum dot (QD) optical film product (e.g., a QD resin layer) to reduce the exposure of the QDs to moisture. This approach increases the thickness and cost of the QD layer and limits the availability of the resulting QD optical film.

[0003] Therefore, elimination of the barrier layer may be desirable to reduce manufacturing cost and complexity, however, doing so may expose the QDs to conditions (e.g., moisture and / or air) that degrade performance.

[0004] The present invention aims to provide a photoluminescent nanocomposite material that can stabilize QDs and provide long-term protection.

[0005] A photoluminescent nanocomposite material according to one aspect of the present invention is a photoluminescent nanocomposite material comprising: a carrier matrix; a plurality of photoluminescent nanostructures distributed within the carrier matrix; and an additive comprising one or more coordination complexes having thiol and lipophilic properties.

[0006] According to the above invention, a photoluminescent nanocomposite material can be provided that can stabilize QDs and protect them for a long period of time.

[0007] Figure 1A shows the molecular structure of 2,2,6,6-tetramethylpiperidin-4-yl, which may be used herein as a hindered amine light stabilizer. Figure 1B shows the molecular structure of melamine, which may be used herein as an auxiliary base. Figure 1C shows the molecular structure of an exemplary substituted melamine compound, which may be used herein as an auxiliary base. Figure 2A shows the molecular structure of an exemplary substituted melamine compound, which may be used herein as an auxiliary base. Figure 2B shows the molecular structure of an exemplary substituted melamine compound, which may be used herein as an auxiliary base. Figure 2 ... ２ 2B shows exemplary reliability data for green- and red-emitting QDs at 16 mW / cm for different mixtures of antioxidants, 60 °C, and 90% RH. ２ 2C shows exemplary reliability data for green- and red-emitting QDs at 16 mW / cm for different mixtures of antioxidants, 60 °C, and 90% RH. ２ 2D shows exemplary reliability data for green- and red-emitting QDs at 16 mW / cm for different mixtures of antioxidants, 60 °C, and 90% RH. ２ 3A shows exemplary reliability data for green- and red-emitting QDs at 6 mW / cm for different zinc dithiocarbamate salts, 60 °C, and 90% RH. ２ 3B shows exemplary reliability data for green- and red-emitting QDs at 6 mW / cm for different zinc dithiocarbamate salts. ２ 4A shows exemplary reliability data for green- and red-emitting QDs at 50 mW / cm for different mixtures of antioxidants, 50 °C, and 90% RH. ２ 4B shows exemplary reliability data for green- and red-emitting QDs at 50 mW / cm for different mixtures of antioxidants, 50 °C, and ambient RH. ２ 4C shows exemplary reliability data for green- and red-emitting QDs at 50 mW / cm for different mixtures of antioxidants, 50 °C, and ambient RH. ２ 4D shows exemplary reliability data for green- and red-emitting QDs at 50 mW / cm for different mixtures of antioxidants, 50 °C, and ambient RH. ２4E shows exemplary reliability data for green- and red-emitting QDs at 50 mW / cm for different mixtures of antioxidants. ２ 4F shows exemplary reliability data for green- and red-emitting QDs at 50 mW / cm for different mixtures of antioxidants, 50 °C, and ambient RH. ２ 5A shows exemplary reliability data for green- and red-emitting QDs at 16 mW / cm for different mixtures of antioxidants, 50 °C, and ambient RH. ２ 5B shows exemplary reliability data for green- and red-emitting QDs at 16 mW / cm for different mixtures of antioxidants, 60 °C, and 90% RH. ２ 5C shows exemplary reliability data for green- and red-emitting QDs at 50 mW / cm for different mixtures of antioxidants, 60 °C, and 90% RH. ２ 5D shows exemplary reliability data for green- and red-emitting QDs at 50 mW / cm for different mixtures of antioxidants. ２, 50°C, and ambient RH. FIG. 6 shows example reliability data for green- and red-emitting QDs under different test conditions. FIG. 7 shows example reliability data illustrating the effect of adding 3,9-bis(octadecyloxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane (hereinafter also referred to as "DSPP") to a comparative example composition herein. FIG. 8A shows performance data for, e.g., photoluminescent nanostructures used in the examples. FIG. 8B shows performance data for, e.g., photoluminescent nanostructures used in the examples. FIG. 9A shows performance data for, e.g., photoluminescent nanostructures used in the examples. FIG. 9B shows performance data for, e.g., photoluminescent nanostructures used in the examples. FIG. 10 shows an embodiment of an exemplary photoluminescent nanocomposite material in which nanostructures are disposed in a coating on support particles. Figure 11 shows an embodiment of an exemplary photoluminescent nanocomposite material in which nanostructures are disposed within the material structure. Figure 12 shows an embodiment of an exemplary film including a photoluminescent nanocomposite material. Figure 13A shows an embodiment of a photoluminescent nanocomposite material in which nanostructures are disposed within the material structure. ２ ) excitation at 450 nm, 50°C and 90% relative humidity (RH), e.g., green-emitting QDs. Figure 13B shows the performance retention over time under stress conditions of 6 milliwatts per square centimeter (mW / cm ２14A shows an embodiment of performance retention over time under stress conditions, e.g., for red-emitting QDs, with excitation at 450 nm, 50°C, and 90% relative humidity (RH). FIG. 14A shows an embodiment of performance retention and stability of emission wavelength (PWL) under stress conditions, e.g., for green-emitting QDs. FIG. 14B shows an embodiment of performance retention and stability of emission wavelength (PWL) under stress conditions, e.g., for green-emitting QDs. FIG. 14C shows an embodiment of performance retention and stability of emission wavelength (PWL) under stress conditions, e.g., for red-emitting QDs. FIG. 14D shows an embodiment of performance retention and stability of emission wavelength (PWL) under stress conditions, e.g., for red-emitting QDs. FIG. 15A shows an embodiment of an exemplary display device including a photoluminescent nanocomposite material. FIG. 15B shows an embodiment of an exemplary display device including a photoluminescent nanocomposite material. FIG. 16 shows an embodiment of an exemplary electronic device operable in conjunction with the display devices of FIGS. 15A and 15B.

[0008] One aspect of the present disclosure relates to a photoluminescent nanocomposite material comprising a carrier matrix, a plurality of photoluminescent nanostructures distributed within the carrier matrix, and an additive comprising one or more coordination complexes having thiol and lipophilic properties.

[0009] This Summary is provided to introduce a selection of concepts in a simplified form that are further described in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any shortcomings noted in any part of this disclosure.

[0010] Nanocomposites containing QDs in polymers are used in barrier-less QD-enhanced films (QDEFs), QD thermoplastic plates, and other technologies. These nanocomposites comprise a novel class of bright and / or narrow-band emitting materials for display applications. To improve the stability of these materials against photooxidation, combinations of additives with different functional groups, such as chain-breaking antioxidants, peroxide decomposers, light stabilizers, and metal deactivators, can be incorporated into the nanocomposites. Some additive combinations have been found to enhance QD photoluminescence lifetime and improve the operational lifetime of devices in which the nanocomposites are used. This disclosure reports further improvements in QD performance through next-generation additive compositions and structures that stabilize QDs in the polymer matrix, enabling long-term protection. A novel class of co-additives is disclosed herein that exhibits synergistic protection against photodegradation, enabling further improvements in the photoluminescence lifetime and operational lifetime of nanocomposites containing QDs in polymers. In particular, these additive compositions and structures significantly retard oxidative degradation under light excitation under humid aerobic conditions.

[0011] Photooxidation of semiconductor light-emitting QDs, which can be catalyzed by water and / or metal ions and accelerated by heat, typically generates highly reactive species, such as peroxide, hydroxyl, and (alkyl)peroxy radicals. These species attack the inorganic nanostructure of the light-emitting material, reducing photoluminescence quantum yield and lifetime and limiting device lifetime. Formulating effective multi-component antioxidants and / or structures with synergistic protection against QD photooxidation is desirable to improve operational stability, particularly in barrier-less QDEFs and QD thermoplastic optical plates. Success in this area could enable low-cost solutions for bright and / or narrow-band emitters in optical components and expand the market share of QDs in electronic displays.

[0012] In some examples, the photoluminescent nanocomposite material may include a secondary antioxidant. Secondary antioxidants are compounds that can react with hydroperoxides to form, for example, non-reactive alcohol products. Secondary antioxidants include, for example, trivalent phosphorus compounds, thioethers, and organic sulfides. Reference to a secondary antioxidant does not imply that a primary antioxidant is also present in the photoluminescent nanocomposite material; the term "secondary" in this context will be understood by those skilled in the art as relating to the function of the antioxidant being described.

[0013] Extruded structures containing quantum dots (QDs) have the potential to significantly reduce the cost of utilizing QDs in display applications compared to cast film systems. However, the process conditions during extrusion are more detrimental than those used during film fabrication and are more likely to impair QD performance. Therefore, mitigating extrusion-related damage could potentially improve extruded QD composites to match or exceed the performance of QD laminate film structures.

[0014] Dispersed and / or dissolved in the carrier matrix as a stabilizing additive, secondary antioxidant compounds (secondary antioxidants) can consume reactive species generated during extrusion, thus at least partially preventing these reactive species from reacting with QDs and helping to maintain QD performance. Primary antioxidants, which react with free radicals, have been found to adversely affect QD performance in extruded composites in some cases. Therefore, in some instances, the composition does not contain a primary antioxidant.

[0015] In some examples, the secondary antioxidant compound may include phosphorus. In some examples, the secondary antioxidant compound may include a phosphonate group or a phosphaspiro group.

[0016] In some examples, the photoluminescent nanocomposite composition comprises 0.01 weight percent (wt%) to 10 wt% of a secondary antioxidant compound on a dry weight basis, i.e., the solvent does not count as 100 wt%. In some examples, the composition comprises up to about 1 wt% of a secondary antioxidant compound.

[0017] In some examples, the secondary antioxidant compound has the structure A-[(L)n-R]m, where A is a moiety having a secondary antioxidant functional group; each L is a linker group selected from phenyl, —O—, and —S—; n is selected from 0 or 1; and each R is independently an optionally substituted C ６～４０ and m is a number from 1 to 6 (inclusive).

[0018] In some examples, each R may be substituted with one or more halo or hydroxy substituents. Each R may be linear or branched. Each R may include unsaturated bonds, such as one or two unsaturated bonds. In some examples herein, each R may be a linear saturated alkyl group.

[0019] In some examples herein, A is 2,4,8,10-tetraoxa-3,9diphosphaspiro[5.5]undecane. In some examples, n is 0 and m is 2. In some examples, the secondary antioxidant compound is 3,9-bis(octadecyloxy)-2,4,8,10-tetraoxa-3,9diphosphaspiro[5.5]undecane (DSPP).

[0020] Without binding the present disclosure to any particular theory, it is believed that the R groups may bind to the ligand corona on the surface of the luminescent nanostructures, for example, via van der Waals forces. Such binding localizes the secondary antioxidant to the surface of the nanostructures and improves retention of QD performance compared to other antioxidants, as demonstrated in the examples below.

[0021] In some examples, the photoluminescent nanocomposite material may further include a hindered amine light stabilizer (hereinafter also referred to as "HALS") as a stabilizing additive. Hindered amine light stabilizers are compounds containing amine functional groups that can be incorporated into polymers, including plastics, for example. The amine groups are hindered to reduce or minimize side reactions or the conversion of the HALS to nitrone species. For example, hindered amines may in some cases lack an alpha hydrogen to reduce or minimize the conversion to nitrone. HALS can at least partially prevent photooxidation and possibly other forms of polymer degradation, such as ozonolysis. HALS generally do not absorb ultraviolet (UV) light, but act to inhibit polymer degradation by continuously and periodically scavenging free radicals generated by polymer photooxidation. The overall process is sometimes referred to as the Denisov cycle. Generally, HALS can react with the initial polymer peroxy radical (ROO.) or alkyl polymer radical (R.) formed by the reaction of the polymer with oxygen to at least partially prevent further radical oxidation. These reactions can oxidize HALS to their corresponding aminoxyl radicals, but then revert to their initial amine form through a series of subsequent radical reactions.

[0022] In some instances, the HALS may comprise 2,2,6,6-tetramethylpiperidin-4-yl. Referring now to the drawings, Figure 1A shows the molecular structure of the 2,2,6,6-tetramethylpiperidin-4-yl moiety, with the asterisk indicating the point of attachment to the remainder of the compound structure. Note that HALS containing a piperidine moiety may be resistant to intramolecular Cope reactions, which is an added advantage.

[0023] It is observed that the two novel HALS compounds disclosed herein may provide improvements over existing HALS compounds both by themselves and in combination with existing HALS compounds. By inference, one HALS compound may be better than the other HALS compound in a given formulation due to (1) thermal stability, (2) synergy with other formulation components, (3) resistance to inactivation by acids or other chemical antagonists, and / or (4) dispersion and migration within the thermoplastic article. Multiple related HALS compounds may be used in combination with each other to provide improved stabilization due to complementary pathways to oxidant inactivation.

[0024] In some examples, the HALS comprises a polymer backbone, for example, 2,2,6,6-tetramethylpiperidin-4-yl is attached to the polymer backbone within a repeat unit of the polymer. In some such examples, the HALS can comprise poly([[6-[(1,1,3,3-tetramethylbutyl)amino]-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidinyl)imino]-1,6-hexanediyl[(2,2,6,6-tetramethyl-4-piperidinyl)imino]]), which in some particular examples can have a molecular weight in the range of about 2000 to 3100 grams per mole (g / mol). In some such examples, the HALS may include the reaction product of 2,4,6 trichloro-1,3,5-triazine with 1,6 hexanediamine, N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-polymer, N-butyl-1-butanamine, and N-butyl-2,2,6,6-tetramethyl-4-piperidinamine, which in some particular examples may have a molecular weight ranging from 2600 to 3400 grams per mole (g / mol). In some such examples, the HALS may include poly(4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol-alt-1,4-butanedioic acid), which in some particular examples may have a molecular weight ranging from 3100 to 4000 grams per mole (g / mol).

[0025] The photooxidative degradation rate of QDs in photoluminescent nanocomposites can be further reduced by the incorporation of one or more coordination complexes (hereinafter also referred to as "CCTLs") with thiol and lipophilic properties. A coordination complex has thiol properties if it contains at least one ligand coordinated to a metal via a thiolate (RS-) anion, where R is a functionalized or non-functionalized alkyl or aryl group. A coordination complex has lipophilic properties if it is more soluble in relatively non-polar solvents, such as hydrocarbons, than in relatively polar solvents, such as water or alcohols. An exemplary prototypical CCTL is zinc dodecanethiolate (hereinafter also referred to as "ZnDDT"). ZnDDT is a complex consisting of a Zn-based thiolate (ZDDT) and a Zn-based thiolate (ZDDT). ２＋ It is a coordination complex with two dodecanethiolate (1-) ligands for the dication (some of which may participate in cross-linking). The thiol character of ZnDDT is imparted by the terminal thiolate group. The lipophilic character of ZnDDT is imparted by the 12-carbon aliphatic chain. When incorporated into various QD matrices with additional antioxidants, ZnDDT reduces the photooxidative degradation rate of QDs at elevated temperatures and humid conditions (see below).

[0026] The zinc dithiocarbamates shown in Table 1 are 6 mW / cm ２ , 50°C, 90% RH, and 16 mW / cm ２ , 60°C, 90% RH as a co-additive for antioxidant effect.

[0027]

[0028] However, recent studies have shown that ZnDDT is not unique among CCTL compounds and their mixtures for retarding QD photodegradation. As qualitatively shown in Table 1, photodegradation (6 mW / cm ２ , 50°C, 90% relative humidity (RH), and 16 mW / cm ２, 60°C, 90% RH) can be further reduced by incorporating zinc dithiocarbamate complex salts into the antioxidant mixture. The latter can include phosphorus-containing antioxidants (e.g., 3,9-bis(octadecyloxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane), S-containing antioxidants (e.g., ZnDDT), and light stabilizers such as HALS (e.g., N,N'-bis(2,2,6,6-tetramethylpiperidin-4-yl)hexane-1,6-diamine; 2,4,6-trichloro-1,3,5-triazine; 2,4,4-trimethylpentan-2-amine) and triazines (e.g., melamine). Figures 2A-5D provide quantitative data demonstrating the effect in certain examples. In particular, Figures 2A-2D show that the 16 mW / cm 2 reduction was achieved for different antioxidant mixtures. ２ 3A-3B show exemplary reliability data (power vs. time) for green- and red-emitting QDs at 60°C and 90% RH for different zinc dithiocarbamate salts. ２ 4A-4F show exemplary reliability data (power vs. time) for green- and red-emitting QDs at 50 mW / cm 2 for different mixtures of antioxidants at 50°C and 90% RH. ２ 5A-5D show exemplary reliability data (power versus time) for green- and red-emitting QDs at 50 mW / cm for different mixtures of antioxidants at 50 °C and ambient RH. ２ 1 shows exemplary reliability data (power versus time) for green and red emitting QDs at 50° C. and ambient RH.

[0029] The amount of antioxidant additive in the polystyrene / QD carrier plate and the corresponding optical properties are shown in Table 2. Figures 2A and 2B show that ZnDDT alone is less than ZnDDT + dithiocarbamate; Figures 2C and 2D show that ZnDDT is less than dithiocarbamate; Figures 3A, 3B, 4E, and 4F confirm Table 1; Figures 4A and 4B show that DDT + dithiocarbamate can maintain power (over 90%); and Figures 4C and 4D show that dithiocarbamate alone can maintain power.

[0030]

[0031] Table 3 shows the amounts of antioxidant additives in the polystyrene / QD carrier plates and their corresponding optical properties.

[0032]

[0033] Importantly, ZnDDT can replace commercially available zinc stearate in the antioxidant mixture, resulting in superior stability of QDs under harsh conditions, as shown in Figures 5A-5D and Table 3.

[0034] Zinc dithiocarbamates represent a class of zinc complexes of dithioic acids that are highly effective catalytic peroxide decomposers and photoantioxidants that are also used to inhibit the oxidative degradation of polyolefins (see [1] below). These antioxidants offer high UV and thermal stability, the latter being important under the high-temperature processing conditions of QD-based articles.

[0035] The photoantioxidant activity of zinc dithiocarbamates is affected by their solubility in the polymer matrix (e.g., polystyrene) and their compatibility with other antioxidants in the mixture. As shown in Table 1 and Figures 2A-2D, the highest efficacy was observed for zinc dibutyldithiocarbamate and dibenzyl dibenzyldithiocarbamate, and the lowest efficacy was observed for zinc ethylphenyldithiocarbamate.

[0036] Al-Malaika et al. (see below [2]) showed that the active catalyst for peroxide decomposition is sulfur acid formed during the oxidation of dithiocarbamate salts. ２ It should be noted that the highest antioxidant efficacy of zinc dithiocarbamate salts was observed under the 60°C, 90% RH test conditions. At high flux, high temperature, and high humidity, sulfur acid catalysts are likely generated at the highest rate, leading to efficient protection of QDs from reactive species. In contrast, as shown in Figures 4A-4F, zinc dithiocarbamate without any other zinc salts exhibited only 50 mW / cm ２ , 50°C, ambient RH test conditions provide only moderate protection of QDs.

[0037] Pairing zinc dithiocarbamate with lipophilic zinc salts such as zinc stearate or zinc dodecanethionate provides 50 mW / cm ２ , 50°C, and ambient RH. As shown in Figures 5A-5D and Table 3, the combination of the additive mixture with zinc stearate was particularly potent, resulting in one of the most reliable and highest BFEs and the lowest QD burn-in of all tested samples. The enhanced activity of zinc stearate can be explained based on its good compatibility with basic costabilizers (e.g., melamine) (see [3] below) and its suitability as an ancillary ligand for QDs (see [4] below). These factors may improve the integration of all antioxidant components with QDs.

[0038] Any aspect of the foregoing description of CCTL should not be construed in a limiting sense, as numerous variations, additions, and omissions are contemplated. For example, other thiocarbamate derivatives can be used in place of, for example, zinc dithiocarbamate diamyldithiocarbamate. ２＋ Instead of or Zn ２＋ In addition to various metal cations, Cd ２＋ , Al ３＋ Various other lipophilic salts and / or complexes can be used in place of zinc stearate, zinc laurate, aluminum stearate, etc. CCTLs can also be used with InP and AIGS-based QDs and in differently processed QD-in-polymer matrices, such as extruded and / or laminated matrices.

[0039] For more details, the interested reader is referred to the following references, which are incorporated herein by reference for all purposes: [1] S. Al-Malaika (2003) Oxidative degradation and stabilization of polymers, International Materials Reviews, 48:3, 165-185 [2] S. Al-Malaika (1993) Chapter 5 Antioxidants - Preventive Mechanisms, Editor(s): G. Scott, Atmospheric Oxidation and Antioxidants, Elsevier, 161-224 [3] Synergistic UV absorber combinations / US 7,332,105 B2 [4] P. Reiss (2002) Highly luminescent CdSe / ZnSe core / shell nanocrystals of low size dispersion, Nano Letters 2002, 2, 7, 781-784

[0040] In some examples, the photoluminescent nanocomposite material may further comprise an alkylalkoxysilane and a coordination polymer. The alkylalkoxysilane is an alkoxysilane with a linear or branched alkyl substituent, such as hexyltrimethoxysilane (HTMS). In some cases, the alkylalkoxysilane exhibits a boiling point of >200°C, such as dodecyltrimethoxysilane or dodecyltriethoxysilane. The coordination polymer may be an inorganic or organometallic polymer structure containing a metal cation center linked by a ligand, such as a CCTL, such as ZnDDT or other metal thiolates. The alkylalkoxysilane and the coordination polymer (e.g., a metal thiolate) may form a silanated coordination polymer that may be water-repellent. The presence of the silanated coordination polymer may thereby increase the resistance of the nanostructure to performance degradation by water.

[0041] Selection of the appropriate alkylalkoxysilane offers practical and performance advantages. Some alkylalkoxysilanes are more volatile than others (e.g., hexyltrimethoxysilane has a boiling point of ∼200°C, while the two additional compounds listed above have higher boiling points (dodecyltrimethoxysilane has a boiling point of ∼280°C; dodecyltriethoxysilane has a boiling point of ∼330°C). Because compounding and extrusion of QD thermoplastic plates in polystyrene occurs at ∼220°C, less volatile silanes can offer advantages in yield and efficacy because (1) they are more likely to remain within the QD thermoplastic plates and (2) evaporation into the local atmosphere is reduced.

[0042] In some examples, the photoluminescent nanocomposite material may include a silanated coordination polymer that is the reaction product of an alkylalkoxysilane and a coordination polymer (e.g., a metal thiolate), and in some examples, a silanated coordination polymer that is the reaction product of a linear alkylalkoxysilane and a metal thiolate. In some examples, the silanated coordination polymer may be formed from an alkylalkoxysilane and a metal thiolate in a weight ratio of about 1:5. In some examples, the silanated coordination polymer may be formed from hexyltrimethoxysilane and zinc dodecanethiolate.

[0043] In some examples, the silanated coordination polymer can be the reaction product of an alkylalkoxysilane and a metal thiolate in the presence of a surfactant. In some such examples, the surfactant can be an anionic surfactant that can contain sulfate, sulfonate, phosphate, and / or carboxylate groups. In some specific examples, the anionic surfactant can be an alkyl sulfate, such as ammonium dodecyl sulfate and sodium dodecyl sulfate, or an alkyl ether sulfate, such as sodium laureth sulfate or sodium myreth sulfate. In some specific examples, the anionic surfactant can be sodium dodecyl sulfate. In some specific examples, the anionic surfactant can be a metal carboxylate. In some specific examples, the metal carboxylate can include a lithium salt of a fatty acid. Non-limiting examples of lithium salts of fatty acids include lithium stearate, lithium oleate, and lithium palmitate. The presence of a surfactant during the reaction of an alkylalkoxysilane and a metal thiolate can improve luminance, power retention, and / or wavelength stability over time in some examples.

[0044] The QD photooxidation protection efficacy of a multi-additive antioxidant mixture containing preventative antioxidants such as phosphorus-containing antioxidants (e.g., 3,9-bis(octadecyloxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane), sulfur-containing antioxidants (e.g., zinc dodecanethiolate), and light stabilizers such as hindered amine stabilizers (e.g., N,N'-bis(2,2,6,6-tetramethylpiperidin-4-yl)hexane-1,6-diamine; 2,4,6-trichloro-1,3,5-triazine; 2,4,4-trimethylpentan-2-amine) can be significantly improved by the addition of a basic additive such as 2,4,6-triamino-1,3,5-triazine (melamine). This exemplary compound appears to exhibit synergistic effects with all components of the multifunctional antioxidant. Figure 1B shows the structure of a melamine that can be used as an auxiliary base. Figure 1C shows the structure of an exemplary substituted melamine that can also be used as an auxiliary base. In the illustrated structures, each R can include a hydrogen atom or an alkyl or aryl group. The R groups can be equivalent to each other in some instances and different in other instances. Any, some, or all of the R groups can be selected to enhance the dispersibility of the secondary amine compound in the carrier matrix.

[0045] Melamine can act as a hindered amine stabilizer (e.g., via deactivation of the piperidinyl moiety) or as an antioxidant and / or basic protector of QDs against in situ generated acids that can deactivate the stabilizing function of phosphorus- and / or sulfur-containing antioxidants (e.g., via catalytic hydrolysis of phosphites or sulfides), or can trigger etching of light-emitting semiconductor QDs with subsequent degradation of their optical properties.

[0046] Furthermore, melamine is a strong thermal stabilizer that increases the resistance of both QDs and antioxidants to thermal degradation, which can be a serious problem during QD composition processing (e.g., high-temperature extrusion, molding, spinning, calendaring, coating) and applications (e.g., barrier-less QDEF or QD thermoplastic plates in displays where temperatures near blue light sources (LEDs or mini-LEDs) can approach and exceed 50°C).

[0047] The combination of the above properties of melamine improves the antioxidant behavior of the multi-additive mixture, allowing for a significant reduction in the rate of oxidation-induced degradation under light excitation under humid conditions.

[0048] Figure 6 shows exemplary reliability data (power versus time) for green- and red-emitting QDs under different test conditions. The multi-additive mixture includes 1.5 wt% N,N'-bis(2,2,6,6-tetramethylpiperidin-4-yl)hexane-1,6-diamine; 2,4,6-trichloro-1,3,5-triazine; 2,4,4-trimethylpentan-2-amine; 1.5 wt% zinc dodecanethiolate; 0.5 wt% 3,9-bis(octadecyloxy)-2,4,8,10-tetraoxa-3,9diphosphaspiro[5.5]undecane; 0.2 wt% hexyltrimethoxysilane; and 0.65 wt% melamine. The first row of Figure 6 shows the condition of 16 mW / cm. ２ , 60°C, and 90% relative humidity. The second column shows the conditions: 6 mW / cm ２ , 50°C, and relative humidity of 90%. The third condition is 50 mW / cm ２ , 50°C and ambient relative humidity.

[0049] The antioxidant mixture herein includes at least one auxiliary base. Each auxiliary base can be a Bronsted base or a Lewis base. In some examples, the Bronsted base can be a metal carbonate. In some particular examples, the Bronsted base can be lithium carbonate.

[0050] The auxiliary base may be an aromatic or aliphatic amine, which may be saturated, unsaturated, bridged, cyclic or open-chain, straight-chain or branched, with or without any type of ring. The amine may be primary, secondary, or tertiary. The amine may be polymeric, oligomeric, monomeric, or low molecular weight. In some instances, the auxiliary base may be a Mannich compound, i.e., a product of Mannich condensation. The auxiliary base may be thermally stable using nitrogen-containing heterocyclic and amine-based functional groups.

[0051] The auxiliary base may be a triazine or triazine derivative (including triazine isomers) containing one or more amine-based functional groups. In some examples, the auxiliary base may include an aromatic imine base.

[0052] The auxiliary base may include melamine (2,4,6-triamino-1,3,5-triazine) or a melamine derivative.

[0053] Table 4 shows the amount of antioxidant additives in the polystyrene / QD carrier plates and their corresponding optical properties.

[0054]

[0055] In some examples, photoluminescent nanocomposite materials according to the present disclosure may contain multiple heterogeneous domains dispersed within a carrier matrix. The average size of the heterogeneous domains is not particularly limited, but may range, for example, from tens of nanometers to tens of micrometers. In photoluminescent nanocomposite materials containing heterogeneous domains, at least one photoluminescent nanostructure and at least one stabilizing additive may be distributed together as heterogeneous domains within a carrier matrix, such that the photoluminescent nanostructures are in direct contact with the stabilizing additive. Examples of stabilizing additives include one or more hindered amine stabilizers, one or more alkylalkoxysilanes and coordination polymers, one or more silanated coordination polymers, and one or more secondary antioxidants. All subcombinations of these variations are contemplated. In this manner, photoluminescent nanostructures may be placed in contact with any, some, or all of the agents that stabilize their luminescent performance.

[0056] In some embodiments, the photoluminescent nanostructures may further comprise light-scattering particulates that scatter light at wavelengths absorbed by the nanostructures and / or emitted by the nanostructures. This light-scattering property increases the effective path length in proximity to the photoluminescent nanostructures, thereby increasing the interaction of excitation photons with the nanostructures and increasing down-conversion efficiency. In some such examples, the material comprising the light-scattering particles has a band gap greater than about 3 electron volts (eV). In some examples, the light-scattering particles comprise inorganic materials. Also, in some examples, the light-scattering particles are metal oxides or sulfides, such as silicon dioxide (SiO ２ ), titanium dioxide (TiO ２ ), zinc oxide (ZnO), or zinc sulfide (ZnS).

[0057] In some instances, any, some, or all of the following: secondary antioxidants, HALS, CCTLs, alkylalkoxysilanes, coordination polymers, silanated coordination polymers, surfactants, basic additives, and light-scattering particles, along with the photoluminescent nanostructures themselves, are dispersed in a carrier matrix, or "carrier." In some instances, the carrier comprises a thermoplastic material or a precursor to a thermoplastic material. In some instances, the carrier material comprises polystyrene.

[0058] In some examples, the carrier comprises a liquid, such as a solvent, where the photoluminescent nanocomposite material behaves as a liquid entraining a suspension of solid particles in the liquid. The liquid carrier may be at least partially removed from the composition before or during extrusion. In some examples, the carrier may comprise heptane.

[0059] In some examples, the photoluminescent nanocomposite material is a solid structure comprising any of the photoluminescent nanocomposite materials herein. The solid structure can be formed by processes including extrusion. In some cases, the solid structure is entirely or substantially planar and may be referred to as a plate, layer, or film. In some examples, "substantially planar" indicates that the thickness of the structure is less than about 5%, e.g., less than about 1%, of its width and length. In some examples, "substantially planar" indicates that the thickness of the structure is within about 10% of the average thickness overall, e.g., on average ±5%. Planar structures can have thicknesses ranging from about 0.03 mm to about 3.0 mm, for example.

[0060] In some examples, the photoluminescent nanocomposite material may be a solid, substantially planar structure, which may alternatively be described as a plate, film, layer, etc. In some examples, the solid structure may be formed by mixing the components of the photoluminescent nanocomposite material with a liquid carrier (e.g., a solvent), drying to remove the solvent, and extruding the photoluminescent nanocomposite material. Some variations may include subsequent steps of heating to dry the extruded composition (e.g., solvent removal) and / or curing the components of the photoluminescent nanocomposite material by exposure to light or heat.

[0061] In some instances, no additional barrier film needs to be applied to the photoluminescent nanocomposite material because the photoluminescent nanostructures are protected from moisture and / or air by the secondary antioxidant and / or auxiliary base.

[0062] In the following examples and comparative examples, the following dry powders were mixed: polystyrene, SiO ２ The powder mixture consisted of 100% fluororesin (light-scattering particles), zinc dodecanethiol, hexyltrimethoxysilane, Chimassorb® 944 (a product of BASF, Ludwigshafen, Germany), and, if present, antioxidants. Quantum dots (photoluminescent nanostructures) suspended in heptane were then added to the powder mixture, and the solvent was evaporated. The resulting mixture was extruded to form a plate, which was then used for testing.

[0063] Chimassorb® 944 is a HALS, poly([[6-[(1,1,3,3-tetramethylbutyl)amino]-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidinyl)imino]-1,6 hexanediyl[(2,2,6,6-tetramethyl-4-piperidinyl)imino]]).

[0064] Comparative Example 1 In this comparative example, no antioxidant was included.

[0065] Example 1 In this example, 0.5 wt% DSPP was added to the powder mixture. The backlight film efficiency (BFE) of the plate of Example 1 was 62.1%, while the BFE of the plate of Comparative Example 1 was 57.5%. Note that BFE is a measure of luminance, which is the percentage of blue photons (wavelengths of 380-484 nm) absorbed by the plate that are emitted as red or green photons (wavelengths of 484-780 nm) measured as a single-pass measurement by a spectrometer on a QD-containing plate with blue light excitation excited by a diffuse 450 nm LED light source.

[0066] In these comparative tests, a series of primary antioxidants were included in the extrusion composition. Figure 7 shows the green QD power retention for Comparative Examples 2A-2D and Example 1. Under the test conditions (flux of 6 mW / cm at 50°C and 90% relative humidity), ２ ) shows that the addition of DSPP significantly improved power retention compared to the primary antioxidant.

[0067] Figure 7 shows the effect of adding DSPP to comparative compositions, each prepared as outlined above.

[0068] Table 5 shows performance data for the luminescent nanostructures in the compositions of the examples and comparative examples.

[0069]

[0070] Table 5 and Figures 8A-9B show the results for a 6 mW / cm ２ The fourth composition has a higher backlight film efficiency than the other compositions.

[0071] Figures 8A and 8B show that the fourth composition from Table 5 has better green QD power retention and significant red QD power retention.

[0072] 9A and 9B show that the fourth composition from Table 5 has significant emission wavelength stability for both green- and red-emitting QDs.

[0073] In some examples, photoluminescent nanostructures, such as quantum dots, can be disposed within a coating that at least partially surrounds support particles. The coating, for example, at least partially protects the nanostructures from moisture and / or air, which may otherwise adversely affect the structural and / or optical properties of the nanostructures. The support particles can also at least partially protect the nanostructures from environmental factors, such as moisture and / or air. In this manner, the coating and / or support particles can be considered to function as a barrier material or layer. Thus, a separate barrier film (e.g., in a so-called quantum dot-enhanced film (QDEF film)) may not be required to protect the photoluminescent nanostructures from moisture and / or air. Furthermore, the coating and / or support particles can also function to space the photoluminescent nanostructures apart, reducing aggregation and quenching of the optical properties of the photoluminescent nanostructures.

[0074] In another example, one or more photoluminescent nanostructures may be disposed within a material selected from at least one material selected from the group consisting of alkoxysilanes with linear or branched alkyl substituents, alkoxysilanes with at least one phenyl, mercapto, or amino substituent, alkoxysilanes with at least one crosslinkable reactive functional group, alkoxysilanes with at least one halide functional group, tetraalkoxysilanes, alkali, alkaline earth, or transition metal silicates, or Group (IV) or transition metal alkoxides, and CCTL or other metal thiolates or carboxylates, fluoropolymers, butylene / isoprene copolymers, styrene-ethylene / butylene-styrene copolymers, styrene-ethylene / propylene-styrene copolymers, polyvinylidene dichloride, or high-boiling waxes. The material may, for example, provide protection from moisture and / or air that may otherwise adversely affect the structural and / or optical properties of the photoluminescent nanostructures. The material may also function to space photoluminescent nanostructures (each as part of a structure and / or an adjacent structure) from one another to reduce aggregation and quenching of the optical properties of the nanostructures.

[0075] In some photoluminescent nanocomposite materials, the coating at least partially surrounds the support particle, and in some instances, completely surrounds the support particle. One such example structure 203 is now described with reference to Figure 10. Support particle 211 is surrounded by coating 213 having photoluminescent nanostructures 215 therein.

[0076] The support particles may be particles or bodies that support the coating and the photoluminescent nanostructures within the coating. Thus, the support particles themselves may not be luminescent, but may contain the photoluminescent nanostructures. In some instances, the support particles may be approximately spherical (e.g., spherical within manufacturing tolerances). The coating may be, for example, a material that coats or covers the support particles as a layer. Thus, the structure may have a core-shell structure, with the core corresponding to the support particle and the shell corresponding to the coating. The coating may be in direct contact with the support particle, or there may be one or more other layers between the support particle and the coating. In some instances, the coating is approximately uniform in thickness, and the resulting structure is approximately spherical. In some instances, the coating is not uniform in thickness, but in such instances, the resulting structure may be approximately spherical due to the relatively thin coating and the approximately spherical support particles. This can aid in the dispersion and / or mixing of the structures in a carrier material (described below) for use in a film or other element of a display device. In other instances, the support particles and / or structures may be non-spherical, e.g., cubic.

[0077] By appropriate concentration and dispersion of photoluminescent nanostructures within the coating, the spacing between photoluminescent nanostructures within the coating can be set according to desired light absorption and / or emission properties.

[0078] The support particles 211 also determine, for example, the spacing between the photoluminescent nanostructures within opposing portions of the coating. Multiple structures may also tend to reduce the concentration of the photoluminescent nanostructures due to incomplete packing of larger structures compared to freely dispersed photoluminescent nanostructures (which may tend to be more densely agglomerated). Additionally, without being bound by theory, it is believed that the presence of the support particles further limits the exposure of the photoluminescent nanostructures to moisture and / or air, as the coating may be exposed to moisture / air on the exterior surface but not the interior surface.

[0079] In some examples, the material, shape, and / or size of the support particles can be selected to provide desired optical functionality. For example, the support particles may comprise a light-scattering material, i.e., a material that scatters (e.g., substantially and / or completely within manufacturing tolerances) light at wavelengths absorbed and / or emitted by the photoluminescent nanostructures. As discussed above, this light-scattering property increases the effective path length in proximity to the photoluminescent nanostructures, thereby increasing the interaction of excitation photons with the photoluminescent nanostructures and increasing downconversion efficiency. In some such examples, the material comprising the support particles has a bandgap greater than about 3 electron volts (eV). With a bandgap in this range, the support particles do not significantly absorb relatively short-wavelength (e.g., blue) excitations, but function primarily as scattering particles. The support particles may have a maximum dimension 217 (e.g., diameter) of about 100 nanometers (nm) to about 10 micrometers (μm), e.g., less than about 5 μm, 3 μm, 2 μm, 1.8 μm, or 1.5 μm. The soft upper size limit allows for efficient scattering of relatively short wavelength light, resulting in optical uniformity in thin films. In some examples, the support particles are solid and / or solid phase. In some examples, the support particles comprise inorganic materials. Also, in some examples, the support particles are metal oxides or sulfides, e.g., silicon dioxide (SiO ２ ), titanium dioxide (TiO ２ ), zinc oxide (ZnO), or zinc sulfide (ZnS).

[0080] Coating 213 may be formed from a material that is optically transparent to at least one or more wavelengths of the input (excitation) light and output (emission) light, in the case of photoluminescent nanostructures.

[0081] In some examples, the coating may comprise or be derived from at least one material selected from the group consisting of CCTL or other metal thiolates or carboxylates; fluoropolymers; butylene / isoprene copolymers; styrene-ethylene / butylene-styrene copolymers; styrene-ethylene / propylene-styrene copolymers; polyvinylidene dichloride; or high-boiling waxes (e.g., waxes having boiling points above about 100°C, 150°C, 200°C, or 250°C). Extrusion and / or film-making processes are typically performed at relatively high temperatures, making relatively high-boiling waxes useful. Such coating materials at least partially repel water and can therefore be considered hydrophobic. In some examples, the coating may comprise a coordination polymer derived from CCTL or other metal thiolates or carboxylates.

[0082] In some examples, the coating may be formed from at least one material selected from the group consisting of: (a) an alkoxysilane having a linear or branched alkyl substituent; an alkoxysilane having at least one phenyl, mercapto, or amino substituent; an alkoxysilane having at least one reactive functional group; an alkoxysilane having at least one halide functional group; a tetrafunctional alkoxysilane; an alkali, alkaline earth, or transition metal silicate; or a Group (IV) or transition metal alkoxide; and / or (b) CCTL or other metal thiolate or carboxylate; a fluoropolymer; a butylene / isoprene copolymer; a styrene-ethylene / butylene-styrene copolymer; a styrene-ethylene / propylene-styrene copolymer; polyvinylidene dichloride or a high-boiling wax. Such coating materials are at least partially water-repellent and therefore can be considered hydrophobic.

[0083] In some instances, the coating may be formed from at least one material selected from the list of (a) above but not (b), or from the list of (b) above but not (a). In some instances, the coating may be formed from at least one material selected from the list of (a) above and at least one material selected from the list of paragraph (b), and possibly a material selected from another list.

[0084] An example of an alkoxysilane having a linear or branched alkyl substituent is hexyltrimethoxysilane. Examples of alkoxysilanes having at least one phenyl, mercapto, or amino substituent include phenyltrimethoxysilane, (3-mercaptopropyl)trimethoxysilane, and 3-aminopropyltrimethoxysilane. In some cases, the crosslinkable reactive functional group is a group that can react in a resin or monomer matrix to crosslink via a covalent bond to the surrounding organic medium. In some cases, the crosslinkable reactive functional group is an unsaturated end group, such as a terminal alkene, acrylate, or methacrylate. Examples of alkoxysilanes having at least one crosslinkable reactive functional group include vinyltrimethoxysilane, 3-(trimethoxysilyl)propyl acrylate, and 3(trimethoxysilyl)propyl methacrylate. An example of an alkoxysilane having at least one halide functional group is chlorotrimethoxysilane. Examples of tetraalkoxysilanes include tetramethyl orthosilicate and tetraethyl orthosilicate.

[0085] In some instances, CCTL or other metal thiolates or carboxylates, such as zinc dodecanethiolate, can form coordination polymers. In some instances, the fluoropolymer is a fluorocarbon polymer that is fully or partially fluorinated along the carbon backbone, such as PTFE.

[0086] In some examples, the weight ratio (a:b) of the components recited in lists (a) and (b) above may range from about 1:50 to about 2:1. In some examples, the weight ratio (a:b) may range from about 1:3 to about 1:7, preferably from 1:4 to about 1:6. In some examples, the weight ratio (a:b) may be about 1:5.

[0087] In some instances, the coating comprises a silanated coordination polymer, suitably a silanated coordination polymer that is the reaction product of an alkylalkoxysilane and a metal thiolate, and in some instances a silanated coordination polymer that is the reaction product of a linear alkylalkoxysilane and a metal thiolate. In some instances, the coating may be formed from an alkylalkoxysilane and a metal thiolate in a weight ratio of about 1:5. In some instances, the coating may be formed from hexyltrimethoxysilane and zinc dodecanethiolate.

[0088] In some examples, the silanized coordination polymer can be the reaction product of an alkylalkoxysilane and a metal thiolate in the presence of a surfactant. In some such examples, the surfactant can be an anionic surfactant that can contain sulfate, sulfonate, phosphate, and / or carboxylate groups. In some specific examples, the anionic surfactant can be an alkyl sulfate such as ammonium dodecyl sulfate and sodium dodecyl sulfate, or an alkyl ether sulfate such as sodium laureth sulfate and sodium myreth sulfate. In some specific examples, the anionic surfactant can be sodium dodecyl sulfate. The presence of a surfactant during the reaction of an alkylalkoxysilane and a metal thiolate can improve the luminance, luminous power retention, and / or luminous wavelength stability over time in some examples.

[0089] In some examples, the thickness 221 of the coating applied to the support particle is from about 10 nm to about 500 nm, or from about 10 nm to about 300 nm, or about 200 nm. Thickness may refer to the distance measured perpendicular to the surface of the support particle from the point of contact of the coating with the support particle to the outer surface of the coating.

[0090] In some examples, the weight ratio of photoluminescent nanostructures 215 to coating material 213 ranges from about 1:1 to about 1:30. The loading of the photoluminescent nanostructures can be selected to achieve a desired emission intensity, which is also affected by the quantum efficiency of the photoluminescent nanostructures. In some examples, the weight ratio of support particles to coating, including the nanostructures in the coating, ranges from about 1:1 to 1:2, and in some examples can be about 2:3.

[0091] In some examples, the largest dimension of the structure 203, e.g., diameter 219, is at most about 10 μm, at most about 5 μm, 3 μm, or 2 μm. Structures having a largest dimension of less than about 2 μm can be more easily incorporated into the film while maintaining the optical uniformity of the film.

[0092] In some examples, the photoluminescent nanostructures 215 are photoluminescent, i.e., incident light excites the photoluminescent nanostructures, which then emit light at longer wavelengths. In some examples, the photoluminescent nanostructures are quantum dots, and in some examples, zinc quantum dots are selected from the group consisting of zinc telluride selenide (ZnTeSe), zinc telluride (ZnTe), zinc selenide (ZnSe), zinc sulfide (ZnS), indium phosphide (InP), indium gallium phosphide (InGaP), indium arsenide (InAs), indium zinc phosphide (InZnP), indium arsenide phosphide (InAsP), indium gallium arsenide phosphide (InGaAsP), and the like. The quantum dots may include at least one of silver indium gallium sulfide (AgInGaS or AIGS), copper indium sulfide (CuInS or CIS), copper indium gallium selenide (CuInGaSe or CIGS), cadmium selenide (CdSe), cadmium sulfide (CdS), cadmium telluride (CdTe), cadmium selenide telluride (CdSeTe), cadmium zinc selenide (CdZnSe), molybdenum sulfide (MoS), or alloys thereof. The quantum dots may have a core-shell structure, as described below. Some quantum dots may be configured to absorb incident blue light and emit red or green light.

[0093] In some other examples, structures according to the present disclosure include a material having one or more photoluminescent nanostructures therein. This type of structure 303 will now be described with reference to FIG. 11 . The structure 303 has a material 313 having multiple photoluminescent nanostructures 315 embedded therein. In other examples, there may be only one photoluminescent nanostructure 315 per structure 303 in the material. In some examples, the material may be referred to as a barrier material. In such examples without support particles, the structure may be, for example, approximately spherical. In some examples, the structure may be a film of a material having multiple photoluminescent nanostructures therein.

[0094] In examples that do not include support particles, the material may be formed from: (a) at least one material selected from the group consisting of an alkoxysilane with linear or branched alkyl substituents; an alkoxysilane with at least one phenyl, mercapto, or amino substituent; an alkoxysilane with at least one crosslinkable reactive functional group; an alkoxysilane with at least one halide functional group; a tetraalkoxysilane; an alkali, alkaline earth, or transition metal silicate; or a Group (IV) or transition metal alkoxide; and (b) at least one material selected from the group consisting of CCTL or other metal thiolates or carboxylates; a fluoropolymer; a butylene / isoprene copolymer; a styrene ethylene / butylene styrene copolymer; a styrene ethylene / propylene styrene copolymer; a polyvinylidene dichloride; or a high boiling point wax.

[0095] In some examples, CCTL or other metal thiolates or carboxylates can form coordination polymers such as zinc dodecanethiolate. Thus, the "coordination polymer" herein can optionally include a metal thiolate. In some examples, the fluoropolymer is a fluorocarbon polymer that is fully or partially fluorinated along the carbon backbone, such as PTFE. More generally, at least one of (i) an alkylalkoxysilane and a coordination polymer, or (ii) a silanated coordination polymer, can be referred to as a "stabilizing polymeric additive," and is one of various types of stabilizing additives that can be used in accordance with the present disclosure.

[0096] In some examples, the weight ratio (a:b) of the materials listed above under (a) and (b), excluding the support particles, may range from about 1:50 to about 2:1. In some examples, the weight ratio (a:b) may range from about 1:3 to about 1:7, or from 1:4 to about 1:6. In some examples, the weight ratio (a:b) may be about 1:5.

[0097] In some instances, the material comprises a silanated coordination polymer, preferably a reaction product of an alkylalkoxysilane and a metal thiolate, and in some instances, a reaction product of a linear alkylalkoxysilane and a metal thiolate. In some instances, the coating may be formed by forming an alkylalkoxysilane and a metal thiolate in a weight ratio of about 1:5. In some instances, the coating may be formed from hexyltrimethoxysilane and ZnDDT.

[0098] In some examples, the silanized coordination polymer can be the reaction product of an alkylalkoxysilane and a metal thiolate in the presence of a surfactant. In some such examples, the surfactant can be an anionic surfactant that can contain sulfate, sulfonate, phosphate, and / or carboxylate groups. In some specific examples, the anionic surfactant can be an alkyl sulfate such as ammonium dodecyl sulfate and sodium dodecyl sulfate, or an alkyl ether sulfate such as sodium laureth sulfate and sodium myreth sulfate. In some specific examples, the anionic surfactant can be sodium dodecyl sulfate. The presence of a surfactant during the reaction of an alkylalkoxysilane and a metal thiolate can improve the luminance, luminous power retention, and / or luminous wavelength stability over time in some examples.

[0099] Next, methods for making the above-described structures are provided, followed by a description of other compositions, films, and devices that include the structures.

[0100] The structure including the support particles can be formed by (a) mixing photoluminescent nanostructures with at least one of a coating material or one or more precursors for a coating material to form a first mixture; (b) contacting the first mixture with the support particles; and (c) forming a coating from the first mixture, wherein the coating at least partially surrounds the support particles and the photoluminescent nanostructures are within the coating.

[0101] In some examples, the method includes mixing the photoluminescent nanostructures with a first precursor of the coating to form a first mixture, mixing the support particles and a second precursor of the coating to form a second mixture, and combining the first and second mixtures. In some such examples, the first mixture can be provided in a solvent, such as a non-polar organic solvent (e.g., toluene, chloroform), which is removed after the two mixtures are combined.

[0102] In some methods, if support particles are present in the fabricated structure, a catalyst or binder can be added to the mixture to promote adhesion of the coating to the support particles. In some examples, this can be tetrabutylammonium chloride or a similar binder. Other suitable materials include (1) reactive silanes, (2) polyfunctional molecules with carboxyl or phosphonic acid, mercapto, silyl, amino, allyl, or acrylate moieties, and (3) acid / base catalysts including quaternary ammonium salts and hydroxides. Bonding can be via van der Waals-type interactions between the QD ligand, the functionalized scattering medium, and binder molecules containing alkyl chain functional groups. Alternatively, covalent bonds can be formed between these same groups (ligand, surface functionalization, or binder), preferably via a thermally activated "click" type reaction, such as a thiol-ene or amine / anhydride.

[0103] The support particle-free structures can be formed by mixing the photoluminescent nanostructures with the material or one or more precursors of the material. In some examples, the luminescent nanostructures can be introduced into a solvent from which they are subsequently removed. In some examples, the method can include mixing the photoluminescent nanostructures with a first precursor for the material to form a first mixture, and then mixing with a second precursor for the material. In some such examples, the first mixture can be provided in a solvent, such as a non-polar organic solvent, from which the second precursor for the material is added and then removed.

[0104] Photoluminescent nanocomposite materials according to the present disclosure can include a plurality of structures within a carrier material, each structure being as described above. In some examples, the carrier material is a thermoplastic material or a precursor to a thermoplastic material. In some examples, the thermoplastic material includes polystyrene. In some examples, the carrier material is a liquid. In other examples, the photoluminescent nanocomposite material is a film having a solid carrier material, and can have a thickness ranging from about 0.03 millimeters (mm) to about 3.0 mm, from about 0.3 to about 3.0 mm, or from about 0.5 mm to 1.5 mm, or about 1.0 mm.

[0105] Referring now to FIG. 12 , a film 100 including a plurality of structures 103 according to an embodiment of the present disclosure will be described. The structures 103 are supported by a carrier material 101. For example, the carrier material may be a material such as a resin, thermoplastic, or powder that surrounds or encapsulates the structures and supports them in doing so. The structures 103 include photoluminescent nanostructures configured to absorb light 107 and emit light 109. The structures 103 may be, for example, of the type shown in FIG. 10 or FIG. 11 , or in some instances, a mixture of these two structure types. This film may be referred to herein as a quantum dot-enhanced film (QDEF).

[0106] The structures and compositions herein provide, for example, protection from moisture and / or air, which may otherwise adversely affect the structural and / or optical properties of the actuating nanostructures. This protection is available throughout film handling and manufacturing. In some examples, the structures can be incorporated into films including cured resin substrates. In some examples, the structures can be incorporated into films 100 formed from thermoplastic substrates 101, such as polystyrene. Other suitable thermoplastics include polymethyl methacrylate, polyethylene terephthalate, polypropylene, polycarbonate, polyimide, and polyvinyl chloride. Such thermoplastic materials may be porous, lightweight, and / or extrudable, and may be usable with the presence of a barrier or coating. Thus, the structures offer the potential for incorporation into films with less expensive substrate materials, improved film properties (e.g., lighter weight or thinner thickness), and / or via simplified manufacturing processes. This, in turn, can simplify the manufacture of devices including the structure (e.g., display devices), reduce the display stack size in such devices, and / or, if the support particles are light scattering, eliminate the need for a separate light-scattering material incorporated into the membrane or other element of the device. In some instances, no protective or barrier layer (which would reduce exposure of the carrier to oxygen / moisture) needs to be included in the device, i.e., the film is a so-called barrier-less QDEF or xQDEF.

[0107] The film 100 of FIG. 12 can have a thickness 105 in some examples ranging from about 0.03 mm to about 3.0 mm, from about 0.3 to about 3.0 mm, or from about 0.5 mm to about 1.5 mm, preferably about 1 mm.

[0108] The composition in which the structure is in a liquid carrier material can be made by mixing the structure with a liquid carrier.In some examples, the method for making the film containing such a structure comprises at least one of the following: (a) extruding the composition comprising a plurality of any of the structures in the examples herein or at least one of the precursors of the structure into a liquid carrier material; (b) forcing the composition comprising a plurality of any of the structures in the examples herein or at least one of the precursors of the structure into a liquid carrier material; Or (c) forming a film from the composition comprising a plurality of any of the structures in the examples herein or at least one of the precursors of the structure into a liquid carrier material.

[0109] In some such examples, the liquid carrier material can form the solid carrier material of the film, for example, as a molten carrier material that hardens or as a liquid carrier material that hardens to form a solid. In some examples, the liquid carrier material can be a solvent or other liquid that is removed in forming the solid film, and thus the extruded composition can include additional solid carrier material to provide structural support when the solvent is removed. In some examples, the liquid carrier material can include material that forms the solid carrier material and material that is removed in forming the solid film.

[0110] In some examples, the method can include (a) mixing the structure with a carrier material, and (b) extruding or pressing the resulting mixture.

[0111] In some exemplary methods, structures are fabricated prior to incorporation into the film. In the following discussion, specific materials are referenced; however, those skilled in the art will understand that other materials presented as alternatives in the preceding disclosures may be used instead of those identified below. Assembly of components can be achieved in a controllable manner through evaporation- and / or precipitation-induced deposition of QDs / zinc thiolate onto alkoxysilane / light-scattering particles ( FIG. 12 ). The method includes: (a) mixing colloidal luminescent QDs and zinc thiolate in a nonpolar organic solvent (e.g., toluene, chloroform) to form a homogeneous QD / zinc thiolate system (Mixture I); (b) mixing alkoxysilane and light-scattering particles in a nonpolar / polar organic solvent to form a heterogeneous alkoxysilane / light-scattering particle system (Mixture II); and (c) assembling multiple components into hydrophobic beads by combining Mixture I and Mixture II and subsequently depositing the QDs and zinc thiolate onto the alkoxysilane / light-scattering particles by solvent evaporation or controlled diffusion (precipitation) of a nonsolvent.

[0112] In other examples, the structures are synthesized during incorporation into a film containing the structures. In some examples, the method includes (a) combining photoluminescent nanostructures with one or more precursors for the coating to form a first mixture, (b) combining one or more precursors for the coating, support particles, and a carrier material into the first mixture to form a second mixture, and (c) extruding or pressing the second mixture to form a film.

[0113] While specific materials are referenced in the following examples, those skilled in the art will understand that other materials presented as alternatives in the preceding disclosure may be used in place of those identified below. Assembly of the components is achieved in a controllable manner via evaporation- and / or precipitation-induced deposition of QDs / zinc thionate onto alkoxysilane / light-scattering particles ( FIG. 12 ). The method includes (a) mixing colloidal luminescent QDs and alkoxysilane in a nonpolar organic solvent (e.g., toluene, chloroform) to form a homogeneous system of QDs / alkoxysilane (Mixture I); (b) mixing zinc thiophosphate and a thermoplastic material (e.g., polystyrene beads <5 mm in diameter) and light-scattering particles into Mixture I (Mixture II); and (c) extruding Mixture II to form a film together with solvent evaporation, forming the structures described herein embedded in the thermoplastic film.

[0114] In some examples, a method of making a film containing structures as described herein without support particles includes (a) mixing photoluminescent nanostructures and a material, or one or more precursors for the material, to form a first mixture; (b) mixing a carrier material and one or more precursors for the material with the first mixture; and (c) extruding or pressing the resulting mixture. In some such examples, the first mixture may be provided in a solvent, which is removed after the extrusion or pressing step.

[0115] Example 3 Example 3 is a control example included for comparative purposes. Red and green emitting quantum dots (QDs) were dissolved in a non-polar organic solvent and combined with polystyrene thermoplastic beads (<5 mm) and a silicone scattering medium (TOSPEARL 120 or ETERPEARL DF10A0). The QD / silicone scatterer / polystyrene mixture was then compounded in a twin-screw compounder at 200-220°C. After compounding, the mixture was pressed to form a 1.5 mm thick film.

[0116] In Examples 4-8, additional additive components were included in the QD / polystyrene films to modify the composition and morphology of the environment surrounding the QDs, thereby affecting QD power retention (operational lifetime) under both operational and accelerated stress testing conditions. These additives can be added to the QDs, the polystyrene, or both prior to compounding and extrusion, as described below.

[0117] Example 4: The same procedure was followed as described in Example 3. However, a linear alkylalkoxysilane (e.g., hexyltrimethoxysilane) was added to the QD stock solution before mixing with the polystyrene. The silane was added at a concentration of 0.1-1.0 wt % relative to the mass of the polystyrene.

[0118] Example 5: The same procedure was followed as described in Example 4. However, a metal thiolate (e.g., zinc dodecanethiolate) was added to the QD / polystyrene mixture prior to compounding / extrusion. The metal thiolate was added at a concentration of 0.5-5.0 wt % relative to the mass of polystyrene.

[0119] Example 6 The same procedure was followed as described in Example 3. However, a metal thiolate (e.g., zinc dodecanethiolate) was mixed with the QD / polystyrene mixture prior to compounding / extrusion. The metal thiolate was added at a concentration of 0.5-5.0 wt % relative to the mass of polystyrene.

[0120] Example 7: The same procedure as described in Example 6 was followed. However, a binder / catalyst (e.g., tetrabutylammonium chloride) was combined with the QD / polystyrene mixture prior to compounding / extrusion. The binder / catalyst promotes adhesion of the QD / hydrophobic medium to the surface of the silicone scattering medium and was added at a concentration of 0.05-1.0 wt % relative to the mass of the polystyrene.

[0121] Example 8: The same procedure as described in Example 7 was followed. However, a linear alkylalkoxysilane (e.g., hexyltrimethoxysilane) was added to the QD stock solution before mixing with the polystyrene. The silane was added at a concentration of 0.1-1.0 wt % relative to the mass of the polystyrene.

[0122] Stress conditions (6 milliwatts per square centimeter (mW / cm)) at 450 nm, 50°C and 90% relative humidity (RH) ２ ) excitation flux) over time is shown in Figure 13A for green-emitting QDs and Figure 13B for red-emitting QDs.

[0123] Although the power retention of Example 4 is less than the control (Example 3), the structure of Example 4 reduces aggregation of the photoluminescent nanostructures. It can be seen that the power retention of Examples 5-8 is improved compared to the control. Example 8 provides better performance.

[0124] Examples 9-11 In Examples 9-11, the procedure of Example 5 was followed. However, in Examples 10 and 11, sodium dodecyl sulfate (a surfactant) was added to the QD stock solution before mixing with the polystyrene.

[0125] In Table 6, ZnDDT = zinc dodecanethiophosphate; HTMS = hexyltrimethoxysilane; SDS = sodium dodecyl sulfate; wt% is the percentage given relative to the mass of polystyrene; BFE (film brightness) is the fraction of blue photons (wavelengths 380-484 nm) absorbed by the film and emitted as red or green photons (wavelengths 484-700 nm), measured by a single pass spectrometer measurement of the QD-containing film with blue light excitation from a diffuse 450 nm LED source.

[0126]

[0127] The luminescence brightness of the resulting film is improved by including a surfactant in the formation of the silanated coordination polymer on the support particles.

[0128] The stress conditions (6 mW / cm at 450 nm, 50 °C and 90% RH) are shown in Figures 14A and 14B for green-emitting QDs and in Figures 14C and 14D for red-emitting QDs. ２ 1 shows the performance retention and stability of the emission wavelength (PWL) over time under different excitation fluxes.

[0129] In some examples, a device includes such a composition, e.g., a film or a plurality of structures within a carrier material. Such a device may include a light source configured to emit light of one or more wavelengths absorbed by the photoluminescent nanostructures. In some examples, a filter array includes a red light filter for transmitting red light, a green light filter for transmitting green light, a blue light filter for transmitting blue light, and a light valve array. In other such examples, the light source is a light-emitting diode (LED) including the composition or film, e.g., a layer (e.g., a top layer) of the LEDs arranged to receive light generated by the LEDs and forward output light from the photoluminescent nanostructures. In this manner, each light source may be comprised of a composition or film. Another device, each light source having a corresponding film or composition described herein, is an array or plurality of compositions or films, each arranged to receive light emitted from a respective light source of the plurality of light sources. Such a plurality or array may, for example, be provided as a separate layer from the light sources and inkjet printed.

[0130] In some examples, a device includes a planar structure (e.g., a plate, film, or layer) formed from the aforementioned photoluminescent nanocomposite material, e.g., a photoluminescent nanocomposite material. Such a device may include a light source configured to emit light at one or more wavelengths absorbed by the photoluminescent nanostructures. In some examples, a filter array includes a red light filter for transmitting red light, a green light filter for transmitting green light, a blue light filter for transmitting blue light, and a light valve array. In other such examples, the light source is an LED including the composition or film, e.g., as a layer (e.g., a top layer) of the LEDs arranged to receive light generated by the LEDs and forward output light from the photoluminescent nanostructures. In this manner, each light source may be comprised of a composition or film. Another device, where each light source has a corresponding film or composition, is, for example, an array or plurality of compositions or films arranged to receive light emitted from a respective one of a plurality of light sources. Such a plurality or array may, for example, be provided as a separate layer from the light sources and inkjet printed. Further details of such devices are described in more detail below.

[0131] 15A and 15B, a device consonant according to the present disclosure will now be described. These figures illustrate aspects of an exemplary display device 402 having functional elements configured to generate and output images. Several such functional elements are stacked and collectively referred to as a display stack 404. The display stack 404 includes, for example, a light source 410 configured to emit light 407 (e.g., an LED or organic LED (OLED) backlight), a light valve array 414 (e.g., a liquid crystal display (LCD) panel) for modulating the amount of light received from the light source, and a filter array 416 (e.g., a color filter array such as a red, green, and blue subpixel filter array) for determining the color of light output by the display device 402 (e.g., by each subpixel region of the device). An example plate 400 may be positioned between the light source 410 and the light valve array 414 (as shown in FIG. 15A), or between the light valve array 414 and the filter array 416 (e.g., as shown in FIG. 15B).

[0132] The display device 402 has a light source 410 arranged to provide, for example, a backlit or edge-lit display device. The light source may be, for example, at least one of an LED, an LED array, an organic LED (OLED), an OLED array, a laser, a laser array, or a lamp. The light source may be configured to illuminate multiple pixels of the display device, or there may be multiple light sources each illuminating a single pixel. A pixel may be, for example, a subpixel or pixel of a display device. A display device typically comprises multiple picture elements that are independently controllable to display an image. The pixels are arranged according to a pattern, for example, as an array, matrix, or grid, as will be understood by those skilled in the art. A display device capable of displaying color images typically has multiple pixels, each pixel comprising multiple subpixels; for example, a pixel comprises a red (R), a green (G), and a blue (B) subpixel that together function as an RGB pixel. There may be an additional, independently controllable subpixel, for example, a white (W) subpixel, to provide an RGBW pixel.

[0133] In addition to such a light source, the display device includes a light modulator configured to modulate the light emitted by the light source to display an image. The light modulator has an array of light modulator regions that modulate the light. Each light modulator region corresponds to a respective pixel of the display device. Thus, for example, when looking at the viewing side of the display device to display an image to a user's eye, the perimeter of one light modulator region determines the extent of one pixel. The light source or light guide has an area that is covered by the array of light modulator regions, so that each light modulator region can be illuminated by the light source. The light valve array 414 described above is an example of such a light modulator.

[0134] A display device control system (not shown) is configured to control the array of light modulator regions through which the display device outputs images. Each light modulator region is independently controllable to modulate, for each pixel, the amount of light transmitted through the modulator region toward the viewer. Thus, one light modulator region can be switched to transmit less light (a darker state) than another light modulator region (a brighter state), so that with appropriate light modulation across the array of light modulator regions (and thus pixels), the display device can display a desired image.

[0135] As those skilled in the art will appreciate, one type of light modulator uses liquid crystal (LC) molecules for light modulation. By applying an electric field of appropriate magnitude to the electrodes in the light modulator region, the orientation of the LC molecules can be changed to modulate the light output by each pixel and display an image on the viewer side. An LC-type light modulator has a polarizing layer that linearly polarizes the light input to the light modulator. The polarizing layer is on a substrate (e.g., glass). On the substrate is a circuit layer connected to an array of electrodes (e.g., indium tin oxide (ITO)), each of which is electrically insulated from the others and has an area that determines the shape and size of each pixel. On the electrodes is a layer containing LC molecules, whose LC molecules and their density in the layer are selected to provide the required rotation of linearly polarized light depending on the magnitude of the applied electric field. An alignment layer is in contact with the layer containing LC molecules and orients the LC molecules in contact with the alignment layer in a specific orientation. Another linear polarizer layer is used to polarize the light exiting the light modulator, which is oriented, for example, to linearly polarize the light in a direction perpendicular to the polarizer layer. Above the other linear polarizer layer is a substrate (e.g., glass).An electrode, sometimes called a common electrode, covers two or more (e.g., all) pixels.

[0136] Each pixel also includes a color filter between the alignment layer and the separate linear polarizer layer in these examples. By appropriate selection of the color filters for each pixel, an RGB pixel (of three subpixels) can be created using a red filter that transmits red light, e.g., at a wavelength of 630 nm, a green filter that transmits green light, e.g., at a wavelength of 532 nm, and a blue filter that transmits blue light, e.g., at a wavelength of 467 nm. Such an array of color filters is one example of the filter array referred to above.

[0137] For example, a display device may have a display stack of functional elements including a light source, a QDEF, and a filter array. In these examples, there may also be a light modulator, and starting from the bottom of the stack, there may be a substrate (e.g., glass), a light source circuit layer on the substrate, and a plurality of LEDs as light sources connected to the circuit layer. In the example of a backlight, a plurality of LEDs may be configured and arranged to illuminate the light modulator, for example, as an array of LEDs overlaid by the light modulator.

[0138] The density and positioning of the LEDs depends at least in part on the shape and size of the display's pixels, but also on the illumination characteristics of each LED and any layers, such as diffusers or reflectors for transmitting light from the LEDs to the light modulator. In some such examples, each LED of a plurality of LEDs in an illumination device is configured to illuminate multiple pixels (e.g., 50-100 or even thousands) of the display device. Each of the multiple pixels can be considered a zone having a so-called mini-LED configuration, and in some examples, each zone is independently controllable compared to the other zones. Switching different zones differently can improve contrast, for example, by turning off one zone to provide a darker black, and is sometimes referred to as "local dimming."

[0139] In other edge-lit examples, instead of an array of LEDs, there is a light guide overlaid with a light modulator, and at least one of the LEDs is positioned along at least a portion of the periphery of the light guide to illuminate the light modulator through the light guide. In some such or other examples, there is a light diffuser overlaid with the light modulator.

[0140] Between the LEDs and the light modulator may be one or more layers, such as a diffuser to distribute the light from the LEDs more evenly across the light modulator, and / or an alignment layer (e.g., a so-called brightness enhancement film (BEF)) that uses, for example, prisms to align the light from the LEDs with each pixel. In some examples, multiple diffusers and / or alignment layers of this type may be used. As one skilled in the art will appreciate, various other functional elements may be used, for example, to modify the light. Examples include so-called "dual BEFs" (DBEFs), which may include, for example, a thin film encapsulation (TFE) layer, a prism layer, a reflector, a partial reflector, a polarizer, a diffuser, a barrier layer, an anti-reflective layer, or a collimator that polarizes light for the liquid crystal light valve array and reflects light that is not of the desired polarization for the liquid crystal light valve array back into the backlight to be reflected back toward the DBEF.

[0141] The circuit layers for the light source and the light modulator are each connected to a display control system and configured for control of the light source and the light modulator by the display control system to output a desired image. The circuit layer of the light modulator is configured for so-called active matrix control of the light modulator regions, for example, by using switching elements (e.g., thin film transistors (TFTs)) for each pixel and configuring each light modulator region to transmit a desired amount of light by appropriately applying electrical signals to the source and gate terminals of each TFT. The circuit layer of the light source is configured to control the light output by the LEDs, for example, by turning on certain zones of LEDs while turning off other zones of LEDs. Depending on the number of LEDs and their layout, the circuit layer of the light source may even include switching elements (e.g., TFTs) for active matrix control of the LEDs.

[0142] A display control system is connected to the circuit layer and the common electrode by signal lines. The display control system has, for example, a data input for receiving data representing one or more images for the display device. As those skilled in the art will appreciate, the display control system includes circuitry for determining and applying appropriate electrical signals to the electrodes of the light modulators and the LEDs of the light source (and based on the data representing the image to be displayed).

[0143] As those skilled in the art will appreciate, the magnitude of the voltage applied between the common electrode and the electrode of a given pixel's light modulator region, and therefore the magnitude of the applied electric field, determines the rotational orientation of the LC molecules passing through the pixel relative to the orientation set by the alignment layers and also relative to the linear polarizer layer. Thus, the degree of light modulation of each light modulator region can be controlled, which in turn can control the amount of transmitted light that is aligned with the alignment layers or at least partially rotated in orientation relative to the alignment layers.

[0144] As one skilled in the art will appreciate, other types of examples are envisioned that have a light modulator combined with a light source, but that use a technology other than LC technology for light modulation (e.g., microelectromechanical (MEM) or electrophoretic technology).

[0145] Embodiments are further envisioned in which each LED of the light source corresponds to a respective pixel and can be controlled to modulate the light output by each pixel, rather than using a separate light modulator in combination with the lighting device. For example, each subpixel may comprise a blue LED, and multiple subpixels may be illuminated by a single white LED, or alternatively, by green and red LEDs. By appropriately controlling each of the blue, green, and red LEDs, the color of the image output by the display device can be adjusted.

[0146] A display device as described herein may be, for example, a display panel, display unit, or display screen for devices such as a television, a computer monitor, a tablet computing device, a laptop computing device, a mobile telecommunications device such as a smartphone, a portable (e.g., mobile) device, an electronic reader device, a watch, a satellite navigation device, a head-up display device, a game console, a flexible display, an augmented reality (XR) device, a virtual reality (VR) device, and / or an augmented reality (AR) device.

[0147] The display device may, for example, be incorporated into an apparatus comprising a display device, at least one processor, and at least one memory comprising computer program instructions, the at least one memory and the computer program including instructions operable together with the at least one processor to control a display device control system for controlling the display device to output images.

[0148] A system diagram illustrating an example of the basic hardware architecture of system 650 is shown in Figure 16, which is an electronic device such as a laptop computing device. Note that in some other implementations, the components shown in Figure 16 are not present; for example, in the case of a computer monitor implementation, system storage and / or a battery may not be present. System 650 includes a display device 654, at least one processor 658 connected to and therefore in data communication with, for example, a display device control system 652 (e.g., according to the previous example), a communication system 656, a user input system 660, a power system 662, and system storage 664. The display device control system is connected to and therefore in data communication with display device 654.

[0149] The display device control system 652 includes, for example, driver components for use in applying voltages to any of the pixels and addressing different such pixels. In an example, the light modulator regions of the pixels are driven using an active matrix control scheme, and the display device control system is configured to control switching elements, such as thin film transistors (TFTs), of the display device 654 via circuitry to control the pixels. The circuitry may include signal lines and control lines. For example, the display device control system 652 may include display drivers, such as a display column driver and a display row driver.

[0150] The at least one processor 658 herein may be, for example, a general-purpose processor, a microprocessor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a programmable logic device, discrete gate or transistor logic, discrete hardware components, or any suitable combination thereof configurable for the functions described herein. A processor may be a combination of computing devices, such as a DSP and a microprocessor, multiple microprocessors, a microprocessor in conjunction with a DSP core, or any other such configuration. The processor 658 may be coupled to read information from or write information to a memory of a storage device via one or more buses. The processor 658 may additionally or alternatively include memory, such as processor registers.

[0151] The communications system 656, for example, configures the system 650 to communicate with computing devices via a data network, a computer network such as the Internet, a local area network (LAN), a wide area network (WAN), a telecommunications network, a wired network, a wireless network, or another network. The communications system may include an input / output (I / O) interface such as a universal serial bus (USB) connection, a Bluetooth connection, or an infrared connection, or a data network interface for connecting the device to a data network such as any of the above. Content data, as described below, may be transferred to the system via the communications system.

[0152] User input system 660 may comprise input devices for receiving input from a user of the system. Exemplary input devices include, but are not limited to, keyboards, roller balls, buttons, keys, switches, pointing devices, mice, joysticks, remote controls, infrared detectors, voice recognition systems, barcode readers, scanners, video cameras (possibly coupled with video processing software for detecting hand or facial gestures), motion detectors, microphones (possibly coupled with audio processing software for detecting voice commands), VR gloves, AR gloves, haptic input devices, computer vision devices, simultaneous localization and mapping (SLAM) devices, eye tracking devices, hand tracking devices, or other devices capable of transmitting information from a user to a device. The input devices may also take the form of a touchscreen associated with display device 654, where the user responds to prompts on display device 654 by touch. The user can input textual information via an input device such as a keyboard or touchscreen.

[0153] The system may also include a user output system (illustrated) including, for example, an output device for providing output to a user of the system. Examples include, but are not limited to, a printing device, an audio output device including, for example, one or more speakers, headphones, earphones, an alarm, or a tactile output device. The output device may also be a connector port for connecting to one of the other output devices described, such as earphones.

[0154] The power system 662 includes, for example, power circuitry for use in transmitting and controlling the power consumed by the system. Power can be provided by a mains power source or from a battery (not shown) via the power circuitry. The power circuitry may also be used to charge the battery from the mains power source.

[0155] The storage device 664 includes memory, e.g., at least one volatile memory 666 and nonvolatile memory 670, and may comprise a non-transitory computer-readable storage medium. The volatile memory may be, for example, random access memory (RAM). The non-volatile (NV) memory may be, for example, a solid-state drive (SSD), such as flash memory or read-only memory (ROM). Additional storage technologies may be used, e.g., magnetic, optical, or tape media, compact discs (CDs), digital versatile discs (DVDs), Blu-ray, or other data storage media. The volatile and / or non-volatile memory may be removable or non-removable.

[0156] Any of the memories may store data for controlling the system. Such data may be in the form of, for example, computer-readable and / or executable instructions, e.g., computer program instructions. Thus, at least one memory and computer program instructions may be operable to control, with at least one processor, a display device control system for controlling the display device 654 to output images.

[0157] In the example of FIG. 16 , volatile memory 666 stores, for example, display device data 668 indicating an image to be provided by the system. Based on display device data 668, processor 658 can send data to control system 652 to display image 675, which then outputs signals to the display device to apply voltages to pixels. Non-volatile memory 670 stores, for example, program data 672 and / or content data 674. Program data is, for example, data representing computer-executable instructions in the form of computer software, which the system executes applications or program modules for the system or components of the system to perform particular functions or tasks and / or to control the components or components of the system. For example, application or program module data includes any of routines, programs, objects, components, data structures, etc. Content data is, for example, data representing user content; such content can represent any form of media, for example, text, at least one image or portion thereof, at least one video or portion thereof, at least one sound or music or portion thereof. The data representing an image or part thereof may, for example, represent an image to be provided by at least one pixel of a display device. Such data may comprise one type of content data, but may alternatively comprise a mixture of different types of content data, for example a movie may be represented by data including at least image data and audio data.

[0158] The term "about" indicates that a numerical value may be approximate. This may be due to acceptable function and / or measurement tolerances. For example, approximation allows for ±5% of the quoted numerical value.

[0159] The term nanostructure, as used herein, refers to a structure having at least one region or characteristic dimension, e.g., less than about 500 nm. In some examples, nanostructures have dimensions less than about 200 nm, less than about 100 nm, less than about 50 nm, less than about 20 nm, or less than about 10 nm. Typically, the region or characteristic dimension is along the smallest axis of the structure. Examples of such nanostructures include nanowires, nanorods, nanotubes, branched nanostructures, nanodots, quantum dots (QDs), nanoparticles, etc. In some examples, each of the three orthogonal dimensions of the nanostructure is less than about 500 nm, less than about 200 nm, less than about 100 nm, less than about 50 nm, less than about 20 nm, or less than about 10 nm.

[0160] The term "quantum dot" or "QD" as used herein refers to, for example, a nanostructure that is substantially single-crystalline (e.g., includes a single crystal). For example, a QD can have a core-shell structure, where the core is substantially single-crystalline and has one or more shells thereon. A QD has, for example, at least one region or characteristic dimension having a dimension of less than about 500 nm, down to the order of less than about 1 nm. In some examples, a QD has a maximum dimension of about 2 nm to about 30 nm. Quantum dots described herein can be considered fluorescent semiconductor structures having semiconductor crystallites each having a diameter of no more than twice the Bohr radius of an exciton induced in the semiconductor crystallite. Such a radius results in quantum confinement of the exciton when induced in the semiconductor crystallite. The Bohr radius depends on the elemental composition of the semiconductor crystallite. For example, the Bohr radius of cadmium selenide (CdSe) is 5.4 nm, so a quasi-spherical CdSe semiconductor crystallite is a quantum dot if its radius is less than 5.4 nm. Further examples include 4-5 nm diameter zinc selenide telluride (ZnSeTe) crystallites, which are blue-emitting quantum dots; 2-2.5 nm diameter indium phosphide (InP) crystallites, which are green-emitting quantum dots; and 2.8-3.5 nm diameter InP crystallites, which are red-emitting quantum dots. Quantum confinement of excitons produces fluorescence. Quantum confinement can be induced in three dimensions, two dimensions (quantum wires), or one dimension (quantum wells). Other morphologies of semiconductor crystallites, such as cubic or tetrahedral, are envisioned.Quantum dots include III-V semiconductors, II-VI semiconductors, zinc telluride selenide (ZnTeSe), zinc telluride (ZnTe), zinc selenide (ZnSe), zinc sulfide (ZnS), indium phosphide (InP), indium gallium phosphide (InGaP), indium arsenide (InAs), indium arsenide phosphide (InAsP), indium gallium arsenide phosphide (InGaAsP), silver indium gallium sulfide (AgInGaAs), The quantum dots may include at least one of copper indium sulfide (CuInS or AIGS), copper indium gallium selenide (CuInGaSe or CIGS), cadmium selenide (CdSe), cadmium sulfide (CdS), cadmium telluride (CdTe), cadmium selenide telluride (CdSeTe), cadmium zinc selenide (CdZnSe), molybdenum sulfide (MoS), or alloys thereof. The ratio between the elements of the alloy is not specified, and various ratios are contemplated as will be understood by those skilled in the art. Each quantum dot may include a core-shell structure having at least one shell on a core, the diameter of the core corresponding to or less than 2x the Bohr radius. The shell may be, for example, a metal sulfide and / or a metal oxide. Exemplary core-shell structures may be formed from CdSe(core) / CdS / ZnS or InP(core) / ZnSe / ZnS. The quantum dots may be functionalized with at least one ligand, e.g., polyethylene glycol, polythiol, and / or carboxylate. Shell and / or ligand functionalization can enhance quantum dot properties, such as quantum yield, thermal stability, and / or photostability. The quantum dots may be encapsulated, for example, to reduce the toxicity of the quantum dots. As one skilled in the art will appreciate, many encapsulants are contemplated, such as silanes or metal oxides.

[0161] The term "maximum dimension" with respect to a structure refers, for example, to the largest linearly measurable distance of that structure in any direction. For example, in the context of a spherical structure, the maximum dimension is the diameter.

[0162] The term "thickness" in reference to a film, coating, layer, etc., refers to the depth of that film, coating, or layer. For example, if the film or layer is planar, thickness relates to the distance measured perpendicular to the plane.

[0163] The above examples should be understood as illustrative examples. It should be understood that any feature described in connection with any one example may be used alone or in combination with other features described, and may also be used in combination with one or more features of any other example, or any combination of any other example. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the appended claims.

[0164] The present disclosure is presented, by way of example, with reference to the accompanying drawings. Components, process steps, and other elements that may be substantially the same in one or more figures are co-identified and described with minimal repetition. It should be noted, however, that co-identified elements may differ to some extent. It should be further noted that the figures are schematic and generally not drawn to scale. Rather, the scale, aspect ratios, and number of elements of the various figures shown in the figures may be intentionally distorted to better visualize certain features or relationships.

[0165] It will be understood that the configurations and / or approaches described herein are illustrative and that numerous variations are possible, and therefore, these specific embodiments or examples should not be considered in a limiting sense. The specific routines or methods described herein may represent one or more of any number of processing strategies. Accordingly, the various operations illustrated and / or described may be performed in the order illustrated and / or described, in other orders, in parallel, or in omitted orders. Similarly, the order of steps described above may be changed. In that spirit, the phrase "based at least in part on" is intended to remind the reader that the functional and / or conditional logic illustrated herein does not require or preclude appropriate additional logic to provide additional benefits executed in combination with the illustrated logic.

[0166] The subject matter of the present disclosure includes all novel and non-obvious combinations and subcombinations of the various processes, systems, and configurations, as well as other features, functions, acts, and / or properties disclosed herein, and any and all equivalents thereof.

[0167] The photoluminescent nanocomposite material according to the embodiment of the present invention has, for example, the following configuration: (1) A photoluminescent nanocomposite material comprising: a carrier matrix; a plurality of photoluminescent nanostructures distributed within the carrier matrix; and an additive comprising one or more coordination complexes having thiol and lipophilic properties. (2) The photoluminescent nanocomposite material according to (1) above may further comprise: the one or more coordination complexes being Zn. ２＋(3) The photoluminescent nanocomposite material according to (1) or (2) above, wherein the additive comprises a coordination complex having both thiol and lipophilic properties. (4) The photoluminescent nanocomposite material according to any one of (1) to (3) above, wherein the additive comprises zinc dodecanethiol. (5) The photoluminescent nanocomposite material according to any one of (1) to (4) above, wherein the additive comprises a metal cation coordinated to an alkylated or arylated dithiocarbamate ligand. (6) The photoluminescent nanocomposite material according to any one of (1) to (5) above, wherein the additive comprises a thiolated coordination complex and a lipophilic coordination complex different from the thiolated coordination complex. (7) The photoluminescent nanocomposite material according to any one of (1) to (6) above, wherein the thiolated coordination complex comprises a metal cation coordinated to a dithiocarbamate ligand. (8) The photoluminescent nanocomposite material according to (7) above, wherein the dithiocarbamate ligand is an alkyl- or aryl-substituted dithiocarbamate ligand. (9) The photoluminescent nanocomposite material according to any one of (6) to (8) above, wherein the lipophilic coordination complex comprises a metal cation coordinated to a carboxylate. (10) The photoluminescent nanocomposite material according to (9) above, wherein the carboxylate comprises an aliphatic chain of 5 or more carbon atoms. (11) The photoluminescent nanocomposite material according to any one of (1) to (10) above, wherein the additive further comprises a secondary antioxidant. (12) The photoluminescent nanocomposite material according to any one of (1) to (11) above, wherein the additive further comprises a hindered amine light stabilizer. (13) The photoluminescent nanocomposite material according to any one of (1) to (12) above, wherein the one or more coordination complexes having thiol and lipophilic properties are disposed in a coordination polymer. (14) The photoluminescent nanocomposite material according to (13) above, wherein the coordination polymer further comprises an alkylalkoxysilane.(15) The photoluminescent nanocomposite material according to (13) above, wherein the coordination polymer is a silanized coordination polymer. (16) The photoluminescent nanocomposite material according to (15) above, wherein the silanized coordination polymer comprises a reaction product of an alkylalkoxysilane and a metal thiolate in the presence of a surfactant. (17) The photoluminescent nanocomposite material according to (16) above, wherein the one or more coordination complexes having thiol and lipophilic properties comprise the metal thiolate. (18) The photoluminescent nanocomposite material according to any one of (1) to (17) above, wherein the additive further comprises a basic additive. (19) The photoluminescent nanocomposite material according to (18) above, wherein the basic additive comprises melamine or a melamine derivative. (20) The photoluminescent nanocomposite material according to any one of (1) to (19) above, wherein the plurality of photoluminescent nanostructures are arranged on or together with support particles.

Claims

1. A photoluminescent nanocomposite material comprising: a carrier matrix; a plurality of photoluminescent nanostructures distributed within said carrier matrix; and an additive comprising one or more coordination complexes having thiol and lipophilic properties.

2. The one or more coordination complexes are Zn ２＋ 10. The photoluminescent nanocomposite material of claim 1, comprising:

3. The photoluminescent nanocomposite material of claim 1 or 2, wherein the additive comprises a coordination complex having both thiol and lipophilic properties.

4. The photoluminescent nanocomposite material of any one of claims 1 to 3, wherein the additive comprises zinc dodecanethiol.

5. The photoluminescent nanocomposite material of any one of claims 1 to 4, wherein the additive comprises a metal cation coordinated to an alkylated or arylated dithiocarbamate ligand.

6. The photoluminescent nanocomposite material of any one of claims 1 to 5, wherein the additive comprises a thiolated coordination complex and a lipophilic coordination complex different from the thiolated coordination complex.

7. The photoluminescent nanocomposite material of any one of claims 1 to 6, wherein the thiolated coordination complex comprises a metal cation coordinated to a dithiocarbamate ligand.

8. The photoluminescent nanocomposite material of claim 7, wherein the dithiocarbamate ligand is an alkyl- or aryl-substituted dithiocarbamate ligand.

9. The photoluminescent nanocomposite material of any one of claims 6 to 8, wherein the lipophilic coordination complex comprises a metal cation coordinated to a carboxylate.

10. The photoluminescent nanocomposite material of claim 9, wherein the carboxylate comprises an aliphatic chain of five or more carbon atoms.

11. The photoluminescent nanocomposite material of any one of claims 1 to 10, wherein the additive further comprises a secondary antioxidant.

12. The photoluminescent nanocomposite material of any one of claims 1 to 11, wherein the additive further comprises a hindered amine light stabilizer.

13. The photoluminescent nanocomposite material of any one of claims 1 to 12, wherein the one or more coordination complexes having thiol and lipophilic properties are disposed in a coordination polymer.

14. The photoluminescent nanocomposite material of claim 13, wherein the coordination polymer further comprises an alkylalkoxysilane.

15. The photoluminescent nanocomposite material of claim 13, wherein the coordination polymer is a silanated coordination polymer.

16. The photoluminescent nanocomposite material of claim 15, wherein the silanated coordination polymer comprises the reaction product of an alkylalkoxysilane and a metal thiolate in the presence of a surfactant.

17. The photoluminescent nanocomposite material of claim 16, wherein the one or more coordination complexes having thiol and lipophilic properties comprise the metal thiolate.

18. The photoluminescent nanocomposite material of any one of claims 1 to 17, wherein the additive further comprises a basic additive.

19. The photoluminescent nanocomposite material of claim 18, wherein the basic additive comprises melamine or a melamine derivative.

20. The photoluminescent nanocomposite material of any one of claims 1 to 19, wherein the plurality of photoluminescent nanostructures are disposed on or with support particles.

Images