Cross-linked ligand

Abstract

The invention relates to semiconductor luminescent nanoparticles comprising a polymeric layer.

Description

Field of the Invention

[0001] The present invention relates to a semiconductor luminescent nanoparticle comprising a polymeric outer layer, and to a method for preparing the semiconductor luminescent nanoparticle. In addition, the present invention relates to a composition and a formulation comprising at least the semiconductor luminescent nanoparticle, and to the use of the semiconductor luminescent nanoparticle in an optical device. Background of the Invention

[0003] Semiconductor luminescent nanoparticles have attracted much attention as color converter materials in optical devices due to their narrow autofluorescence emission.

[0004] For example, US 2010 / 068522 A1 presents the synthesis of quantum dots (hereafter QDs) having ligands containing terminal unsaturated groups.The cross-linking concept described in the patent application requires a catalytic process for the cross-linking of double bonds.

[0005] US 2011 / 281388A describes the cross-linking of QDs in the solid state after spin coating of a QD solution on a glass substrate. In this case, cross-linking is performed to prevent the first layer of QDs spun on from being redissolved by the second layer to be deposited on the first layer.

[0006] US 9115097 B2 and US 9840664 B2 describe crosslinking of ligands by adding crosslinking agents.

[0007] In201747022708 mentions cross-linking of QDs each having a different type of ligand, which can react with each other, or mentions the use of a cross-linking agent. In addition, cross-linking is performed on a solid phase.

[0008] Colloids and Surfaces A: Physicochem. Eng. Aspects 402 (2012) 72-79 discloses cross-linking of glutathione using bifunctional PED as a cross-linking agent.

[0009] US 7151047 B2 discloses the cross-linking of mercapto acids using lysine as a cross-linking agent.

[0010] EP 3163372A2 describes that the addition of bulky ligands to QD formulations results in a reduction in the effective concentration of QDs in the final product. Cross-linking is performed by a cross-linking agent, which results in partial protection of the QDs.

[0011] J. Phys. Chem. B 2014, 118, 14103-14109 describes the photocatalytic crosslinking of mercaptodiacetylene, which is adsorbed on CdSe / ZnS QDs, showing that QDs covered with crosslinked ligands remain stable over time in polar solvents.

[0012] The use of fluorescent quantum dots in applications such as down-conversion layers in liquid crystal displays (LCDs), color filters in light emitting diodes (LEDs), or as light-emitting layers in electroluminescent devices requires that the semiconductor luminescent nanoparticles be stable under extreme conditions such as elevated heat and high light flux, and that they be prevented from external elements from the environment or surrounding matrix such as oxygen, water, free radicals, and free charges passing through the outer layer of the nanoparticles.

[0013] Typically, semiconductor nanoparticles are incorporated into the film to provide protection for the nanocrystals. Various polymers have been used for this purpose, such as acrylates, siloxanes, silazanes, epoxies, or silicones.

[0014] However, incorporating quantum dots into these types of layers results in a reduction in their emission quantum yield (QY). This is due to the aggregation of semiconductor nanoparticles in the solid polymer layer and to the polymerization process, which affects the organic molecules (usually called "ligands") attached to the surface of the nanoparticles and causes the ligands to detach from the nanoparticle surface.

[0015] Furthermore, it is not always possible to apply a polymer layer, for example when a semiconductor nanoparticle layer needs to be conductive, as in the case of electroluminescent devices. In such devices, the semiconductor nanoparticles are deposited as a solid layer and the surface of the nanoparticles must be protected.

[0016]

[0006] Therefore, there remains a need for novel concepts for protecting semiconductor luminescent nanoparticles from external elements that overcome one or more of the disadvantages described in the prior art. SUMMARY OF THE INVENTION

[0018] The present invention has been accomplished in view of the above problems, and therefore an object of the present invention is to provide a novel concept of protecting the surface of semiconductor light-emitting nanoparticles from external elements, which concept is not affected by the above disadvantages.

[0019] The inventors have surprisingly found that one or more of the above problems can be solved by the features as defined in the claims.

[0020] Specifically, in order to solve one or more of the above problems, the present invention provides a semiconductor luminescent nanoparticle comprising

[0021] nuclear,

[0022] one or more shells, and

[0023] at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, which are attached to the outermost surface of the shell, wherein

[0024] At least one organic ligand A comprises a crosslinkable functional group X,

[0025] At least one organic ligand B comprises a cross-linkable functional group Y, and

[0026] At least one organic ligand C comprises a crosslinkable functional group Z,

[0027] It is characterized in that the groups X, Y and Z are each capable of acting as a crosslinking acceptor and as a crosslinking donor.

[0028] In addition, in order to solve one or more of the above problems, the present invention provides a semiconductor luminescent nanoparticle comprising

[0029] nuclear,

[0030] one or more shells,

[0031] at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, which are attached to the outermost surface of the shell, and

[0032] Polymeric outer layer,

[0033] The characteristic is that the polymer outer layer is formed by direct bonding between at least one organic ligand A, at least one organic ligand B and at least one organic ligand C via crosslinkable functional groups X, Y and Z.

[0034] One or more of the above problems are also solved by a method for preparing semiconductor luminescent nanoparticles having a polymeric outer layer, the method comprising the steps of:

[0035] a) providing a semiconductor luminescent nanoparticle comprising a core, one or more shell layers and at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, which are attached to the outermost surface of the shell layer, wherein at least one organic ligand A comprises a crosslinkable functional group X, at least one organic ligand B comprises a crosslinkable functional group Y, and at least one organic ligand C comprises a crosslinkable functional group Z; and

[0036] b) crosslinking at least one organic ligand A, at least one organic ligand B and at least one organic ligand C to form a polymeric outer layer by subjecting the nanoparticles of step a) to conditions that allow direct linkages to form between at least one organic ligand A, at least one organic ligand B and at least one organic ligand C via crosslinkable functional groups X, Y and Z.

[0037] The present invention also relates to semiconductor luminescent nanoparticles obtainable or obtained by this method.

[0038] That is, the present inventors unexpectedly discovered that by using such a functionalized ligand comprising a nanoparticle surface attachment group and a cross-linkable or polymerizable group as a surface-attached ligand, and by cross-linking of the surface-attached ligand itself, a polymeric network is formed, which forms or corresponds to a polymeric outer layer surrounding the surface of the nanoparticle, which provides steric protection against any kind of external elements and also prevents the ligand detached from the surface from diffusing away, on the contrary, it is likely to allow the detached ligand to reattach to the surface.

[0039] Furthermore, advantageously, this protection concept does not require the addition of any additional materials, compounds or agents to the semiconductor nanoparticles and thus allows the coating of highly concentrated semiconductor light-emitting nanoparticle layers to increase the light emission output from optoelectronic devices based on the quantum material layer as the emissive element.

[0040] Furthermore, the present invention relates to a composition comprising semiconductor luminescent nanoparticles and to a formulation comprising semiconductor luminescent nanoparticles or the composition and at least one solvent.

[0041] Furthermore, the present invention relates to the use of semiconductor luminescent nanoparticles or the composition or the formulation in electronic devices, optical devices or biomedical devices.

[0042] The present invention also relates to an optical medium comprising semiconductor luminescent nanoparticles or the composition.

[0043] The invention further relates to an optical device comprising the optical medium.

[0044] Other advantages of the present invention will become apparent from the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 FT-IR spectra of quantum dots before and after ligand exchange with 11-MPA are shown.

[0047] Figure 2a is a SEM image of the 11-MPA sample obtained after exposure to light (365 nm, 1 hour) in Working Example 1, and Figure 2b is a SEM image of the initial quantum dot sample.

[0048] Figure 3a and Figure 3b FT-IR spectra of quantum dots are shown before coordination cross-linking (CL) (but after exchange with 11-phosphononyl undecyl acrylate ligands) and after cross-linking (CL).

[0049] Figure 4 The initial quantum yield (t=0 hour) and the quantum yield after exposure to 365 nm light (t=1 hour) of the quantum dots obtained from Working Example 1 and Comparative Example 1 are shown.

[0050] Detailed description of the invention

[0051] Hereinafter, the best mode for carrying out the present invention is described in detail.

[0052] The present invention provides a semiconductor luminescent nanoparticle comprising

[0053] nuclear,

[0054] one or more shells, and

[0055] at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, which are attached to the outermost surface of the shell, wherein

[0056] At least one organic ligand A comprises a crosslinkable functional group X,

[0057] At least one organic ligand B comprises a cross-linkable functional group Y, and

[0058] At least one organic ligand C comprises a crosslinkable functional group Z,

[0059] It is characterized in that the groups X, Y and Z are each capable of acting as a crosslinking acceptor and as a crosslinking donor.

[0060] According to the present invention, the functional groups X, Y and Z are crosslinkable or polymerizable chemical groups, which terms are used interchangeably herein, that is, the functional groups provide the ability to act as crosslink acceptors and as crosslink donors, and are capable of being polymerized by chemical crosslinking, such as unsaturated groups such as vinyl groups, thereby forming linkages (i.e., intramolecular linkages) between the surfaces of the same nanoparticles connected with at least one organic ligand A, at least one organic ligand B and at least one organic ligand C around the surface, thereby forming a polymerized outer layer, which will be described below.

[0061] Preferably, the crosslinkable functional groups X, Y and Z are terminal groups respectively related to the ligands A, B and C. Furthermore, preferably, each of the ligands A, B and C comprises exactly one crosslinkable functional group X, Y and Z respectively.

[0062] As defined herein, the ability to serve as a crosslink acceptor and to serve as a crosslink donor is understood to mean that during the chemical crosslinking reaction, each of the crosslinkable or polymerizable functional groups X, Y and Z is capable of being impacted by an active propagation center (representing a crosslink acceptor) to form a new propagation center, which in turn is capable of impacting another crosslinkable or polymerizable functional group (representing a crosslink donor) to again form a new propagation center, and so on.

[0063] The form that the propagation center takes depends on the specific type of polymerization mechanism, as will be described below, which is not limited by the present invention. Accordingly, without intending to be bound by any theory, the functional groups X, Y and Z follow a chain-building polymerization type reaction, thereby crosslinking at least three organic ligands A, B and C within the molecule to form a polymeric network that produces a polymeric outer layer or equivalent to a polymeric outer layer.

[0064] For example, according to the present invention, the group X can be used as a crosslinking acceptor with respect to the group Y and as a crosslinking donor with respect to the group Z, and / or as a crosslinking acceptor with respect to the group Z and as a crosslinking donor with respect to the group Y; the group Y can be used as a crosslinking acceptor with respect to the group Z and as a crosslinking donor with respect to the group X, and / or as a crosslinking acceptor with respect to the group X and as a crosslinking donor with respect to the group Z; and / or the group Z can be used as a crosslinking acceptor with respect to the group X and as a crosslinking donor with respect to the group Y, and / or as a crosslinking acceptor with respect to the group Y and as a crosslinking donor with respect to the group X, without being limited thereto. For example, in the present invention, the group X may also be able to be used as a crosslinking acceptor with respect to another group X and / or as a crosslinking donor. The same applies to the groups Y and Z.

[0065] According to the present invention, organic ligands A, B and C comprising crosslinkable functional groups X, Y and Z, respectively, are attached to the outermost surface of the shell layer of the nanoparticle in a concentration that allows the formation of a polymeric outer layer that completely surrounds the core (by crosslinking the organic ligands A, B and C via the functional groups X, Y and Z) and one or more shell layers of the nanoparticle.

[0066] Preferably, the concentration of organic ligand A, the concentration of organic ligand B and the concentration of organic ligand C attached to the outermost surface of the nanoparticle shell are substantially the same.

[0067] In a preferred embodiment of the present invention, at least one organic ligand A, at least one organic ligand B and at least one organic ligand C are each represented by the following general formula (I):

[0068] UVW (I)

[0069] In the general formula (I), in at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, the group U is the same or different nanoparticle surface connecting group at each occurrence, which can react or bind to the outermost surface of one or more shells. The interaction or binding can be covalent binding or ionic binding or dipole-dipole interaction and is not limited thereto.

[0070] Preferably, in at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, the group U is selected, at each occurrence, identically or differently, from the group consisting of: phosphonic acid group, thiol group, thiolate group, thioacid group, dithioacid group, mercaptoester group, carboxylic acid group, carboxylate group, especially Zn carboxylic acid, phosphonate group, especially Zn phosphonic acid, thiocarbamate group, especially Zn thiocarbamate, phosphine group, phosphine oxide group, amine group, amide group and selenol group. Most preferably, the group U is a phosphonic acid group (-P(O)(OH)2).

[0071] In formula (I), group W represents a terminal crosslinkable functional group corresponding to the crosslinkable functional groups X, Y and Z, respectively, depending on which of the organic ligands A, B or C is represented by general formula (I). Preferably, groups X, Y and Z are each independently selected from the group consisting of a thiol group, an acrylate group (-OC(O)CHCH2), a styrene group (-(C6H4)CHCH2), a carbonate group and a carbamate (urethane) group.

[0072] In formula (I), in at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, the group V is the same or different linker group each time it appears, that is, a chemical group connecting the nanoparticle surface linking group U with each crosslinkable functional group X, Y or Z.

[0073] Preferably, the linker group V is independently selected at each occurrence from the group consisting of: a straight-chain alkylene group having 1 to 20 C atoms or a branched alkylene group having 3 to 20 C atoms, wherein one or more non-adjacent methylene structural units (-CH2-) in the straight-chain and branched alkylene groups may in each case be replaced by a phenylene, sulfonyl, carbonyl, ether, thioether, sulfoxide, ester, phosphate, amide or imine group; or a straight-chain alkenylene or alkynylene group having 2 to 20 C atoms or a branched alkenylene or alkynylene group having 3 to 20 C atoms, wherein one or more methylene structural units (-CH2-) in the straight-chain and branched alkenylene or alkynylene groups may in each case be replaced by a phenylene, sulfonyl, carbonyl, ether, thioether, sulfoxide, ester, phosphate, amide or imine group.

[0074] For the purposes of the present invention, straight-chain alkylene having 1 to 20 C atoms, branched alkylene having 3 to 20 C atoms, straight-chain alkenylene or alkynylene having 2 to 20 C atoms or branched alkenylene or alkynylene having 3 to 20 C atoms, in which furthermore individual methylene structural units (—CH—) may be substituted by the radicals mentioned above, preferably means the following radicals: methylene, ethylene, n-propylene, isopropylene, n-butylene, isobutylene, sec-butylene, tert-butylene, 2-methylbutylene, n-pentylene, sec-pentylene, cyclopentylene, neopentylene, n-hexylene, neohexylene, n-heptylene, n-octylene, n-nonylene, n-decylene, n-undecylene, n-dodecylene, 2-ethylhexylene, vinylene, propenylene, butenylene, pentenylene, hexenylene, heptenylene, octenylene, nonenylene, decenylene, undecenylene, dodecenylene, ethynylene, ethynylene, n-propynylene, isopropynylene, n-butynylene, isobutynylene, sec-butynylene, tert-butynylene, 2-methylbutynylene, n-pentynylene, sec-pentynylene, cyclopentynylene, neopentynylene, n-hexynylene, neohexynylene, n-heptynylene, n-octynylene, n-nonynylene, n-decynylene, n-undecynylene, n-dodecynylene, 2-ethylhexynylene, ethenynylene, propenynylene, butenynylene, pentenynylene, hexenynylene, heptenynylene, octenynylene or nonenynylene.

[0075] Most preferably, the linker group V is a straight-chain alkylene group having 1 to 20 C atoms, wherein one or more non-adjacent methylene structural units (-CH2-) in the straight-chain alkylene group may be replaced by a phenylene, sulfonyl, carbonyl, ether, thioether, sulfoxide, ester, phosphate, amide or imine group.

[0076] In another preferred embodiment of the present invention, in each of at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, the group U is the same and / or in each of at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, the group V is the same.

[0077] In other words, it is preferred according to the present invention that the organic ligands A, B and C are connected to the surface of the nanoparticles via the same functional group U. Alternatively or additionally, it is preferred according to the present invention that in the organic ligands A, B and C, the surface connecting group U and each crosslinkable functional group X, Y or Z are bonded via the same linker group V.

[0078] Further preferably, in each of at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, group U is a phosphonic acid group and group V is a straight-chain alkylene group having 1 to 20 C atoms, wherein one or more non-adjacent methylene structural units (-CH2-) in the straight-chain alkylene group may be replaced by a phenylene group, a sulfonyl group, a carbonyl group, an ether group, a thioether group, a sulfoxide group, an ester group, a phosphate ester group, an amide group or an imine group.

[0079] In another preferred embodiment of the present invention, the crosslinkable functional groups X, Y and Z are the same, which means that the organic ligands A, B and C have the same crosslinkable functional groups X, Y and Z. Accordingly, it is preferred according to the present invention that the functional groups used for crosslinking to the outermost surface of the nanoparticles A, B and C and thereby for forming the polymeric outer layer are the same.

[0080] It is further preferred according to the present invention if at least one organic ligand A, at least one organic ligand B and at least one organic ligand C are identical. This means that it is preferred according to the present invention that the organic ligands A, B and C attached to the outermost surface of the nanoparticles which are crosslinked to form the polymeric outer layer are identical.

[0081] It is further preferred that the functional groups X, Y and Z are identically selected from thiol groups, acrylate groups and styrene groups.

[0082] In another preferred embodiment of the invention, at least one organic ligand A, at least one organic ligand B and at least one organic ligand C are identically selected from 11-mercaptoundecylphosphonic acid, 11-phosphonylundecanyl acrylate and p-[(4-vinylphenyl)methyl]phosphonic acid.

[0083] The semiconductor light-emitting nanoparticles can be prepared by following the reaction step a) of the method to be described below, or can be obtained from the reaction step a) of the method to be described below, or can be obtained or separated from this step.

[0084] The present invention further provides a semiconductor luminescent nanoparticle comprising

[0085] nuclear,

[0086] one or more shells,

[0087] at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, which are attached to the outermost surface of the shell, and

[0088] Polymeric outer layer,

[0089] The characteristic is that the polymer outer layer is formed by direct bonding between at least one organic ligand A, at least one organic ligand B and at least one organic ligand C via crosslinkable functional groups X, Y and Z.

[0090] In other words, the semiconductor luminescent nanoparticles provided by the present invention are characterized in that at least one organic ligand A, at least one organic ligand B and at least one organic ligand C connected to the outermost surface of one or more shell layers of the nanoparticles are cross-linked by direct bonding via cross-linkable functional groups X, Y and Z, thereby forming a polymerized outer layer.

[0091] For example, according to the present invention, the polymer outer layer can be formed by the following via crosslinkable functional groups X, Y and Z: at least one organic ligand A is directly bonded to at least one organic ligand B and one organic ligand C, at least one organic ligand B is directly bonded to at least one organic ligand A and one organic ligand C, and / or at least one organic ligand C is directly bonded to at least one organic ligand A and one organic ligand B.

[0092] As mentioned above, according to the present invention, the concentration of organic ligands A, B and C attached to the outermost surface of the shell layer of the nanoparticle is such that a polymeric outer layer can be formed by crosslinking the organic ligands A, B and C via functional groups X, Y and Z, which layer completely surrounds the core and one or more shell layers of the nanoparticle.

[0093] As used herein, the term "direct linkage" is understood to mean that at least one organic ligand A, at least one organic ligand B and at least one organic ligand C are linked to each other as defined above via direct chemical, preferably covalent bonding between the atoms of the respective crosslinkable or polymerizable functional groups X, Y and Z, i.e., the crosslinking reaction is carried out without the use and / or incorporation of any additional linking / crosslinking agents, such as bifunctional polyethylene glycol, melamine-based compounds such as hexamethoxymethylmelamine, dicyclohexylcarbodiimide, or any external polymeric or copolymeric ligands that are not attached to the surface of the nanoparticles.

[0094] The at least one organic ligand A, the at least one organic ligand B and the at least one organic ligand C comprising the functional groups X, Y and Z in their non-crosslinked form are respectively as defined above.

[0095] Accordingly, in a preferred embodiment of the present invention, at least one organic ligand A, at least one organic ligand B and at least one organic ligand C are each represented by the following general formula (I) in their non-crosslinked form:

[0096] UVW (I),

[0097] wherein the groups U, V and W are as defined above.

[0098] According to another preferred embodiment of the present invention, in each of at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, the group U is the same, and / or in each of at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, the group V is the same.

[0099] Further preferably, in each of at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, group U is a phosphonic acid group and group V is a straight-chain alkylene group having 1 to 20 C atoms, wherein one or more non-adjacent methylene structural units (-CH2-) in the straight-chain alkylene group may be replaced by a phenylene group, a sulfonyl group, a carbonyl group, an ether group, a thioether group, a sulfoxide group, an ester group, a phosphate ester group, an amide group or an imine group.

[0100] According to another preferred embodiment of the present invention, the cross-linkable functional groups X, Y and Z in each of the at least one organic ligand A, the at least one organic ligand B and the at least one organic ligand C are the same. Accordingly, it is preferred according to the present invention that the direct linkage between the organic ligands A, B and C attached to the outermost surface of the nanoparticle is formed via the same functional group, thereby forming a polymeric outer layer.

[0101] According to yet another preferred embodiment of the present invention, at least one organic ligand A, at least one organic ligand B and at least one organic ligand C are identical. This means that according to the present invention it is preferred that the polymeric outer layer is formed via direct linkage of at least three identical organic ligands attached to the outermost surface of the nanoparticle.

[0102] More preferably, the functional groups X, Y and Z are identically selected from thiol groups, acrylate groups and styrene groups.

[0103] In another preferred embodiment of the present invention, at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, each in their non-crosslinked form, are identically selected from 11-mercaptoundecylphosphonic acid, 11-phosphonylundecanyl acrylate and p-[(4-vinylphenyl)methyl]phosphonic acid.

[0104] The semiconductor luminescent nanoparticles according to the present invention have a polymeric outer layer formed by intramolecular self-crosslinking of surface-attached ligands without the addition and / or incorporation of any (bifunctional) crosslinking agent or external polymeric or copolymeric ligand.

[0105] The polymeric outer layer formed by intramolecular self-crosslinking of the surface-bound ligands prevents the penetration of oxidative elements from, for example, the environment or the surrounding matrix, which react with the ligands and detach them from the nanoparticle surface.

[0106] In addition, the polymeric outer layer formed by the intramolecular self-crosslinking of the surface-attached ligands prevents the ligands that have detached from the surface from diffusing away, and instead, it is likely to reattach the detached ligands to the surface. By this, the reduction in quantum yield of quantum dots caused by the detachment of ligands under heat and light conditions and in a free radical-rich environment can be avoided. In contrast, semiconductor nanoparticles have better performance and higher stability in solution and can resist free radical-rich environments.

[0107] Semiconductor luminescent nanoparticles:

[0108] According to the present invention, a wide variety of semiconductor light-emitting nanoparticles known to the public can be used as the inorganic portion of the semiconductor light-emitting nanoparticles as desired.

[0109] The shape type of the semiconductor light-emitting nanoparticles of the present invention is not particularly limited. Any type of semiconductor light-emitting nanoparticles can be used, such as spherical, elongated, star-shaped, and polyhedral semiconductor light-emitting nanoparticles.

[0110] According to the present invention, the one or more shells of the semiconductor luminescent nanoparticles are preferably single shells, double shells or multiple shells having more than two shells, and most preferably double shells.

[0111] As used herein, the term "shell" means that the structure completely or partially covers the core. Preferably, the one or more shells completely cover the core. The terms "core" and "shell" are well known in the art and are commonly used in the field of quantum materials, such as US 8221651B2.

[0112] As used herein, the term "nanometer" means a size between 0.1 nm and 999 nm, preferably, it is 0.1 nm to 150 nm.

[0113] In a preferred embodiment of the present invention, the semiconductor luminescent nanoparticles of the present invention are quantum-sized materials.

[0114] As used herein, the term "quantum size" refers to the size of the semiconductor material itself without ligands or other surface modifications, as described, for example, in ISBN: 978-3-662-44822-9, which can exhibit quantum confinement effects. In general, quantum-sized materials are said to emit light of adjustable, intense, and vivid colors due to the "quantum confinement" effect.

[0115] Preferably, the size of the overall structure of the quantum-sized material is from 1 nm to 100 nm, more preferably, it is from 1 nm to 30 nm, even more preferably, it is from 5 nm to 15 nm.

[0116] According to the present invention, the core of the semiconductor light-emitting nanoparticles can be changed. For example, CdS, CdSe, CdTe, ZnS, ZnSe, ZnSeS, ZnTe, ZnO, GaAs, GaP, GaSb, HgS, HgSe, HgSe, HgTe, InAs, InP, InPS, InPZnS, InPZn, InPGa, InSb, AlAs, AlP, AlSb, Cu2S, Cu2Se, CuInS2, CuInSe2, Cu2(ZnSn)S4, Cu2(InGa)S4, TiO2 alloys and any combination of these can be used.

[0117] In a preferred embodiment of the present invention, the core of the semiconductor light-emitting nanoparticles comprises one or more elements of Group 13 of the periodic table and one or more elements of Group 15 of the periodic table, such as GaAs, GaP, GaSb, InAs, InP, InPS, InPZnS, InPZn, InPGa, InSb, AlAs, AlP, AlSb, CuInS2, CuInSe2, Cu2(InGa)S4, and any combination of these.

[0118] Even more preferably, the core comprises In and P atoms, such as InP, InPS, InPZnS, InPZn or InPGa.

[0119] According to another preferred embodiment of the present invention, at least one of the shells comprises a first element of group 12, 13 or 14 of the periodic table and a second element of group 15 or 16 of the periodic table. Preferably, all shells comprise a first element of group 12, 13 or 14 of the periodic table and a second element of group 15 or 16 of the periodic table.

[0120] More preferably, at least one of the shells comprises a first element of group 12 of the periodic table and a second element of group 16 of the periodic table. For example, CdS, CdZnS, ZnS, ZnSe, ZnSSe, ZnSSeTe, CdS / ZnS, ZnSe / ZnS or ZnS / ZnSe shells may be used. Even more preferably, all shells comprise a first element of group 12 of the periodic table and a second element of group 16 of the periodic table.

[0121] Particularly preferably, at least one shell layer is represented by the following formula (II),

[0122] ZnS x Se y Te z, - (II),

[0123] Where 0≤x≤1, 0≤y≤1, 0≤z≤1, and x+y+z=1, where 0≤x≤1, 0≤y≤1, z=0 and x+y=1 is even more preferred.

[0124] Most preferably ZnS, ZnSe, ZnSeS, ZnSeSTe, CdS / ZnS, ZnSe / ZnS, ZnS / ZnSe shells are used.

[0125] Even more preferably, all shell layers are represented by formula (II).

[0126] For example, as semiconductor luminescent nanoparticles for green and / or red light emission purposes, CdSe / CdS, CdSeS / CdZnS, CdSeS / CdS / ZnS, ZnSe / CdS, CdSe / ZnS, InP / ZnS, InP / ZnSe, InP / ZnSe / ZnS, InP / ZnS / ZnSe, InPZn / ZnS, InPZn / ZnSe / ZnS, InPZn / ZnS, InPZn / ZnSe / ZnS, InPZn / ZnS / ZnSe, ZnSe / CdS, ZnSe / ZnS semiconductor luminescent nanoparticles or any combination of these can be used.

[0127] More preferably, InP / ZnS, InP / ZnSe, InP / ZnSe / ZnS, InP / ZnS / ZnSe, InPZn / ZnS, InPZn / ZnSe / ZnS, InPZn / ZnS / ZnSe can be used.

[0128] In a preferred embodiment of the present invention, the shell of the semiconductor luminescent nanoparticle is a double shell. The semiconductor luminescent nanoparticle is publicly available, for example, from Sigma-Aldrich and / or described in, for example, ACS Nano, 2016, 10 (6), pp 5769-5781, Chem. Moter. 2015, 27, 4893-4898 and International Patent Application No. WO 2010 / 095140 A2.

[0129] Additional ligands:

[0130] In addition to the organic ligands A, B and C defined above, the semiconductor luminescent nanoparticles according to the present invention optionally contain one or more different types of ligands attached to the outermost surface of the shell layer, provided that these ligands do not affect or interfere with the crosslinking or polymerization reaction, then the ligands of this type do not participate in the crosslinking or polymerization reaction used to form the polymeric outer layer.

[0131] Accordingly, the outermost surface of the shell layer of the semiconductor luminescent nanoparticle according to the present invention may be over-coated with different types of surface ligands and / or the organic ligands A, B and C as defined above as needed.

[0132] According to a preferred embodiment of the present invention, the total amount of organic ligands A, B and C attached to the outermost surface of one or more shell layers as defined above is in the range of 30 wt.% to 99.9 wt.% of the total ligands attached to the outermost surface of the shell layer, preferably in the range of 50 wt.% to 99.9 wt.%, and most preferably in the range of 70 wt.% to 99.9 wt.%.

[0133] Without intending to be bound by theory, it is believed that the surface ligands can make the nano-sized fluorescent material more easily dispersed in the solvent.

[0134] Commonly used surface ligands include phosphines and phosphine oxides, such as trioctylphosphine oxide (TOPO), trioctylphosphine (TOP) and tributylphosphine (TBP); phosphonic acids, such as dodecylphosphonic acid (DDPA), tridecylphosphonic acid (TDPA), octadecylphosphonic acid (ODPA) and hexylphosphonic acid (HPA); amines, such as oleylamine, dodecylamine (DDA), tetradecylamine (TDA), hexadecylamine (HDA) and octadecylamine (ODA), oleylamine (OLA); thiols, such as hexadecylthiol and hexanethiol; carboxylic acids, such as oleic acid, stearic acid, myristic acid; acetic acid and any combination of these.

[0135] Examples of surface ligands have been described, for example, in International Patent Application No. WO 2012 / 059931A.

[0136] method:

[0137] The problem solved by the present invention is also solved by a method for preparing semiconductor luminescent nanoparticles having a polymeric outer layer, the method comprising the following steps:

[0138] a) providing a semiconductor luminescent nanoparticle comprising a core, one or more shell layers and at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, which are attached to the outermost surface of the shell layer, wherein at least one organic ligand A comprises a crosslinkable functional group X, at least one organic ligand B comprises a crosslinkable functional group Y, and at least one organic ligand C comprises a crosslinkable functional group Z; and

[0139] b) crosslinking at least one organic ligand A, at least one organic ligand B and at least one organic ligand C to form a polymeric outer layer by subjecting the nanoparticles of step a) to conditions that allow direct linkages to form between at least one organic ligand A, at least one organic ligand B and at least one organic ligand C via crosslinkable functional groups X, Y and Z.

[0140] For example, according to the present invention, in the step of cross-linking at least one organic ligand A, at least one organic ligand B and at least one organic ligand C to form a polymeric outer layer, a direct bond between at least one organic ligand A and at least one organic ligand B and one organic ligand C, a direct bond between at least one organic ligand B and at least one organic ligand A and one organic ligand C, and / or a direct bond between at least one organic ligand C and at least one organic ligand A and one organic ligand B can be formed via cross-linkable functional groups X, Y and Z.

[0141] The core and one or more shells of the semiconductor luminescent nanoparticles are as defined above.

[0142] The at least one organic ligand A, the at least one organic ligand B and the at least one organic ligand C and the respective functional groups X, Y and Z are as defined above.

[0143] Accordingly, in a preferred embodiment of the present method, at least one organic ligand A, at least one organic ligand B and at least one organic ligand C are each represented by the general formula (I):

[0144] UVW(I),

[0145] wherein the groups U, V and W are as defined above.

[0146] According to another preferred embodiment of the method according to the invention, in each of at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, the groups U are identical and / or in each of at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, the groups V are identical.

[0147] Further more preferably, in each of at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, group U is a phosphonic acid group, and group V is a straight-chain alkylene group having 1 to 20 C atoms, wherein one or more non-adjacent methylene structural units (-CH2-) in the straight-chain alkylene group may be replaced by a phenylene group, a sulfonyl group, a carbonyl group, an ether group, a thioether group, a sulfoxide group, an ester group, a phosphate ester group, an amide group or an imine group.

[0148] According to another preferred embodiment of the method according to the present invention, the crosslinkable functional groups X, Y and Z in each of the at least one organic ligand A, the at least one organic ligand B and the at least one organic ligand C are identical.

[0149] Accordingly, it may be preferred according to the invention that the semiconductor nanoparticles obtainable or obtainable by the process according to the invention have a polymeric outer layer which is formed by direct bonding of the organic ligands A, B and C via the same crosslinkable functional groups.

[0150] According to yet another preferred embodiment of the method according to the invention, at least one organic ligand A, at least one organic ligand B and at least one organic ligand C are identical.

[0151] This means that it may be preferred according to the invention that the semiconductor nanoparticles obtainable or obtainable by the process of the invention have a polymeric outer layer which is formed by direct bonding of the same organic ligands A, B and C attached to the outermost surface of the nanoparticle.

[0152] More preferably, the functional groups X, Y and Z are identically selected from thiol groups, acrylate groups and styrene groups.

[0153] In a further preferred embodiment of the process according to the invention, at least one organic ligand A, at least one organic ligand B and at least one organic ligand C are identically selected from 11-mercaptoundecylphosphonic acid, 11-phosphonoundeyl acrylate and p-[(4-vinylphenyl)methyl]phosphonic acid.

[0154] In the method of the present invention, in step b) of crosslinking at least one organic ligand A, at least one organic ligand B and at least one organic ligand C via crosslinkable functional groups X, Y and Z to thereby form a polymeric outer layer, the type of crosslinking or polymerization reaction (i.e., reaction mechanism) is not particularly limited.

[0155] Any type of polymerization mechanism known to the person skilled in the art is suitable, such as condensation polymerization (polycondensation) or addition polymerization (polyaddition), in particular anionic polymerization, cationic polymerization, free-radical polymerization or coordination polymerization.

[0156] The type of polymerization mechanism depends primarily on the type of crosslinkable or polymerizable functional groups and / or the way in which the polymerization reaction is initiated and / or on the reaction conditions, all of which factors are known to those skilled in the art.

[0157] The conditions allowing the formation of the linkages of step b) of the process according to the invention are not particularly limited and any suitable conditions known to the person skilled in the art for initiating and propagating linkages and polymerisation reactions, respectively, may be applicable.

[0158] For example, a system including semiconductor light-emitting nanoparticles having at least one organic ligand A, at least one organic ligand B, and at least one organic ligand C (each in its non-crosslinked form) attached to the outermost surface of one or more shells can be heated to a temperature of, for example, about 20°C to about 200°C to initiate and propagate a crosslinking or polymerization reaction.

[0159] Alternatively, the system may be exposed to light of a predetermined wavelength, preferably UV (having a wavelength of about 100 nm to about 400 nm), to initiate and propagate the crosslinking or polymerization reaction.

[0160] Alternatively or in addition to applying heat or light exposure to the system, a polymerization initiator may be added to the system to initiate and promote the crosslinking or polymerization reaction. This allows crosslinking or polymerization to be initiated and propagated at lower temperatures or even without applying heat.

[0161] As used herein, a polymerization initiator is a molecule or compound that forms reactive species (free radicals, cations, or anions) through various pathways including dissociation and electron transfer.

[0162] Accordingly, a photoinitiator is a molecule or compound that forms the reactive species when exposed to light (UV or visible light), and a thermal initiator is a molecule or compound that forms the reactive species when heat is applied.

[0163] In the present method, the polymerization initiator is not particularly limited and may be, for example, a photoinitiator, a nucleophilic initiator, a free radical initiator or a thermal initiator, suitable examples of which are known to those skilled in the art. Preferably, a photoinitiator or a thermal initiator is used.

[0164] The reaction time for preparing the polymeric outer layer, i.e. the duration of the crosslinking or polymerization reaction is not particularly limited and can be appropriately selected. For example, crosslinking can be performed for more than or equal to about 1 minute, for example, from about 10 minutes to about 12 hours, but is not limited thereto.

[0165] The applied temperature and the wavelength and intensity of the light exposure can be selected based on the type and amount of thermal initiator and photoinitiator, respectively, and the type and amount of quantum dots, among other things.

[0166] It is further preferred that, when a polymerization initiator is used, it is added in a relatively low amount of not more than 1.0 wt.-%, based on the total weight of the nanoparticles (ie including the surface-attached ligands).

[0167] As mentioned above, it is preferred according to the invention that the at least one organic ligand A, the at least one organic ligand B and the at least one organic ligand C are crosslinked with each other as defined above without adding and / or incorporating any (bifunctional) crosslinking agents.

[0168] Accordingly, in a preferred embodiment of the process according to the invention, in step b), the crosslinking is carried out in the absence of any crosslinking agent.

[0169] According to yet another preferred embodiment of the method according to the present invention, the step a) of providing nanoparticles comprises the following steps

[0170] a1) preparing a solution containing nanoparticle precursor species, the particles comprising a core and one or more shell layers and optionally an initial organic ligand compound attached to the outermost surface of the shell layer, and

[0171] a2) adding at least one organic ligand A, at least one organic ligand B and at least one organic ligand C comprising crosslinkable functional groups X, Y and Z to the solution, respectively.

[0172] As the solvent of step a1), for example, toluene, hexane, chloroform, ethyl acrylate, benzene, xylene, ether, tetrahydrofuran, dichloromethane, and heptane, and a mixture thereof may be used, without being limited thereto.

[0173] When at least one organic ligand A, at least one organic ligand B and at least one organic ligand C are added to a solution containing nanoparticle precursor species, if the initial organic ligand compound is present, it is replaced through ligand exchange and the linkage of each organic ligand A, B and C through the nanoparticle surface attached functional group is affected.

[0174] The initial organic ligand compound is not particularly limited and can be any compound known to those skilled in the art and commonly used in the art, for example to improve the storage behavior of nanoparticle precursor species, or it may be retained from the process of preparing nanoparticle precursors.

[0175] By following method step a) of the method of the present invention as described above, in particular method steps a1) and a2), a semiconductor luminescent nanoparticle can be prepared by this reaction step or can be obtained by this reaction step or can be obtained or separated therefrom, which comprises a core, one or more shell layers and at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, each of which is connected in its non-crosslinked form to the outermost surface of the shell layer, wherein at least one organic ligand A comprises a crosslinkable functional group X, at least one organic ligand B comprises a crosslinkable functional group Y, and at least one organic ligand C comprises a crosslinkable functional group Z, characterized in that the groups X, Y and Z can each serve as a crosslinking acceptor and as a crosslinking donor.

[0176] Therefore, the present invention also relates to a semiconductor luminescent nanoparticle, which is or is obtainable by reaction step a) of the method described herein.

[0177] The semiconductor luminescent nanoparticles obtained or obtainable by the method described herein comprise a core, one or more shell layers, at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, wherein the ligands are connected to the outermost surface of the shell layer, and a polymeric outer layer, characterized in that the polymeric outer layer is formed by direct bonding between at least one organic ligand A, at least one organic ligand B and at least one organic ligand C via crosslinkable functional groups X, Y and Z.

[0178] Therefore, the present invention further relates to a semiconductor luminescent nanoparticle having a polymeric outer layer obtainable or obtainable by the method described herein.

[0179] The method as described herein allows the preparation of semiconductor luminescent nanoparticles surrounded by a protective polymeric outer layer formed by intramolecular self-crosslinking of ligands attached to the surface of the nanoparticles and without the presence of any additional crosslinking agents or (co)polymers or other protective elements.

[0180] Based on the quantum material layer as the emitting element, the protective layer is formed using only surface-attached ligands, i.e., without adding any additional crosslinking agents and the like, so that the semiconductor light-emitting nanoparticles are kept at a high concentration in the layer of the organic device, thereby improving the light emission output from the optoelectronic device.

[0181] In addition, by using a functionalized ligand as defined herein, which comprises a nanoparticle surface attachment functional group and a cross-linkable functional group, it is possible to perform ligand exchange of the initial organic ligand compound and form a polymeric outer layer in one step. That is, a polymeric outer layer can be formed around the quantum dot while ligand exchange occurs.

[0182] The described polymeric outer layer of the semiconductor luminescent nanoparticle obtained by the method described herein prevents oxidative elements from such as the environment or surrounding matrix from penetrating, and this element reacts with the ligand and makes the ligand detach from the nanoparticle surface. In addition, this polymeric outer layer prevents the ligand detached from the surface from diffusing away, on the contrary, it is very likely to make the detached ligand be reconnected to the surface.

[0183] By this, the quantum yield reduction of quantum dots due to ligand detachment under heat and light conditions and in a free radical-rich environment can be avoided. In contrast, using the method described herein for preparing semiconductor light-emitting nanoparticles, the semiconductor nanoparticles have better performance and higher stability in solution and can resist free radical-rich environments.

[0184] Composition:

[0185] In another aspect, the present invention further relates to a composition comprising semiconductor luminescent nanoparticles having a polymeric outer layer as defined herein or obtained according to the method described herein, and at least one additional material, preferably an organic functional material, the additional material being more preferably selected from the group consisting of: a fluorescent emitter, a phosphorescent emitter, a host material, a matrix material, an electron transport material, an electron injection material, a hole transport material, a hole injection material, an electron blocking material, a hole blocking material, a wide bandgap material, a delayed fluorescence emitter and a delayed fluorescence host.

[0186] In a preferred embodiment of the invention, the additional material is a matrix material.

[0187] According to the present invention, a wide variety of transparent substrate materials known to the public to be suitable for optical devices can be preferably used.

[0188] According to the present invention, the term "transparent" means that the incident light transmission at a certain wavelength or a range of wavelengths used during the operation of the optical medium at the thickness used in the optical medium is at least about 60%. Preferably, it exceeds 70%, more preferably exceeds 75%, and most preferably exceeds 80%.

[0189] In some embodiments of the present invention, the transparent matrix material may be a transparent polymer.

[0190] According to the present invention, the term "polymer" means a material having a repeating unit and having a weight average molecular weight (Mw) of 1000 or more.

[0191] In some embodiments of the present invention, the glass transition temperature (Tg) of the transparent polymer is 70° C. or higher and 250° C. or lower.

[0192] Tg is measured based on the change in heat capacity observed in differential scanning calorimetry as described in Rickey J Seyler, Assignment of the Glass Transition, ASTM Publication No. (PCN) 04-012490-50.

[0193] For example, poly(meth)acrylate, epoxy resin, polyurethane, polysiloxane can be preferably used as the transparent polymer for the transparent matrix material.

[0194] In a preferred embodiment of the present invention, the weight average molecular weight (Mw) of the polymer as the transparent matrix material is in the range of 1,000 to 300,000.

[0195] More preferably, it is 10,000 to 250,000.

[0196] Formulation:

[0197] The present invention further relates to a formulation comprising semiconductor luminescent nanoparticles having a polymeric outer layer as defined herein or a composition as defined herein, and at least one solvent.

[0198] The solvent is preferably selected from one or more members of the group consisting of aromatic, halogenated and aliphatic hydrocarbon solvents, more preferably selected from one or more members of the group consisting of toluene, xylene, ether, tetrahydrofuran, chloroform, dichloromethane and heptane.

[0199] The amount of solvent in the formulation can be freely controlled according to the method of coating the formulation. For example, if the formulation is sprayed, it can contain 90wt.% or more of solvent. In addition, if a slot coating method is performed, which is often used for coating large substrates, the content of solvent is usually 60wt.% or more, preferably 70wt.% or more.

[0200] use:

[0201] The present invention further relates to the use of a semiconductor luminescent nanoparticle having a polymeric outer layer as defined herein or a composition or formulation according to the invention in an electronic, optical or biomedical device.

[0202] Optical Media:

[0203] The invention further relates to an optical medium comprising semiconductor luminescent nanoparticles having a polymeric outer layer as defined herein or a composition according to the invention.

[0204] In some embodiments of the present invention, the optical medium may be an optical film, such as an optical filter, a color conversion film, a remote phosphor strip, or other film or filter.

[0205] Optical device:

[0206] The invention further relates to an optical device comprising the optical medium according to the invention.

[0207] The optical device is preferably a liquid crystal display, an organic light emitting diode (OLED), a backlight unit for a display, a light emitting diode (LED), a microelectromechanical system (hereinafter “MEMS”), an electrowetting display or an electrophoretic display, a lighting device and / or a solar cell.

[0208] The present invention provides a new concept of using functionalized ligands as surface-attached ligands and making the surface-attached ligands themselves cross-linked (i.e., intramolecularly), the ligands comprising nanoparticle surface-attached functional groups and cross-linkable or polymerizable functional groups, thereby forming a polymeric network that forms or corresponds to a polymeric outer layer around the surface of the nanoparticles. The polymeric outer layer advantageously provides steric protection against any kind of external elements and also prevents the ligands detached from the surface from diffusing away, instead, it is likely to reattach the detached ligands to the surface.

[0209] Furthermore, advantageously, this protection concept does not require the addition of any additional materials, compounds or linkers to the semiconductor nanoparticles and therefore allows the coating of highly concentrated layers of semiconductor luminescent nanoparticles, thereby increasing the light emission output from optoelectronic devices based on the quantum material layer as the emissive element.

[0210] Preferred Implementation

[0211] Implementation 1.

[0212] A semiconductor luminescent nanoparticle comprising a core,

[0213] one or more shells, and

[0214] at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, which are attached to the outermost surface of the shell,

[0215] in

[0216] At least one organic ligand A comprises a crosslinkable functional group X,

[0217] At least one organic ligand B comprises a cross-linkable functional group Y, and

[0218] At least one organic ligand C comprises a crosslinkable functional group Z,

[0219] It is characterized in that the groups X, Y and Z are each capable of acting as a crosslinking acceptor and as a crosslinking donor.

[0220] Embodiment 2. The nanoparticle according to embodiment 1, characterized in that

[0221] The group X can act as a crosslink acceptor with respect to the group Y and as a crosslink donor with respect to the group Z, or as a crosslink acceptor with respect to the group Z and as a crosslink donor with respect to the group Y;

[0222] The group Y is capable of acting as a crosslink acceptor with respect to the group Z and as a crosslink donor with respect to the group X, or as a crosslink acceptor with respect to the group X and as a crosslink donor with respect to the group Z; and

[0223] The group Z can act as a crosslinking acceptor with respect to the group X and as a crosslinking donor with respect to the group Y, or as a crosslinking acceptor with respect to the group Y and as a crosslinking donor with respect to the group X.

[0224] Embodiment 3. The nanoparticle according to Embodiment 1 or 2, characterized in that at least one organic ligand A, at least one organic ligand B and at least one organic ligand C are each represented by the following general formula (I):

[0225] UVW (I)

[0226] wherein U is the same or different nanoparticle surface linking group each time it appears in ligands A, B and C, V is the same or different linker group each time it appears in ligands A, B and C, and W corresponds to the crosslinkable functional groups X, Y and Z, respectively.

[0227] Embodiment 4. The nanoparticle according to Embodiment 3, characterized in that, in formula (I),

[0228] U is selected, identically or differently, on each occurrence in the ligands A, B and C from the group consisting of a phosphonic acid group, a thiol group, a thiolate group, a thioacid group, a dithioacid group, a mercaptoester group, a carboxylic acid group, a carboxylate group, in particular a Zn carboxylic acid group, a phosphonate group, in particular a Zn phosphonic acid, a thiocarbamate group, in particular a Zn thiocarbamate group, a phosphine group, a phosphine oxide group, an amine group, an amide group and a selenol group;

[0229] V is selected, at each occurrence in the ligands A, B and C, identically or differently from the group consisting of: a straight-chain alkylene group having 1 to 20 C atoms or a branched-chain alkylene group having 3 to 20 C atoms, wherein one or more non-adjacent methylene structural units (-CH2-) in the straight-chain and branched alkylene groups may be replaced in each case by a phenylene, sulfonyl, carbonyl, ether, thioether, sulfoxide, ester, phosphate, amide or imine group, or a straight-chain alkenylene or alkynylene group having 2 to 20 C atoms or a branched alkenylene or alkynylene group having 3 to 20 C atoms, wherein one or more methylene structural units (-CH2-) in the straight-chain and branched alkenylene or alkynylene groups may be replaced in each case by a phenylene, sulfonyl, carbonyl, ether, thioether, sulfoxide, ester, phosphate, amide or imine group; and

[0230] X, Y and Z are independently selected from the group consisting of a thiol group, an acrylate group, a styrene group, a carbonate group and a carbamate (urethane) group.

[0231] Embodiment 5. Nanoparticles according to Embodiment 3 or 4, characterized in that in each of at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, the groups U are the same, and / or in each of at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, V is the same.

[0232] Embodiment 6. Nanoparticles according to any one of Embodiments 3 to 5, characterized in that U is a phosphonic acid group and the group V is a straight-chain alkylene group having 1 to 20 C atoms, wherein one or more non-adjacent methylene structural units (-CH2-) in the straight-chain alkylene group can be replaced by a phenylene group, a sulfonyl group, a carbonyl group, an ether group, a thioether group, a sulfoxide group, an ester group, a phosphate ester group, an amide group or an imine group.

[0233] Embodiment 7. Nanoparticles according to any one of embodiments 1 to 6, characterized in that the groups X, Y and Z are identical.

[0234] Embodiment 8. The nanoparticle according to any one of embodiments 1 to 7, characterized in that at least one organic ligand A, at least one organic ligand B and at least one organic ligand C are identical.

[0235] Embodiment 9. Nanoparticles according to any one of embodiments 1 to 8, characterized in that the groups X, Y and Z are identically selected from thiol groups, acrylate groups and styrene groups.

[0236] Embodiment 10. Nanoparticles according to any one of embodiments 1 to 9, characterized in that at least one organic ligand A, at least one organic ligand B and at least one organic ligand C are identically selected from 11-mercaptoundecylphosphonic acid, 11-phosphonylundecyl acrylate and p-[(4-vinylphenyl)methyl]phosphonic acid.

[0237] Embodiment 11. The semiconductor luminescent nanoparticle according to any one of embodiments 1 to 10, comprising

[0238] nuclear,

[0239] one or more shells,

[0240] at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, which are attached to the outermost surface of the shell, and

[0241] A polymeric outer layer, characterized in that

[0242] The polymeric outer layer is formed by direct bonding between at least one organic ligand A, at least one organic ligand B and at least one organic ligand C via crosslinkable functional groups X, Y and Z.

[0243] Embodiment 12. A semiconductor luminescent nanoparticle according to embodiment 11, characterized in that the polymer outer layer is formed by directly bonding at least one organic ligand A with at least one organic ligand B and one organic ligand C, directly bonding at least one organic ligand B with at least one organic ligand A and one organic ligand C, and / or directly bonding at least one organic ligand C with at least one organic ligand A and one organic ligand B through crosslinkable functional groups X, Y and Z.

[0244] Embodiment 13. A method for preparing semiconductor luminescent nanoparticles having a polymeric outer layer, the method comprising the following steps:

[0245] a) providing a semiconductor luminescent nanoparticle comprising a core, one or more shell layers and at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, which are attached to the outermost surface of the shell layer, wherein at least one organic ligand A comprises a crosslinkable functional group X, at least one organic ligand B comprises a crosslinkable functional group Y, and at least one organic ligand C comprises a crosslinkable functional group Z; and

[0246] b) crosslinking at least one organic ligand A, at least one organic ligand B and at least one organic ligand C to form a polymeric outer layer by subjecting the nanoparticles of step a) to conditions that allow direct linkages to form between at least one organic ligand A, at least one organic ligand B and at least one organic ligand C via crosslinkable functional groups X, Y and Z.

[0247] Embodiment 14. The method according to Embodiment 13, characterized in that at least one organic ligand A, at least one organic ligand B and at least one organic ligand C are each represented by the following general formula (I):

[0248] UVW (I)

[0249] wherein U is the same or different nanoparticle surface linking group at each occurrence in ligands A, B and C, V is the same or different linker group at each occurrence, and W corresponds to the crosslinkable functional groups X, Y and Z, respectively.

[0250] Embodiment 15. The method according to embodiment 14, characterized in that in formula (I), U is selected, identically or differently, on each occurrence in ligands A, B and C from the group consisting of: phosphonic acid, thiol, thiolate, thioacid, dithioacid, mercaptoester, carboxylic acid, carboxylate, in particular Zn carboxylic acid, phosphonate, in particular Zn phosphonic acid, thiocarbamate, in particular Zn thiocarbamate, phosphine, phosphine oxide, amine, amide and selenol;

[0251] V is selected, at each occurrence in the ligands A, B and C, identically or differently from the group consisting of: a straight-chain alkylene group having 1 to 20 C atoms or a branched-chain alkylene group having 3 to 20 C atoms, wherein one or more non-adjacent methylene structural units (—CH—) in the straight-chain and branched alkylene groups may in each case be replaced by a phenylene, sulfonyl, carbonyl, ether, thioether, sulfoxide, ester, phosphate, amide or imine group, or a straight-chain alkenylene or alkynylene group having 2 to 20 C atoms or a branched alkenylene or alkynylene group having 3 to 20 C atoms, wherein one or more methylene structural units (—CH—) in the straight-chain and branched alkenylene or alkynylene groups may in each case be replaced by a phenylene, sulfonyl, carbonyl, ether, thioether, sulfoxide, ester, phosphate, amide or imine group;

[0252] X, Y and Z are each independently selected from the group consisting of a thiol group, an acrylate group, a styrene group, a carbonate group and a carbamate (urethane) group.

[0253] Embodiment 16. The method according to embodiment 14 or 15, characterized in that in each of at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, the group U is the same, and / or in each of at least one organic ligand A, at least one organic ligand B and at least one organic ligand C, the group V is the same.

[0254] Embodiment 17. A method according to any one of embodiments 14 to 16, characterized in that U is a phosphonic acid group and V is a straight-chain alkylene group having 1 to 20 C atoms, wherein one or more non-adjacent methylene structural units (-CH2-) in the straight-chain alkylene group can be replaced by a phenylene group, a sulfonyl group, a carbonyl group, an ether group, a thioether group, a sulfoxide group, an ester group, a phosphate ester group, an amide group or an imine group.

[0255] Embodiment 18. The process according to any one of embodiments 13 to 17, characterized in that the groups X, Y and Z are identical.

[0256] Embodiment 19. The method according to any one of embodiments 13 to 18, characterized in that at least one organic ligand A, at least one organic ligand B and at least one organic ligand C are identical.

[0257] Embodiment 20. The process according to any one of embodiments 13 to 19, characterized in that the groups X, Y and Z are identically selected from thiol groups, acrylate groups and styrene groups.

[0258] Embodiment 21. The method according to any one of embodiments 13 to 20, characterized in that at least one organic ligand A, at least one organic ligand B and at least one organic ligand C are identically selected from 11-mercaptoundecylphosphonic acid, 11-phosphonylundecanyl acrylate and p-[(4-vinylphenyl)methyl]phosphonic acid.

[0259] Embodiment 22. A method according to any one of embodiments 13 to 21, characterized in that in step b), the condition allowing the formation of a direct bond between at least one organic ligand A, at least one organic ligand B and at least one organic ligand C is the application of heat, optionally in the presence of a polymerization initiator, in particular in the presence of a thermal initiator.

[0260] Embodiment 23. A method according to any one of embodiments 13 to 21, characterized in that, in step b), the conditions allowing the formation of a direct bond between at least one organic ligand A, at least one organic ligand B and at least one organic ligand C are light exposure, optionally in the presence of a polymerization initiator, in particular in the presence of a photoinitiator.

[0261] Embodiment 24. The method according to embodiment 22 or 23, characterized in that the polymerization initiator is present in an amount of not more than 1.0 wt.-%, based on the total weight of the nanoparticles.

[0262] Embodiment 25. The method according to any one of embodiments 13 to 24, characterized in that the crosslinking in step b) is carried out without any crosslinking agent.

[0263] Embodiment 26. The method according to any one of embodiments 13 to 25, characterized in that step a) of providing nanoparticles comprises

[0264] a1) preparing a solution containing nanoparticle precursor species, the particles comprising a core and one or more shell layers and optionally an initial organic ligand compound attached to the outermost surface of the shell layer, and

[0265] a2) adding at least one organic ligand A, at least one organic ligand B and at least one organic ligand C comprising crosslinkable functional groups X, Y and Z to the solution, respectively.

[0266] Embodiment 27. A semiconductor luminescent nanoparticle obtained or obtainable by reaction step a) of embodiment 13.

[0267] Embodiment 28. A semiconductor luminescent nanoparticle having a polymeric outer layer, obtained or obtainable by the method of any one of embodiments 13 to 26.

[0268] Embodiment 29. A composition comprising at least one semiconductor luminescent nanoparticle according to embodiment 11 or 28 and at least one additional material, preferably an organic functional material, and the additional material is more preferably selected from the group consisting of: fluorescent emitters, phosphorescent emitters, host materials, matrix materials, electron transport materials, electron injection materials, hole transport materials, hole injection materials, electron blocking materials, hole blocking materials, wide bandgap materials, delayed fluorescence emitters and delayed fluorescence hosts.

[0269] Embodiment 30. A formulation comprising at least one semiconductor luminescent nanoparticle according to embodiment 11 or 28, or at least one composition according to embodiment 29, and at least one solvent, the solvent is preferably selected from one or more members of the group consisting of aromatic, halogenated and aliphatic hydrocarbon solvents, more preferably selected from one or more members of the group consisting of toluene, xylene, ether, tetrahydrofuran, chloroform, dichloromethane and heptane.

[0270] Embodiment 31. Use of the semiconductor luminescent nanoparticles according to embodiment 11 or 28, or the composition according to embodiment 29, or the formulation according to embodiment 30 in an electronic device, an optical device, or a biomedical device.

[0271] Embodiment 32. An optical medium comprising at least one semiconductor luminescent nanoparticle according to embodiment 11 or 28 or at least one composition according to embodiment 29 or a formulation according to embodiment 30.

[0272] Embodiment 33. An optical device comprising the optical medium according to embodiment 32.

[0273] The present invention is described in more detail below with the aid of examples, which should not be construed as limiting the scope of the present invention.

[0274] Working Example

[0275] Working Example 1 - Quantum Dot (QD) Ligand Exchange with 11-Mercaptoundecylphosphonic Acid (11-MPA) as Ligand:

[0276] 5mL of a solution containing a quantum dot precursor (50mg / mL QD in toluene) was mixed with 0.06g 11-MPA (purchased from Sigma-Aldrich-754269) and first stirred continuously at 50°C for 1 hour under argon to dissolve 11-MPA, and then further stirred overnight at 20°C for ligand exchange. The mixture was transferred to a centrifuge bottle, and 5mL of dry methanol was added. Subsequently, the mixture was centrifuged at 4000rpm under argon for 5 minutes. Subsequently, the colorless supernatant was removed, and the red precipitate was suspended in 5mL of dry toluene.

[0277] To demonstrate ligand exchange, the quantum dots thus obtained and the precursor quantum dots (i.e., QDs before ligand exchange) were analyzed by Fourier transform infrared spectroscopy (FT-IR). All FT-IR measurements shown herein were measured using Bruker's Vertex 70 (ATR diamond A225 / QHP).

[0278] Figure 1 FT-IR spectra of the quantum dot samples before and after ligand exchange with 11-MPA. 1450cm -1 and 1550cm -1 The disappearance of the peak at indicates effective ligand exchange. To this end, 50 uL of 11-MPA-capped QDs dissolved in toluene were deposited on the ATR Diamond A225 / QHP surface at room temperature. The solvent was allowed to evaporate for 1 minute before measurement.

[0279] Cross-linking:

[0280] 100 mg of the quantum dots thus obtained were dissolved in 2 mL of dry toluene and mixed with 3 mg of a photoinitiator, Irgacure TPO (diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, purchased from Sigma-Aldrich-415952). The mixture was stirred at 20° C. for 1 hour under argon while irradiating with 2 mW / cm 2 Expose it to light with a wavelength of 365nm at an intensity of

[0281] Figure 2a is an image of a 11-MPA sample after cross-linking (i.e., after exposure to light), and Figure 2b : are SEM images of the precursor quantum dot sample (i.e., before ligand exchange, corresponding to Comparative Example 1 below), each of which was taken under a scanning electron microscope (SEM). SEM image of the 11-MPA sample of Working Example 1 ( Figure 2a ) shows large structures, indicating the aggregation of 11-MPA, while the SEM image of the precursor quantum dot sample ( Figure 2b ) do not display these structures.

[0282] Working Example 2 - Quantum Dots with p-[(4-vinylphenyl)methyl]phosphonic acid as ligand

[0283] Ligand exchange:

[0284] 5 mL of a solution containing a quantum dot precursor (50 mg / mL QD in tetrahydrofuran (THF)) was mixed with 0.16 g of p-[(4-vinylphenyl)methyl]phosphonic acid (specific polymer; SP-51-003) and stirred overnight at 50° C. under argon for ligand exchange. Subsequently, THF was evaporated, and the quantum dots obtained therefrom were redissolved in toluene at a concentration of 50 mg / mL. The mixture was transferred to a centrifuge bottle, and dry methanol was added. The final ratio of toluene:methanol in the mixture was 2:1. Subsequently, the mixture was centrifuged at 4000 rpm under argon for 5 minutes. Subsequently, the colorless supernatant was removed, and the red precipitate was suspended in dry toluene at a concentration of 50 mg / mL.

[0285] Cross-linking:

[0286] In order to initiate and propagate the cross-linking reaction, the suspension thus obtained was heated to a temperature of 200° C. while maintaining the concentration of quantum dots at 15 mg / mL.

[0287] Working Example 3 - Quantum Dots with p-[(4-vinylphenyl)methyl]phosphonic acid as ligand

[0288] Ligand exchange:

[0289] Ligand exchange was performed as described for working example 2.

[0290] Cross-linking:

[0291] The thermal initiator 2,2′-azobis(2-methylpropionitrile) (0.2 M solution in toluene) (purchased from Sigma-Aldrich-714887) was added to the suspension thus obtained in an amount of about 1 wt.-% compared to the mass of the quantum dots, and the suspension was heated to 80° C., thereby initiating and propagating the cross-linking reaction, while maintaining the concentration of the quantum dots at 15 mg / mL.

[0292] Working Example 4 - Quantum Dots with 11-Phosphonoundecyl Acrylate as Ligand

[0293] Ligand exchange:

[0294] 15mL solution containing quantum dot precursor (25mg / mL in toluene) is mixed with 0.124g acrylic acid 11-phosphonyl undecyl ester (purchased from Sigma-Aldrich-795739) and stirred overnight at 50°C under argon for ligand exchange. 4mL mixture is transferred to a centrifuge bottle, and 4mL dry methanol is added. Subsequently, the mixture is centrifuged at 4000rpm for 10 minutes under argon. Subsequently, the red supernatant is evaporated, and the red precipitate is redissolved in 1mL hexane. The solution is transferred to a centrifuge bottle, and 2mL dry methanol is added. Subsequently, the mixture is centrifuged at 4000rpm for 10 minutes under argon. Subsequently, the near colorless supernatant is removed, and the red precipitate is redissolved in dry toluene at a concentration of 50mg / mL.

[0295] Cross-linking:

[0296] In order to initiate and propagate the cross-linking reaction, the solution thus obtained was heated to a temperature of 100° C. while maintaining the concentration of quantum dots at 15 mg / mL.

[0297] Figure 3a and Figure 3b The FT-IR spectra of the quantum dot sample of Working Example 4 before cross-linking (but after exchange with 11-phosphonoundecyl acrylate ligand) and after cross-linking (i.e., the spectra are the same, but depicting different wavenumber ranges), and the intensities of the peaks associated with carbon-carbon double bonds are compared. To this end, 50 uL of quantum dots covered with 11-phosphonoundecyl acrylate dissolved in toluene were deposited on an ATR diamond A225 / QHP surface at room temperature.

[0298] The solvent was allowed to evaporate for 1 minute before measurement. During crosslinking, the peak intensity associated with the carbon-carbon double bond decreases (i.e., 809 cm -1 、1407cm -1 and 1636cm -1 , see Combination Figure 3a and Figure 3b Table 1) shows that these bonds open during the crosslinking reaction. In addition, after crosslinking, the 1610 cm -1 The new peak at represents the aggregation of ligands.

[0299] Determine peak intensity:

[0300]

[0301]

[0302] "Band @ X" means C = C vibration.

[0303] "Bandwidth @ 1735cm -1 ” represents the integral of C=O vibration.

[0304] "ratio 非CL " means the integral of C=C vibration (bandwidth @X) and the integral of C=O vibration (bandwidth @1735cm -1 ) ratio.

[0305] "ratio CL " represents the integral of C=C vibration (bandwidth @X) and C=O vibration (bandwidth @1735cm after cross-linking. -1 ) ratio.

[0306] In other words, the "bandwidth" refers to the FT-IR signal at the wavenumber that matches the known vibrational wavenumber of one of the bonds in the molecule being detected. This will appear as a Gaussian distribution in the FTIR spectrum.

[0307] When acrylic monomers polymerize, the C=C bonds open, while the C=O bonds remain intact. The C=O bond is at 1735 cm -1 wavenumber, so we will 1735cm -1 Used as a reference and to which the intensities of other vibrations are compared.

[0308] Then, we take the integral (also called ratio) of the C=C vibration (bandwidth @ X) before crosslinking. 非CL ) and C=O vibration after cross-linking (bandwidth @ 1735cm -1 ) of the integral (ratio) CL ) comparison. When the ratio CL Less than ratio 非CL , this means that we have fewer C=C bonds than C=O bonds, indicating true crosslinking.

[0309] Table 1:

[0310] <![CDATA[Wavenumber [cm -1 > <![CDATA[Ratio 非CL / Ratio CL > 1735 1 1636 2.3 1610 0.5 1407 2.1 809 2.8

[0311] Working Example 5 - Quantum Dots with 11-Phosphonoundecyl Acrylate as Ligand

[0312] Ligand exchange:

[0313] Ligand exchange was performed as described for working example 4.

[0314] Cross-linking:

[0315] The photoinitiator Irgacure TPO was added to the solution obtained above in an amount of about 1 wt.-% compared to the mass of the quantum dots. The mixture was stirred at 20° C. for 1 hour under argon while irradiating with 2 mW / cm 2 The cross-linking reaction is initiated and propagated by exposure to light at a wavelength of 365 nm.

[0316] Working Example 6 - Measurement of Quantum Yield (QY)

[0317] All measurements on quantum yield were performed using a Hamamatsu Quantaurus absolute PL quantum yield spectrometer model c11347-11.

[0318] A sample of the mixture of Working Example 1 before exposure to light (i.e., after ligand exchange, but before crosslinking) and a sample of the mixture of Working Example 1 after exposure to light (365 nm, 1 hour) were selected, and each sample was diluted with dry toluene to a concentration of 0.08 mg / mL. Subsequently, the initial quantum yield of the quantum dots (i.e., after ligand exchange, but before exposure to light) and the quantum yield after exposure to light (365 nm, 1 hour) were measured (see FIG. 3 ).

[0319] Comparative Example 1 - Measurement of Precursor Quantum Dots and Quantum Yield (QY)

[0320] Precursor quantum dots as originally used in Working Examples 1 to 5 (i.e., the QDs still have their initial ligands attached to the surface, which are not ligands of the present invention and have not undergone ligand exchange with ligands according to the present invention) were dissolved in dry toluene at a concentration of 0.08 mg / mL, and the initial quantum yield was measured.

[0321] Subsequently, 100 mg of the precursor quantum dots were dissolved in 2 mL of toluene and mixed with 3 mg of the photoinitiator Irgacure TPO. The mixture was then stirred at 20° C. for 1 hour while irradiating with 2 mW / cm 2 The sample was then exposed to light at a wavelength of 365 nm at an intensity of 1.5 Å. The sample was then taken out, diluted with dry toluene to a concentration of 0.08 mg / mL and the quantum yield was measured again.

[0322] exist Figure 4, the normalized quantum yields measured in Working Example 6 and Comparative Example 1 are shown. Figure 4 The initial quantum yield (t = 0 hours) and the quantum yield after exposure to 365 nm light (t = 1 hour) of the quantum dots obtained from Working Example 6 and Comparative Example 1 (precursor quantum dots) are shown. It can be seen that due to ligand exchange and crosslinking with 11-MPA as a ligand, the QDs pass the stability test better than the precursor QDs. Under the same conditions, the ligand-exchanged QDs with crosslinked ligands (Working Example 6) show a decrease in QY of 11% after 1 hour, while the precursor QDs with initial, non-crosslinked ligands (Comparative Example 1) show a decrease of 30%.

Claims

1. A semiconductor luminescent nanoparticle comprising nuclear, one or more shells, and at least one organic ligand A, at least one organic ligand B and at least one organic ligand C attached to the outermost surface of the shell, in The at least one organic ligand A comprises a crosslinkable functional group X, The at least one organic ligand B comprises a cross-linkable functional group Y, and The at least one organic ligand C comprises a crosslinkable functional group Z, Features The groups X, Y and Z are each capable of acting as a crosslinking acceptor and as a crosslinking donor, It is characterized in that the at least one organic ligand A, the at least one organic ligand B and the at least one organic ligand C are each represented by the general formula (I) UVW (I) wherein U is the same or different nanoparticle surface linking group each time it appears in ligands A, B and C, V is the same or different linking group each time it appears in ligands A, B and C, and W corresponds to the crosslinkable functional groups X, Y and Z, respectively, and U is a phosphonic acid group, Semiconductor luminescent nanoparticles are quantum-sized materials. wherein the core of the semiconductor luminescent nanoparticle comprises one or more elements of Group 13 of the periodic table and one or more elements of Group 15 of the periodic table, wherein at least one of the shells comprises a first element of Group 12, Group 13, or Group 14 of the periodic table and a second element of Group 15 or Group 16 of the periodic table.

2. The nanoparticle according to claim 1, characterized in that The group X can act as a crosslink acceptor with respect to the group Y and as a crosslink donor with respect to the group Z, or as a crosslink acceptor with respect to the group Z and as a crosslink donor with respect to the group Y; The group Y is capable of acting as a crosslink acceptor with respect to the group Z and as a crosslink donor with respect to the group X, or as a crosslink acceptor with respect to the group X and as a crosslink donor with respect to the group Z; and The group Z can act as a crosslinking acceptor with respect to the group X and as a crosslinking donor with respect to the group Y, or as a crosslinking acceptor with respect to the group Y and as a crosslinking donor with respect to the group X.

3. The nanoparticle according to claim 1, characterized in that In formula (I), U is a phosphonic acid group; V is selected, at each occurrence in the ligands A, B and C, identically or differently from the group consisting of: a straight-chain alkylene group having 1 to 20 C atoms or a branched-chain alkylene group having 3 to 20 C atoms, wherein one or more non-adjacent methylene structural units (-CH2-) in the straight-chain and branched alkylene groups may be replaced in each case by a phenylene, sulfonyl, carbonyl, ether, thioether, sulfoxide, ester, phosphate, amide or imine group, or a straight-chain alkenylene or alkynylene group having 2 to 20 C atoms or a branched alkenylene or alkynylene group having 3 to 20 C atoms, wherein one or more methylene structural units (-CH2-) in the straight-chain and branched alkenylene or alkynylene groups may be replaced in each case by a phenylene, sulfonyl, carbonyl, ether, thioether, sulfoxide, ester, phosphate, amide or imine group; and X, Y and Z are independently selected from the group consisting of an acrylate group, a styrene group, a carbonate group and a urethane group.

4. Nanoparticles according to claim 1 or 3, characterized in that In each of the at least one organic ligand A, the at least one organic ligand B and the at least one organic ligand C, the group U is the same, and / or in each of the at least one organic ligand A, the at least one organic ligand B and the at least one organic ligand C, V is the same.

5. The nanoparticle according to claim 1 or 3, characterized in that U is a phosphonic acid group, and the group V is a straight-chain alkylene group having 1 to 20 C atoms, wherein one or more non-adjacent methylene structural units (-CH2-) in the straight-chain alkylene group may be replaced by a phenylene group, a sulfonyl group, a carbonyl group, an ether group, a thioether group, a sulfoxide group, an ester group, a phosphate ester group, an amide group or an imine group.

6. Nanoparticles according to claim 1 or 2, characterized in that The groups X, Y and Z are identical.

7. Nanoparticles according to claim 1 or 2, characterized in that The at least one organic ligand A, the at least one organic ligand B and the at least one organic ligand C are the same.

8. The nanoparticle according to claim 1 or 2, characterized in that The groups X, Y and Z are identically selected from thiol groups, acrylate groups and styrene groups.

9. The nanoparticle according to claim 1 or 2, characterized in that The at least one organic ligand A, the at least one organic ligand B and the at least one organic ligand C are identically selected from 11-mercaptoundecylphosphonic acid, 11-phosphonylundecanyl acrylate and p-[(4-vinylphenyl)methyl]phosphonic acid.

10. The semiconductor luminescent nanoparticle according to claim 1 or 2, comprising nuclear, one or more shells, at least one organic ligand A, at least one organic ligand B and at least one organic ligand C attached to the outermost surface of the shell, and A polymeric outer layer characterized in that The polymeric outer layer is formed by direct bonding between the at least one organic ligand A, the at least one organic ligand B and the at least one organic ligand C via the crosslinkable functional groups X, Y and Z.

11. A method for preparing semiconductor luminescent nanoparticles having a polymeric outer layer, the method comprising the following steps: c) providing a semiconductor luminescent nanoparticle comprising a core, one or more shell layers, and at least one organic ligand A, at least one organic ligand B, and at least one organic ligand C connected to the outermost surface of the shell layer, wherein the at least one organic ligand A comprises a crosslinkable functional group X, the at least one organic ligand B comprises a crosslinkable functional group Y, and the at least one organic ligand C comprises a crosslinkable functional group Z; and d) crosslinking the at least one organic ligand A, the at least one organic ligand B and the at least one organic ligand C to form a polymeric outer layer by subjecting the nanoparticles of step a) to conditions that allow direct linkages to form between the at least one organic ligand A, the at least one organic ligand B and the at least one organic ligand C via the crosslinkable functional groups X, Y and Z, The at least one organic ligand A, the at least one organic ligand B and the at least one organic ligand C are each represented by the following general formula (I): UVW (I) wherein U is the same or different nanoparticle surface linking group each time it appears in ligands A, B and C, V is the same or different linking group each time it appears, and W corresponds to the crosslinkable functional groups X, Y and Z, respectively, and U is a phosphonic acid group, Semiconductor luminescent nanoparticles are quantum-sized materials. wherein the core of the semiconductor luminescent nanoparticle comprises one or more elements of Group 13 of the periodic table and one or more elements of Group 15 of the periodic table, wherein at least one of the shells comprises a first element of Group 12, Group 13, or Group 14 of the periodic table and a second element of Group 15 or Group 16 of the periodic table.

12. The method according to claim 11, characterized in that In formula (I), U is a phosphonic acid group; V is selected, at each occurrence in the ligands A, B and C, identically or differently from the group consisting of: a straight-chain alkylene group having 1 to 20 C atoms or a branched-chain alkylene group having 3 to 20 C atoms, wherein one or more non-adjacent methylene structural units (—CH—) in the straight-chain and branched alkylene groups may in each case be replaced by a phenylene, sulfonyl, carbonyl, ether, thioether, sulfoxide, ester, phosphate, amide or imine group, or a straight-chain alkenylene or alkynylene group having 2 to 20 C atoms or a branched alkenylene or alkynylene group having 3 to 20 C atoms, wherein one or more methylene structural units (—CH—) in the straight-chain and branched alkenylene or alkynylene groups may in each case be replaced by a phenylene, sulfonyl, carbonyl, ether, thioether, sulfoxide, ester, phosphate, amide or imine group; X, Y and Z are each independently selected from the group consisting of an acrylate group, a styrene group, a carbonate group and a urethane group.

13. A method according to claim 11 or 12, characterised in that In each of the at least one organic ligand A, the at least one organic ligand B and the at least one organic ligand C, the group U is the same, and / or in each of the at least one organic ligand A, the at least one organic ligand B and the at least one organic ligand C, the group V is the same.

14. A method according to claim 11 or 12, characterised in that U is a phosphonic acid group, and V is a straight-chain alkylene group having 1 to 20 C atoms, wherein one or more non-adjacent methylene structural units (-CH2-) in the straight-chain alkylene group may be replaced by a phenylene group, a sulfonyl group, a carbonyl group, an ether group, a thioether group, a sulfoxide group, an ester group, a phosphate ester group, an amide group or an imine group.

15. A method according to claim 11 or 12, characterised in that The groups X, Y and Z are identical.

16. A method according to claim 11 or 12, characterised in that The at least one organic ligand A, the at least one organic ligand B and the at least one organic ligand C are the same.

17. The method according to claim 11, characterized in that The groups X, Y and Z are identically selected from thiol groups, acrylate groups and styrene groups.

18. Semiconductor luminescent nanoparticles having a polymeric outer layer, obtainable by the method according to any one of claims 11 to 16.

19. A composition comprising at least one semiconductor luminescent nanoparticle according to claim 10 or 18 and at least one additional material.

20. The composition according to claim 19, wherein the additional material is an organofunctional material.

21. The composition of claim 19, wherein the additional material is selected from the group consisting of a fluorescent emitter, a phosphorescent emitter, a host material, a matrix material, an electron transport material, an electron injection material, a hole transport material, a hole injection material, an electron blocking material, a hole blocking material, a wide bandgap material, a delayed fluorescent emitter, and a delayed fluorescent host.

22. Formulation comprising at least one semiconductor luminescent nanoparticle according to claim 10 or 18, or at least one composition according to any one of claims 19 to 21, and at least one solvent.

23. The formulation according to claim 22, wherein the solvent is selected from one or more members of the group consisting of aromatic, halogenated and aliphatic hydrocarbon solvents.

24. The formulation according to claim 22, wherein the solvent is selected from one or more members of the group consisting of toluene, xylene, ether, tetrahydrofuran, chloroform, dichloromethane and heptane.

25. Use of semiconductor luminescent nanoparticles according to claim 10 or 18, or a composition according to any one of claims 19 to 21, or a formulation according to any one of claims 22 to 24, in an electronic device, an optical device or a biomedical device.

26. An optical medium comprising at least one semiconductor luminescent nanoparticle according to claim 10 or 18 or at least one composition according to any one of claims 19 to 21 or a formulation according to any one of claims 22 to 24.

27. An optical device comprising the optical medium according to claim 26.

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