WO2020099284A1

WO2020099284A1 - Nanoparticle

Info

Publication number: WO2020099284A1
Application number: PCT/EP2019/080781
Authority: WO
Inventors: Elizaveta KOSSOY; Shany NEYSHTADT; Kobi Yaacov Netanel Oded
Original assignee: Merck Patent Gmbh
Priority date: 2018-11-14
Filing date: 2019-11-11
Publication date: 2020-05-22

Abstract

The present invention relates to a light emitting nanoparticle; and a process for synthesizing the nanoparticle.

Description

Nanoparticle

Field of the invention

The present invention relates to a light emitting nanoparticle; a process for preparing a light emitting nanoparticle; composition, formulation and use of a light emitting nanoparticle, an optical medium; and an optical device.

Background Art

Light emitting nanoparticles are known in the prior art documents.

For example, EP 3072940 A1 , EP3072939 A1 , and EP 3072944 A2 describe CdSe/CdS, CdSe/CdZnS, and CdSe/ZnS core/shell nanoplatelets.

US 2014/0264172 A1 discloses process for synthesizing InPZnSe cores using zinc acetate and octane selenol.

WO 2008/132455 A1 mentions a use of selenol in a synthesis process of CIGS (copper indium zinc selenide) nanocrystals for photovoltaic cells. Patent Literature

1. EP 3072940 A1

2. EP3072939 A1

3. EP 3072944 A2

4. US 2014/0264172 A1

5. WO 2008/132455 A1

Non- Patent Literature

No literature Summary of the invention

However, the inventors newly have found that there is still one or more of considerable problems for which improvement is desired, as listed below; improvement of particle size distribution, better Full Width at Half Maximum (FWHM) value, improved self-absorption value, improvement of absorption per mg of nanoparticle(s), improvement of quantum yield of nanoparticle, well-controlled shell thickness, improved charge injection ability of nanoparticle, higher device efficiency, lowering trap emission of

nanoparticle, optimizing a surface condition of shell part of nanoparticle, reducing lattice defects of a shell layer of nanoparticle, reducing / preventing formation of dangling bonds of shell layer, better thermal stability, better chemical stability, optimizing fabrication process of nanoparticle, providing new fabrication process to improve size control of nanoparticle, providing new fabrication process for better kinetics control in shell formation, new shell formation process to realize well controlled shell thickness and/or reducing lattice defects of a shell layer, environmentally more friendly and safer fabrication process.

The inventors aimed to solve one or more of the above-mentioned problems.

Then it was found a novel process for fabricating a light emitting

nanoparticle comprising, essentially consisting of, or consisting of, at least following steps,

(a) mixing at least a first semiconducting nanomaterial and another material to get a reaction mixture, preferably said another material is a solvent,

(b) forming a shell layer onto the first semiconducting nanomaterial in the reaction mixture by reacting at least a chalcogen source selected from selenols, diselenides, a combination of these, or a combination of these with thiols and/or disulfides, preferably said chalcogen source is a selenium source selected from selenols, diselenides, or a combination of these, and a cation shell precursor in a reaction mixture, wherein said chalcogen source is injected into the reaction mixture during step (b),

(c) cooling the reaction mixture from step (b).

In another aspect, the present invention relates to a light emitting nanoparticle obtainable or obtained from the process of the present invention, preferably it is a light emitting semiconducting nanoparticle. In another aspect, the present invention also relates to composition comprising, essentially consisting of, or consisting of, at least one light emitting nanoparticle of the present invention, and at least one additional material, preferably the additional material is selected from the group consisting of organic light emitting materials, inorganic light emitting materials, charge transporting materials, scattering particles, host materials, nanosized plasmonic particles, photo initiators, and matrix materials. In another aspect, the present invention relates to formulation comprising, essentially consisting of, or consisting of, at least one light emitting nanoparticle of the present invention, or a composition of the present invention, and at least one solvent, preferably the solvent is 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, ethers,

tetrahydrofuran, chloroform, dichloromethane and heptane, purified water, ester acetates, alcohols, sulfoxides, formamides, nitrides, ketones. In another aspect, the present invention relates to use of the light emitting nanoparticle, the composition, or the formulation, in an electronic device, optical device or in a biomedical device. In another aspect, the present invention further relates to an optical medium comprising at least one light emitting nanoparticle of the present invention, or the composition.

In another aspect, the present invention further relates to an optical device comprising at least said optical medium.

Description of drawings

Figure 1 shows the emission spectrum of the nanoparticle obtained in working example 7.

Detailed description of the invention

- Process

According to the present invention, in one aspect, said process for fabricating a light emitting nanoparticle comprising, essentially consisting of, or consisting of, at least following steps,

(c) cooling the reaction mixture from step (b).

-Chalcogen source

According to the present invention, the term“chalcogen” means a chemical element of the group 16 chemical elements of the periodic table., preferably it is sulfur (S), selenium (Se), and/or tellurium (Te).

Thus, according to the present invention, the term“chalcogen source” means a material containing at least one chemical element of the group 16 chemical elements of the periodic table, preferably said chemical element of the group 16 chemical elements is sulfur (S), selenium (Se), and/or tellurium (Te), more preferably it is sulfur (S), or selenium (Se).

In a preferred embodiment of the present invention, said chalcogen source is a selenium source. More preferably, a selenium source is selected from selenols, diselenides, or a combination of these,

Step (a) - Mixing

In a preferred embodiment of the present invention, step (a) is carried out in an inert condition such as under Argon (Ar) or N2 condition, more preferably under Ar condition.

In a preferred embodiment of the present invention, said another material used in step (a) is a solvent, more preferably it is an organic solvent, even more preferably it is selected from one or more members of the group consisting of squalenes, squalanes, heptadecanes, octadecanes, octadecenes, nonadecanes, icosanes, henicosanes, docosanes, tricosanes, pentacosanes, hexacosanes, octacosanes, nonacosanes, triacontanes, hentriacontanes, dotriacontanes, tritriacontanes,

tetratriacontanes, pentatriacontanes, hexatriacontanes, oleylamines, and trioctylamines, with preferably being of squalene, squalane, heptadecane, octadecane, octadecene, nonadecane, icosane, henicosane, docosane, tricosane, pentacosane, hexacosane, octacosane, nonacosane,

triacontane, hentriacontane, dotriacontane, tritriacontane, tetratriacontane, pentatriacontane, hexatriacontane, oleylamine, and trioctylamine, more preferably octadecenes, oleylamine, squalane, pentacosane, hexacosane, octacosane, nonacosane, trioctylamine or triacontane, even more preferably octadecenes, oleylamine, squalane, pentacosane, trioctylamine or hexacosane.

In a preferred embodiment of the present invention, said mixing step is carried out at the temperature in the range of from 0°C to 100°C, preferably from 5 to 60°C, more preferably from 10 to 40°C.

In a preferred embodiment of the present invention, a plurality of first semiconducting nanomaterials can be used in step (a).

- First semiconducting material

According to the present invention, several kinds of semiconducting material can be used as a core in step (a), for example, CdS, CdSe, CdTe, PbSe, PbS, ZnS, ZnSe, ZnSeS, ZnTe, ZnO, GaAs, GaP, GaSb, HgS, HgSe, HgSe, HgTe, InAs, InP, InPS, InPZnS, InPSe, InPZn, InPZnSe, InPZnSeS, InPGa, InPGaZn, InP/ZnSe, InZnP/ZnSe, InP/ZnSeTe,

InZnP/ZnSeTe, InGaP/ZnSe, InP/lnGaP, InZnP/lnGaP, InCdP, InPCdS, InPCdSe, InGaP, InGaPZn, InSb, AIAs, AIP, AlSb, CU2S, Cu2Se, CulnS2, CulnSe2, Cu2(ZnSn)S4, Cu2(lnGa)S4, T1O2 and a combination of any of these.

In some embodiments of the present invention, the first semiconducting material comprises at least a first element of group 13 or group 14 elements of the periodic table and a second element of group 14 or 15 elements of the periodic table, preferably said first element is an element of group 13 elements of the periodic table and said second element is an element of group 15 elements of the periodic table, more preferably the first element is In, Ga or a combination of In and Ga, the second element is P.

In a preferred embodiment of the present invention, the first semiconducting material can further comprise additional element selected from one or more member of the group consisting of Ga, Zn, S, and Se.

In some embodiments of the present invention, the first semiconducting material represented by following chemical formula (VIII) can be used more preferably in step (a) from a view point of less toxicity and environmental friendly,

wherein 0<x<1 , 0<y<1 , 0<z<1 , 0<q<1 , 0<x+y+z+q <1. In a preferred embodiment of the present invention, said first

semiconducting material is selected from the group consisting of InP, lnP:Zn, lnP:ZnS, InP nSe, lnP:ZnSSe, lnP:Ga,or lnP:GaZn, InP/ZnSe, InZnP/ZnSe, InGaP/ZnSe, InP/lnGaP, InZnP/lnGaP. In a preferable embodiment, the first semiconducting material is alloyed.

According to the present invention, a type of shape of the first

semiconducting nanosized material of the semiconducting light emitting nanoparticle, and shape of the semiconducting light emitting nanoparticle to be synthesized are not particularly limited. For examples, spherical shaped, elongated shaped, star shaped, polyhedron shaped, pyramidal shaped, multipod shaped such as tetrapod shaped, tetrahedron shaped, platelet shaped, cone shaped, and irregular shaped first semiconducting nanosized material and - or a semiconducting light emitting material can be synthesized.

In some embodiments of the present invention, the average diameter of the first semiconducting nanosized material is in the range from 1 to 12 nm, preferably from 1.5 nm to 3.5 nm.

Step (b) - Shell formation

According to the present invention, a shell layer is formed by applying following step (b),

(b) forming a shell layer onto the first semiconducting nanomaterial in a reaction mixture by reacting at least a chalcogen source selected from selenols, diselenides, a combination of these, or a combination of these with thiols and/or disulfides, preferably said chalcogen source is a selenium source selected from selenols, diselenides, a combination of these, and a cation shell precursor in a reaction mixture, wherein said chalcogen source is injected into the reaction mixture during step (b),

In a preferred embodiment of the present invention, said selenols are hydrocarbyl selenols and said diselenides are hydrocarbyl deselenides, more preferably said selenium source is represented by the following chemical formula (I) or (II),

R⁶-(CH₂)n-Se-H (I),

R⁷-(CH₂)n-Se-Se-(CH₂)n-R⁸ (II), n is 0 or an integer 1 to 3. R⁶ is a hydrocarbyl (alkyl, aryl, aralkyl and alkylaryl) group, preferably R⁶ is an aryl, alkylaryl, alkyl or aralkyl group.

More preferably, R⁶ is selected that the length of alkyl chain having 1 to 30 carbon atoms which maybe linear or branched, saturated or containing one or more unsaturated carbon-carbon bond, a linear alkyl group having 1 to 30 carbon atoms, a branched alkyl group having 3 to 30 carbon atoms, preferably R⁶ is a linear alkyl group having 1 to 30 carbon atoms, more preferably, R⁶ is a linear alkyl group having 5 to 25 carbon atoms, even more preferably R⁶ is a linear alkyl group having 8 to 20 carbon atoms,

Or R⁶ is an aryl group, means aromatic group containing 5-18 ring atoms, and can contain optional fused ring, which maybe saturated, unsaturated, or aromatic. Examples of an aryl groups include phenyl, naphthyl, biphenyl, phenanthryl, and anthracyl.

R⁷ is a hydrocarbyl (alkyl, aryl, aralkyl and alkylaryl) group, preferably R⁷ is an aryl, alkylaryl, alkyl or aralkyl group. More preferably, R⁷ is selected that the length of alkyl chain having 1 to 30 carbon atoms which maybe linear or branched, saturated or containing one or more unsaturated carbon-carbon bond, a linear alkyl group having 1 to 30 carbon atoms, a branched alkyl group having 3 to 30 carbon atoms, preferably R⁷ is a linear alkyl group having 1 to 30 carbon atoms, more preferably, R⁷ is a linear alkyl group having 5 to 25 carbon atoms, even more preferably R⁷ is a linear alkyl group having 8 to 20 carbon atoms,

Or R⁷ is an aryl group, means aromatic group containing 5-18 ring atoms, and can contain optional fused ring, which maybe saturated, unsaturated, or aromatic. Examples of an aryl groups include phenyl, naphthyl, biphenyl, phenanthryl, and anthracyl. R⁸ is a hydrocarbyl (alkyl, aryl, aralkyl and alkylaryl) group, preferably R⁸ is an aryl, alkylaryl, alkyl or aralkyl group.

More preferably, R⁸ is selected that the length of alkyl chain having 1 to 30 carbon atoms which maybe linear or branched, saturated or containing one or more unsaturated carbon-carbon bond, a linear alkyl group having 1 to 30 carbon atoms, a branched alkyl group having 3 to 30 carbon atoms, preferably R⁸ is a linear alkyl group having 1 to 30 carbon atoms, more preferably, R⁸ is a linear alkyl group having 5 to 25 carbon atoms, even more preferably R⁸ is a linear alkyl group having 8 to 20 carbon atoms,

Or R⁸ is an aryl group, means aromatic group containing 5-18 ring atoms, and can contain optional fused ring, which maybe saturated, unsaturated, or aromatic. Examples of an aryl groups include phenyl, naphthyl, biphenyl, phenanthryl, and anthracyl.

R⁷ and R⁸ can be same or different.

Other conditions for formation of a shell layer is described, for example in US8679543 B2 and Chem. Mater. 2015, 27, pp 4893-4898.

In some embodiments of the present invention, the chalcogen source is injected in two or more (n) aliquots of a fraction (1/n) of the whole amount of the chalcogen source in step (b).

Preferably (n) is in the range from 1 to 20, preferably 1 to 15, more preferably 1 to 12 to control shell formation and the thickness of the shell layer more precisely and easily by adjusting said injection number and the amount of the precursor. Preferably, said chalcogen source is a selenium source. In some embodiments of the present invention, the injection rate of chalcogen source is in the range from 0.15 mol%/min to 100 mol%/min, preferably from 0.3 mol%/min to 10 mol%/min, more preferably from 0.5 mol%/min to 5 mol%/min to control shell formation and the thickness of the shell layer more precisely and easily. Mol% is defined as % of the injected chalcogen source in relation to the total molar amount of the chalcogen source.

In some embodiments of the present invention, the chalcogen source is injected in two or more (n) aliquots of a fraction (1/n) of the whole amount of the chalcogen source in step (b) with the injection rate of chalcogen source in the range from 0.15 mol%/min to 100 mol%/min, preferably from 0.3 mol%/min to 10 mol%/min, more preferably from 0.5 mol%/min to 5 mol%/min to control shell formation and the thickness of the shell layer more precisely and easily. Mol% is defined as % of the injected chalcogen source in relation to the total molar amount of the chalcogen source.

Preferably it is in the range from 1 to 20, preferably 1 to 15, more preferably 1 to 12 to control shell formation and the thickness of the shell layer more precisely and easily by adjusting said injection number and the amount of the precursor. Preferably, said chalcogen source is a selenium source.

In some embodiments, said injection of chalcogen source is done

continuously during step (b) and the injection rate of chalcogen source is in the range from 0.15 mol%/min to 100 mol%/min, preferably from 0.3 mol%/min to 10 mol%/min, more preferably from 0.5 mol%/min to 5 mol%/min to control shell formation and the thickness of the shell layer more precisely and easily. Mol% is defined as % of the injected chalcogen source in relation to the total molar amount of the chalcogen source.to control shell formation and the thickness of the shell layer more precisely and easily. In a preferred embodiment of the present invention, the step (b) is carried out at the temperature in the range from 200°C to 320°C, preferably in the range from 200°C to 300 °C, more preferably in the range from 220°C to 300°C, even more preferably from 250°C to 300°C.

In a preferred embodiment of the present invention, step (b) is carried out in the range from 1 minute to 10 hours, preferably from 10 minutes to 5 hours, more preferably 20 minutes to 3 hours. In some embodiments of the present invention, ratio of the total molar amount of the chalcogen source, preferably a selenium source, to the total molar amount of the first semiconducting nanoparticle in step (b) is in the range from 125:1 to 60000:1 , more preferably 150:1 to 45000:1 , even more preferably 200:1 to 12000:1.

In some embodiments of the present invention, only said selenium source selected from selenols, diselenides or a combination of these, is used as the chalcogen source in step (b) to form the shell layer. in a preferable embodiment, said chalcogen source in each step is a selenium source as described in the section of“Chalcogen source” on page 5.

In a preferred embodiment of the present invention, said cation shell precursor is a salt of an element of the group 12 of the periodic table, more preferably said cation shell precursor is selected from one or more members of the group consisting of Zn-stearate, Zn-myristate, Zn-oleate, Zn-laurate, Zn-palmitate, Zn-acetylacetonate, Zn-undecylenate, Cd- stearate, Cd-myristate, Cd-oleate, Cd-laurate, Cd-palmitate, Cd- acetylacetonate, Cd-undecylenate, a metal halogen represented by chemical formula (III) and a metal carboxylate represented by chemical formula (IV), MX²n (III) wherein M is Zn²⁺, or Cd²⁺, preferably M is Zn²⁺, X² is a halogen selected from the group consisting of Cl , Br and I , n is 2,

[M(0₂CR¹) (O2CR²)] - (IV) wherein M is Zn²⁺, or Cd²⁺, preferably M is Zn²⁺;

R¹ is a linear alkyl group having 1 to 30 carbon atoms, a branched alkyl group having 3 to 30 carbon atoms, a linear alkenyl group having 2 to 30 carbon atoms, or a branched alkenyl group having 3 to 30 carbon atoms, preferably R¹ is a linear alkyl group having 1 to 30 carbon atoms, or a linear alkenyl group having 2 to 30 carbon atoms, more preferably, R¹ is a linear alkyl group having 2 to 25 carbon atoms, or a linear alkenyl group having 6 to 25 carbon atoms, even more preferably R¹ is a linear alkyl group having 2 to 20 carbon atoms, or a linear alkenyl group having 10 to 20 carbon atoms, furthermore preferably R¹ is a linear alkyl group having 2 to 20 carbon atoms,

R² is a linear alkyl group having 1 to 30 carbon atoms, a branched alkyl group having 3 to 30 carbon atoms, a linear alkenyl group having 2 to 30 carbon atoms, or a branched alkenyl group having 3 to 30 carbon atoms, preferably R² is a linear alkyl group having 1 to 30 carbon atoms, or a linear alkenyl group having 2 to 30 carbon atoms, more preferably R² is a linear alkyl group having 2 to 25 carbon atoms, or a linear alkenyl group having 6 to 25 carbon atoms, even more preferably R² is a linear alkyl group having 2 to 20 carbon atoms, or a linear alkenyl group having 10 to 20 carbon atoms, furthermore preferably R² is a linear alkyl group having 2 to 20 carbon atoms. In a preferred embodiment, R¹ and R² are the same.

In a preferred embodiment of the present invention, the ratio of the total amount of the chalcogen source, preferably a selenium source, and the total amount of the cation shell precursor used in step (b) is in the range from 20 : 1 to 1 : 20, preferably in the range from 12 : 1 to 1 : 12.

Step (b) can be applied for synthesizing not only a first shell layer but also a second shell layer and/or a multishell layer.

-Cooling step (c)

According to the present invention, cooling the reaction mixture is carried out in step (c), preferably to stop shell forming reaction accordingly. As a cooling method, several methods can be used singly or in

combination.

Such as removing a heat source, injecting a solvent such as a solvent at a room temperature, and/or applying air cooling. In some embodiment, the cooling rate in step (c) can be in the range from 0.03^°C/s to 50^°C/s, preferably it is from 0.1 ^°C/s to 10^°C/s.

In a preferred embodiment, the reaction mixture is cooled down to the temperature less than 100^°C, more preferably in the rage from 100^°C to 0^°C, even more preferably from 50^°C to 5^°C, furthermore preferably from

30^°C to 15^°C.

Step (e) - Mixing step to make a second mixture In some embodiments of the invention, the process further comprises step (e), preferably the process comprises step (e) before step (b), (e) mixing said chalcogen source and said cation shell precursor with the first semiconducting nanoparticle, optionally with another material, to make the second mixture at the temperature in the range of from 0°C to 100°C, preferably from 5 to 60°C, more preferably from 10 to 40°C.

In some embodiments, as an option, premixing the first semiconducting material and the chalcogen source to make a premixed mixture and then injecting the cation source to the premixed mixture can be done as step (e^') instead of said step (e) to make the second mixture. The same temperature range as described in step (e) can be applied for injecting the cation source to the premixed mixture.

Preferably, said chalcogen source is injected after injection of said cation shell precursor.

In some embodiments of the invention, the process further comprises following step (f)

(f) preparing a first semiconducting nanosized material in a first mixture by reacting at least one indium precursor and at least one phosphor precursor or by using a cluster being obtainable by reacting the metal cation precursor and the anion precursor, preferably said cluster is a magic sized cluster, said indium precursor is a metal halide represented by following chemical formula (V), metal carboxylate represented by following chemical formula (VI), or a combination of these, and said phosphor precursor is an amino phosphine represented by following chemical formula (VII), alkyl silyl phosphine such as tris trimethyl silyl phosphine, or a combination of these, lnX¹ ₃ (V) wherein X¹ is a halogen selected from the group consisting of Ch, Br and h, [ln(0₂CR³)₃] - (VI) wherein R³ is a linear alkyl group having 1 to 30 carbon atoms, a branched alkyl group having 3to 30 carbon atoms, a linear alkenyl group having 2 to 30 carbon atoms, or a branched alkenyl group having 3 to 30 carbon atoms, preferably R³ is a linear alkyl group having 1 to 30 carbon atoms, or a linear alkenyl group having 2 to 30 carbon atoms, more preferably, R³ is a linear alkyl group having 5 to 25 carbon atoms, or a linear alkenyl group having 6 to 25 carbon atoms, even more preferably R³ is a linear alkyl group 0 having 10 to 20 carbon atoms, or a linear alkenyl group having 10 to 20 carbon atoms, furthermore preferably R³ is a linear alkyl group having 10 to 20 carbon atoms,

(R⁴R⁵N)sP (VII)

5

wherein R⁴ and R⁵ are at each occurrence, independently or dependently, a hydrogen atom or a linear alkyl group having 1 to 25 carbon atoms or a linear alkenyl group having 2 to 25 carbon atoms, preferably a linear alkyl group having 1 to 10 carbon atoms, more preferably a linear alkyl group0 having 2 to 4 carbon atoms, even more preferably a linear alkyl group

having 2 carbon atoms, optionally, a zinc salt and/or a zinc carboxylate is added in step (f), preferably said zinc salt is represented by following chemical formula (III), (IV’) ₅ ZnX²n (III) wherein X² is a halogen selected from the group consisting of Cl , Br and I , n is 2, _n [Zn(0₂CR¹) (0₂CR²)] - (IV^') wherein R¹ is a linear alkyl group having 1 to 30 carbon atoms, a branched alkyl group having 3 to 30 carbon atoms, a linear alkenyl group having 2 to 30 carbon atoms, or a branched alkenyl group having 3 to 30 carbon atoms, preferably R¹ is a linear alkyl group having 1 to 30 carbon atoms, or a linear alkenyl group having 2 to 30 carbon atoms, more preferably, R¹ is a linear alkyl group having 5 to 25 carbon atoms, or a linear alkenyl group having 6 to 25 carbon atoms, even more preferably R¹ is a linear alkyl group having 10 to 20 carbon atoms, or a linear alkenyl group having 10 to 20 carbon atoms, furthermore preferably R¹ is a linear alkyl group having 10 to 20 carbon atoms,

R² is a linear alkyl group having 1 to 30 carbon atoms, a branched alkyl group having 3 to 30 carbon atoms, a linear alkenyl group having 2 to 30 carbon atoms, or a branched alkenyl group having 3 to 30 carbon atoms, preferably R² is a linear alkyl group having 1 to 30 carbon atoms, or a linear alkenyl group having 2 to 30 carbon atoms, more preferably R² is a linear alkyl group having 5 to 25 carbon atoms, or a linear alkenyl group having 6 to 25 carbon atoms, even more preferably R² is a linear alkyl group having 10 to 20 carbon atoms, or a linear alkenyl group having 10 to 20 carbon atoms, furthermore preferably R² is a linear alkyl group having 10 to 20 carbon atoms.

R¹ and R² can be the same or different.

(g) quenching the formation of the first semiconducting nanoparticle by cooling the first mixture in step (f).

-Clusters used in step (f)

In some embodiments of the present invention, the first semiconducting nanosized material in step (f) is prepared in a first mixture by using a cluster being obtainable by reacting the metal cation precursor and the anion precursor.

In some embodiments of the present invention, the first semiconducting nanosized material in step (f) is prepared in a first mixture by using the cluster, and the cluster is a Magic Sized Cluster(MSC) selected from the group consisting of InP, InAs, InSb, GaP, GaAs, and GaSb, magic sized clusters (MSC), preferably InP magic sized cluster (MSC InP), more preferably, it is ln₃₇P2o(02CR4)5i, wherein said O2CR4 of said

ln₃₇P₂o(0₂CR₄)_5i is -02CCH2Phenyl, or a substituted or unsubstituted fatty acid such as hexanoate, heptanoate, octanoate, nonanoate, decanoate, undecanoate, dodecanoate, tridecanoate, tetradecanoate, pentadecanoate, hexadecanoate, heptadecanoate, octadecanoate, nonadecanoate, icosanoate or oleate.

In some embodiments of the present invention, the first semiconducting nanosized material in step (f) is prepared in a first mixture by using the cluster, and the cluster is a Magic Sized Cluster(MSC), wherein the magic sized cluster (MSC), is based on a nanocrystal core, which consists solely of fused 6-membered rings with all phosphorus atoms coordinated to four indium atoms in a pseudo-tetrahedral arrangement, preferably the nanocrystal core have the formula [ln2iP2o]³⁺, [ln42P4o]⁶⁺, [I^h63Rqo]⁹⁺,

[ln₈ P8o]¹²⁺, [ln₉₅P9o]¹⁵⁺, [I^h ₃iR₃o]³⁺, [I^h ₄iR o]³⁺, [I^h ₅iR₅o]³⁺, [ln_6iP₆o]³⁺,

[ln_7i P₇₀]³⁺, [ln_8iP₈o]³⁺, and/or [ln_9iP₉o]³⁺.

In some embodiments of the present invention, the first semiconducting nanosized material in step (f) is prepared in a first mixture by using the cluster, and the cluster is a Magic Sized Cluster(MSC), wherein the magic sized cluster (MSC) comprises an Indium based carboxylate ligand, preferably ln(0₂CR⁹)₃, wherein said O2CR⁹ of said ln(0₂CR⁹)₃ is - 02CCH2Phenyl, or a substituted or unsubstituted fatty acid such as hexanoate, heptanoate, octanoate, nonanoate, decanoate, undecanoate, dodecanoate, tridecanoate, tetradecanoate, pentadecanoate,

hexadecanoate, heptadecanoate, octadecanoate, nonadecanoate, icosanoate or oleate. Such InP magic sized clusters (MSCs) as single source precursors (SSP) can be fabricated as described in D. Gary et al., Chem. Mater., 2015, 27, 1432.

Step (g) - Quenching step

According to the present invention, the quenching of the formation of the first semiconducting material can be done by cooling the reaction mixture.

As a cooling method, several methods can be used singly or in

combination.

Such as removing a heat source, injecting a solvent such as a solvent at a room temperature, and/or applying air cooling.

In a preferred embodiment of the present invention, the cooling rate in step

(g) is in the range from 0.01 ^°C/s to 10^°C/s, preferably it is from 0.05^°C/s to 5^°C/s, more preferably it is from 0.1 ^°C/s to 1 ^°C/s, even more preferably it is from 0.2^°C/s to 0.7^°C/s.

Step (h) - Surface treatment process

In some embodiments of the present invention, the process further comprises following step (h) before step (a), preferably before step (a) after step (g),

(h) subjecting said a first semiconducting material to a surface treatment with a metal halide represented by following chemical formula (III), or with an alkyl ammonium halide,

MX²n (III) wherein M is Zn²⁺, or Cd²⁺, preferably M is Zn²⁺, X² is a halogen selected from the group consisting of Cl , Br and I , n is 2.

In some embodiments of the present invention, the step (h) is carried out at the temperature in the range from 150°C to 350°C, preferably in the range from 200°C to 320 °C, more preferably in the range from 250°C to 300°C, even more preferably from 250°C to 280°C.

In some embodiments of the present invention, the treatment time of step (h) is in the range from 10 minutes to 10 hours, preferably from 20 minutes to 4 hours, more preferably from30 minutes to 3 hours.

In some embodiments of the present invention, the total molar ratio between the amount of the metal halide in step (h) and the amount of the first semiconducting material is in the range from 500 to 50,000, preferably from 1 ,000 to 20,000, more preferably from 1400 to 10,000.

In some embodiments of the present invention, step (h) is carried out in a solution comprising at least one solvent selected from one or more members of the group consisting of squalenes, squalanes, heptadecanes, octadecanes, octadecenes, nonadecanes, icosanes, henicosanes, docosanes, tricosanes, pentacosanes, hexacosanes, octacosanes, nonacosanes, triacontanes, hentriacontanes, dotriacontanes,

tritriacontanes, tetratriacontanes, pentatriacontanes, hexatriacontanes, oleylamines, and trioctylamines, with preferably being of squalene, squalane, heptadecane, octadecane, octadecene, nonadecane, icosane, henicosane, docosane, tricosane, pentacosane, hexacosane, octacosane, nonacosane, triacontane, hentriacontane, dotriacontane, tritriacontane, tetratriacontane, pentatriacontane, hexatriacontane, oleylamine, and trioctylamine, more preferably octadecene, trioctylamines, oleylamine, squalane, pentacosane, hexacosane, octacosane, nonacosane, or triacontane, even more preferably octadecene, trioctylamines, oleylamine, squalane, pentacosane, or hexacosane.

In a preferred embodiment of the present invention, each step of the steps (a) to (h) is carried out in an inert condition such as under N2 or Argon (Ar) condition, preferably under Ar condition.

- Light emitting nanoparticle

In another aspect of the present invention, the invention also relates to a light emitting nanoparticle obtainable or obtained from the process of the present invention, preferably said light emitting nanoparticle is a light emitting semiconducting nanoparticle.

In some embodiments of the present invention, the nanoparticle has a full width half maximum (FWHM) of at most 55nm measured at 25°C using a toluene solution, preferably a full width half maximum (FWHM) in the range of 30 to 55nm, more preferably from 30 to 47nm.

- Determination of the full width half maximum (FWHM)

Preferably, the determination of the full width half maximum (FWHM) is made with an appropriate data base preferably comprising at least 10, more preferably at least 20 and even more preferably at least 50 data points. The determination is preferably performed by using LabVIEW Software

(LabVIEW 2017; May 2017) with the following Vis (Virtual Instrument): 1. 'Peak detector' for finding center wavelength and y-value (counts).

The following parameters are preferably used: width: 10, threshold: maximum value of input data divided by 5.

2. Dividing the counts (y-value) at the center wavelength value (see item 1 ) by 2 giving the y-value for the half-width of the peak. The two points having this half-width y-value were found and the difference between their two wavelength values were taken to give the FWHM parameter. - Measurements of quantum yield

According to the present invention the QY is measured using Hamamatsu absolute quantum yield spectrometer (model: Quantaurus C11347). - Calculation of trap emission value

In some embodiments of the present invention, the trap emission value of the nanoparticle is in the range from 0.02 to 0.15, preferably 0.05 to 0.1.

According to the present invention, the trap emission value is calculated using following formula,

wherein the symbols have the following meanings;

CWL=the peak maximum light emission wavelength of the

photoluminescence spectra,

FWHM=full width at half maximum of the photoluminescence spectra, RI_(l)= photoluminescence intensity at wavelength of l.

The photoluminescence spectra (hereafter“PL”) of the nanoparticles is measured using Jasco FP fluorimeter, in the range between 460 and 850 nm, using 450 nm excitation.

According to the present invention, the Self-absorption value is calculated preferably according to the following procedure:

According to the present invention, the optical density (hereafter“OD”) of the nanoparticles is preferably measured using Shimadzu UV-1800, double beam spectrophotometer, using toluene baseline, in the range between 300 and 750 nm. The photoluminescence spectra (hereafter“PL”) of the nanoparticles is preferably measured using Jasco FP fluorimeter, in the range between 460 and 850 nm, using 450 nm excitation. The OD(A) and PL (A) are the measured optical density and the photoluminescence at wavelength of A.

ODi represented by the formula (X) is the optical density normalized to the optical density at 450 nm, and ai represented by formula (XI) is the absorption corresponding to the normalized optical density.

OP (A)

OD_l

OD (A = 450 nm)

(X)

a_x = 1 -10 ^O£>l (XI)

The self-absorption value of the nanoparticles is preferably calculated based on the OD and PL measurement raw data.

It is believed that lower-self absorbance of the nanoparticles is expected to prevent the QY decrease in high emitter concentrations.

Preferably, the nanoparticle emits light having the peak maximum light emission wavelength in the range from 430nm to 700nm, preferably from 450nm to 650nm, more preferably from 520nm to 650nm. According to the present invention, the term“nanosized” means the size in between 0.1 nm and 999 nm, preferably 1 nm to 150 nm, more preferably 3nm to 50 nm. Thus, according to the present invention,“light emitting nanoparticle” is taken to mean that the light emitting material which size is in between 0.1 nm and 999 nm, preferably 1 nm to 150 nm, more preferably 3nm to 50nm.

According to the present invention, the term“semiconductor” means a material having electrical conductivity to a degree between that of a conductor (such as copper) and that of an insulator (such as glass) at room temperature, preferably, a semiconductor is a material whose electrical conductivity increases with the temperature.

Therefore, according to the present invention, the term“semiconductor light emitting nanoparticle” is taken to mean that a material having bulk electrical conductivity to a degree between that of a conductor (such as copper) and that of an insulator (such as glass) at room temperature, preferably, a semiconductor is a material whose electrical conductivity increases with the temperature and the size is in between 0.1 nm and 999 nm, preferably 0,5 nm to 150 nm, more preferably 1 nm to 50 nm. According to the present invention, the term“size” means the average diameter of the circle with the area equivalent to the measured TEM projection of the semiconducting nanosized light emitting particles.

In a preferred embodiment of the present invention, the semiconducting light emitting nanoparticle of the present invention is a quantum sized material.

According to the present invention, the term“quantum sized” means the size of the semiconducting material itself without ligands or another surface modification, which can show the quantum confinement effect, like described in, for example, ISBN:978-3-662-44822-9. Generally, it is said that the quantum sized materials can emit tunable, sharp and vivid colored light due to“quantum confinement” effect.

In some embodiments of the invention, the size of the overall structures of the quantum sized material, is from 1 nm to 50 nm.

In a preferred embodiment of the present invention, the average diameter of the first semiconducting material is in the range from 2 to 4 nm, preferably it is in the range from 1.5 to 3.5nm.

The average diameter of the semiconducting nanosized light emitting particles are calculated based on 100 semiconducting light emitting nanoparticles in a TEM image created by a Tecnai G2 Spirit Twin T-12 Transmission Electron Microscope. The average diameter of the semiconducting nanosized light emitting particles are calculated using FijiJmageJ program.

According to the present invention, in a preferred embodiment, the size distribution of the first semiconducting material is 25% or less, preferably it is in the range from 20% to 3%, more preferably from 15% to 4%.

- Elemental Analysis

According to the present invention, the following elemental analysis is used in order to determine the molar ratio between group 12 element and group 13 element.

The semiconducting light emitting nanoparticle is dispersed in toluene and the obtained solution is deposited on a Si substrate and dried in vacuum.

SEM/EDS measurements are carried out on FEI Sirion machine equipped with Oxford detector and INCA software operating at 200kV. According to the present invention, in some embodiments, the first semiconducting material as a core is at least partially embedded in the first shell layer, preferably said first semiconducting material is fully embedded into the shell layer.

-First shell layer

In some embodiments of the present invention, said shell layer comprises at least a 1^st element of group 12 of the periodic table and a Se atom, preferably, the 1^st element is Zn.

In a preferred embodiment of the present invention, the first shell layer is represented by following formula (IX),

ZnS_xSe(i-x-z)Te_z, - (IX) wherein 0<x<1 , 0<z<1 , and x+z<1 , preferably, the shell layer is ZnSe, ZnSxSe(i-x), ZnSe(i-_X)Te_z, more preferably it is ZnSe.

In some embodiments of the present invention, said shell layer is an alloyed shell layer or a graded shell layer preferably said graded shell layer is ZnSe, ZnS_xSe_(i-x), or ZnSe_(i-Z)Te_z, more preferably it is ZnSe.

In some embodiments of the present invention, optionally, the first semiconducting material as a core and a first shell layer can be at least partially embedded in the 2^nd shell, preferably said first semiconducting material is fully embedded into the shell layer.

In some embodiments of the present invention, said 2^nd shell layer comprises at least a 1^st element of group 12 of the periodic table and a 2^nd element of group 16 of the periodic table, preferably, the 1 ^st element is Zn, and the 2^nd element is S, Se, or Te. In a preferred embodiment of the present invention, the second shell layer is represented by following formula (IX^'),

ZnS_xSe(i-x-z)Te_z, (IX ), wherein 0£x<1 , 0£z<1 , preferably, the shell layer is ZnSe, ZnS_xSe_y, ZnSe_yTe_zor ZnS_xTe_z, or ZnS, more preferably ZnSeS or ZnS

In some embodiments of the present invention, said shell layer is an alloyed shell layer or a graded shell layer preferably said graded shell layer is ZnS_xSe_y, ZnSe_yTe_z, or ZnS_xTe_z, more preferably it is ZnS_xSe_y.

In some embodiments of the present invention, the concentration of Se in the shell layer varies from a high concentration of the first semiconducting material side in the shell layer to a low concentration of the opposite side in the shell layer, more preferably, the concentration of S in the shell layer varies from a low concentration of first semiconducting material side of the shell layer to a higher concentration to the opposite side of the shell layer, the concentration of Te in the shell layer varies from a low concentration of first semiconducting material side of the shell layer to a higher

concentration to the opposite side of the shell layer.

In some embodiments of the present invention, the semiconducting light emitting nanoparticle can further comprise one or more additional shell layers onto the 2^nd shell layer as a multishell.

According to the present invention, the term“multishell” stands for the stacked shell layers consisting of three or more shell layers. In some embodiments of the present invention, the surface of the semiconducting light emitting nanoparticle can be over coated with one or more kinds of surface ligands. Without wishing to be bound by theory it is believed that such surface ligands may lead to disperse the nanosized fluorescent material in a solvent more easily.

The surface ligands in common use 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), amines such as Oleylamine, Dodecyl amine (DDA), Tetradecyl amine (TDA),

Hexadecyl amine (HDA), and Octadecyl amine (ODA), Oleylamine (OLA), 1 -Octadecene (ODE), thiols such as hexadecane thiol, dodecane thiol and hexane thiol; selenols, when organic moiety of selenol may include linear or branched alkyl chain which can be saturated or include one or more unsaturated carbon bonds and/or aromatic rings; mercapto carboxylic acids such as mercapto propionic acid and mercaptoundecanoicacid; carboxylic acids such as oleic acid, stearic acid, myristic acid; acetic acid and a combination of any of these. Furthermore, the ligands can include Zn- oleate, Zn-acetate, Zn-myristate, Zn-Stearate, Zn-laurate and other Zn- carboxylates.

Examples of surface ligands have been described in, for example, the laid- open international patent application No. WO 2012/059931 A. - Composition

In another aspect, the present invention also relates to composition comprising, essentially consisting of, or consisting of, at least one light emitting nanoparticle of the present invention, and at least one additional material, preferably the additional material is selected from the group consisting of organic light emitting materials, inorganic light emitting materials, charge transporting materials, scattering particles, host materials, nanosized plasmonic particles, photo initiators, and matrix materials.

Such suitable inorganic light emitting materials described above can be well known phosphors including nanosized phosphors, quantum sized materials like mentioned in the phosphor handbook, 2^nd edition (CRC Press, 2006), pp. 155 - pp. 338 (W.M.Yen, S.Shionoya and H. Yamamoto),

WO2011/147517A, WO2012/034625A, and WO2010/095140A.

According to the present invention, as said organic light emitting materials, charge transporting materials, any type of publicly known materials can be used preferably. For example, well known organic fluorescent materials, organic host materials, organic dyes, organic electron transporting materials, organic metal complexes, and organic hole transporting materials.

For examples of scattering particles, small particles of inorganic oxides such as S1O2, SnC>2, CuO, CoO, AI2O3 PO2, Fe2C>3, Y2O3, ZnO, MgO;

organic particles such as polymerized polystyrene, polymerized PMMA; inorganic hollow oxides such as hollow silica or a combination of any of these; can be used preferably.

- Matrix material

According to the present invention, a wide variety of publicly known transparent matrix materials suitable for optical devices can be used preferably.

According to the present invention, the term“transparent” means at least around 60 % of incident light transmit at the thickness used in an optical medium and at a wavelength or a range of wavelength used during operation of an optical medium. Preferably, it is over 70 %, more preferably, over 75%, the most preferably, it is over 80 %. In a preferred embodiment of the present invention, as said matrix material, any type of publicly known transparent matrix material, described in for example, WO 2016/134820A can be used.

In some embodiments of the present invention, the transparent matrix material can be a transparent polymer.

According to the present invention the term“polymer” means a material having a repeating unit and having the weight average molecular weight (Mw) 1000 g/mol, or more.

The molecular weight M_w is determined by means of GPC (= gel

permeation chromatography) against an internal polystyrene standard.

In some embodiments of the present invention, the glass transition temperature (Tg) of the transparent polymer is 70 °C or more and 250 °C or less. Tg is measured based on changes in the heat capacity observed in

Differential scanning colorimetry like described in

http://pslc.ws/macroq/dsc.htm; Rickey J Seyler, Assignment of the Glass Transition, ASTM publication code number (PCN) 04-012490-50. For example, as the transparent polymer for the transparent matrix material, poly(meth)acrylates, epoxys, polyurethanes, polysiloxanes, can be used preferably.

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 from 1 ,000 to 300,000 g/mol, more preferably it is from 10,000 to 250,000 g/mol. In a preferable embodiment of the present invention, the composition comprises a plural of the light emitting nanoparticles and/or a plural of the semiconducting materials.

- Formulation

In another aspect, the present invention relates to formulation comprising, essentially consisting of, or consisting of, at least one light emitting nanoparticle or the composition of the present invention,

and at least one solvent.

Preferably the solvent is 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, ethers, tetrahydrofuran, chloroform, dichloromethane and heptane, purified water, ester acetates, alcohols, sulfoxides, formamides, nitrides, ketones.

Preferably, the formulation contains a plurality of light emitting

nanoparticles.

The amount of the solvent in the formulation can be freely controlled according to the method of coating the composition. For example, if the composition is to be spray-coated, it can contain the solvent in an amount of 90 wt. % or more. Further, if a slit-coating method, which is often adopted in coating a large substrate, is to be carried out, the content of the solvent is normally 60 wt. % or more, preferably 70 wt. % or more.

- Use

in another aspect, the present invention relates to use of the

semiconducting light emitting nanoparticle, or the semiconducting material, or the composition, or the formulation, in an electronic device, optical device or in a biomedical device.

- Optical medium

In another aspect, the present invention further relates to an optical medium comprising at least one light emitting nanoparticle of the present invention, or the composition, or the formulation.

In some embodiments of the present invention, the optical medium can be an optical sheet, for example, a color filter, color conversion film, remote phosphor tape, or another film or filter.

According to the present invention, the term“sheet” includes film and / or layer like structured mediums.

In some embodiments of the present invention, the optical medium comprises an anode and a cathode, and at least one layer such as an organic layer, comprising at least one light emitting nanoparticle or the composition of the present invention, preferably said one organic layer is a light emission layer, more preferably the medium further comprises one or more additional layers selected from the group consisting of hole injection layers, hole transporting layers, electron blocking layers, hole blocking layers, electron blocking layers, and electron injection layers.

According to the present invention, any kinds of publicly available inorganic, and/or organic materials for hole injection layers, hole transporting layers, electron blocking layers, light emission layers, hole blocking layers, electron blocking layers, and electron injection layers can be used preferably, like as described in WO 2018/024719 A1 , US2016/233444 A2, US7754841 B, WO 2004/037887 and WO 2010/097155. In a preferable embodiment of the present invention, the optical medium comprises a plural of the light emitting nanoparticles and/or a plural of the semiconducting materials. Preferably, the anode and the cathode of the optical medium sandwich the layer.

More preferably said additional layers are also sandwiched by the anode and the cathode.

In some embodiments of the present invention, the layer comprises at least one light emitting nanoparticle of the present invention, and a host material, preferably the host material is an organic host material. - Optical device

In another aspect, the invention further relates to an optical device comprising the optical medium.

In some embodiments of the present invention, the optical device can be a liquid crystal display device (LCD), Organic Light Emitting Diode (OLED), backlight unit for an optical display, Light Emitting Diode device (LED), Micro Electro Mechanical Systems (here in after“MEMS”), electro wetting display, or an electrophoretic display, a lighting device, and / or a solar cell

Technical effects

The present invention provides one or more of following effects;

improvement of particle size distribution, better Full Width at Half Maximum (FWHM) value, improved self-absorption value, improvement of absorption per mg of nanoparticle(s), improvement of quantum yield of nanoparticle, well-controlled shell thickness, improved charge injection ability of nanoparticle, higher device efficiency, lowering trap emission of nanoparticle, optimizing a surface condition of shell part of nanoparticle, reducing lattice defects of a shell layer of nanoparticle, reducing / preventing formation of dangling bonds of shell layer, better thermal stability, better chemical stability, optimizing fabrication process of nanoparticle, providing new fabrication process to improve size control of nanoparticle, providing new fabrication process for better kinetics control in shell formation, new shell formation process to realize well controlled shell thickness and/or reducing lattice defects of a shell layer, environmentally more friendly and safer fabrication process.

The working examples 1 - 7 below provide descriptions of the present invention, as well as an in-detail description of their fabrication.

Working Examples

Working Example 1 : Synthesis of Magic Sized Clusters (MSCs) Cluster Synthesis

In a 500ml_ 4-neck flask, weight 4.65 g (15.9 mmol) of indium acetate and 13.25 g (58.0 mmol) of myhstic acid. The flask is equipped with a reflux condenser, septa and a tap between the flask and the condenser.

Put under vacuum at 100 °C for 8 h 15 min to off-gas acetic acid under reduced pressure, and overnight at room T.

Day after, the solution heat again to 100 °C and evacuate for 1 hour and 45min in those conditions.

Total evacuation time at 100 °C for10 hours,

At pressure: 85 mtorr.

Fill the reaction flask with argon and add 100 ml_ of dry toluene. Heat the reaction to 110°C.

Inject the mixture of 2.33 ml_ (2.0 g) of PTMS and 50 ml_ (43.5 g) of toluene into the Indium-myristate flask at 110 °C.

The formation of MSCs was monitored via UV-vis of timed aliquots taken from the reaction solution. There was a gradual improvement in the peak shape (red shift and sharpness).

When the improvement in the peak shape (red-shift and sharpness) stopped, the 2nd PTMS solution (1 ml (0.86 g) PTMS in 10.2 ml (8.77 g) Toluene) was added in portions of 2ml_ to reach the optimal optical parameters. For example:

2 ml PTMS solution was added after 13 min

2 ml PTMS solution was added after 19 min

2 ml PTMS solution was added after 32 min

After 44 min cool the reaction with fan and store the flask under inert atmosphere. Results:

InP magic size clusters are formed with exciton at 387nm.

The InP magic size clusters (MSCs) are cleaned with anhydrous acetonitrile (the ratio of crude:acetonitrile 18:13). The process is repeated with a mixture of anhydrous toluene and acetonitrile in ratio toluene:acetonitrile 1.5:1 , 1.4:1 , 1.75:1. This product is called“magic size clusters (MSCs)”.

Working Example 2: Core synthesis:

Synthesis of InP cores having an exciton wavelength of 593 nm

A 50ml_, 14/20, four-neck round-bottom flask equipped with a reflux condenser is evacuated, and 10 ml_ of distilled squalane is injected into it. The apparatus is evacuated with stirring (pressure is lowered from 300mtorr to 200 mTorr during 1 hour) and heated to 375°C under argon. In a glove box a solution of MSCs with a concentration of 3.15x10⁰⁴M is prepared in distilled squalene. 4 ml_ (1.26E-06 moles) of this solution is injected to the flask at 375°C, using a 16-gauge needle and 6 ml_ syringe;

after 4 minutes the mantle is removed, and the flask is cooled to 200°C by blowing air with a fan. The mantle is then brought back, and the flask is heated to 265°C.

At this point more MSCs is added, using the same solution that is initially injected; 20-gauge needle and 3ml syringe are used, the addition is done at a rate of 0.7ml/min at the given times (compared to the initial injection): Minute 15 - 0.6 ml_ (1.89E-07 mol)

Minute 25 - 0.7 ml_ (2.21 E-07 mol)

Minute 32 - 0.7 ml_

Results:

InP QDs are formed with exciton at 593nm. Reference Example 1 : ZnSe shell synthesis on InP cores, (trioctyl phosphine selenide (TOP-Se) as Se source) The InP cores in the solution from working example 2 are cleaned with a mixture of anhydrous toluene and ethanol (the ratio of crude:toluene:ethanol: 1 :2:8). The process is repeated with ratio crude:toluene:ethanol: 1 :2:6. This solution is called“SSP InP cores”. Post-synthesis core treatment: In a glove box, the SSP InP cores (3.5X1 O ⁷mol) are dissolved with 0.2ml_ toluene and transferred into 50ml round bottom flask with 4.8ml_ pumped oleylamine (OLAm) and 0.085g ZnCh. After short pumping at 50°C, the flask is heated to 250°C for 30min. The solution is then cooled down to 180°C.

Shelling process: At 180°C, 2.6ml_ of a 0.55M concentrated solution of Zn(CI)2 in OLAm and 1 amount (0.72mL of 2M TOP-Se) of anion shell precursor are added to SSP InP cores after core treatment. After

30minutes, the solution is heated to 200°C. After 30minutes the solution is heated to 320°C, 3.1 mL of 0.4M Zn(stearate)2 is injected and the reaction kept at 320°C for 3 hours. After 3hours at 320°C the reaction is terminated by cooling down the reaction mixture.

Working Example 3: ZnSe shell synthesis on InP cores in oleylamine, with 1-octadecane selenol as Se source

In this synthesis InP cores from working example 2 are used and have core exciton CWL of 593 nm. The final core solution is cleaned with a mixture of anhydrous toluene and ethanol (ratio crude:toluene:ethanol:1 :2:8). The process is repeated with the ratio crude:toluene:ethanol = 1 :2:6. This is called“SSP InP cores”. Post-synthesis core treatment: In GB, SSP InP cores (2.7X10⁷mol) are dissolved with 0.3ml toluene and transferred into 50ml round bottom flask with 2.9ml pumped oleylamine (OLAm) and 0.065g ZnCh. After short pumping at 50°C, the flask is heated to 250°C for 30min. The solution is then cooled down to 180°C.

Shelling process: At 180°C, 2ml_ of a 0.55M concentrated solution of Zn(CI)2 in OLAm and 1 amount (2.2mL of 0.36M 1 -octadecane selenol) of anion shell precursor are added to SSP InP cores after core treatment. After 30min, the solution is heated to 200°C. After 30minutes the solution is heated to 250°C. After 30 minutes 2.4mL of 0.4M Zn(stearate)2 is injected and the reaction kept at 250°C for 1 hour 25 minutes. After that the solution was heated to 320°C and the reaction kept at 320°C for 1 hour. After 1 hour at 320°C the reaction is terminated by cooling down the reaction mixture.

Working Example 4: ZnSe shell synthesis on InP cores, with 1- dodedecane selenol as Se source

The nanoparticles are fabricated in the same manner as described in the working example 3, except for dodecaneselenol is used as selenium precursor instead of 1-octadecane selenol.

Working Example 5: ZnSeS shell synthesis on InP cores, with 1- dodedecane selenol as Se source and dodecanthiol as the S -source

The nanoparticles are fabricated in the same manner as described in the working example 3, except for dodecanthiol is added 30 min after the injection of selenol, keeping the amount of Se+S ions same as before. The QY, FWHM and trap emission values are measured, and calculated as described in the section of“Determination of the full width half maximum (FWHM)”,“Calculation of quantum yield”,“Calculation of trap emission value” above.

Working Example 6: ZnSe shell synthesis on InP cores in ODE, with 1-dodedecane selenol as a Se source

The working example differs from the working example 3 by shelling process. The InP cores in the solution from working example 2 are cleaned with a mixture of anhydrous toluene and ethanol (the ratio of

crude:toluene:ethanol: 1 :2:8). The process is repeated with ratio

crude:toluene:ethanol: 1 :2:6. This solution is called“SSP InP cores”. Post-synthesis core treatment: In a glove box, the SSP InP cores (3.5X10- 7mol) are dissolved with 0.2ml_ toluene and transferred into 50ml round bottom flask with 4.8ml_ pumped oleylamine (OLAm) and 0.085g ZnCI2. After short pumping at 50°C, the flask is heated to 250°C for 30min. The solution is then cooled down to room temperature. The treated InP cores are cleaned with a mixture of anhydrous toluene and ethanol (the ratio of crude:toluene:ethanol: 4.8:1 :5).

Shelling process: 433mg of zinc undecelynate (1 mmol) are weighted in a 50ml_ 4-neck round bottom flask. The flask is equipped with a stirring bar and connected to Schlenk line via an adapter with a tap. Pumped for 5min, put under Ar, pumped for 9 min, put under Ar, introduced to the Glove box. To 1 vial with SSP InP cores treated with ZnC in oleylamine (3.5X10⁷mol) is added 100 uL of toluene, vortexed to dissolve the cores, 1 ml_ of ODE is added, vortexed. The resulting solution is transferred to 50ml_ 4-neck flask. Collect the left-overs of cores with 1 mL of ODE, add to the flask. Add 6ml_ ODE (8ml_ in total). Put under vacuum at room temperature, 36min.

Put under Ar. Heated (in 34mn) to 300°C.

Addition 200uL of 0.5M selenol in ODE at t=0min

Addition 200uL of 0.5M selenol in ODE at t=20min

Afterwards stay 35min at 300°C. End. Total 55min@300°C. The reaction is terminated by cooling down the reaction mixture.

Working Example 7: ZnSe shell synthesis on InP cores in ODE, with 1- dodedecane selenol as Se source

The working example differs from the working example 6 by shell thickness and the amount of selenol added.

Shelling process: 433mg of zinc undecelynate (1 mmol) are weighted in a 50ml_ 4-neck round bottom flask. The flask is equipped with a stirring bar and connected to Schlenk line via an adapter with a tap. Pumped for 5min, put under Ar, pumped for 9 min, put under Ar, introduced to the Glove box. To 1 vial with the SSP InP cores treated with ZnCh in oleylamine (3.5X1 O ⁷mol) is added 100 uL of toluene, vortexed to dissolve the cores, 1 ml_ of ODE is added, vortexed. The resulting solution is transferred to 50ml_ 4- neck flask. Collect the left-overs of cores with 1 ml_ of ODE, add to the flask. Add 6ml_ ODE (8ml_ in total).

Put under vacuum at room T, 36min.

Put under Ar. Heated (in 34min) to 300°C.

Add 200uL of 0.5M selenol in ODE at t=0min

Add 200uL of 0.5M selenol in ODE at t=15min

Add 200uL of 0.5M selenol in ODE at t=30min

Add 200uL of 0.5M selenol in ODE at t=45min

Add 200uL of 0.5M selenol in ODE at t=60min

Add 200uL of 0.5M selenol in ODE at t=75min

Add 200uL of 0.5M selenol in ODE at t=90min Add 200uL of 0.5M selenol in ODE at t=105min

Add 200uL of 0.5M selenol in ODE at t=120min

Add 200uL of 0.5M selenol in ODE at t=135min

Add 200uL of 0.5M selenol in ODE at t=150min

Add 200uL of 0.5M selenol in ODE at t=165min

Afterwards stay 15min at 300°C. End. Total 180min at 300°C.

Table 1 : The optical results of the working examples 3, and 6-7

The Zn/ln ratios are calculated using EDS measurement as described in the section of“Elemental Analysis” above.

Table 2 shows particle size control as a function of precursor amount - dodecane selenol as limiting reagent of the working example 7.

Table 2

Claims

Patent Claims

1. A process for fabricating a light emitting nanoparticle comprising at least following steps,

(a) mixing at least a first semiconducting nanomaterial and another material to get a reaction mixture, preferably said another material is a solvent, (b) forming a shell layer onto the first semiconducting nanomaterial in the reaction mixture by reacting at least a chalcogen source selected from selenols, diselenides, a combination of these, or a combination of these with thiols and/or disulfides, preferably said chalcogen source is a selenium source selected from selenols, diselenides, or a combination of these, and a cation shell precursor in a reaction mixture, wherein said chalcogen source is injected into the reaction mixture during step (b),

(c) cooling the reaction mixture from step (b).

2. The process of claim 1 , wherein the chalcogen source is injected in two or more (n) aliquots of a fraction (1/n) of the whole amount of the chalcogen source in step (b), preferably it is in the range from 1 to 20, preferably 1 to 15, more preferably 1 to 12. 3. The process of claim 1 or 2, wherein the injection rate of chalcogen source is in the range from 0.15 mol%/min to 100 mol%/min, preferably from 0.

3 mol%/min to 10 mol%/min, more preferably from 0.5 mol%/min to 5 mol%/min.

4.The process according to any one of claims 1 to 3, the step (b) is carried out at the temperature in the range from 200°C to 320°C, preferably in the range from 200°C to 300 °C, more preferably in the range from 220°C to 300°C, even more preferably from 250°C to 300°C.

5. The process according to any one of claims 1 to 4, wherein step (b) is carried out in the range from 1 minute to 10 hours, preferably from 10 minutes to 5 hours, more preferably 20 minutes to 3 hours.

6. The process according to any one of claims 1 to 5, the ratio of the total molar amount of the chalcogen source to the total molar amount of the first semiconducting nanoparticle in step (b) is in the range from 125:1 to

60000:1 , more preferably 150:1 to 45000:1 , even more preferably 200:1 to 12000:1.

7. The process according to any one of claims 1 to 6, wherein only a selenium source selected from selenols, diselenides or a combination of these, is used as the chalcogen source in step (b) to form the shell layer.

8. The process according to any one of claims 1 to 7, wherein said cation shell precursor is a salt of an element of the group 12 of the periodic table, more preferably said cation shell precursor is selected from one or more members of the group consisting of Zn-stearate, Zn-myristate, Zn-oleate, Zn-laurate, Zn-palmitate, Zn-acetylacetonate, Zn-undecylenate, Cd- stearate, Cd-myristate, Cd-oleate, Cd-laurate, Cd-palmitate, Cd- acetylacetonate, Cd-undecylenate, a metal halogen represented by chemical formula (III) and a metal carboxylate represented by chemical formula (IV),

MX²n (III) wherein M is Zn²⁺, or Cd²⁺, preferably M is Zn²⁺, X² is a halogen selected from the group consisting of Cl , Br and I , n is 2, [M(0₂CR¹) (O2CR²)] - (IV) wherein M is Zn²⁺, or Cd²⁺, preferably M is Zn²⁺; R¹ is a linear alkyl group having 1 to 30 carbon atoms, a branched alkyl group having 3 to 30 carbon atoms, a linear alkenyl group having 2 to 30 carbon atoms, or a branched alkenyl group having 3 to 30 carbon atoms, preferably R¹ is a linear alkyl group having 1 to 30 carbon atoms, or a linear alkenyl group having 2 to 30 carbon atoms, more preferably, R¹ is a linear alkyl group having 2 to 25 carbon atoms, or a linear alkenyl group having 6 to 25 carbon atoms, even more preferably R¹ is a linear alkyl group having 2 to 20 carbon atoms, or a linear alkenyl group having 10 to 20 carbon atoms, furthermore preferably R¹ is a linear alkyl group having 2 to 20 carbon atoms,

R² is a linear alkyl group having 1 to 30 carbon atoms, a branched alkyl group having 3 to 30 carbon atoms, a linear alkenyl group having 2 to 30 carbon atoms, or a branched alkenyl group having 3 to 30 carbon atoms, preferably R² is a linear alkyl group having 1 to 30 carbon atoms, or a linear alkenyl group having 2 to 30 carbon atoms, more preferably R² is a linear alkyl group having 2 to 25 carbon atoms, or a linear alkenyl group having 6 to 25 carbon atoms, even more preferably R² is a linear alkyl group having 2 to 20 carbon atoms, or a linear alkenyl group having 10 to 20 carbon atoms, furthermore preferably R² is a linear alkyl group having 2 to 20 carbon atoms, preferably R¹ and R² are the same.

9. The process according to any one of claims 1 to 8, wherein the ratio of the total amount of the chalcogen source and the total amount of the cation shell precursor used in step (b) is in the range from 20 : 1 to 1 : 20, preferably in the range from 12 : 1 to 1 : 12.

10. The process according to any one of claims 1 to 9, wherein the process further comprises step (e), preferably the process comprises step (e) before step (b), (e) mixing said chalcogen source and said cation shell precursor with the first semiconducting nanoparticle, optionally with another material, to make the second mixture at the temperature in the range of from 0°C to 100°C, preferably from 5 to 60°C, more preferably from 10 to 40°C.

11. A light emitting nanoparticle obtainable or obtained from the process according to any one of claims 1 to 10, preferably it is a light emitting semiconducting nanoparticle.

12. A composition comprising at least one light emitting nanoparticle according to claim 11 , and at least one additional material, preferably the additional material is selected from the group consisting of organic light emitting materials, inorganic light emitting materials, charge transporting materials, scattering particles, host materials, nanosized plasmonic particles, photo initiators, and matrix materials.

13. Formulation comprising at least one light emitting nanoparticle according to claim 11 , or a composition according to claim 12, and at least one solvent, preferably the solvent is 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, ethers,

tetrahydrofuran, chloroform, dichloromethane and heptane, purified water, ester acetates, alcohols, sulfoxides, formamides, nitrides, ketones.

14. Use of the light emitting nanoparticle according to claim 11 , or a composition according to claim 12, or the formulation according to claim 13 in an electronic device, optical device or in a biomedical device.

15. An optical medium comprising at least one light emitting nanoparticle according to claim 11 , or at least a composition according to claim 12.

16. The optical medium of claim 15, comprising an anode and a cathode, and at least one layer comprising at least one light emitting nanoparticle according to claim 11 , or a composition according to claim 12, preferably said one layer is a light emission layer, more preferably the medium further comprises one or more layers selected from the group consisting of hole injection layers, hole transporting layers, electron blocking layers, hole blocking layers, electron blocking layers, and electron injection layers.

17. The optical medium of claim 15 or 16, wherein the layer comprises at least one light emitting nanoparticle according to claim 11 , and a host material, preferably the host material is an organic host material.

18. An optical device comprising at least said optical medium according to any one of claims 15 to 17.