Method for producing znse cores, method for producing tellurium-doped znse(TE) cores and method for producing znse(TE) / znse / zns quantum dots emitting light in the blue range

Abstract

The subject of the present invention is a method for obtaining ZnSe cores in flow, ZnSe cores obtained by this method, a method for obtaining tellurium doped ZnSe(Te) cores, a method for obtaining ZnSe(Te) / ZnSe / ZnS quantum dots emitting light in the blue range, and ZnSe(Te) / ZnSe / ZnS quantum dots obtained by this method.

Description

[0001] METHOD FOR PRODUCING ZNSE CORES, METHOD FOR PRODUCING TELLURIUM-DOPED ZNSE(TE) CORES AND METHOD FOR PRODUCING

[0002] ZNSE(TE) / ZNSE / ZNS QUANTUM DOTS EMITTING LIGHT IN THE BLUE RANGE

[0003] The present invention relates to a method for producing ZnSe seeds (cores), ZnSe seeds (cores), a method for producing tellurium doped ZnSe(Te) cores, and a method for producing ZnSe(Te) / ZnSe / ZnS quantum dots which emit light in the blue range and ZnSe(Te) / ZnSe / ZnS quantum dots which emit light in the blue range.

[0004] Quantum dots (QDs) are semiconductor nanocrystals with a size of approximately 10 nm. They typically consist of an inorganic core and a shell, the composition and size of which, among other parameters, strongly determine the optical properties of the material. Quantum dots absorb light of a given wavelength and convert it to light of a different wavelength. Due to their unique physical and chemical properties, quantum dots have found wide application in various industrial segments, such as displays, lighting, biomedicine, anticounterfeit systems and sensors. Quantum dots proved to be needed in the new technology market when there was a need for light-emitting, light-absorbing or light-converting materials with high optical quality and good stability over time. The demand for this nanomaterial is also due to the significant impact of QDs on the quality and energy efficiency of next-generation devices. QDs are an alternative to organic dyes, among others. Current emitters, including blue light, are essential in all visual applications (displays) and in those generating white light (lighting), since the three RGB (Red, Green, Blue) colours are needed to reproduce the colour palette. International patent application WQ2021030432 discloses highly luminescent nanostructures, particularly highly luminescent nanostructures containing a ZnSe1-xTex core and ZnS and / or ZnSe shell layers. Nanostructures consisting of a ZnSel- xTex core and ZnS and / or ZnSe shell layers exhibit low photoluminescence half-width at half (FWHM) and high photoluminescence quantum yield (QY). This document also reveals methods for producing such nanostructures. Specifically, this application describes a nanostructure containing a core surrounded by at least one shell, wherein the core contains ZnSe1-xTex, where 0<x<1, wherein the at least one shell is selected from the group comprising ZnS, ZnSe, ZnTe and their alloys, and wherein the photoluminescence half-width (FWHM) of the nanostructure is from about 20 nm to about 30 nm, and a method for obtaining this structure.

[0005] U.S. patent application US2019390109A1 relates to a nanostructure containing a core surrounded by at least one shell, wherein the core contains ZnSe1-xTex, where 0<x<1, wherein the at least one shell contains ZnS or ZnSe, and wherein FWHM value of the photoluminescence spectrum is from about 10 nm to about 30 nm. This application also discloses a method of producing a ZnSe1-xTex nanocrystal comprising: (a) mixing a selenium source and at least one ligand to produce a reaction mixture; and (b) contacting the reaction mixture obtained in (a) with a zinc source and a solution containing: a tellurium source, a reducing agent, and zinc carboxylate; in order to provide a ZnSe1-xTex nanocrystal.

[0006] Chinese patent description CN111201305B discloses a quantum dot with FWHM value of less than 25 nm and coated with a ligand such as a carboxylate, phosphine or amine.

[0007] Chinese patent application CN110945105A describes a Cd-free quantum dot with a photoluminescence spectrum FWHM of 40 nm or less, with a core formed of ZnTe, ZnTeS, ZnTeSe or ZnTeSeS.

[0008] The purpose of the present invention was to develop a method to reproducibly obtain homogeneous ZnSe seeds (cores) with specific physical and chemical parameters, and then to use the obtained seeds (cores) to produce quantum dots emitting light in the blue colour range.

[0009] This objective is achieved by the methods and products according to the present invention.

[0010] Thus, an object of the present invention is a method for obtaining ZnSe seeds (cores) by reaction in a flow reaction reactor, and then a method for obtaining tellurium doped ZnSe(Te) cores + ZnSe / ZnS shell in a flask.

[0011] Further objects of the invention are ZnSe seeds (cores), tellurium doped ZnSe(Te) cores and doped cores + shell, thus ZnSe(Te) / ZnSe / ZnS quantum dots. More specifically, the subject of the present invention is a method for obtaining ZnSe cores in flow, characterised in that it comprises the steps wherein:

[0012] - a mixture of anhydrous zinc acetate Zn(Ac)i, oleic acid OA and 1 -octadecene ODE is prepared in a reaction vessel using stirring;

[0013] - the resulting mixture is degassed at room temperature, reducing the pressure to 1 mbar, followed by heating to 110-130°C and further degassing for 45-90 minutes;

[0014] - the degassed mixture is placed in an argon atmosphere and a solution of a selenium precursor in diphenylphosphine Se-DPP is added to give the reaction mixture, which is then incubated at 110-130°C for 30-60 minutes with continuous stirring;

[0015] - the reaction mixture is then passed at a rate of 1.0 to 1.5 ml / minute through a tubular reactor heated to a temperature in the range of 250-300°C, collecting at the exit of the reactor the reaction solution containing the resulting ZnSe cores.

[0016] Advantageously, zinc acetate Zn(Ac)i, oleic acid OA and 1 -octadecene ODE are used in a mole ratio ranging from 1 : 3 : 23 to 1 : 4 : 24.

[0017] Advantageously, a solution of the selenium precursor in diphenylphosphine Se-DPP is used in such an amount that the ratio of Se to Zn is in a mole range of 1 : 1.19 to 1 : 1.21.

[0018] Advantageously, the selenium precursor mixture is passed at a rate of 1.3 ml / minute through a tubular reactor heated to a temperature in the range of 250-300°C. Advantageously, the selenium precursor mixture is passed at a rate of 1.3 ml / minute through a tubular reactor heated to 250°C.

[0019] Advantageously, the mixture of anhydrous zinc acetate Zn(Ac)i, oleic acid OA and 1- octadecene ODE in a reaction vessel is stirred at 400-600 rpm.

[0020] The subject of the present invention are also ZnSe cores obtained by the above defined method, which exhibit the following properties:

[0021] - wavelength corresponding to the first exciton absorption band of ZnSe seeds (cores): 335 - 392 nm;

[0022] - absorbance value for the wavelength corresponding to the first band of exciton absorption of ZnSe seeds (cores): 0.20 - 0.45. An object of the present invention is also a method for obtaining tellurium doped ZnSe(Te) cores, characterised in that the ZnSe cores are obtained by the above-described method and then:

[0023] - the obtained mixture of ZnSe cores is degassed at 90-110°C for 10-15 minutes;

[0024] - the degassed mixture of ZnSe cores is placed in an Ar atmosphere, heated to 200-220°C and a solution of tellurium in trioctylphosphine Te-TOP is added, and then the whole reaction solution is heated to 290-310°C, after which the solution is incubated for 45-90 minutes at 290-310°C.

[0025] Advantageously, the mixture of ZnSe cores and tellurium solution in trioctylphosphine Te- TOP in a volume ratio ranging from 24 : 1 ml to 24.5 : 1 ml is used.

[0026] A further object of the present invention is a method for obtaining ZnSe(Te) / ZnSe / ZnS quantum dots emitting light in the blue range, wherein tellurium-doped ZnSe(Te) cores are obtained by the above-described method and then

[0027] - a ZnSe shell is formed on the tellurium doped ZnSe(Te) cores, followed by

[0028] - an additional ZnS shell is formed on the tellurium doped ZnSe(Te) cores with a ZnSe shell.

[0029] Advantageously, the ZnSe shell is formed on tellurium doped ZnSe(Te) cores, by a method comprising steps in which:

[0030] - to a reaction solution containing ZnSe(Te) cores is added a solution of selenium in trioctylphosphine Se-TOP and a solution of zinc precursor Zn(OA)i in a mass ratio of Zn to Se in the range of 5.4 : 1 g to 5.8: 1 g at 190-210°C, under an argon atmosphere, using 150-250 rpm stirring for 100-150 minutes, after which the mixture is allowed to cool;

[0031] - in order to precipitate the ZnSe(Te) / ZnSe reaction product from the solution, ethanol and 2-propanol in a mass ratio of about 1 : 1 : 2 are added to the mixture, centrifuged for 10-15 minutes at 4000-5000 rpm and the precipitate obtained is dried, after which its solution is prepared by dispersion in hexane; and then on tellurium doped ZnSe(Te) cores with a ZnSe shell, an additional ZnS shell is produced by a method involving steps in which:

[0032] - a solution containing hexadecylamine (HDA), oleic acid (OA), trioctylamine (TOA) and anhydrous zinc acetate is prepared in a glass flask in a mole ratio of 2 : 3 : 22 : 1 to 2 : 3.5 : 23 : 1, then the resulting solution is stirred at 400-600 rpm, followed by degassing for 5-10 minutes at room temperature, reducing the pressure to the range of 1-10 mbar and heating to 110-130°C and further degassing for 10-15 minutes;

[0033] - the degassed mixture is placed in an argon atmosphere, heated to 170-190°C and the previously obtained ZnSe(Te) / ZnSe is added;

[0034] - the whole reaction solution is heated from a temperature of 170-190°C to 320-340°C and the sulphur precursor in trioctylphosphine and the zinc precursor in oleic acid are added simultaneously in a mass ratio of sulphur to zinc in the range of 1 : 13.9 g to 1 : 14.1 g over 60-75 minutes, after which it is allowed to cool; after which, in order to precipitate the ZnSe(Te) / ZnSe / ZnS reaction product from the solution, ethanol and 2-propanol are added to the mixture in a mass ratio of about 1 : 1 : 2, centrifuged for 10-15 min at 4000-5000 rpm and the precipitate obtained is dried.

[0035] Another object of the present invention are ZnSe(Te) / ZnSe / ZnS quantum dots emitting light in the blue range, obtained by the above-described method, which have the following physical and chemical properties:

[0036] - emission maximum wavelength (PL): 442-465 nm;

[0037] - FWHM of the photoluminescence spectrum: 10-50 nm;

[0038] - QY: >65%.

[0039] The objects of the invention are depicted in the drawings, in which:

[0040] - Fig.1 shows an example photograph of ZnSe(Te) / ZnSe / ZnS quantum dots emitting light in the blue range taken on an HR.-TEM microscope;

[0041] - Fig.2 shows a schematic of the reactor for the flow reaction; - Fig.3 shows a plot of absorbance and photoluminescence versus wavelength for a selected sample of ZnSe(Te) / ZnSe / ZnS quantum dots.

[0042] The key parameters for the method according to the present invention are the flow rate and the associated reaction time and temperature, the wavelength for the absorbance spectrum maximum (Abs) of the obtained ZnSe seeds (cores), the Abs value (for the first exciton peak) of the ZnSe seeds (cores).

[0043] The synthesis methods according to the present invention provide greater homogeneity and higher reproducibility of the obtained ZnSe seeds (cores) compared to a standard reaction performed in batch reactors (e.g. in a flask), due to the absence of the so-called batch-to- batch variation, i.e. certain differences in product parameters between consecutive production batches. The method for obtaining ZnSe seeds (cores) according to the present invention eliminates this problem due to the flow mode of the reaction, meaning that theoretically, exactly the same product is always produced. This makes it possible to obtain the substrate for further steps in the synthesis of quantum dots - ZnSe seeds (cores) in flow with the desired physico-chemical parameters.

[0044] In a batch reactor, obtaining ZnSe cores which are small and yet homogeneous in size is challenging, as this requires rapid initiation followed by rapid termination of the reaction, e.g. by rapid heating and cooling of the reaction mixture. In a batch reactor, it is difficult to carry out this process homogeneously throughout the reaction mixture, especially at larger synthesis scales, making it difficult to obtain cores of exactly the same size. This problem does not occur when the reaction is carried out in flow. Therefore, another advantage of the present invention is the high homogeneity of ZnSe seeds, i.e. ZnSe nanocrystalline cores of sufficiently small size, formed in the flow reaction. The high homogeneity of the ZnSe seeds (cores) has a direct impact on obtaining a homogeneous final product, i.e. quantum dots with the desired physico-chemical parameters.

[0045] In the case of ZnSe-based quantum dots, the key to achieving emission in the 440-470 nm wavelength range is doping their core with tellurium. At the same time, the nucleation process of standard doped seeds leads to a deterioration of their properties relative to undoped seeds. On the other hand, the introduction of a dopant into previously obtained ZnSe cores of a too large size is inefficient and may lead to a significant broadening of the emission spectrum, or the dopant may not be incorporated into the core structure at all. Therefore, the advantage of the seeds, i.e. the small ZnSe cores obtained in the described flow-mode reaction, is that tellurium doping can be introduced into them at a subsequent stage in order to achieve emission in the expected wavelength range and with a low value of half-wavelength broadening of the emission spectrum. The separation of the processes of nucleation of ZnSe seeds (cores) and their doping with tellurium allows independent control of both processes and ultimately makes it possible to obtain homogeneous ZnSe(Te) doped cores with controlled physico-chemical parameters, representing a homogeneous substrate for further stages of quantum dots synthesis.

[0046] The advantages of this method are the aforementioned homogeneity and reproducibility of the product and, in addition, the product - ZnSe seeds (cores) - can be collected at a selected time and a sample of the product, which is the substrate of quantum dots, taken at this stage, can be used for further reaction steps. In the case of conducting this step of the synthesis in a flask, this is technically not possible. Furthermore, in the case of flask-guided synthesis, injection of the tellurium dopant must occur within seconds of the start of ZnSe nucleation. A delay in injection can have significant negative consequences on the physicochemical properties of the final product, i.e. the quantum dots.

[0047] In view of the above, the described synthesis procedure taking into account flow-mode nucleation of seeds and doping of small cores in a separate process allows a process- controlled modification of the product.

[0048] Key value ranges for the methods and products according to the present invention:

[0049] 1. Method for obtaining ZnSe seeds (cores):

[0050] - temperature range of the reaction carried out: 250 - 300 degrees Celsius;

[0051] - flow rate of the reaction solution through the reactor: 300 - 2000 pl / min.

[0052] 2. Product, substrate - ZnSe seeds (cores):

[0053] - wavelength corresponding to the first exciton absorption band of ZnSe seeds (cores):

[0054] 335 - 392 nm; - absorbance value for the wavelength corresponding to the first exciton absorption band of ZnSe seeds (cores): 0.20 - 0.45.

[0055] 3. Method for obtaining tellurium doped ZnSefTe) cores:

[0056] - temperature range of the reaction carried out: up to 300 degrees Celsius;

[0057] - reaction time in reactor: 30-60 min;

[0058] - amount of tellurium added: 0.00 - 0.00026 mol;

[0059] 4. Final product - ZnSe(Te) / ZnSe / ZnS quantum dots emitting light in the blue range:

[0060] - emission maximum wavelength (PL): 442-465 nm;

[0061] - FWHM of photoluminescence spectrum: 10-50 nm;

[0062] - QY: >65 %

[0063] Additional data and measurements:

[0064] Photoluminescence spectra were measured to determine the position and broadening of the photoluminescence peak. The wavelength of the emission maximum (PL) and half-width of the photoluminescence spectrum (FWHM) were measured using the PerkinElmer FL 8500 fluorescence spectrometer (excitation wavelength set to 405 nm) or the Avantes AvaSpec- 2048XL spectrometer (excitation wavelength set to 365 nm). Absorbance was measured using the PerkinElmer model Lambda 364 UV-VIS spectrophotometer. Photoluminescence quantum yield was measured on the Hamamatsu Quantaurus-QY Absolute PL quantum yield spectrometer, C11347-11. Quantum dots size was measured using the Anton-Paar Litesizer 500 (DLS). The morphology of the quantum dots was observed using the high-resolution transmission electron microscopy HR.-TEM Microscope (FEI Titan G2 60-300).

[0065] An example photograph of ZnSefTe) / ZnSe / ZnS quantum dots emitting light in the blue range taken on the HR.-TEM microscope is shown in Fig. 1.

[0066] Particle size (volume-based) distribution (DLS) results for three selected samples of final product - ZnSefTe) / ZnSe / ZnS quantum dots emitting light in the blue range.

[0067] A schematic of the flow reaction reactor is shown in Fig. 2.

[0068] Parameters of the flow reaction reactor:

[0069] - maximum temperature: 1100°C;

[0070] - power: 13.8 kW;

[0071] - length of heating zone: 117 cm.

[0072] Values of quantum yield (QY) and emission wavelength of the photoluminescence (PL) spectrum maximum for three selected samples of the final product - ZnSe(Te) / ZnSe / ZnS quantum dots emitting light in the blue range.

[0073] A plot of absorbance and photoluminescence versus wavelength for a selected sample of ZnSe(Te) / ZnSe / ZnS quantum dots is shown in Fig. 3.

[0074] Conclusion:

[0075] The object of the present invention is to synthesise ZnSe seeds (cores) in flow, which provide a substrate for further quantum dots syntheses.

[0076] The obtained ZnSe seeds (cores) are then doped with tellurium and covered with shell to obtain blue-emitting quantum dots consisting of tellurium-doped ZnSe(Te) cores coated with ZnSe / ZnS shells.

[0077] EXAMPLES

[0078] Example 1. Flow synthesis of ZnSe seeds (cores) and tellurium doping of the resulting ZnSe seeds (cores)

[0079] The system for the flow synthesis consists of a furnace (tubular reactor) and a steel tube 160 cm long and 0.3175 cm (1 / 8 inch) in diameter, through which a flow of reaction solution is conducted, a flow meter with apparatus, a peristaltic pump, an argon source, and also flexible tubes with high chemical and thermal resistance surrounded by heating bands connected to temperature controllers.

[0080] 1.1 g (0.006 moles) of anhydrous zinc acetate (Zn(Ac)i), 5.37 g (0.019 moles) of oleic acid (OA) and 35.51 g (0.14 moles) of 1 -octadecene (ODE) were weighed and all the ingredients were placed in a glass flask.

[0081] Under the fume cupboard, the system was connected to a Schlenk line and the flask with the reagents was placed in a heating basket and connected to a temperature controller set on a magnetic stirrer (500 rpm). The solution was pre-gassed at room temperature for 5 minutes and with the pressure in the flask gradually reduced until it reached 1 mbar. Later, the solution was heated to 120°C in about 12 minutes. At this temperature, the solution was degassed again for a further hour. Argon was then connected to the system and a 1.5 M solution of selenium precursor (0.237 g selenium) in diphenylphosphine (1.56 g diphenylphosphine) (Se-DPP) was rapidly injected and the solution incubated at 120°C for 30 min.

[0082] After this time, a peristaltic pump set to a speed of 1.3 ml / min was started and the reaction solution was passed through a tubular reactor, heated to 250°C, which is part of the flow synthesis system. For the first 10 minutes, the reaction solution was collected in a separate beaker. Subsequently, the reaction solution containing the resulting ZnSe seeds (cores) was collected into a flask for about 42 minutes, until a volume of 54 ml was collected. The collected solution was degassed again for 10 minutes at 100°C. The Ar supply was turned off, the solution was heated to 210°C and then 0.056 M tellurium solution (0.016 g tellurium) in trioctylphosphine (1.86 g trioctylphosphine) (Te-TOP) was injected into the reaction mixture. The solution was then heated to 300°C and incubated for 60 minutes at 300°C. The resulting ZnSe(Te) cores were used further in the synthesis, i.e. during the growth of the ZnSe shell.

[0083] Example 2. Synthesis of ZnSe shell

[0084] In an anaerobic atmosphere, 60 ml of a 0.75 M solution of zinc precursor (8.25 g zinc) in oleic acid (26.73 g OA), 12.46 g TOP and 12.13 g trioctylamine (TOA) was melted on a hotplate at 180°C and then transferred to a glass bottle. 15.12 ml of a 1.2 M solution of selenium (1.48 g Se) in trioctylphosphine (12.47 g TOP) (Se-TOP) was drawn into a syringe.

[0085] Under the fume hood, a tube and needle were connected to the syringe with Se-TOP. The syringe was placed in a syringe pump set to a flow rate of 126 pl / min.

[0086] The zinc precursor bottle was placed on a heating plate set at 180°C and with 200 rpm stirring. The bottle was capped with a ferrule cap, and a hose fitted to the peristaltic pump was drawn through one of the ferrules (feed rate 501 pl / min), an argon feed hose was connected to the other and the argon was unscrewed.

[0087] To the solution of the ZnSe(Te) cores obtained in the earlier step, after their incubation at 300°C, precursor solutions were supplied by connecting hoses with needles and septum to the flask, and the injection of Se-TOP (126 pl / min) and Zn(OA)2 (501 pl / min) was started. Both injections should last 120 min. After the injections were completed, the heating basket was turned off and the flask was left in the heating basket to cool the reaction solution.

[0088] The reaction solution was poured into a vessel and weighed. A mass of ethanol corresponding to the mass of the reaction solution and a mass of 2-propanol corresponding to twice the mass of the reaction solution were added to the vessel. The solution was centrifuged for 10 min at 4500 rpm. After completion, the precipitate was dried and dispersed in 17.5 g (0.2 moles) of hexane. The resulting ZnSeTe / ZnSe product was used in the further part of the synthesis, namely during the growth of the ZnS shell.

[0089] Example 3. Synthesis of ZnS shell

[0090] 8.69 g (0.036 moles) of hexadecylamine (HDA), 16.11 g (0.057 moles) of oleic acid (OA), 145.65 g (0.412 moles) of trioctylamine (TOA) and 3.3 g (0.018 moles) of anhydrous zinc acetate were weighed and all ingredients were placed together in a glass flask. In an anaerobic atmosphere, 54 ml of a 0.75 M solution of the zinc precursor (7.43 g Zn) in oleic acid (24.06g OA) was melted on a hotplate at 180°C and transferred to a glass bottle. A 13.5 ml 1.2 M solution of the sulphur precursor (0.53 g sulphur) in trioctylphosphine (11.22 g TOP) was drawn into a syringe.

[0091] Under the fume hood, a tube and needle were connected to the syringe containing the sulphur precursor. The syringe was placed in a syringe pump set to a flow rate of 225 pl / min. The bottle containing the zinc precursor was placed on a heating plate set at 180°C and with stirring at 200 rpm. The bottle was capped with a ferrule cap, and a hose fitted to the peristaltic pump (feed rate 900 pl / min) was threaded through one ferrule, an argon feed hose was connected to the other and the argon was unscrewed. The sulphur precursor and zinc precursor are ready to be added at a further stage of the synthesis.

[0092] A system was connected to the Schlenk line under the fume cupboard and the flask with the reagents weighed in the first step (HDA, OA, TOA and anhydrous zinc acetate) was placed in a heating basket and connected to a temperature controller set on a magnetic stirrer (500 rpm). Initially, the solution was degassed at room temperature for 5 minutes and with the pressure in the flask gradually reduced until a range of 1-10 mbar was reached. Later, the solution was heated to 120°C in about 12 minutes. At this temperature, the solution was degassed again for 10 minutes. Argon was then connected to the system and the solution was heated to 180°C. The ZnSeTe / ZnSe product obtained at the earlier stage (dissolved in hexane) was then taken into syringes and injected vigorously into the solution over about 1 minute. The solution was heated to 185°C and simultaneous administration of the prepared zinc and sulphur precursors was initiated over approximately 60 min. Simultaneously, the solution was heated to 33O°C during the administration of the precursors. Once 33O°C was reached and the feed of both precursors was completed, the heating basket was turned off and the flask was left to cool in the heating basket.

[0093] The reaction solution was poured into a vessel and weighed. A mass of ethanol corresponding to the mass of the reaction solution and a mass of 2-propanol corresponding to twice the mass of the reaction solution were added to the vessel. The solution was centrifuged for 10 minutes at 4500 rpm. After completion, the precipitate was dried and dispersed in toluene so that the final concentration of the product was about 100 mg / ml.

Claims

AMENDED CLAIMS received by the International Bureau on 17 April 2025 (17.04.2025)Claims1. A method for obtaining ZnSe cores in flow, characterised in that it comprises the steps wherein:- a mixture of anhydrous zinc acetate Zn(Ac)i, oleic acid OA and 1 -octadecene ODE is prepared in a reaction vessel using stirring;- the resulting mixture is degassed at room temperature, reducing the pressure to 1 mbar, followed by heating to 110-130°C and further degassing for 45-90 minutes;- the degassed mixture is placed in an argon atmosphere and a solution of the selenium precursor in diphenylphosphine Se-DPP is added to give the reaction mixture, which is then heated at 110-130°C for 30-60 minutes with continuous stirring;- then the reaction mixture is passed at a rate of 1.0 to 1.5 ml / minute through a tubular reactor heated to a temperature in the range of 250-300°C, collecting at the exit of the reactor the reaction solution containing the resulting ZnSe cores.

2. The method according to claim 1, characterized in that zinc acetate Zn(Ac)i, oleic acid OA and 1 -octadecene ODE in a mole ratio ranging from 1 : 3 : 23 to 1 : 4 : 24 are used.

3. The method according to claim 1 or 2, characterized in that the solution of selenium precursor in diphenylphosphine Se-DPP is used in such an amount that the ratio of Se to Zn is in a mole range of 1 : 1.19 to 1 : 1.21.

4. The method according to any of claims 1 to 3, characterized in that the selenium precursor mixture is passed at a rate of 1.3 ml / minute through a tubular reactor heated to a temperature in the range of 250-300°C.

5. The method according to any of claims 1 to 4, characterized in that the mixture of anhydrous zinc acetate Zn(Ac)i, oleic acid OA and 1 -octadecene ODE in a reaction vessel is stirred at 400-600 rpm.

6. Method for obtaining tellurium doped ZnSe(Te) cores, characterized in that ZnSe cores are obtained by the method described in any of claims 1 to 5, and then:- the obtained mixture of ZnSe cores is degassed at 90-110°C for 10-15 minutes;- the degassed mixture of ZnSe cores is placed in an Ar atmosphere, heated to 200-220°C and a solution of tellurium in trioctylphosphine Te-TOP is added, and then the whole reaction solution is heated to 290-310°C, after which the solution is heated for 45- 90 minutes at 290-310°C.

7. The method according to claim 6, characterized in that the mixture of ZnSe cores and tellurium solution in trioctylphosphine Te-TOP in a volume ratio ranging from 24 : 1 ml to 24.5 : 1 ml is used.

8. A method for obtaining ZnSe(Te) / ZnSe / ZnS quantum dots emitting light in the blue range, characterized in that tellurium doped ZnSe(Te) cores are obtained by the method described in any of claims 6 to 7, and then- a ZnSe shell is formed on the tellurium doped ZnSe(Te) cores, followed by- an additional ZnS shell is formed on tellurium doped ZnSe(Te) cores with a ZnSe shell.

9. The method according to claim 8, characterized in that- a ZnSe shell is formed on tellurium doped ZnSe(Te) cores by a method comprising steps in which:- to a reaction solution containing ZnSe(Te) cores is added a solution of selenium in trioctylphosphine Se-TOP and a solution of zinc precursor Zn(OA)i in a mass ratio of Zn to Se in the range of 5.4 : 1 g to 5.8: 1 g at 190-210°C, under an argon atmosphere, using stirring 150-250 rpm for 100-150 minutes, after which the mixture is allowed to cool;- in order to precipitate the ZnSe(Te) / ZnSe reaction product from the solution, ethanol and 2-propanol are added to the mixture in a mass ratio of about 1 : 1 : 2, centrifuged for 10-15 min at 4000-5000 rpm and dried the precipitate obtained, after which its solution is prepared by dispersion in hexane;- on tellurium doped ZnSe(Te) cores with a ZnSe shell, an additional ZnS shell is formed by a method involving steps in which:- a solution containing hexadecylamine (HDA), oleic acid (OA), trioctylamine (TOA) and anhydrous zinc acetate is prepared in a glass flask in a mole ratio of 2 : 3 : 22 : 1 to 2 : 3.5 : 23 : 1, then the resulting solution is stirred at 400-600 rpm, followed by degassing for 5-10 minutes at room temperature, reducing the pressure to the range of 1-10 mbar and heating to 110-130°C and further degassing for 10-15 minutes;- the degassed mixture is placed in an argon atmosphere, heated to 170-190°C and the previously obtained ZnSe(Te) / ZnSe is added;- the whole reaction solution is heated from a temperature of 170-190°C to 320-340°C and the sulphur precursor in trioctylphosphine and the zinc precursor in oleic acid are added simultaneously in a mass ratio of sulphur to zinc in a range of 1 : 13.9 g to 1 : 14.1 g over 60-75 minutes, after which it is allowed to cool;- in order to precipitate the ZnSe(Te) / ZnSe / ZnS reaction product from the solution, ethanol and 2-propanol are added to the mixture in a mass ratio of about 1 : 1 : 2, centrifuged for 10-15 min at 4000-5000 rpm and the precipitate obtained is dried.Statement under Article 19(1) PCT for amendments for applicationPCT / IB2023 / 063053Applicant submits herewith an Amendment under Article 19 PCT in which the differences between the claims as filed and the claims as amended are as follows:Claim 1Line 9 - word “incubated” has been replaced by word “heated”.Claim 6 has been deleted.New claim 6, previous claim 7Line 7 - word “incubated” has been replaced by word “heated”.New claim 7, previous claim 8 is now dependent on claim 6.New claim 9, previous claim 10 is now dependent on claim 8.Claim 11 has been deleted.The numbering of the remaining claims has been adjusted appropriately.The amendments are fully supported by the application as filed and no new matter has been introduced.The present amendments have no impact on the description of the International Application.

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