Method for controlled preparation of quantum dots from prenucleation clusters

Abstract

The application belongs to the technical field of semiconductor light-emitting materials, and particularly relates to a size-controllable quantum dot, a preparation method thereof and application thereof. The quantum dot is prepared by the following method: a sample in an induction period of a quantum dot pre-nucleation stage is dispersed in a solvent, and the reaction is carried out at a temperature of 25-105 DEG C for 0.5-24h. The application can accurately control the particle size of the quantum dot and further adjust the light-emitting characteristics of the quantum dot, can effectively expand the application of the quantum dot, and has a good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor light-emitting materials technology, specifically relating to a method for controllable preparation of quantum dots from pre-nucleated clusters. Background Technology

[0002] Semiconductor quantum dots (QDs), due to their quantum size effect and excellent optoelectronic properties, have been a research hotspot in the field of nanotechnology for nearly 30 years, leading the innovation of next-generation lighting and display technologies and becoming a key focus of research and development in both industry and academia. At the same time, the application of quantum dot materials in new energy (solar cells), biomedicine, and other fields is also attracting increasing attention.

[0003] Semiconductor light-emitting materials are materials that release light through the recombination of electrons and holes, and they have great application prospects in light-emitting devices. Light-emitting devices of different colors are made from various specific light-emitting materials. Quantum dots, with their emission spectra varying with size, can cover the entire visible light region, thus becoming a hot research topic.

[0004] Quantum dot preparation methods can be categorized by system type into organic phase and aqueous phase, and by preparation method into one-pot method, injection method, etc. Organic phase synthesis yields higher fluorescence quantum yields for quantum dots, while aqueous phase synthesis offers advantages in lower cost and less pollution. Currently reported organic phase synthesis of pure CdTe quantum dots covers an absorption range of 475 to 750 nm and an emission range of green to red light; however, CdTe quantum dots with absorption peaks below 475 nm have not been reported. Similarly, reported organic phase synthesis of pure ZnSe quantum dots covers an absorption range of 320 to 470 nm and an emission range of green to red light; however, ZnSe quantum dots with absorption peaks below 320 nm have not been reported. Furthermore, existing quantum dot preparation methods require stringent conditions and strict control. In addition, there is currently a lack of methods for precise control of quantum dot size. Summary of the Invention

[0005] In view of the problems of the prior art, the present invention provides a quantum dot with controllable size, its preparation method and its uses.

[0006] A quantum dot with controllable size is prepared by dispersing a sample of semiconductor material in an induction period in a solvent and reacting it at a temperature of 25-105℃ for 0.5-24h; wherein the semiconductor material is selected from CdTe, ZnSe, CdSe, CdS or CdSeS.

[0007] Preferably, when the semiconductor material is selected from CdTe, the quantum dot absorption peak is in the range of 417-560 nm, the emission peak is in the range of 460-570 nm, and the full width at half maximum (FWHM) is about 34-37 nm.

[0008] When the semiconductor material is selected from ZnSe, the quantum dot absorption peak is in the range of 303-320 nm.

[0009] When the semiconductor material is selected from CdSe, the quantum dot absorption peak is in the range of 361-373 nm.

[0010] When the semiconductor material is selected from CdS, the quantum dot absorption peak is in the range of 300-350 nm.

[0011] When the semiconductor material is selected from CdSeS, the quantum dot absorption peak is in the range of 299-335 nm.

[0012] Preferably, the size of the quantum dot is 2.5-3.0 nm.

[0013] Preferably, the solvent is selected from at least one of toluene, cyclohexane, n-hexane, methanol, and water.

[0014] Preferably, the semiconductor material is selected from CdTe, the solvent is selected from toluene, and the quantum dot has an absorption peak at 440-520 nm and an emission peak at 482-545 nm.

[0015] Alternatively, the semiconductor material is selected from CdTe, the solvent is selected from cyclohexane, and the quantum dot has an absorption peak at 417-465 nm and an emission peak at 460-485 nm.

[0016] Alternatively, the semiconductor material is selected from ZnSe, the solvent is selected from cyclohexane, and the quantum dot absorption peak is in the range of 305-319 nm;

[0017] Alternatively, the semiconductor material is selected from ZnSe, the solvent is selected from a mixed solvent prepared from cyclohexane and methanol, and the quantum dot absorption peak is in the range of 303-320 nm;

[0018] Alternatively, the semiconductor material is selected from CdSe, the solvent is selected from water, and the quantum dot absorption peak is in the range of 361-373 nm;

[0019] Alternatively, the semiconductor material is selected from CdS, the solvent is selected from water, and the quantum dot absorption peak is in the range of 300-350 nm;

[0020] Alternatively, the semiconductor material is selected from CdSeS, the solvent is selected from water, and the quantum dot absorption peak is in the range of 299-335 nm.

[0021] Preferably, the semiconductor material is selected from CdTe, the solvent is selected from toluene, and the CdTe quantum dot has absorption peaks at 440nm±1%, 449nm±1%, 475nm±1%, 481nm±1%, 490nm±1%, 495nm±1%, 500nm±1%, 510nm±1%, or 520nm±1%, and emission peaks at 473nm±1%, 482nm±1%, 493nm±1%, 505nm±1%, 512nm±1%, 518nm±1%, 525nm±1%, 535nm±1%, or 545nm±1%.

[0022] Alternatively, the semiconductor material is selected from CdTe, the solvent is selected from cyclohexane, and the quantum dot absorption peak is at 417nm±5%, 428nm±1%, 440nm±1%, 450nm±1%, 458nm±1%, or 465nm±1%, and the emission peak is at 460nm±1%, 468nm±1%, 475nm±1%, 480nm±1%, or 485nm±1%.

[0023] Alternatively, the semiconductor material is selected from ZnSe, the solvent is selected from cyclohexane, and the quantum dot absorption peak is at 305nm±1%, 314nm±1%, 318nm±1%, or 319nm±1%;

[0024] Alternatively, the semiconductor material is selected from ZnSe, the solvent is selected from a mixed solvent prepared from cyclohexane and methanol, and the quantum dot absorption peak is at 303nm±5%, 306nm±1%, 307nm±1%, 310nm±1%, 311nm±1%, 319nm±1%, or 320nm±1%;

[0025] Alternatively, the semiconductor material is selected from CdSe, the solvent is selected from water, and the CdSe quantum dot absorption peak is at 361nm±1% or 373nm±1%;

[0026] Alternatively, the semiconductor material is selected from CdS, the solvent is selected from water, and the quantum dot absorption peaks are at 300nm±1%, 302nm±1%, 303nm±1%, 311nm±1%, 323nm±1%; 330nm±1%, 337nm±1%, 340nm±1%, 343nm±1%, 346nm±1% or 350nm±1%;

[0027] Alternatively, the semiconductor material is selected from CdSeS, the solvent is selected from water, and the quantum dot absorption peak is at 299nm±1%, 304nm±1%, 306nm±1%, 318nm±1%, or 335nm±1%.

[0028] Preferably, the ratio of the induction period sample to the solvent is a volume ratio of (0.5-6):100.

[0029] Preferably, the semiconductor material is selected from CdTe, and the preparation of the induction period sample includes the following steps:

[0030] (1) Cadmium acetate dihydrate was reacted with oleylamine to obtain the oleylamine-cadmium acetate precursor;

[0031] (2) The tellurium powder was mixed with trioctylphosphine and reacted to obtain the trioctylphosphine tellurium precursor;

[0032] (3) The trioctylphosphine telluride precursor is added to the oleylamine cadmium acetate precursor to react and obtain the product;

[0033] Alternatively, the semiconductor material is selected from ZnSe, and the preparation of the induction period sample includes the following steps:

[0034] (1) Zinc oxide, oleic acid and 1-octadecene were reacted to obtain zinc oleate precursor;

[0035] (2) Selenium powder and trioctylphosphine are mixed and reacted to obtain trioctylphosphine selenium precursor.

[0036] (3) The trioctylphosphine selenide precursor and diphenylphosphine are mixed and added to the zinc oleate precursor for reaction to obtain the product;

[0037] Alternatively, the semiconductor material is selected from CdSe, and the preparation of the induction period sample includes the following steps: dissolving cadmium chloride 2.5 water and mercaptopropionic acid in deionized water, adjusting the pH to 12.0-12.8, and then adding selenourea to the solution to react, thus obtaining the sample;

[0038] Alternatively, the semiconductor material is selected from CdS, and the preparation of the induction period sample includes the following steps: dissolving cadmium chloride 2.5 water and mercaptopropionic acid in deionized water, adjusting the pH to 12.0-12.8, and then adding thioacetamide to the solution to react, thus obtaining the sample;

[0039] Alternatively, the semiconductor material is selected from CdSeS, and the preparation of the induction period sample includes the following steps: dissolving cadmium chloride 2.5 water and mercaptopropionic acid in deionized water, adjusting the pH to 12.0-12.8, and then adding selenourea and thioacetamide to the solution to react, thereby obtaining the sample.

[0040] The present invention also provides a method for preparing the above-mentioned quantum dots, wherein a sample of semiconductor material induction period is dispersed in a solvent and reacted at a temperature of 25-105℃ for 0.5-24h to obtain the quantum dots.

[0041] The present invention also provides the use of the above-mentioned quantum dots as semiconductor light-emitting materials.

[0042] The induction period sample (IPS) described in this invention is an intermediate proposed in Professor Yu Kui's research (Nat. Commun. 2017, 8, 15467; Chem. Mater. 2017, 29, 5727−5735; Adv. Sci. 2018, 5, 1800632; J. Phys. Chem. Lett. 2018, 9, 2818–2824.). The active ingredient in the IPS is a precursor compound. The precursor compound does not exhibit characteristic UV absorption at the end of the synthesis, but it can be converted into corresponding magic number nanoclusters through a period of incubation or by the addition of external reagents, and then exhibit characteristic UV absorption. The CdTe induction period sample used in this invention can be synthesized with reference to existing technology (J.Phys.Chem.Lett.2019,10,4345−4353.), the ZnSe induction period sample can be synthesized with reference to existing technology (Adv.Sci.2018,5,1800632.), the CdS induction period sample can be synthesized with reference to existing technology (NatCommun.2020,11,4199.), and the CdSe induction period sample can be synthesized with reference to existing technology (Nano.Res.2022,15,2634–2642.).

[0043] Specifically, the preparation of the CdTe induction period sample includes the following steps:

[0044] (1a) Cadmium acetate dihydrate was reacted with oleylamine to obtain the oleylamine-cadmium acetate precursor;

[0045] (2a) The tellurium powder was mixed with trioctylphosphine and reacted to obtain the trioctylphosphine tellurium precursor.

[0046] (3a) Trioctylphosphine telluride precursor was added to oleylamine cadmium acetate precursor to react and obtain CdTe induction period sample.

[0047] Step (1a) specifically includes the following steps:

[0048] (1.1a) Mix cadmium acetate dihydrate and oleylamine;

[0049] (1.2a) The reaction is carried out under vacuum conditions at a temperature of 100-140℃, preferably 120℃; after the reaction is completed, the oleylamine cadmium acetate precursor is obtained.

[0050] And / or, in step (1.1a), the operation of purging the reaction system with an inert gas and then evacuating it is performed at least three times;

[0051] And / or, the reaction time in step (1.2a) is 0.5-1.5 h, preferably 1 h;

[0052] And / or, step (2a) specifically includes the following steps:

[0053] (2.1a) Mix tellurium powder and trioctylphosphine;

[0054] (2.2a) The reaction is carried out under a nitrogen atmosphere at a temperature of 280-320℃, preferably 300℃;

[0055] (2.3a) The reaction was carried out under vacuum at room temperature. After the reaction was completed, the trioctylphosphine tellurium precursor was obtained.

[0056] The reaction conditions for step (3a) are as follows: heating the oleylamine cadmium acetate precursor to 80-120°C, preferably 120°C, adding the trioctylphosphine telluride precursor and heating to 135°C for 10-30 min, preferably 18 min.

[0057] Specifically, the preparation of the ZnSe induction period sample includes the following steps:

[0058] (1b) Zinc oxide and oleic acid are reacted in 1-octadecene to obtain zinc oleate precursor;

[0059] (2b) Selenium powder is mixed with trioctylphosphine and reacted to obtain trioctylphosphine selenium precursor.

[0060] (3b) Trioctylphosphine selenium precursor and diphenylphosphine were added to zinc oleate precursor to react and obtain ZnSe induction period sample.

[0061] Step (1b) specifically includes the following steps:

[0062] (1.1b) Mix zinc oxide, oleic acid and 1-octadecene;

[0063] (1.2b) The reaction is carried out under inert gas conditions at a temperature of 280-320℃, preferably 290℃; after the reaction is completed, zinc oleate precursor is obtained.

[0064] And / or, in step (1.1b), the operation of purging the reaction system with an inert gas and then evacuating it is performed at least three times;

[0065] And / or, the reaction time in step (1.2b) is 1.5-3 hours, preferably 2 hours;

[0066] And / or, step (2b) specifically includes the following steps:

[0067] (2.1b) Mix selenium powder and trioctylphosphine;

[0068] (2.2b) The reaction is carried out under a nitrogen atmosphere at a temperature of 25-60°C, preferably 25°C;

[0069] The reaction conditions for step (3b) are as follows: heating the zinc oleate precursor to 80-120°C, preferably 80°C, adding the trioctylphosphine selenide precursor and diphenylphosphine, and heating to 160°C for 20-40 min, preferably 30 min.

[0070] Specifically, the preparation of the CdSe induction period sample includes the following steps:

[0071] (1c) Dissolve cadmium chloride 2.5 water and mercaptopropionic acid in deionized water, adjust the pH of the solution to 12.0 with sodium hydroxide, and then add selenourea to the solution to react and obtain the CdSe induction period sample.

[0072] The specific steps (1c) include the following:

[0073] (1.1c) This reaction is a one-pot synthesis at room temperature. After preparing the sample, the precursor compound can be obtained by stirring at room temperature. The preferred time is 60-180 min.

[0074] Specifically, the preparation of the CdS induction period sample includes the following steps:

[0075] (1d) Dissolve cadmium chloride 2.5 water and mercaptopropionic acid in deionized water, adjust the pH of the solution to 12.0 with sodium hydroxide, and then add thioacetamide to the solution to react and obtain the CdS induction period sample.

[0076] The specific steps (1d) include the following:

[0077] (1.1d) The reaction is synthesized in a one-pot method at room temperature. After the sample is prepared, the precursor compound can be obtained by stirring at room temperature. The preferred time is 60-180 min.

[0078] Specifically, the preparation of the CdSeS induction period sample includes the following steps:

[0079] (1e) Dissolve cadmium chloride 2.5 water and mercaptopropionic acid in deionized water, adjust the pH of the solution to 12.0 with sodium hydroxide, and then add thioacetamide to the solution to react and obtain CdSeS induction period sample.

[0080] The specific steps (1e) include the following:

[0081] (1.1e) This reaction is synthesized in a one-pot method at room temperature. After the sample is prepared, it is stirred at room temperature.

[0082] Precursor compounds can be obtained, with a preferred time of 60-180 min.

[0083] This invention provides a novel method for preparing quantum dots. Specifically, using a CdTe induction phase sample as raw material, the sample is dispersed in a solvent, and the precursor compound is decomposed into monomers. The monomers are supersaturated in the solution, causing quantum dots to nucleate and grow. The preparation method of this invention allows for precise control of the CdTe quantum dot size by adjusting the solvent type, reaction temperature, and reaction time, thereby controlling their light absorption and emission properties. Using this method, CdTe quantum dots with absorption peaks below 475 nm, ZnSe quantum dots with absorption peaks below 320 nm, CdSe quantum dots with absorption peaks at 373 nm, CdS quantum dots with absorption peaks at 323 nm, and CdSeS quantum dots with absorption peaks at 335 nm can be prepared. These quantum dots with absorption peaks in the low-wavelength region are difficult to prepare using existing methods. Therefore, this invention effectively expands the application range of quantum dots and has excellent application prospects in fields such as displays, lighting, and biomarkers.

[0084] Obviously, based on the above description of the present invention, and according to common technical knowledge and conventional methods in the field, various other modifications, substitutions or alterations can be made without departing from the basic technical concept of the present invention.

[0085] The following detailed embodiments further illustrate the above-described content of the present invention. However, this should not be construed as limiting the scope of the present invention to the following examples. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention, including but not limited to methods for obtaining other semiconductor quantum dot materials by processing pre-nucleated clusters in induction-phase samples. Attached Figure Description

[0086] Figure 1 TEM characterization of the CdTe quantum dots prepared in Example 1.

[0087] Figure 2 The absorption and emission spectra of quantum dots synthesized in Examples 1 and 2 at different temperatures are shown.

[0088] Figure 3 The absorption and emission spectra of quantum dots synthesized in Examples 3 and 4 at different reaction times are shown.

[0089] Figure 4 The absorption spectrum of ZnSe quantum dots obtained in CH in Example 5 is shown.

[0090] Figure 5 The absorption spectrum of ZnSe quantum dots was obtained by adding a small amount of methanol to CH in Example 5.

[0091] Figure 6The absorption spectra of CdSe, CdS, and CdSeS quantum dots obtained in water in Examples 6, 7, and 8 are shown.

[0092] Figure 7 The absorption spectrum of CdS quantum dots was obtained by dispersing the purified CdS pre-nucleated clusters in water and reacting them at 60°C, as shown in Example 7. Detailed Implementation

[0093] In the following examples, all reagents and raw materials used, unless otherwise specified, are commercially available products.

[0094] Example 1: Preparation of CdTe quantum dots using toluene (Tol) as solvent and controlled holding temperature

[0095] This embodiment includes the following steps:

[0096] 1. Prepare CdTe induction period samples.

[0097] The oleylamine-cadmium acetate (Cd(OAc)2 / OLA) precursor was prepared by mixing cadmium acetate dihydrate (Cd(OAc)2·2H2O) with oleylamine (OLA);

[0098] (1) Place cadmium oxide (1.5995 g, 6 mmol) and oleylamine (36 mL, 78 mmol) in a three-necked flask;

[0099] (2) Vacuuming at room temperature, followed by three vacuum / nitrogen exchange operations (to be completed within 30 minutes);

[0100] (3) Under nitrogen protection, the temperature was raised to 120°C and the reaction was carried out under vacuum for 1 hour;

[0101] (4) Cool down to room temperature and collect the product, which is the cadmium oleylamine acetate precursor.

[0102] Trioctylphosphine tellurium (TeTOP) precursor was prepared by mixing tellurium powder (Te) with oleylamine (trioctylphosphine);

[0103] (1) Mix tellurium powder and trioctylphosphine;

[0104] (2) Vacuuming at room temperature, and vacuum / nitrogen gas exchange operation three times (completed within 30 minutes).

[0105] (3) Under nitrogen protection, the temperature is raised to 300℃ and the reaction is carried out for 40 min;

[0106] (4) Cool to room temperature and evacuate for 35 min. The product obtained is the trioctylphosphine telluride precursor. Cadmium oleylamine acetate reacts with trioctylphosphine telluride at 135 °C for 18 min to obtain CdTeIPS;

[0107] 2. Quantum dots were prepared by controlling the heat preservation temperature using induction period samples and Tol as raw materials.

[0108] Take 30 μL of the induction period sample and disperse it in 3 mL of Tol at room temperature, with a volume ratio of 1:100. Keep the solution at different temperatures for 30 min using a gradient heating method. The holding temperatures are 25, 35, 45, 55, 65, 75, 85, 95, and 105 °C, and take samples for testing at each temperature.

[0109] Its absorption curve is as follows Figure 2 As shown in a1, the absorption range is 440-520 nm, and the fluorescence spectrum is as follows. Figure 2 As shown in a2, the emission range is 482-545 nm. Specific absorption / fluorescence peak positions are shown in Table 1.

[0110] Table 1. Variation of CdTe quantum dots with Tol as solvent as holding temperature

[0111]

[0112] Example 2: Preparation of CdTe quantum dots using cyclohexane (CH) as solvent and controlled holding temperature.

[0113] Includes the following steps:

[0114] 1. The induction period sample is as described in Example 1.

[0115] 2. Quantum dots were prepared by controlling the insulation temperature using induction period samples and CH as raw materials.

[0116] Take 30 μL of the induction period sample and disperse it in 3 mL of CH at room temperature, with a volume ratio of 1:100. Keep the solution at different temperatures for 30 min by gradient heating. The heating temperatures are 25, 35, 45, 55, 65 and 75 °C respectively. Take samples for testing at each temperature.

[0117] Its absorption curve is as follows Figure 2 As shown in b1, the absorption range is 417-465 nm, and the fluorescence spectrum is as follows. Figure 2 As shown in b2, the emission range is 460-485nm.

[0118] The specific absorption / fluorescence peak positions are shown in Table 2:

[0119] Table 2 shows the variation of CdTe quantum dots with CH4 as solvent as the holding temperature.

[0120]

[0121] Example 3: Preparation of CdTe quantum dots using Tol as solvent and controlled holding time

[0122] Includes the following steps:

[0123] 1. The induction period sample is as described in Example 1;

[0124] 2. Quantum dots were prepared using CdTe induction period samples and Tol as raw materials.

[0125] Take 30 μL of the induction period sample and disperse it in 3 mL of Tol at room temperature (volume ratio 1:100). Heat the solution to 45 °C and keep it at this temperature for 0-24 h. Take samples at regular intervals during the incubation period for testing.

[0126] Absorption curves as follows Figure 3 As shown in a1, the absorption range is 479-490 nm, and the fluorescence spectrum is as follows. Figure 3 As shown in a2, the emission range is 498-515nm.

[0127] The specific absorption / fluorescence peak positions are shown in Table 3:

[0128] Table 3. Variation of CdTe quantum dots with Tol as solvent as a function of heat preservation time.

[0129]

[0130] Figure 1 a is a TEM image of the CdTe quantum dots prepared in Example 3 with an absorption peak at 482 nm. The quantum dot sizes were statistically analyzed and found to be distributed within the range of 3.0 ± 0.5 nm.

[0131] Example 4: Preparation of CdTe quantum dots using CH4 as solvent and controlled holding time

[0132] Includes the following steps:

[0133] 1. The induction period sample is as described in Example 1.

[0134] 2. Quantum dots were prepared using induction period samples and CH as raw materials.

[0135] Take 30 μL of the induction period sample and disperse it in 3 mL of CH at room temperature (volume ratio 1:100). Heat the solution to 45 °C and keep it at this temperature for 0-24 h. Take samples at regular intervals during the incubation period for testing.

[0136] Its absorption curve is as follows Figure 3 As shown in b1, the absorption range is 431-450 nm, and the fluorescence spectrum is as follows. Figure 3 As shown in b2, the emission range is 465-477nm.

[0137] The specific absorption / fluorescence peak positions are shown in Table 4:

[0138] Table 4. Variation of CdTe quantum dots with CH4 solvent as a function of heat preservation time.

[0139]

[0140] Figure 1 b is a TEM image of the CdTe quantum dots prepared in Example 4 with an absorption peak at 470 nm. The quantum dot sizes were statistically analyzed and found to be distributed within the range of 2.5 ± 0.5 nm.

[0141] The luminescence properties of the samples prepared in the four embodiments above were compared:

[0142] 1. Temperature-controlled CdTe quantum dots and their luminescence properties

[0143] Figure 2 These are CdTe quantum dots prepared in Examples 1 and 2. Figure 2 a1 and a2 are CdTe quantum dots prepared with Tol as solvent. As the temperature increases, the absorption peak of the quantum dots redshifts from 440nm to 520nm, and the emission peak redshifts from 482nm to 545nm. Figure 2 b1 and b2 are CdTe quantum dots prepared using CH4 as a solvent. With increasing holding time, the absorption peak of the quantum dots redshifts from 417 nm to 465 nm, and the emission peak redshifts from 460 nm to 485 nm. As the holding temperature increases, the size of the quantum dots increases, and different luminescent quantum dots can be obtained by controlling the temperature.

[0144] 2. Solvent-controlled CdTe quantum dots and their luminescence properties.

[0145] Figure 3 These are CdTe quantum dots prepared in Examples 3 and 4. Figure 3 a1 and a2 are CdTe quantum dots prepared with Tol as solvent. As the holding time increases, the absorption peak of the quantum dots redshifts from 479nm to 490nm, and the emission peak redshifts from 498nm to 515nm. Figure 3 CdTe quantum dots, b1 and b2, were prepared using CH4 as a solvent. With prolonged holding time, the absorption peak of the quantum dots red-shifted from 435 nm to 449 nm, and the emission peak red-shifted from 465 nm to 477 nm. The quantum dots obtained using CH4 as a solvent were smaller than those obtained using Tol. The lowest absorption peak of the quantum dots was at 435 nm, and the emission wavelength was 465 nm, emitting near-blue light. Compared to other existing CdTe quantum dot preparation methods, the emission peak showed a blue shift, and different luminescence patterns could be obtained by controlling the type of solvent.

[0146] In addition, the emission peak has a full width at half maximum (FWHM) of 35 nm and emits light in defect-free states.

[0147] Example 5: ZnSe quantum dots prepared at room temperature using CH4 as solvent.

[0148] This embodiment 5 includes the following steps:

[0149] 1. Prepare ZnSe induction period samples.

[0150] Zinc oleate (Zn(OA)2) precursor was prepared by mixing zinc oxide (ZnO), oleic acid (OA), and 1-octadecene (ODE);

[0151] (1) Place zinc oxide (0.492 g, 6.04 mmol), oleic acid (3.729 g, 13.2 mmol) and 1-octadecene 5.000 g in a 50 mL three-necked flask;

[0152] (2) Vacuuming at room temperature, followed by three vacuum / nitrogen exchange operations (to be completed within 30 minutes);

[0153] (3) Heat to 120°C under nitrogen protection and evacuate for 2 hours;

[0154] (4) Under nitrogen protection, the temperature is raised to 290℃ and the reaction is carried out for 2 hours;

[0155] (5) Reduce the temperature to 120℃ and evacuate for 2 hours;

[0156] (6) Cool down to room temperature and collect the product, which is the zinc oleate precursor.

[0157] Trioctylphosphine telluride (SeTOP) precursor was prepared by mixing selenium powder (Se) with trioctylphosphine (TOP);

[0158] (1) Mix selenium powder (0.328 g, 4.15 mmol) and trioctylphosphine (3.390 g, 9.15 mmol);

[0159] (2) Vacuuming at room temperature, and vacuum / nitrogen gas exchange operation three times (completed within 30 minutes).

[0160] (3) Under nitrogen protection, the temperature is raised to 40℃ and the reaction is carried out for 20 min;

[0161] (4) The product obtained is the trioctylphosphine selenide precursor.

[0162] ZnSe induction period samples were prepared using zinc oleate, trioctylphosphine selenium, and diphenylphosphine.

[0163] (1) Add 1.82g of zinc oleate and 2.77g of 1-octadecene to a 50mL three-necked flask, heat to 80℃ under nitrogen, stir and evacuate for 30min, and perform evacuation and nitrogen replacement three times during the process.

[0164] (2) Heat to 120°C in a nitrogen atmosphere and evacuate until no more bubbles are generated (~2h).

[0165] (3) Cool down to 80℃, inject trioctylphosphine selenide (330μL, 0.30mmol) and diphenylphosphine (52μL, 0.30mmol) under a nitrogen atmosphere, and heat up to 160℃. React at 160℃ for 30min to obtain the ZnSe induction period sample.

[0166] 2. Quantum dots were prepared by controlling the reaction time using induction period samples and CH as raw materials.

[0167] 15 μL of the induction period sample was dispersed in 3.0 mL of CH4 at room temperature (volume ratio 0.5:100) for dispersion times of 0, 20, 40, 60 min, 2, 4, 24, 48, and 72 h. The absorption curves are shown below. Figure 4 As shown, the absorption range is 305-319nm.

[0168] The specific absorption peak positions are shown in Table 5:

[0169] Table 5. ZnSe quantum dots prepared using CH4 as solvent

[0170]

[0171] Take 15 μL of the induction period sample and disperse it in 3.0 mL of CH and 10 μL of methanol at room temperature, with a volume ratio of 0.5:100. The dispersion time is 0, 20, 40, 60 min, 2, 4, 24, 48, 72 h.

[0172] Its absorption curve is as follows Figure 5 As shown, the absorption range is 303-320 nm. Specific absorption peak positions are shown in Table 6.

[0173] Table 6. ZnSe quantum dots prepared using CH4 and methanol as solvents.

[0174]

[0175] Example 6: Preparation of CdSe quantum dots at room temperature using water as a solvent

[0176] This embodiment includes the following steps:

[0177] 1. Prepare CdSe induction period samples.

[0178] CdSe induction period samples were prepared by a mixed reaction of cadmium chloride diphenylhydrate (CdCl2•2.5H2O), mercaptopropionic acid (MPA), and selenourea (SeU).

[0179] (1) Place cadmium chloride 2.5 water (45.7 mg, 0.20 mmol) in a glass bottle, add 9.75 mL of deionized water and stir to dissolve;

[0180] (2) Add mercaptopropionic acid (35 μL, 0.40 mmol) to the solution and stir to disperse it evenly;

[0181] (3) Adjust the pH of the solution to 12.0 with 5 mol / L sodium hydroxide (210 μL); add deionized water to bring the solution to 10.00 mL;

[0182] (4) Finally, selenourea (6.2 mg, 0.05 mmol) was added to the sample and stirred for 60-180 min to obtain the CdSe induction period sample.

[0183] 2. Quantum dots were prepared by controlling the reaction time using induction period samples and water as raw materials.

[0184] Take 60 μL of the induction period sample and disperse it in 3.0 mL of deionized water at room temperature for reaction at a volume ratio of 2:100. The reaction times are 0 h, 2 h, 5 h, 15 h, 20 h, 24 h, 48 h, and 135 h.

[0185] Its absorption curve is as follows Figure 6 As shown in Figure a, the absorption range is 361-373 nm.

[0186] The specific absorption peak positions are shown in Table 7:

[0187] Table 7 CdSe quantum dots prepared with aqueous solvent

[0188]

[0189] Example 7: Preparation of CdS quantum dots at room temperature using water as a solvent

[0190] This embodiment 7 includes the following steps:

[0191] 1. Prepare CdS induction period samples.

[0192] CdS-induced period samples were prepared by a mixed reaction of cadmium chloride diphenylhydrate (CdCl2•2.5H2O), mercaptopropionic acid (MPA), and thioacetamide (TAA).

[0193] (1) Place cadmium chloride 2.5 water (45.7 mg, 0.20 mmol) in a glass bottle, add 9.75 mL of deionized water and stir to dissolve;

[0194] (2) Add mercaptopropionic acid (35 μL, 0.40 mmol) to the solution and stir to disperse it evenly;

[0195] (3) Adjust the pH of the solution to 12.0 with 5 mol / L sodium hydroxide (210 μL); add deionized water to bring the solution to 10.00 mL;

[0196] (4) Finally, thioacetamide (3.8 mg, 0.05 mmol) was added to the sample and stirred for 60-180 min to obtain the CdS-induced sample.

[0197] 2. Quantum dots were prepared by controlling the reaction time using induction period samples and water as raw materials.

[0198] Take 60 μL of the induction period sample and disperse it in 3.0 mL of deionized water at room temperature for reaction at a volume ratio of 2:100. The reaction times are 0 h, 2 h, 5 h, 15 h, 20 h, 24 h, 48 h, and 135 h.

[0199] Its absorption curve is as follows Figure 6 As shown in b, the absorption range is 300-323nm.

[0200] The specific absorption peak positions are shown in Table 8:

[0201] Table 8. CdS quantum dots prepared with water solvent

[0202]

[0203] Figure 7 The precursor compound was purified and dispersed in water at 60°C for 5 min, 2 h, 8 h, 12 h, 24 h, and 48 h, with an absorption range of 300-350 nm.

[0204] The specific absorption peak positions are shown in Table 9:

[0205] Table 9. CdS quantum dots prepared from purified samples using aqueous solvent.

[0206]

[0207] Example 8: Preparation of CdSeS quantum dots at room temperature using water as a solvent.

[0208] This embodiment includes the following steps:

[0209] 1. Preparation of CdSeS induction period samples.

[0210] CdS induction period samples were prepared by a mixed reaction of cadmium chloride diphenylhydrate (CdCl2•2.5H2O), mercaptopropionic acid (MPA), selenourea (SeU), and thioacetamide (TAA).

[0211] (1) Place cadmium chloride 2.5 water (45.7 mg, 0.20 mmol) in a glass bottle, add 9.75 mL of deionized water and stir to dissolve;

[0212] (2) Add mercaptopropionic acid (35 μL, 0.40 mmol) to the solution and stir to disperse it evenly;

[0213] (3) Adjust the pH of the solution to 12.0 with 5 mol / L sodium hydroxide (210 μL); add deionized water to bring the solution to 10.00 mL;

[0214] (4) Finally, selenourea (3.2 mg, 0.025 mmol) and thioacetamide (1.9 mg, 0.025 mmol) were added to the sample and stirred for 60-180 min to obtain the CdSeS induction period sample.

[0215] 2. Quantum dots were prepared by controlling the reaction time using induction period samples and water as raw materials.

[0216] Take 60 μL of the induction period sample and disperse it in 3.0 mL of deionized water at room temperature for reaction at a volume ratio of 2:100. The reaction times are 0 h, 2 h, 5 h, 15 h, 20 h, 24 h, 48 h, and 135 h.

[0217] Its absorption curve is as follows Figure 6 As shown in Figure c, the absorption range is 299-335nm.

[0218] The specific absorption peak positions are shown in Table 10:

[0219] Table 10 CdSeS quantum dots prepared with aqueous solvent

[0220]

[0221] As can be seen from the above embodiments, the present invention provides a novel method for preparing quantum dots, which can accurately control the particle size of quantum dots and thus regulate their luminescence properties. At the same time, the present invention has for the first time prepared CdTe quantum dots with absorption peaks below 475 nm, ZnSe quantum dots with absorption peaks below 320 nm, CdSe quantum dots with absorption peaks at 373 nm, CdS quantum dots with absorption peaks at 323 nm, and CdSeS quantum dots with absorption peaks at 335 nm, which can effectively expand the application of quantum dots and has a very good application prospect.

Claims

1. A method for preparing size-controllable quantum dots, characterized in that, Semiconductor material induction period samples are dispersed in a solvent and reacted at 25-105℃ for 0.5-24 hours to obtain the desired product. The semiconductor material is selected from CdTe, the solvent is selected from cyclohexane, and the quantum dot has an absorption peak at 417-465 nm and an emission peak at 460-485 nm. The preparation of the induction period sample includes the following steps: (1) Cadmium acetate dihydrate was reacted with oleylamine to obtain the oleylamine-cadmium acetate precursor; (2) The tellurium powder was mixed with trioctylphosphine and reacted to obtain the trioctylphosphine tellurium precursor; (3) The trioctylphosphine telluride precursor is added to the oleylamine cadmium acetate precursor to react and obtain the product.

2. The preparation method according to claim 1, characterized in that, The quantum dot absorption peaks are at 417nm±5%, 428nm±1%, 440nm±1%, 450nm±1%, 458nm±1%, or 465nm±1%, and the emission peaks are at 460nm±1%, 468nm±1%, 475nm±1%, 480nm±1%, or 485nm±1%.

3. A method for preparing size-controllable quantum dots, characterized in that, Semiconductor material induction period samples are dispersed in a solvent and reacted at 25-105℃ for 0.5-24 hours to obtain the desired product. The semiconductor material is selected from ZnSe, the solvent is selected from a mixed solvent prepared from cyclohexane and methanol, and the quantum dot absorption peak is in the range of 303-320 nm. The preparation of the induction period sample includes the following steps: (1) Zinc oxide, oleic acid and 1-octadecene were reacted to obtain zinc oleate precursor; (2) Selenium powder was mixed with trioctylphosphine and reacted to obtain trioctylphosphine selenium precursor; (3) The trioctylphosphine selenide precursor and diphenylphosphine are mixed and added to the zinc oleate precursor for reaction to obtain the product.

4. The preparation method according to claim 3, characterized in that, The quantum dot absorption peaks are at 303nm±5%, 306nm±1%, 307nm±1%, 310nm±1%, 311nm±1%, 319nm±1%, or 320nm±1%.

5. A method for preparing size-controllable quantum dots, characterized in that, Semiconductor material induction period samples are dispersed in a solvent and reacted at 25-105℃ for 0.5-24 hours to obtain the desired product. The semiconductor material is selected from CdSe, the solvent is selected from water, and the quantum dot absorption peak is in the range of 361-373 nm. The preparation of the induction period sample includes the following steps: dissolving cadmium chloride 2.5 water and mercaptopropionic acid in deionized water, adjusting the pH to 12.0-12.8, and then adding selenourea to the solution to react, thus obtaining the sample.

6. The preparation method according to claim 5, characterized in that, The absorption peaks of the CdSe quantum dots are at 361 nm ± 1% or 373 nm ± 1%.

7. A method for preparing size-controllable quantum dots, characterized in that, Semiconductor material induction period samples are dispersed in a solvent and reacted at 25-105℃ for 0.5-24 hours to obtain the desired product. The semiconductor material is selected from CdS, the solvent is selected from water, and the quantum dot absorption peak is in the range of 300-350 nm. The preparation of the induction period sample includes the following steps: dissolving cadmium chloride 2.5 water and mercaptopropionic acid in deionized water, adjusting the pH to 12.0-12.8, and then adding thioacetamide to the solution to react, thus obtaining the sample.

8. The preparation method according to claim 7, characterized in that, The quantum dot absorption peaks are at 300nm±1%, 302nm±1%, 303nm±1%, 311nm±1%, 323nm±1%; 330nm±1%, 337nm±1%, 340nm±1%, 343nm±1%, 346nm±1% or 350nm±1%.

9. A method for preparing size-controllable quantum dots, characterized in that, Semiconductor material induction period samples are dispersed in a solvent and reacted at 25-105℃ for 0.5-24 hours to obtain the desired product. The semiconductor material is selected from CdSeS, the solvent is selected from water, and the quantum dot absorption peak is in the range of 299-335 nm. The preparation of the induction period sample includes the following steps: dissolving cadmium chloride 2.5 water and mercaptopropionic acid in deionized water, adjusting the pH to 12.0-12.8, and then adding selenourea and thioacetamide to the solution to react, thus obtaining the sample.

10. The preparation method according to claim 9, characterized in that, The quantum dot absorption peaks are at 299nm±1%, 304nm±1%, 306nm±1%, 318nm±1%, or 335nm±1%.

11. The preparation method according to any one of claims 1 to 10, characterized in that: The induction period sample to solvent feeding ratio is (0.5-6):100 by volume.

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