Silver telluride colloidal quantum dots and a method for preparing the same

Abstract

The application provides a kind of silver telluride quantum dots and its preparation method, belongs to the field of nanometer materials.The preparation method of silver telluride quantum dots provided by the application includes the following steps: under the protection of inert gas, silver source, mercaptan, halogenated alkane, tellurium precursor and solvent are mixed, the synthesis of quantum dots is regulated by nucleophilic substitution reaction, and silver telluride colloidal quantum dots are obtained.The results of examples show that the preparation method provided by the application enhances the colloidal stability of quantum dots, and the fluorescence emission peak of silver telluride colloidal quantum dots is 1176-2023nm, with a wide fluorescence emission window.

Description

Technical Field

[0001] This invention relates to the field of nanomaterials, and more particularly to a silver telluride colloidal quantum dot and its preparation method. Background Technology

[0002] Currently, semiconductor fluorescent quantum dots (QDs) have shown great potential in lighting, displays, and biomedical applications, which has also placed higher demands on their synthesis. In recent years, continuous improvements in quantum dot synthesis methods have facilitated the synthesis of high-quality quantum dots, attracting widespread attention. However, maintaining the colloidal stability of quantum dots while achieving continuous growth remains a significant challenge.

[0003] As is well known, surface ligands for quantum dots play a crucial role in regulating their growth and stabilizing. By introducing different ligands during synthesis, precise control over the size of quantum dots can be achieved. Suitable ligands can restrict quantum dot growth or promote growth in specific directions through surface adsorption, thereby controlling their morphology and size. Ligands enhance the stability of quantum dots by forming coordination bonds or interacting with the quantum dot surface. Appropriate ligands can prevent quantum dots from agglomerating or precipitating in solution, maintaining their dispersed state and ensuring the performance and stability of quantum dots in practical applications.

[0004] Silver telluride (Ag₂Te) quantum dots, free of highly toxic heavy metal ions, hold great potential for biomedical applications. The growth of colloidal silver telluride quantum dots can be effectively controlled by adjusting the reactivity of the precursor using ligands with different coordination abilities and molecular structures (considering steric hindrance). Zhang et al. successfully synthesized high-quality Ag₂Te quantum dots (with a fluorescence quantum yield as high as 14.7%) by adjusting the coordination number of thiol and trialkylphosphine ligands with the silver precursor. The exciton absorption peak of the synthesized Ag₂Te quantum dots was tunable in the range of 900–1150 nm, but the fluorescence emission window was relatively narrow. Liu et al. found that tri-n-butylphosphine (TBP) ligands can induce the dissolution of small-sized Ag₂Te quantum dots. By balancing the nucleation and dissolution processes, the fluorescence emission wavelength of the obtained Ag₂Te quantum dots was tunable in the range of 950 nm to 2100 nm. However, when using sterically hindered trialkylphosphine, the colloidal stability of the prepared Ag₂Te quantum dots was poor. Summary of the Invention

[0005] The purpose of this invention is to provide a silver telluride colloidal quantum dot and its preparation method. The silver telluride colloidal quantum dots prepared by the method provided by this invention have a wide fluorescence emission window and enhance the colloidal stability of the quantum dots.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for preparing silver telluride colloidal quantum dots, comprising the following steps:

[0008] Under inert gas protection, silver source, thiol, haloalkane, tellurium precursor and solvent are mixed, and quantum dot synthesis is controlled by nucleophilic substitution reaction to obtain silver telluride colloidal quantum dots.

[0009] Preferably, the molar ratio of the silver source, thiol and haloalkane is (1-5):15:(15-225).

[0010] Preferably, the molar ratio of silver in the silver source to tellurium in the tellurium precursor is (3-15):1.

[0011] Preferably, the silver source includes silver acetate and / or silver nitrate.

[0012] Preferably, the thiol contains 8 to 20 carbon atoms.

[0013] Preferably, the haloalkane includes one or more of chloroalkane, bromoalkane, iodoalkane, and fluoroalkane.

[0014] Preferably, the tellurium precursor is a complex of tellurium and tertiary phosphine; the tertiary phosphine contains 12 to 30 carbon atoms.

[0015] Preferably, the solvent is a nonpolar solvent with a boiling point >170°C.

[0016] Preferably, the temperature at which the nucleophilic substitution reaction regulates the synthesis of quantum dots is 150–185 °C.

[0017] This invention provides silver telluride colloidal quantum dots prepared by the preparation method described in the above technical solution.

[0018] This invention provides a method for preparing silver telluride colloidal quantum dots, comprising the following steps: under inert gas protection, a silver source, thiol, haloalkane, tellurium precursor, and solvent are mixed, and the synthesis of quantum dots is controlled by a nucleophilic substitution reaction to obtain silver telluride colloidal quantum dots. This invention utilizes the reaction of the silver source with the halogen in the haloalkane to generate silver halide precipitate, driving the alkyl sulfide anion ligand in the thiol to undergo a nucleophilic substitution reaction with the haloalkane. The coordinated nucleophilic alkyl sulfide anion attacks the electrophilic group of the haloalkane to generate a thioether. As the reaction proceeds, the number of strongly coordinated alkyl sulfide anions gradually decreases, while the number of weakly coordinated thioethers gradually increases. This dynamic process promotes the continuous growth of quantum dots, broadens the fluorescence emission window of the silver telluride colloidal quantum dots, and enables the colloidal quantum dots to exist stably. The results of the examples show that the preparation method provided by this invention enhances the colloidal stability of the quantum dots, and the fluorescence emission peak of the silver telluride colloidal quantum dots is 1176–2023 nm, exhibiting a wide fluorescence emission window. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the mechanism by which nucleophilic substitution reaction regulates quantum dot growth in Example 1 of the present invention;

[0020] Figure 2 The fluorescence emission spectrum of the silver telluride colloidal quantum dots prepared in Example 1 of this invention;

[0021] Figure 3 The absorption spectrum of the silver telluride colloidal quantum dots prepared in Example 1 of this invention;

[0022] Figure 4 The fluorescence emission spectrum of the silver telluride colloidal quantum dots prepared in Example 2 of this invention;

[0023] Figure 5 The absorption spectrum of the silver telluride colloidal quantum dots prepared in Example 2 of this invention;

[0024] Figure 6 The fluorescence emission spectrum of the silver telluride colloidal quantum dots prepared in Example 3 of this invention;

[0025] Figure 7 The absorption spectrum of the silver telluride colloidal quantum dots prepared in Example 3 of this invention;

[0026] Figure 8 The fluorescence emission spectrum of the silver telluride colloidal quantum dots prepared in Example 4 of this invention;

[0027] Figure 9 The absorption spectrum of the silver telluride colloidal quantum dots prepared in Example 4 of this invention;

[0028] Figure 10 The fluorescence emission spectrum of the silver telluride colloidal quantum dots prepared in Example 5 of this invention;

[0029] Figure 11 The absorption spectrum of the silver telluride colloidal quantum dots prepared in Example 5 of this invention;

[0030] Figure 12 The fluorescence emission spectrum of the silver telluride colloidal quantum dots prepared in Example 6 of this invention;

[0031] Figure 13 The absorption spectrum of the silver telluride colloidal quantum dots prepared in Example 6 of this invention;

[0032] Figure 14 The fluorescence emission spectrum of the silver telluride colloidal quantum dots prepared in Comparative Example 1 of this invention is shown.

[0033] Figure 15 The absorption spectrum of the silver telluride colloidal quantum dots prepared in Comparative Example 1 of this invention is shown.

[0034] Figure 16 The continuously tunable fluorescence emission spectrum of silver telluride colloidal quantum dots obtained by the preparation method provided by the present invention in the range of 1176–2023 nm;

[0035] Figure 17 A schematic diagram showing the precise control of the fluorescence emission spectrum of silver telluride colloidal quantum dots obtained by the preparation method provided by the present invention within the range of 1176–2023 nm;

[0036] Figure 18 This is a statistical graph showing the change in fluorescence peak emission position of the silver telluride colloidal quantum dots prepared in Example 1 and Comparative Example 1 of the present invention over storage time. Detailed Implementation

[0037] This invention provides a method for preparing silver telluride colloidal quantum dots, comprising the following steps:

[0038] Under inert gas protection, silver source, thiol, haloalkane, tellurium precursor and solvent are mixed, and quantum dot synthesis is controlled by nucleophilic substitution reaction to obtain silver telluride colloidal quantum dots.

[0039] This invention involves mixing a silver source, thiols, haloalkanes, tellurium precursors, and solvent under inert gas protection, and then controlling the synthesis of quantum dots through nucleophilic substitution reactions to obtain silver telluride colloidal quantum dots.

[0040] In this invention, the preferred molar ratio of the silver source, thiol, and haloalkane is (1–5):15:(15–225), more preferably (1.5–3):15:(15–180), and even more preferably 1.5:15:(150–165). By limiting the molar ratio of the silver source, thiol, and haloalkane to the above range, this invention allows adjustment of the rate and extent of the nucleophilic substitution reaction, thereby adjusting the fluorescence emission window of the quantum dots.

[0041] In this invention, the thiol contains 8 to 20 carbon atoms, preferably 8 to 16. In this invention, the thiol needs to exist in a liquid state during the reaction. If the number of carbon atoms is too small, it is prone to vaporization and escape from the system; if the number of carbon atoms is too large, it may be solid at the reaction temperature or difficult to dissolve in the solvent. Limiting the number of carbon atoms in the thiol to the above-mentioned range ensures the smooth progress of the reaction.

[0042] In this invention, the thiol preferably includes 1-octylthiol, 1-nonylthiol, or 1-decylthiol, more preferably 1-octylthiol. Limiting the types of thiols to the above range ensures that the ligands are in a liquid state in the reaction system, guaranteeing the smooth progress of the nucleophilic substitution reaction, achieving ligand transformation, and thus broadening the fluorescence emission window of silver telluride colloidal quantum dots.

[0043] In this invention, the molar ratio of silver in the silver source to tellurium in the tellurium precursor is preferably (3-15):1, more preferably (5-10):1. By limiting the molar ratio of silver in the silver source to tellurium in the tellurium precursor to the above range, this invention can further broaden the fluorescence emission window of quantum dots.

[0044] In this invention, the silver source preferably includes silver acetate or silver nitrate, more preferably silver acetate. Limiting the type of silver source to the above-mentioned range promotes the reaction.

[0045] In this invention, the haloalkane preferably includes one or more of chloroalkanes, bromoalkanes, iodoalkanes, and fluoroalkanes, more preferably chloroalkanes and / or bromoalkanes. This invention limits the types of haloalkanes to those within the above range to enhance the colloidal stability of quantum dots. This invention does not have a particular limitation on the number of carbon atoms in the alkyl groups of chloroalkanes, bromoalkanes, iodoalkanes, and fluoroalkanes, as long as the haloalkane is in a liquid state at the reaction temperature.

[0046] In this invention, the tellurium precursor is preferably a complex of tellurium and tertiary phosphine; the number of carbon atoms in the tertiary phosphine is preferably 12 to 30, more preferably 20 to 25. In this invention, the molar concentration of tellurium in the tellurium precursor is preferably 0.067 M.

[0047] In a specific embodiment of the present invention, the preparation method of the tellurium precursor is as follows: tellurium powder is placed in a three-necked flask containing tri-n-octylphosphine, argon gas is introduced and heated and stirred at 140°C for 30 minutes. After the solution turns into a clear yellow color, it is cooled to room temperature to obtain the tellurium precursor.

[0048] In this invention, the solvent is preferably a nonpolar solvent with a boiling point >170°C, and more preferably includes 1-octadecene, n-octadecane, 1-hexadecene, or 1-heptadecene. This invention does not have a particular limitation on the amount of solvent added, as long as it ensures that the raw materials are mixed evenly and the reaction proceeds smoothly.

[0049] In this invention, the inert gas is preferably argon. Using an inert gas for protection helps prevent the generation of impurities during the reaction.

[0050] In this invention, the mixing of the silver source, thiol, haloalkane, tellurium precursor and solvent is preferably carried out by first mixing the silver source, thiol, haloalkane and solvent and then mixing them with the tellurium precursor; or, the silver source, thiol and solvent are third mixed and then mixed with the tellurium precursor in a fourth mixing and then mixed with the haloalkane in a fifth mixing.

[0051] In this invention, the temperatures of the first, second, third, fourth, and fifth mixing processes are preferably independently 160–185°C, more preferably 160–170°C. This invention does not specifically limit the time for the first, second, third, fourth, and fifth mixing processes, as long as it ensures the smooth progress of the nucleophilic substitution reaction-regulated quantum dot synthesis. This invention does not specifically limit the mixing operation; commonly used operations in the art are sufficient to mix the raw materials uniformly. Limiting the temperatures of the first, second, third, fourth, and fifth mixing processes to the above-mentioned ranges ensures the subsequent nucleophilic substitution reaction-regulated quantum dot synthesis.

[0052] In this invention, the temperature for nucleophilic substitution reaction-regulated quantum dot synthesis is preferably 150–185°C, more preferably 170–185°C. Limiting the temperature to this range ensures the sufficient completion of the nucleophilic substitution reaction-regulated quantum dot synthesis. This invention does not impose a specific time limit on the nucleophilic substitution reaction-regulated quantum dot synthesis, as long as the reaction is sufficiently completed. In this invention's nucleophilic substitution reaction-regulated quantum dot synthesis, the coordinated nucleophilic alkyl thioion attacks the electrophilic group of the haloalkane, generating a thioether.

[0053] This invention utilizes the reaction of a silver source with halogens in haloalkanes to generate silver halide precipitates, which drive the nucleophilic substitution reaction between alkyl sulfide anion ligands in thiols and haloalkanes. The coordinated nucleophilic alkyl sulfide anions attack the electrophilic groups of the haloalkanes to generate thioethers. As the reaction proceeds, the number of strongly coordinated alkyl sulfide anions gradually decreases, while the number of weakly coordinated thioethers gradually increases. This dynamic process promotes the continuous growth of quantum dots, broadens the fluorescence emission window of silver telluride colloidal quantum dots, and enables the quantum dot colloid to exist stably.

[0054] The present invention also provides quantum dots prepared by the preparation method described in the above technical solution.

[0055] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0056] Example 1

[0057] A method for preparing silver telluride colloidal quantum dots comprises the following steps: Under argon gas protection, silver acetate, 1-octylthiol (OTT), 1-chlorooctane, and 1-octadecene (ODE) are placed in a three-necked flask and heated to 50°C. After stirring at 600 r / min for 30 min for the first mixing, the mixture is stirred at 170°C and 600 r / min to generate silver chloride precipitate, driving a nucleophilic substitution reaction until the solution turns orange-red. Then, it is mixed with tellurium precursor for the second mixing and stirred at 170°C and 600 r / min to carry out the nucleophilic substitution reaction-controlled quantum dot synthesis, obtaining silver telluride colloidal quantum dots.

[0058] The molar ratio of silver acetate, 1-octylthiol (OTT), and 1-chlorooctane is 1.5:15:165.

[0059] The molar ratio of silver in the silver acetate to tellurium in the tellurium precursor is 10:1.

[0060] The sum of the moles of silver acetate, 1-octylthiol (OTT), and 1-chlorooctane is in the volume ratio of 1-octadecene to 0.267 mol: 6 mL.

[0061] The tellurium precursor is a complex of tellurium and tri-n-octylphosphine; the tri-n-octylphosphine contains 24 carbon atoms; the molar concentration of tellurium in the tellurium precursor is 0.067 M.

[0062] The preparation method of the tellurium precursor is as follows: tellurium powder is placed in a three-necked flask containing TOP, argon gas is introduced and heated and stirred at 140°C for 30 minutes. After the solution turns into a clear yellow color, it is cooled to room temperature to obtain the tellurium precursor.

[0063] Example 2

[0064] A method for preparing silver telluride colloidal quantum dots comprises the following steps: Under argon gas protection, silver acetate, 1-octylthiol (OTT), 1-bromooctane and 1-octadecene (ODE) are placed in a three-necked flask and heated to 50°C. After the first mixing at 600 r / min, the mixture is stirred at 170°C and 600 r / min to generate silver bromide precipitate, driving a nucleophilic substitution reaction until the solution turns orange-red. Then, the mixture is mixed with tellurium precursor at 170°C and 600 r / min for a second mixing to synthesize quantum dots controlled by the nucleophilic substitution reaction, thus obtaining silver telluride colloidal quantum dots.

[0065] The molar ratio of silver acetate, 1-octylthiol (OTT), and 1-chlorooctane is 1.5:15:165.

[0066] The molar ratio of silver in the silver acetate to tellurium in the tellurium precursor is 10:1.

[0067] The sum of the moles of silver acetate, 1-octylthiol (OTT), and 1-chlorooctane is in the volume ratio of 1-octadecene to 0.267 mol: 6 mL.

[0068] The tellurium precursor is the same as in Example 1.

[0069] Example 3

[0070] The only difference between Example 3 and Example 1 is that the molar ratio of silver acetate, 1-octylthiol (OTT), and 1-chlorooctane is 1.5:15:15, and the volume ratio of the sum of the molar amounts of silver acetate, 1-octylthiol (OTT), and 1-bromooctane to 1-octadecene is 0.0265 mol:6 mL. All other aspects are the same as in Example 1.

[0071] Example 4

[0072] The only difference between Example 4 and Example 1 is that the molar ratio of silver acetate, 1-octylthiol (OTT), and 1-chlorooctane is 1.5:15:45, and the volume ratio of the sum of the molar amounts of silver acetate, 1-octylthiol (OTT), and 1-bromooctane to 1-octadecene is 0.0904 mol:6 mL. All other aspects are the same as in Example 1.

[0073] Example 5

[0074] The only difference between Example 5 and Example 1 is that the molar ratio of silver acetate, 1-octylthiol (OTT), and 1-chlorooctane is 1.5:15:225, and the volume ratio of the sum of the molar amounts of silver acetate, 1-octylthiol (OTT), and 1-bromooctane to 1-octadecene is 0.355 mol:6 mL. All other aspects are the same as in Example 1.

[0075] Example 6

[0076] A method for preparing quantum dots comprises the following steps: Under argon gas protection, silver acetate, 1-octylthiol (OTT), and 1-octadecene (ODE) are placed in a three-necked flask and heated to 50°C. After stirring at 600 r / min for 30 min (third mixing), the mixture is stirred at 170°C and 600 r / min until the solution turns orange-red. Then, a tellurium precursor is added and stirred at 170°C and 600 r / min (fourth mixing). After adding the tellurium precursor for 10.5 min, 1-chlorooctane is added and stirred at 170°C and 600 r / min (fifth mixing) to generate silver chloride precipitate, driving a nucleophilic substitution reaction. Quantum dots are synthesized under the control of the nucleophilic substitution reaction to obtain silver telluride colloidal quantum dots.

[0077] The molar ratio of silver acetate, 1-octylthiol (OTT), and 1-chlorooctane is 1.5:15:165.

[0078] The molar ratio of silver in the silver acetate to tellurium in the tellurium precursor is 10:1.

[0079] The sum of the moles of silver acetate, 1-octylthiol (OTT), and 1-chlorooctane is in the volume ratio of 1-octadecene to 0.267 mol: 6 mL.

[0080] The preparation method of the tellurium precursor is the same as in Example 1.

[0081] Comparative Example 1

[0082] The only difference between Comparative Example 1 and Example 1 is that no electrophilic reagent (1-chlorooctane) was added; otherwise, they are the same as in Example 1.

[0083] Comparative Example 2

[0084] Comparative Example 2 shows silver telluride quantum dots prepared using the method described in the paper "Breaking through the Size Control Dilemma of Silver Chalcogenide QuantumDots via Trialkylphosphine-Induced Ripening: Leading to Ag2Te Emitting from 950 to 2100 nm" published in the Journal of the American Chemical Society by Liu Zhenya, Liu An'an, Fu Haohao, Cheng Qingyuan, et al. The specific steps are as follows:

[0085] 10 mL of octadecene, 1 mmol of octyl mercaptan, and 1 mmol of silver acetate were added to a three-necked flask, and the temperature was raised to 160 °C. The reaction was stopped immediately after the tellurium precursor (0.05 mmol of Te powder, 1.5 mL of oleylamine, and 0.5 mL of tributylphosphine) was added. Ethanol was added, and the mixture was centrifuged at 10,000 rpm for 5 min. The supernatant was discarded to obtain a precipitate, which was then purified twice by dissolution and precipitation with n-hexane and ethanol, respectively. The precipitate was dispersed in tetrachloroethylene, and the fluorescence emission peak was measured at 980 nm using a fluorescence spectrophotometer.

[0086] The single-pot fluorescence emission wavelength of the silver telluride quantum dots obtained in Comparative Example 2 was 980 nm.

[0087] Comparative Example 3

[0088] Comparative Example 3 shows silver telluride quantum dots prepared using the method described in the paper "Regulation of Silver Precursor Reactivity via Tertiary Phosphine to Synthesize Near-Infrared Ag2Te with Photoluminescence Quantum Yield of up to 14.7%" published in Materials Chemistry by Zhang Mingyu, Liu An'an, Fu Haohao, Zhang Wei, et al. The specific steps are as follows:

[0089] Generally, 1 mmol AgAc, 1.3 mL OTT and 10.0 mL ODE are mixed in a three-necked flask and heated at 110 °C for 10 minutes;

[0090] After heating at 110°C for 10 minutes, 0.5 mL (approximately 1 mmol) of TOP was added, and then the temperature was raised to 160°C. A mixture of 2.344 mL of ODE and 0.156 mL of Te precursor was injected.

[0091] The temperature was then rapidly reduced to 150°C for growth, yielding silver telluride quantum dots.

[0092] The single-pot fluorescence emission wavelength of the silver telluride quantum dots obtained in Comparative Example 3 is tunable in the range of 1260–1375 nm.

[0093] The absorption spectra of the silver telluride colloidal quantum dots prepared in Examples 1-6 and Comparative Example 1 were measured using a Shimadzu UV-3600Plus UV-Vis-NIR spectrophotometer; the fluorescence emission spectra of the silver telluride colloidal quantum dots prepared in Examples 1-6 and Comparative Example 1 were measured using an Edinburgh FLS1000 spectrometer with an excitation light of 808 nm.

[0094] A schematic diagram of the nucleophilic substitution reaction-regulated quantum dot growth of silver telluride colloidal quantum dots prepared in Example 1 is shown below. Figure 1 As shown; the fluorescence emission spectrum of the silver telluride colloidal quantum dots prepared in Example 1 is shown below. Figure 2 As shown; the absorption spectrum of the silver telluride colloidal quantum dots prepared in Example 1 is shown below. Figure 3 As shown, from Figure 1 It can be seen that the mechanism of the SN2 reaction at the quantum dot interface is RS. - Attack the α-carbon of RX (X = Cl, Br, I), while X - The departure of the leaving group and the precipitation of AgX promote the breaking of the CX bond, thereby promoting the SN2 reaction; from Figures 2-3 It can be seen that when 1-chlorooctane and 1-octylthiol are used as mixed ligands, the fluorescence emission peak shifts continuously from 1144 nm to 1860 nm over time.

[0095] The fluorescence emission spectrum of the silver telluride colloidal quantum dots prepared in Example 2 is shown below. Figure 4 As shown; the absorption spectrum of the silver telluride colloidal quantum dots prepared in Example 2 is shown below. Figure 5 As shown, from Figures 4-5 It can be seen that the use of RBr produces a wider wavelength tuning range, and the FL emission wavelength exhibits a more significant redshift within the same sampling interval. This difference can be attributed to Br. - The stronger leaving ability of the quantum dots promotes the occurrence of SN2 reactions, thereby better controlling the fluorescence emission wavelength of the quantum dots.

[0096] The fluorescence emission spectrum of the silver telluride colloidal quantum dots prepared in Example 3 is shown below. Figure 6 As shown; the absorption spectrum of the silver telluride colloidal quantum dots prepared in Example 3 is shown below. Figure 7 As shown; the fluorescence emission spectrum of the silver telluride colloidal quantum dots prepared in Example 4 is shown below. Figure 8 As shown; the absorption spectrum of the silver telluride colloidal quantum dots prepared in Example 4 is shown below. Figure 9 As shown; the fluorescence emission spectrum of the silver telluride colloidal quantum dots prepared in Example 5 is shown below. Figure 10 As shown; the absorption spectrum of the silver telluride colloidal quantum dots prepared in Example 5 is shown below. Figure 11 As shown, from Figures 6-11 It can be seen that when the amounts of RCl and RSH are equal, the fluorescence emission wavelength redshifts from 1142 nm to 1469 nm, a total redshift of 327 nm. Increasing the amount of RCl to 11 times that of RSH significantly broadens the range of fluorescence emission wavelength redshift, with a total redshift of 716 nm. Further increasing RCl leads to uncontrolled growth and aggregation of QDs, which may be attributed to the excessively fast growth rate of QDs caused by the excessively fast SN2 reaction rate.

[0097] The fluorescence emission spectrum of the silver telluride colloidal quantum dots prepared in Example 6 is shown below. Figure 12 As shown; the absorption spectrum of the silver telluride colloidal quantum dots prepared in Example 6 is shown below. Figure 13 As shown, from Figures 12-13 It can be seen that the quantum dot fluorescence emission peak only begins to show a significant redshift about 10 minutes after the addition of RCl. We attribute this delayed redshift to RS. - The nucleophilic substitution reaction between RCl and α-RCl takes time to affect the growth process of silver telluride colloidal quantum dots.

[0098] The fluorescence emission spectrum of the silver telluride colloidal quantum dots prepared in Comparative Example 1 is shown below. Figure 14 As shown; the absorption spectrum of the silver telluride colloidal quantum dots prepared in Comparative Example 1 is shown in Figure 1. Figure 15 As shown. From Figures 14-15 It can be seen that, with 1-octylthiol as the ligand, the exciton absorption peak gradually red-shifts over time, and the fluorescence emission peak red-shifts from 1152 nm to 1220 nm within 45 minutes, indicating that the ability to grow quantum dots using this method is limited and the fluorescence emission wavelength range of silver telluride colloidal quantum dots is relatively narrow.

[0099] The single-pot fluorescence emission wavelength of Comparative Example 2 was 980 nm, while the tunable range of the single-pot fluorescence emission wavelength of Comparative Example 3 was 1260–1375 nm. The single-pot fluorescence emission wavelength range obtained in Comparative Example 2 is smaller than that of the present invention; similarly, the tunable range of the single-pot fluorescence emission wavelength of Comparative Example 3 is also much smaller than the tunable range of the single-pot fluorescence emission wavelength of silver telluride colloidal quantum dots (1176–2023 nm) obtained by the preparation method provided by the present invention.

[0100] Figure 16 The continuously tunable fluorescence emission spectrum of silver telluride colloidal quantum dots obtained by the preparation method provided by the present invention in the range of 1176–2023 nm; Figure 17 A schematic diagram showing the precise control of the fluorescence emission spectrum of silver telluride colloidal quantum dots obtained by the preparation method provided by the present invention within the range of 1176–2023 nm; Figure 18 This is a statistical graph showing the change in fluorescence peak emission position of the silver telluride colloidal quantum dots prepared in Example 1 and Comparative Example 1 of this invention over storage time. Figures 16-17 It can be seen that the quantum dots prepared by the method provided by this invention can achieve precise control of the emission wavelength of silver telluride quantum dots in the range of 1176–2023 nm; from Figure 18 It can be seen that the colloidal quantum dots (SN2 group) synthesized by the preparation method provided by the present invention have excellent stability.

[0101] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing silver telluride colloidal quantum dots, comprising the following steps: Under inert gas protection, silver source, thiol, haloalkane, tellurium precursor and solvent were mixed, and quantum dot synthesis was controlled by nucleophilic substitution reaction to obtain silver telluride colloidal quantum dots; The haloalkane is one or more of chloroalkane, bromoalkane and iodoalkane; The solvent is a nonpolar solvent with a boiling point >170℃.

2. The preparation method according to claim 1, characterized in that: The molar ratio of the silver source, thiol and haloalkane is (1~5):15:(15~225).

3. The preparation method according to claim 1, characterized in that: The molar ratio of silver in the silver source to tellurium in the tellurium precursor is (3~15):

1.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The silver source includes silver acetate and / or silver nitrate.

5. The preparation method according to claim 1, characterized in that: The number of carbon atoms in the thiol is 8 to 20.

6. The preparation method according to claim 1, characterized in that: The tellurium precursor is a complex of tellurium and tertiary phosphine; The tertiary phosphine contains 12 to 30 carbon atoms.

7. The preparation method according to claim 1, characterized in that: The nucleophilic substitution reaction regulates the temperature of quantum dot synthesis to 150~185℃.

8. Silver telluride colloidal quantum dots prepared by the preparation method according to any one of claims 1 to 7.

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