Method for synthesizing monodisperse Ag2Te colloidal quantum dots through regulation and control of zinc halide and application of monodisperse Ag2Te colloidal quantum dots

Abstract

The invention belongs to the technical field of nano materials, and particularly relates to a method for synthesizing monodisperse Ag2Te colloidal quantum dots through regulation and control of zinc halide, which comprises the following steps: adding silver acetate, zinc halide and oleylamine into a flask, and vacuumizing under a heating condition to prepare a silver precursor; the preparation method comprises the following steps: dissolving tellurium dioxide in n-dodecanethiol under a heating condition to prepare a tellurium precursor; rapidly injecting the prepared tellurium precursor into the prepared silver precursor; after the reaction is finished, cooling to room temperature, purifying by using methylbenzene and methanol, and vacuumizing and drying to obtain the Ag2Te colloidal quantum dots; ag2Te CQDs with uniform size are synthesized through a one-step thermal injection process, surface passivation is improved, and the photoluminescence intensity is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of nanomaterials, and particularly relates to a method for synthesizing monodisperse Ag2Te colloidal quantum dots by regulating zinc halide. Background Art

[0002] Ag2Te colloidal quantum dots (CQDs) have excellent optoelectronic properties and are promising candidates for short-wave infrared photodetectors. However, their performance is affected by their size distribution and structural quality. The small exciton Bohr radius makes it difficult to control the size during the synthesis process and it is difficult to form a clear exciton absorption peak. The most widely used method for synthesizing Ag2Te CQDs is to use phosphine-tellurium as a precursor. However, the phosphine produced during the synthesis process will affect the conductivity of the film, thereby reducing the optoelectronic performance. Recently, the Spanish ICFO team developed a phosphine-free Ag2Te CQDs synthesis method, which requires a continuous injection and growth method to achieve an absorption peak greater than 1600nm. The process is complicated, and the high mobility of silver ions leads to more defects in QCDs, which is not conducive to the optoelectronic performance, and the surface passivation of CQDs needs to be further improved.

[0003] Therefore, a method for regulating the synthesis of Ag2Te is needed. Ag2Te CQDs with uniform size are synthesized through a one-step hot injection process to improve surface passivation. Summary of the invention

[0004] The purpose of the present invention is to solve the deficiencies in the prior art, and a method for regulating synthesis by zinc halide (ZnX2, X = Cl, Br, I) is proposed. Ag2TeCQDs with uniform size are synthesized through a one-step hot injection process, with a continuously adjustable optical band gap of 1.22-0.60 eV and a monodisperse size distribution, and surface passivation is also improved. .

[0005] In order to achieve the above object, the present invention is achieved through the following technical solutions:

[0006] In a first aspect, the present invention provides a method for synthesizing monodisperse Ag2Te colloidal quantum dots by zinc halide regulation, the method comprising the following steps:

[0007] Step (1), adding silver acetate, zinc halide and oleylamine into a flask, heating and evacuating the flask to prepare a silver precursor;

[0008] Step (2), dissolving tellurium dioxide in n-dodecyl mercaptan under heating conditions to prepare a tellurium precursor;

[0009] Step (3), rapidly injecting the tellurium precursor prepared in step (2) into the silver precursor prepared in step (1);

[0010] Step (4), after the reaction is completed, cool to room temperature, purify with toluene and methanol, and vacuum dry to obtain Ag2Te colloidal quantum dots.

[0011] Preferably, the zinc halide is ZnCl2, ZnBr2 or ZnI2.

[0012] Preferably, in step (1), the molar ratio of silver acetate to zinc halide is 1:0.5-3.

[0013] The method for synthesizing monodisperse Ag2Te colloidal quantum dots regulated by zinc halide according to claim 1 is characterized in that, in step (3), when the temperature of the silver precursor reaches 50-200°C, the tellurium precursor prepared in step (2) is quickly injected into the silver precursor prepared in step (1).

[0014] In a second aspect, the present invention provides monodisperse Ag2Te colloidal quantum dots prepared by the above method.

[0015] In a third aspect, the present invention provides the application of the monodisperse Ag2Te colloidal quantum dots in short-wave infrared photodetectors.

[0016] The present invention has the following beneficial effects: 1. The use of zinc halide reduces the high reactivity of the precursor, resulting in a balance between CQDs nucleation and growth, forming a clear exciton absorption peak;

[0017] 2. Using zinc halide to regulate synthesis, CQDs with uniform size were synthesized through a single-step hot injection process. The exciton absorption peak was continuously tunable within 1020-2060nm (band gap 1.22-0.60eV), and the size distribution was monodisperse;

[0018] 3. Zn 2+ The incorporation during the synthesis improves the surface passivation of CQDs and increases the photoluminescence intensity. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 : Schematic diagram of the synthesis of Ag2Te CQDs regulated by zinc halide;

[0020] Figure 2 : Optical absorption diagram of Ag2Te CQDs synthesized without zinc halide and with zinc halide at the same temperature (100℃);

[0021] Figure 3 : X-ray diffraction (XRD) patterns of Ag2Te CQDs synthesized without zinc halide and with zinc halide at 100°C;

[0022] Figure 4 : Absorption diagram of Ag2Te CQDs with different molar ratios of silver acetate and zinc iodide at the same temperature (140℃);

[0023] Figure 5 : Optical absorption spectra of Ag2Te CQDs prepared in Example 3-9 in the range of 1020-2060nm;

[0024] Figure 6 : TEM images, monodisperse particle size distribution and HRTEM images of Ag2Te CQDs prepared in Examples 3-9 with absorption peaks of 1150, 1310, 1500, 1710, 1850, and 2060 nm, respectively;

[0025] Figure 7 : ad are X-ray photoelectron spectroscopy (XPS) graphs of Ag 3d, Te 3d, Zn 2p and I 3d of Ag2Te CQDs prepared in Example 5, respectively;

[0026] Figure 8 : Comparison of light absorption and photoluminescence (PL) intensity of Ag2Te CQDs prepared using AgI as silver precursor and Example 5 (both absorption peaks are at 1300nm). DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the embodiments, but they are not intended to limit the present invention.

[0028] Example 1

[0029] 3 mmol of silver acetate (Ag(Ac)), 4.5 mmol of ZnCl2 and 60 mL of oleylamine (OLA) were added into the flask, heated at 100°C and vacuumed for 2 hours to remove water and oxygen.

[0030] Meanwhile, 1.25 mmol of tellurium dioxide (TeO2) was dissolved in 9 mL of n-dodecanethiol (DDT) under heating at 100°C and nitrogen atmosphere to prepare a tellurium precursor.

[0031] The flask was then switched to a nitrogen atmosphere and heated to 100°C. TeO2-DDT was rapidly injected into the flask. Heating was stopped after 20 minutes and the flask was naturally cooled to room temperature.

[0032] The CQDs were purified by toluene and methanol, and the finally collected CQDs solid was dried under vacuum and dissolved in toluene.

[0033] Example 2

[0034] 3 mmol of silver acetate (Ag(Ac)), 4.5 mmol of ZnBr2 and 60 mL of OLA were added into the flask, heated at 100°C and vacuumed for 2 hours to remove water and oxygen.

[0035] Meanwhile, 1.25 mmol TeO2 was dissolved in 9 mL DDT under heating at 100 °C and nitrogen atmosphere to prepare a tellurium precursor.

[0036] The flask was then switched to a nitrogen atmosphere and heated to 100°C. TeO2-DDT was rapidly injected into the flask. Heating was stopped after 20 minutes and the flask was naturally cooled to room temperature.

[0037] The CQDs were purified by toluene and methanol, and the finally collected CQDs solid was dried under vacuum and dissolved in toluene.

[0038] Example 3

[0039] 3 mmol of silver acetate (Ag(Ac)), 4.5 mmol of ZnI2 and 60 mL of OLA were added into the flask, heated at 100°C and vacuumed for 2 hours to remove water and oxygen.

[0040] Meanwhile, 1.25 mmol TeO2 was dissolved in 9 mL DDT under heating at 100 °C and nitrogen atmosphere to prepare a tellurium precursor.

[0041] The flask was then switched to a nitrogen atmosphere and heated to 50°C. TeO2-DDT was rapidly injected into the flask. Heating was stopped after 20 minutes and the flask was naturally cooled to room temperature.

[0042] The CQDs were purified by toluene and methanol, and the finally collected CQDs solid was dried under vacuum and dissolved in toluene.

[0043] Example 4

[0044] Different from Example 3, the flask was switched to a nitrogen atmosphere and heated to 75° C. The specific steps were:

[0045] 3 mmol of silver acetate (Ag(Ac)), 4.5 mmol of ZnI2 and 60 mL of OLA were added into the flask, heated at 100°C and vacuumed for 2 hours to remove water and oxygen.

[0046] Meanwhile, 1.25 mmol TeO2 was dissolved in 9 mL DDT under heating at 100 °C and nitrogen atmosphere to prepare a tellurium precursor.

[0047] The flask was then switched to a nitrogen atmosphere and heated to 75°C. TeO2-DDT was rapidly injected into the flask. Heating was stopped after 20 minutes and the flask was naturally cooled to room temperature.

[0048] The CQDs were purified by toluene and methanol, and the finally collected CQDs solid was dried under vacuum and dissolved in toluene.

[0049] Example 5

[0050] Different from Example 3, the flask was switched to a nitrogen atmosphere and heated to 100° C. The specific steps were:

[0051] 3 mmol of silver acetate (Ag(Ac)), 4.5 mmol of ZnI2 and 60 mL of OLA were added into the flask, heated at 100°C and vacuumed for 2 hours to remove water and oxygen.

[0052] Meanwhile, 1.25 mmol TeO2 was dissolved in 9 mL DDT under heating at 100 °C and nitrogen atmosphere to prepare a tellurium precursor.

[0053] The flask was then switched to a nitrogen atmosphere and heated to 100°C. TeO2-DDT was rapidly injected into the flask. Heating was stopped after 20 minutes and the flask was naturally cooled to room temperature.

[0054] The CQDs were purified by toluene and methanol, and the finally collected CQDs solid was dried under vacuum and dissolved in toluene.

[0055] Example 6

[0056] Different from Example 3, the flask was switched to a nitrogen atmosphere and heated to 125° C. The specific steps were:

[0057] 3 mmol of silver acetate (Ag(Ac)), 4.5 mmol of ZnI2 and 60 mL of OLA were added into the flask, heated at 100°C and vacuumed for 2 hours to remove water and oxygen.

[0058] Meanwhile, 1.25 mmol TeO2 was dissolved in 9 mL DDT under heating at 100 °C and nitrogen atmosphere to prepare a tellurium precursor.

[0059] The flask was then switched to a nitrogen atmosphere and heated to 125°C. TeO2-DDT was rapidly injected into the flask. Heating was stopped after 20 minutes and the flask was naturally cooled to room temperature.

[0060] The CQDs were purified by toluene and methanol, and the finally collected CQDs solid was dried under vacuum and dissolved in toluene.

[0061] Example 7

[0062] Different from Example 3, the flask was switched to a nitrogen atmosphere and heated to 150° C. The specific steps were:

[0063] 3 mmol of silver acetate (Ag(Ac)), 4.5 mmol of ZnI2 and 60 mL of OLA were added into the flask, heated at 100°C and vacuumed for 2 hours to remove water and oxygen.

[0064] Meanwhile, 1.25 mmol TeO2 was dissolved in 9 mL DDT under heating at 100 °C and nitrogen atmosphere to prepare a tellurium precursor.

[0065] The flask was then switched to a nitrogen atmosphere and heated to 150°C. TeO2-DDT was rapidly injected into the flask. Heating was stopped after 20 minutes and the flask was naturally cooled to room temperature.

[0066] The CQDs were purified by toluene and methanol, and the finally collected CQDs solid was dried under vacuum and dissolved in toluene.

[0067] Example 8

[0068] Different from Example 3, the flask was switched to a nitrogen atmosphere and heated to 175° C. The specific steps were:

[0069] 3 mmol of silver acetate (Ag(Ac)), 4.5 mmol of ZnI2 and 60 mL of OLA were added into the flask, heated at 100°C and vacuumed for 2 hours to remove water and oxygen.

[0070] Meanwhile, 1.25 mmol TeO2 was dissolved in 9 mL DDT under heating at 100 °C and nitrogen atmosphere to prepare a tellurium precursor.

[0071] The flask was then switched to a nitrogen atmosphere and heated to 175°C. TeO2-DDT was rapidly injected into the flask. Heating was stopped after 20 minutes and the flask was naturally cooled to room temperature.

[0072] The CQDs were purified by toluene and methanol, and the finally collected CQDs solid was dried under vacuum and dissolved in toluene.

[0073] Example 9

[0074] Different from Example 3, the flask was switched to a nitrogen atmosphere and heated to 200° C. The specific steps were:

[0075] 3 mmol of silver acetate (Ag(Ac)), 4.5 mmol of ZnI2 and 60 mL of OLA were added into the flask, heated at 100°C and vacuumed for 2 hours to remove water and oxygen.

[0076] Meanwhile, 1.25 mmol TeO2 was dissolved in 9 mL DDT under heating at 100 °C and nitrogen atmosphere to prepare a tellurium precursor.

[0077] The flask was then switched to a nitrogen atmosphere and heated to 200 °C. TeO2-DDT was rapidly injected into the flask. Heating was stopped after 20 minutes and the flask was naturally cooled to room temperature.

[0078] The CQDs were purified by toluene and methanol, and the finally collected CQDs solid was dried under vacuum and dissolved in toluene.

[0079] Example 10

[0080] Different from Example 5, the molar ratio of silver acetate to ZnI2 is 1:1. The specific steps are as follows:

[0081] 3 mmol of silver acetate (Ag(Ac)), 3 mmol of ZnI2 and 60 mL of OLA were added into the flask, heated at 100°C and vacuumed for 2 hours to remove water and oxygen.

[0082] Meanwhile, 1.25 mmol TeO2 was dissolved in 9 mL DDT under heating at 100 °C and nitrogen atmosphere to prepare a tellurium precursor.

[0083] The flask was then switched to a nitrogen atmosphere and heated to 100°C. TeO2-DDT was rapidly injected into the flask. Heating was stopped after 20 minutes and the flask was naturally cooled to room temperature.

[0084] The CQDs were purified by toluene and methanol, and the finally collected CQDs solid was dried under vacuum and dissolved in toluene.

[0085] Embodiment 11

[0086] Different from Example 5, the molar ratio of silver acetate to ZnI2 is 1:2. The specific steps are as follows:

[0087] 3 mmol of silver acetate (Ag(Ac)), 6 mmol of ZnI2 and 60 mL of OLA were added into the flask, heated at 100°C and vacuumed for 2 hours to remove water and oxygen.

[0088] Meanwhile, 1.25 mmol TeO2 was dissolved in 9 mL DDT under heating at 100 °C and nitrogen atmosphere to prepare a tellurium precursor.

[0089] The flask was then switched to a nitrogen atmosphere and heated to 100°C. TeO2-DDT was rapidly injected into the flask. Heating was stopped after 20 minutes and the flask was naturally cooled to room temperature.

[0090] The CQDs were purified by toluene and methanol, and the finally collected CQDs solid was dried under vacuum and dissolved in toluene.

[0091] Comparative Example 1

[0092] (1) AgI-OLA precursor: 10 mmol of silver iodide (AgI) was dissolved in 10 mL of OLA in an inert atmosphere to prepare a silver precursor;

[0093] (2) TeO2-DDT precursor: Under heating at 100°C and in an inert atmosphere, 2.5 mmol of tellurium dioxide (TeO2) was dissolved in 10 mL of n-dodecanethiol (DDT) to prepare a tellurium precursor.

[0094] (3) 30 mL of oleylamine (OLA) and 15 mL of 1-octadecene (ODE) were placed in a flask and vacuumed at 100 °C to remove oxygen and moisture. The flask was then switched to a nitrogen atmosphere and heated to the temperature required for CQDs of different sizes. Once the temperature reached the set point, 3 mL of AgI-OLA precursor was injected into the flask. After about 5 minutes, 5 mL of TeO2-DDT precursor was quickly injected into the flask. After 15 minutes, heating was stopped and the flask was cooled naturally. Toluene was used as the positive solvent and methanol as the anti-solvent to clean and purify the CQDs solution. After vacuum drying, the CQDs solid was dissolved in anhydrous toluene of different concentrations. For the synthesis of large-sized (>1600 nm) Ag2Te CQDs, a continuous injection and growth method was used: after injecting 3 mL of AgI-OLA and 5 mL of TeO2-DDT precursor at 140 °C, the flask was kept at this temperature. Then, a syringe pump was used to inject 5 mL of AgI-OLA and 5 mL of TeO2-DDT precursor at a rate of about 0.05 mL min -1 1 mL of AgI-OLAm and 1.8 ml of TeO2-DDT precursor were added dropwise at a speed of 1 0.5 % and multiple cycles were performed depending on the desired size.

[0095] Figure 2 The optical absorption diagram of Ag2Te CQDs synthesized without zinc halide and with zinc halide at the same temperature (100℃). It can be seen that the CQDs synthesized with ZnI2 under the same conditions have the largest size and peak-to-valley ratio. Figure 3 The XRD patterns of Ag2Te CQDs synthesized without zinc halide and with zinc halide are shown in Figure 2. The CQDs prepared under the four conditions all have a monoclinic β-phase lattice structure. Figure 5 It can be seen that the absorption peak of Ag2Te CQDs prepared by regulating different injection temperatures and ZnI2 ratios can be continuously tuned in the range of 1020-2060nm. Figure 6 TEM images and particle size statistical distribution of Ag2TeCQDs with absorption peaks at 1150, 1310, 1500, 1710, 1850, and 2060 nm, respectively, showing monodispersity, and the band gap becomes smaller as the size of CQDs increases. Figure 7 The appearance of Zn2p and I 3d peaks indicates that Zn 2+ and I - Successfully incorporated and passivated CQDs. Figure 8 In comparison, ZnI2-Ag2Te has stronger luminescence intensity, indicating the reduction of defects.

[0096] The above shows and describes the basic principles, main features and advantages of the present invention. However, the above is only a specific embodiment of the present invention, and the technical features of the present invention are not limited thereto. Any other implementation methods derived by any technician in the field without departing from the technical solution of the present invention should be included in the patent scope of the present invention.

Claims

1. A method for synthesizing monodisperse Ag2Te colloidal quantum dots by regulating zinc halide, characterized in that: The method comprises the following steps: Step (1), adding silver acetate, zinc halide and oleylamine into a flask, heating and evacuating the flask to prepare a silver precursor; Step (2), dissolving tellurium dioxide in n-dodecyl mercaptan under heating conditions to prepare a tellurium precursor; Step (3), rapidly injecting the tellurium precursor prepared in step (2) into the silver precursor prepared in step (1); Step (4), after the reaction is completed, cool to room temperature, purify with toluene and methanol, and vacuum dry to obtain Ag2Te colloidal quantum dots.

2. The method for synthesizing monodisperse Ag2Te colloidal quantum dots by zinc halide regulation according to claim 1, characterized in that: The zinc halide is ZnCl2, ZnBr2 or ZnI2.

3. The method for synthesizing monodisperse Ag2Te colloidal quantum dots by zinc halide regulation according to claim 1, characterized in that: In step (1), the molar ratio of silver acetate to zinc halide is 1:0.5-3.

4. The method for synthesizing monodisperse Ag2Te colloidal quantum dots by zinc halide regulation according to claim 1, characterized in that: In step (3), when the temperature of the silver precursor reaches 50-200° C., the tellurium precursor prepared in step (2) is quickly injected into the silver precursor prepared in step (1).

5. Monodisperse Ag2Te colloidal quantum dots prepared by the method according to any one of claims 1 to 4.

6. Use of the monodisperse Ag2Te colloidal quantum dots described in claim 5 in short-wave infrared photodetectors.

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