Preparation method of bismuth-doped silver sulfide quantum dots and optoelectronic device
By preparing bismuth-doped silver sulfide quantum dots at room temperature, the problems of complex high-temperature operation and long alkyl chain ligands are solved, simplified operation and enhanced photoelectric responsiveness are achieved, and suitable for environmentally friendly optoelectronic devices.
Patent Information
- Application Number
- CN202510422795.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-07
- Publication Date
- 2025-07-11
AI Technical Summary
The existing preparation process of bismuth-doped silver sulfide colloidal quantum dots needs to be carried out at high temperatures, which is complex in operation and is not conducive to environmentally friendly optoelectronic device applications, and long alkyl chain ligands are not conducive to carrier transmission, increasing the difficulty of thin film formation.
Under normal temperature, the use of N,N-diphenylthiourea and bismuthioidide were dissolved in N,N-dimethylformamide, and silver iodide was added to dissolve in a short-chain organic amine solution to form a bismuth-doped silver sulfide quantum dot. During the post-treatment, methyl acetate or ethyl acetate were centrifuged to obtain a spin coating solution for photoelectric device assembly.
The preparation of bismuth-doped silver sulfide quantum dots at room temperature is realized, which simplifies operation, has good dispersion of products and direct film formation. It is suitable for environmentally friendly optoelectronic devices and enhances photoelectric responsiveness.
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Figure CN120290171A_ABST
Abstract
Description
Technical Field The present invention belongs to the technical field of material chemistry, and particularly relates to a preparation method of bismuth-doped silver sulfide quantum dots and optoelectronic devices. Background Art Silver sulfide colloidal quantum dots are a kind of direct bandgap compound semiconductor material, with a bandgap width between 0.9 eV and 1.1 eV, and having good optoelectronic response properties in the second near-infrared region. In addition, silver sulfide colloidal quantum dots also have the advantages of environmental friendliness, high chemical stability, high absorption coefficient, and solution-processable film formation. Therefore, silver sulfide colloidal quantum dots have received extensive attention in the field of optoelectronic devices that can be prepared by solution processing.
[0003] Due to the migratory characteristics of silver ions in silver sulfide, silver ion vacancies appear in this material, which affects the optoelectronic properties of silver sulfide semiconductor materials. Currently, people inhibit the migration of silver ions by doping silver sulfide colloidal quantum dots, thereby enhancing their optoelectronic conversion ability. He et al. Small 2018, 14(11), 1703296] used a refined synthesis method to prepare Pb-doped Ag2S colloidal quantum dots. The entire experimental process was carried out under strict argon protection to maintain an oxygen-free and dry reaction environment. They first dissolved the silver source and the lead source in 1-octanethiol (OT) solvent, and then quickly injected a precise amount of hexamethyldisilathiane at 165 °C by means of thermal injection technology to prepare the target quantum dots. Zhang et al. Chem. Mater. 2023, 35(3), 1325–1334] synthesized bismuth-modified Ag2S colloidal quantum dot materials by thermal injection method, and the entire experiment was operated in a strictly anhydrous and oxygen-free environment. First, the silver source and the bismuth source were dissolved in a mixed solvent of oleic acid, oleylamine, and octadecene in proportion, and degassing treatment was carried out at 115 °C to completely remove oxygen and moisture. Subsequently, the reaction atmosphere was switched to inert gas argon, and a diphenyl ether solution of N, N-diphenylthiourea was quickly injected into the flask at 170 °C under continuous stirring, and left to cool naturally to room temperature for 30 minutes to obtain the target product. It was found that bismuth doping can effectively enhance the optoelectronic properties of silver sulfide colloidal quantum dots, but the bismuth doping process mostly needs to be carried out at a relatively high temperature, and high-boiling organic solvents need to be used. The operation process and the post-treatment process are complex, which is not conducive to the research and application of bismuth-doped silver sulfide colloidal quantum dots in the field of solution-processable and environmentally friendly optoelectronic devices.
[0004] When further using colloidal quantum dots to assemble optoelectronic devices, the spin coating or blade coating method is generally mainly used to prepare colloidal quantum dots into a film. The long alkyl chain ligands used to maintain the dispersibility of colloidal quantum dots during the preparation process are not conducive to the transport of carriers in the subsequent formed film. Therefore, small molecules are needed to displace these long alkyl chain ligands, and the ligand displacement process will increase the operation difficulty of forming a colloidal quantum dot film. The silver sulfide-based colloidal quantum dot material also faces the same problem. Summary of the Invention The problem to be solved by the present invention is to provide a preparation method of bismuth-doped silver sulfide quantum dot material and an optoelectronic device in view of the deficiencies of the prior art. The present invention can prepare bismuth-doped silver sulfide colloidal quantum dots under normal temperature conditions; the operation is simple, the post-treatment of the product is convenient, and the obtained product can be directly formed into a film, which is convenient for constructing an environmentally friendly optoelectronic device based on silver sulfide colloidal quantum dots.
[0006] The technical solution adopted by the present invention for the problem to be solved is as follows: A preparation method of bismuth-doped silver sulfide quantum dot material, comprising the following steps: (1) Dissolve silver iodide into a short-chain organic amine solution to form solution A; (2) Dissolve N, N-diphenylthiourea and bismuth iodide into N, N-dimethylformamide to form solution B; (3) Under normal temperature conditions, drop solution A into solution B and stir to obtain bismuth-doped silver sulfide quantum dots. When solution A is dropped into solution B, it can be observed that the color of the solution gradually turns black to obtain bismuth-doped silver sulfide quantum dots.
[0007] According to the above scheme, the particle size of the bismuth-doped silver sulfide quantum dots is 7 - 8 nm.
[0008] According to the above scheme, the carbon length of the short-chain organic amine is 3 - 5.
[0009] According to the above scheme, the short-chain organic amine is specifically selected from n-butylamine, n-propylamine or isobutylamine, etc.
[0010] According to the above scheme, place solution B in a constant temperature water bath to keep the temperature of the reaction system stable, then drop solution A into solution B and stir to prepare bismuth-doped silver sulfide quantum dots. According to the above scheme, after solution A is completely dropped and the reaction is completed, add methyl acetate or ethyl acetate to the system to centrifuge and separate the sample, and redisperse the obtained sample in a polar organic solvent to obtain a spin coating solution (bismuth-doped silver sulfide colloidal quantum dot solution) for the assembly of optoelectronic devices.
[0011] According to the above scheme, the polar organic solvent is N, N-dimethylformamide.
[0012] According to the above scheme, the volume of methyl acetate or ethyl acetate is more than 2 times that of the added system, and further, it is 2 - 4 times.
[0013] According to the above scheme, the centrifugation speed is 8000 - 10000 r / min.
[0014] According to the above scheme, the molar ratio of silver element to sulfur element in the raw materials is 2:1 - 3:1. The chemical environments on the surfaces of bismuth-doped silver sulfide quantum dots obtained with different silver-sulfur ratios are different. The surface chemical environment will affect their subsequent separation from the mixed solution, and further affect the formation of quantum dot inks and film coating. When the molar ratio of silver to sulfur (the molar ratio of silver iodide to N, N-diphenylthiourea) is less than 2:1, the prepared quantum dots are difficult to separate from the solution. Although an excessive amount of silver salt does not affect the separation of quantum dots, it is easy to cause waste of silver salt. When the molar ratio of silver element to sulfur element is preferably 2:1 - 3:1, the obtained bismuth-doped silver sulfide quantum dots are easy to be separated by centrifugation and precipitated, and are convenient for redispersion to obtain a spin-coating solution for the assembly of optoelectronic devices.
[0015] According to the above scheme, the molar ratio of silver element to bismuth element in the raw materials is greater than or equal to 100:1, and specifically can be 100 - 400:1. Bismuth doping affects the preparation of bismuth-doped silver sulfide quantum dots. The molar ratio of silver element to bismuth element being greater than or equal to 100:1 is helpful for preparing bismuth-doped silver sulfide quantum dots with uniform particle size distribution; when the molar ratio of silver element to bismuth element is less than 100:1, the formed particles agglomerate severely and a quantum dot ink with good dispersibility cannot be formed. Preferably, the molar ratio of silver element to bismuth element is 100 - 400:1.
[0016] The present invention provides a photodetector based on the bismuth-doped silver selenide colloidal quantum dot film obtained from the above bismuth-doped silver selenide colloidal quantum dot material.
[0017] According to the above scheme, the channel width of the photodetector is 100μm, and the structure is a photoresistor type.
[0018] The present invention uses N, N-diphenylthiourea as the sulfur source, selects silver and bismuth iodides as the precursors (doping sources), and realizes the preparation of bismuth-doped silver sulfide colloidal quantum dots using silver and bismuth iodides under normal temperature conditions in the presence of iodide ions. The bismuth-doped silver sulfide colloidal quantum dots have good dispersibility and have broad prospects for laboratory device research and industrial applications. By controlling the content of the bismuth source in the precursor, the regulation of the bismuth doping amount and the optoelectronic properties of the product can be realized.
[0019] In addition, the surface of the obtained product is wrapped by iodide anions. The samples after centrifugal separation of methyl acetate or ethyl acetate have good dispersibility in polar organic solvents and can be well dispersed in polar organic solvents to form quantum dot inks for film formation. Then, a thin film can be formed by a simple spin-coating method and used for spin-coating assembly of the light absorption layer in optoelectronic devices. The obtained thin film can be directly used without additional ligand exchange treatment, that is, it has enhanced optoelectronic response properties.
[0020] Advantages of the present invention: 1. The preparation method of bismuth-doped silver sulfide colloidal quantum dots provided by the present invention can prepare bismuth-doped silver sulfide colloidal quantum dots under normal temperature conditions.
[0021] 2. By controlling the content of bismuth source in the precursor, the regulation of bismuth doping amount in the product can be realized, thereby adjusting the optoelectronic properties of the product.
[0022] 3. The synthesized bismuth-doped silver sulfide colloidal quantum dot solution can be used for spin-coating assembly of the light absorption layer in optoelectronic devices. The obtained thin film can be directly used without additional ligand exchange treatment, that is, it has enhanced optoelectronic response properties. Description of the drawings
[0023] Figure 1 XRD test characterization results of the product prepared in the comparative example.
[0024] Figure 2 XPS test results of the product prepared in the comparative example.
[0025] Figure 3 TEM photos of the product prepared in the comparative example.
[0026] Figure 4 XRD test characterization results of the product prepared in Example 1.
[0027] Figure 5 XPS test results of the product prepared in Example 1.
[0028] Figure 6 TEM photos of the product prepared in Example 1.
[0029] Figure 7 XRD test characterization results of the product prepared in Example 2.
[0030] Figure 8 XPS test results of the product prepared in Example 2.
[0031] Figure 9 TEM photos of the product prepared in Example 2.
[0032] Figure 10 XRD test characterization results of the product prepared in Example 3.
[0033] Figure 11 , XPS test results of the product prepared in Example 3.
[0034] Figure 12 , TEM photo of the product prepared in Example 3.
[0035] Figure 13 , XRD test characterization results of the product prepared in Example 4.
[0036] Figure 14 , XRD test characterization results of the product prepared in Example 5.
[0037] Figure 15 , i-t curve test results of the assembled photodetector of the product prepared in Example 1.
[0038] Figure 16 , i-t curve test results of the assembled photodetector of the product prepared in Example 2.
[0039] Figure 17 , i-t curve test results of the assembled photodetector of the product prepared in Example 3.
[0040] Figure 18 , i-t curve test results of the assembled photodetector of the product prepared in the control example. Detailed implementation manners The following is further illustrated by examples.
[0042] Example 1 1. Preparation work. Weigh 1.87 g of AgI (8 mmol) and dissolve it in 12 mL of n-butylamine solution (marked as solution A). Weigh 0.73 g of N, N-diphenylthiourea (3.2 mmol) and 0.012 g of BiI3 (0.02 mmol) and dissolve them simultaneously in 20 mL of DMF (marked as solution B). Solutions A and B are stirred for 1 hour at room temperature respectively. Subsequently, transfer solution B to a 50 mL beaker and place the beaker in a water bath at normal temperature (15 - 25 °C) to keep the temperature of the reaction system stable. 2. Reaction steps. While stirring solution B, slowly add solution A dropwise to solution B. During this process, it can be observed that the color of the solution gradually turns into a black liquid. The formed black substance has good dispersibility and no large particles can be seen with the naked eye.
[0043] 3. Product post-treatment. After the reaction is completed, add methyl acetate with twice the volume to the system as a precipitant. Subsequently, centrifuge at a speed of 5000 r / min for 3 minutes to accelerate the separation of the precipitate. After centrifugation, redisperse the obtained black precipitate in DMF to obtain a bismuth-doped silver sulfide colloidal quantum dot solution.
[0044] Control example: Refer to the above preparation method, without Bi doping, to synthesize silver sulfide colloidal quantum dots.
[0045] Synthesis method: 1. Preparation. Weigh 1.87 g of AgI (8 mmol) and dissolve it in 12 mL of n-butylamine solution (labeled as solution A). Weigh 0.73 g of N, N-diphenylthiourea (3.2 mmol) and dissolve it in 20 mL of DMF at the same time (labeled as solution B). Stir solutions A and B for 1 hour at room temperature. Subsequently, transfer solution B to a 50 mL beaker and place the beaker in a water bath at room temperature (15 - 25 °C) to keep the temperature of the reaction system stable.
[0046] 2. Reaction steps. While stirring solution B, slowly add solution A dropwise to solution B. 3. Product post-treatment. After the reaction is completed, add methyl acetate with twice the volume to the system as a precipitant. Subsequently, centrifuge at a speed of 5000 r / min for 3 minutes to accelerate the separation of the precipitate. After centrifugation, redisperse the obtained black precipitate in DMF.
[0047] Characterization of the product synthesized in the control example. The product obtained in the control example was characterized by XRD and TEM. Figure 1 This is the XRD test characterization result of the product in the control example, which shows good matching with the standard silver sulfide diffraction data at room temperature. Figure 2 This is the XPS test result of the product in the control example. The binding energy positions of S, S 2P 1 / 2 and S 2P 3 / 2 are 162.02 eV and 160.86 eV respectively, which are consistent with the binding energy results of sulfur in silver sulfide. Figure 3 This is the TEM photo of the product, and it can be seen that the obtained product is relatively uniformly dispersed, and the particle size is about 7 nm.
[0048] The product obtained in Example 1 was characterized by XRD, XPS, and TEM.
[0049] Figure 4 This is the XRD test characterization result of the product in Example 1. The XRD results show that the characteristic diffraction peak data of the synthesized product match well with the standard silver sulfide diffraction data.
[0050] Figure 5XPS test results for Example 1. The binding energy positions of S, S 2P 1 / 2 and S 2P 3 / 2 are 161.57 eV and 160.39 eV respectively, different from the binding energy positions of S in silver sulfide, and are consistent with the XPS results reported in the literature ( Nanoscale , 2024, 16, 9325 - 9334. This literature reports the preparation of AgBiS2 ternary sulfide by high-temperature thermal injection method, involving the XPS characterization results of the chemical environment of sulfur elements). By comparing the binding energy of sulfur elements in the present invention with that in this literature, it shows that the incorporation of bismuth in the present invention changes the chemical environment of sulfur in silver sulfide, confirming that bismuth is successfully doped into silver sulfide.
[0051] Combined with the XRD characterization results, the analysis shows that trivalent Bi is successfully doped into silver sulfide in the present invention, and bismuth-doped silver sulfide colloidal quantum dots are synthesized.
[0052] Figure 6 TEM photograph of the product. It can be seen that the obtained product is relatively uniformly dispersed, and the particle size is about 7.40 nm.
[0053] Example 2 1. Preparation work. Weigh 1.87 g of AgI (8 mmol) and dissolve it in 12 mL of n-butylamine solution (labeled as solution A). Weigh 0.73 g of N, N-diphenylthiourea (3.2 mmol) and 0.024 g of BiI3 (0.04 mmol) and dissolve them in 20 mL of DMF at the same time (labeled as solution B). Solution A and solution B are stirred for 1 hour at room temperature respectively. Subsequently, transfer solution B to a 50 mL beaker, and place the beaker in a water bath at normal temperature (15 - 25 °C) to keep the temperature of the reaction system stable. 2. Reaction steps. The same as Example 1.
[0054] 3. Post-treatment of the product. The same as Example 1.
[0055] Characterization of the product. The obtained product is characterized by XRD and TEM. Figure 7 XRD test characterization results of the product, which match well with the standard silver sulfide diffraction data at room temperature. Figure 8 XPS test results. It can be seen that the binding energy position of S is consistent with the results reported in the literature ( Nanoscale , 2024, 16, 9325 - 9334), indicating that trivalent Bi is successfully doped into silver sulfide. Figure 9 TEM photograph of the product. It can be seen that the obtained product is relatively uniformly dispersed, and the particle size is about 7.51 nm.
[0056] Example 3 1. Preparation. Weigh 1.87 g of AgI (8 mmol) and dissolve it in 12 mL of n-butylamine solution (labeled as solution A). Weigh 0.73 g of N, N-diphenylthiourea (3.2 mmol) and 0.047 g of BiI3 (0.08 mmol) and dissolve them simultaneously in 20 mL of DMF (labeled as solution B). Stir solution A and solution B separately for 1 hour at room temperature. Subsequently, transfer solution B to a 50 mL beaker and place the beaker in a water bath at room temperature (15 - 25 °C) to keep the temperature of the reaction system stable. 2. Reaction procedure. The same as in Example 1.
[0057] 3. Post-treatment of the product. The same as in Example 1.
[0058] Product characterization. The obtained product was characterized by XRD and TEM. Figure 10 This is the XRD test characterization result, which shows good matching with the standard silver sulfide diffraction data at room temperature. Figure 11 This is the XPS test result. It can be seen that the binding energy position of S is consistent with the reported results ( Nanoscale , 2024, 16, 9325 - 9334), indicating that trivalent Bi has been successfully doped into silver sulfide. Figure 12 This is the TEM photo of the product. It can be seen that the obtained product is relatively uniformly dispersed, and the particle size is about 7.69 nm.
[0059] Example 4 1. Preparation. Weigh 1.87 g of AgI (8 mmol) and dissolve it in 12 mL of n-butylamine solution (labeled as solution A). Weigh 0.91 g of N, N-diphenylthiourea (4 mmol) and 0.012 g of BiI3 (0.02 mmol) and dissolve them simultaneously in 20 mL of DMF (labeled as solution B). Stir solution A and solution B separately for 1 hour at room temperature. Subsequently, transfer solution B to a 50 mL beaker and place the beaker in a water bath at room temperature (15 - 25 °C) to keep the temperature of the reaction system stable. 2. Reaction procedure. While stirring solution B, slowly add solution A dropwise to solution B. During this process, it can be observed that the color of the solution gradually turns into a black liquid. The formed black substance has good dispersibility, and no large particles can be seen with the naked eye.
[0060] 3. Post-treatment of the product. After the reaction is completed, add twice the volume of methyl acetate to the system as a precipitant. Subsequently, centrifuge at a speed of 5000 r / min for 3 minutes to accelerate the separation of the precipitate. After centrifugation, redisperse the obtained black precipitate in DMF to obtain a bismuth-doped silver sulfide colloidal quantum dot solution. Figure 13XRD test characterization results of the product of Example 4. The XRD results show that the characteristic diffraction peak data of the synthesized product match well with the standard silver sulfide diffraction data.
[0061] Example 5 1. Preparation. Weigh 1.87 g of AgI (8 mmol) and dissolve it in 12 mL of n-butylamine solution (labeled as Solution A). Weigh 0.62 g of N,N-diphenylthiourea (2.7 mmol) and 0.012 g of BiI3 (0.02 mmol), and dissolve them in 20 mL of DMF simultaneously (labeled as Solution B). Stir Solution A and Solution B for 1 hour at room temperature respectively. Subsequently, transfer Solution B to a 50 mL beaker, and place the beaker in a water bath at room temperature (15 - 25 °C) to keep the reaction system temperature stable. 2. Reaction steps. While stirring Solution B, slowly add Solution A dropwise to Solution B. During this process, it can be observed that the color of the solution gradually turns into a black liquid. The formed black substance has good dispersibility, and no large particles can be seen with the naked eye.
[0062] 3. Post-treatment of the product. After the reaction is completed, add twice the volume of methyl acetate to the system as a precipitant. Subsequently, centrifuge at a speed of 5000 r / min for 3 minutes to accelerate the separation of the precipitate. After centrifugation, redisperse the obtained black precipitate in DMF to obtain a bismuth-doped silver sulfide colloidal quantum dot solution. Figure 14 XRD test characterization results of the product of Example 5. The XRD results show that the characteristic diffraction peak data of the synthesized product match well with the standard silver sulfide diffraction data.
[0063] Optoelectronic detector assembly: Optoelectronic detector assembly is carried out on the FTO substrate deposited with ZnO thin film. First, spin-coat 50 μL of a solution of zinc acetate in n-butylamine and n-butanol (volume ratio 1:4) (concentration 0.25 mol / L) onto the FTO substrate, and perform heat treatment at 350 °C to form a zinc oxide thin film. Use a laser to etch a channel 100 μm wide and 2 mm long on this thin film. Spin-coat 30 μL of a 150 mg / mL DMF solution of the bismuth-doped silver sulfide colloidal quantum dots of Examples 1 - 3 onto the surface of the above thin film to complete the assembly of the optoelectronic detector.
[0064] Optoelectronic detector performance test. Under the condition of an external bias voltage of 0.3 V, use light with a wavelength of 680 nm to excite the sample, and test to obtain the i-t curve.
[0065] The i-t curve of the optoelectronic detector assembled with the bismuth-doped silver sulfide colloidal quantum dot solution of Example 1 is shown in Figure 15 .
[0066] The i-t curve of the photodetector assembled with the bismuth-doped silver sulfide colloidal quantum dot solution of Example 2 is shown in Figure 16 .
[0067] The i-t curve of the photodetector assembled with the bismuth-doped silver sulfide colloidal quantum dot solution of Example 3 is shown in Figure 17 .
[0068] Referring to Example 1, the silver sulfide product obtained from the control experiment was also used for the assembly of the photodetector and the performance test of the photodetector was carried out. The i-t curve is shown in Figure 18 .
[0069] Analyze the results of the i-t curves obtained from different samples. First, the i-t curves of the same sample are different under different light intensities. As the light intensity increases, the photocurrent increases, indicating that the device has good intensity discrimination ability for incident light. In addition, under the same illumination conditions, the photocurrent intensities of different samples vary significantly. As the molar ratio of bismuth element to silver element increases during the reaction, the intensity of the photocurrent of the device increases significantly, indicating that the incorporation of bismuth effectively enhances the optoelectronic properties of silver sulfide. By adjusting the content of bismuth source in the precursor, the amount of bismuth doping in the product can be regulated, thereby adjusting the optoelectronic properties of the product.
[0070] The photoresponsivity of the device can be calculated by using the ratio of the photocurrent density to the incident optical power density. In the present invention, when the feeding ratio of silver to bismuth is 1:100, its photoresponsivity (the ratio of the photocurrent density to the incident optical power density) can reach 80 mA / W ( Figure 17 ) or more, indicating that it has good photodetection ability.
[0071] It should be understood that those of ordinary skill in the art can make improvements or modifications according to the above description, and all such improvements and modifications should fall within the protection scope of the appended claims of the present invention.
Claims
1. A preparation method of bismuth-doped silver sulfide quantum dot material, characterized in that: It includes the following steps: (1) Dissolve a certain amount of silver iodide into a short-chain organic amine solution to form solution A; (2) Dissolve N, N-diphenylthiourea and bismuth iodide into N, N-dimethylformamide to form solution B; (3) Under normal temperature conditions, drop solution A into solution B and stir to obtain bismuth-doped silver sulfide quantum dots.
2. The preparation method according to claim 1, wherein: The particle size of the bismuth-doped silver sulfide quantum dots is 7 - 8 nm.
3. The preparation method according to claim 1, characterized in that: The carbon length of the short-chain organic amine is 3 - 5.
4. The preparation method according to claim 1, characterized in that: The short-chain organic amine is selected from n-butylamine, n-propylamine or isobutylamine.
5. The preparation method according to claim 1, wherein: Place solution B in a normal-temperature water bath to keep the temperature of the reaction system stable, then drop solution A into solution B and stir to prepare bismuth-doped silver sulfide quantum dots.
6. The preparation method according to claim 1, characterized in that: The molar ratio of silver element to sulfur element in the raw materials is 2:1 - 3:
1.
7. The preparation method according to claim 1, characterized in that: The molar ratio of silver element to bismuth element in the raw materials is greater than or equal to 100:
1.
8. The preparation method according to claim 1, characterized in that: After dropping solution A and waiting for the reaction to complete, add methyl acetate or ethyl acetate to the system to centrifuge and separate the sample, and redisperse the obtained sample in a polar organic solvent to obtain a spin-coating solution, that is, a dispersion of bismuth-doped silver sulfide colloidal quantum dots, for the assembly of optoelectronic devices.
9. The preparation method according to claim 8, characterized in that: The polar organic solvent is N, N-dimethylformamide; the volume of methyl acetate or ethyl acetate is more than 2 times that of the added system; the centrifugation separation speed is 8000 - 10000 r / min.
10. An optoelectronic detector prepared from the bismuth-doped silver selenide colloidal quantum dot material obtained by the preparation method according to claim 1.