In-situ growth IV-VI group quantum dot film and preparation method thereof

Abstract

The invention relates to the technical field of quantum dot preparation, in particular to an in-situ growth IV-VI group quantum dot film and a preparation method thereof, and the preparation method comprises the following steps: preparing a precursor solution containing a IV group metal compound, a VI group nonmetal compound and a ligand, the ligand comprises at least one of metal halide and ammonium halide; and putting a substrate on which quantum dots are to grow into the precursor solution, and growing for 2-20 hours at the temperature of 30-110 DEG C. The method has the effects of one-step in-situ growth of the quantum dot film, reduction of the difficulty of a quantum dot film preparation process and large-area preparation.

Description

Technical Field

[0001] The present application relates to the technical field of quantum dot films, and in particular to an in-situ grown IV-VI group quantum dot film and a preparation method thereof. Background Art

[0002] Quantum dots (CQDs) are a class of nanoscale semiconductor materials with discrete energy levels, where electrons are confined in three dimensions. Due to their unique optical properties, CQDs have shown great potential across all subfields of optoelectronics, with applications in a wide range of optoelectronics fields, including lighting, displays, photovoltaic cells, and detection.

[0003] Among them, group IV-VI quantum dots have a smaller band gap energy and a larger exciton Bohr radius, so the effective band gap has a larger adjustable range, which can achieve tunable absorption and fluorescence in the near and mid-infrared wavelengths. The fluorescence range covers important optical communication windows, biological tissue translucent windows, and atmospheric transmission windows, and has broad application prospects.

[0004] The main methods for preparing group IV-VI quantum dot films include spin coating, doctor blade coating, inkjet printing, solution dipping, and so on. Among them: the spin coating method is to drip a solution containing quantum dots onto a high-speed rotating substrate. The solution spreads evenly under the action of centrifugal force and forms a uniform thin film after rapid evaporation. The doctor blade coating method uses a fixed "blade" to control the thickness of the liquid film, thereby forming a uniform quantum dot film on the substrate. Inkjet printing is to suspend quantum dots in a liquid carrier to form a special "ink", which is then sprayed onto the substrate with extremely high precision using an inkjet print head to form the desired pattern or layer. The pattern and thickness of the quantum dot film can be precisely controlled, making it suitable for the preparation of complex structures. The solution dipping method is to immerse the substrate in a solution containing quantum dots, then remove it and dry it naturally in the air, repeating this process until the desired film thickness is reached.

[0005] The above methods for preparing quantum dot films all first synthesize quantum dots and clean them. The solution method for synthesizing quantum dots has problems such as harsh experimental conditions, high cost, great environmental pressure, and time-consuming process. Summary of the Invention

[0006] In order to grow quantum dot films in situ in one step, reduce the difficulty of the quantum dot film preparation process, and enable large-area preparation, the purpose of this application is to provide an in-situ grown IV-VI group quantum dot film and its preparation method.

[0007] In the first aspect, the present application provides a method for preparing an in-situ grown IV-VI group quantum dot thin film using the following technical solutions: A method for preparing an in-situ grown IV-VI group quantum dot film comprises the following steps: Preparing a precursor solution comprising a Group IV metal compound, a Group VI non-metal compound, and a ligand, wherein the ligand comprises at least one of a metal halide and an ammonium halide; The substrate on which quantum dots are to be grown is placed in the precursor solution and grown at a temperature of 30-110° C. for 2-20 hours.

[0008] Optionally, the preparation of a precursor solution comprising a Group IV metal compound, a Group VI non-metallic compound, and a ligand comprises: preparing a Group IV metal compound solution; preparing a Group VI non-metal compound solution; Prepare ligand solution; The precursor solution is obtained by mixing the Group IV metal compound solution, the Group VI non-metal compound solution, and the ligand solution.

[0009] Optionally, the preparing the Group IV metal compound solution includes: dissolving the Group IV metal compound in a first solvent; Wherein, the Group IV metal compound comprises at least one of a nitrate, acetate, halide, and halide salt of a Group IV metal; The first solvent includes at least one of methanol, formamide, ethanol, acetonitrile, N-methylformamide, N,N-dimethylformamide, dimethyl sulfoxide, and carbon disulfide; The concentration of the Group IV metal compound in the precursor solution is in the range of 0.005-0.1 mol / L.

[0010] Optionally, the preparing the Group VI non-metal compound solution comprises: dissolving the Group VI non-metal compound in a second solvent; The Group VI non-metallic compound includes at least one of thiourea and its derivatives, selenourea and its derivatives, tellurium and its derivatives, thiols, thiophenols, sulfides, disulfides, selenols, selenophene, selenoethers, diselenides, sulfide salts and selenide salts; The second solvent includes at least one of methanol, formamide, ethanol, acetonitrile, N-methylformamide, N,N-dimethylformamide, dimethyl sulfoxide, and carbon disulfide; The concentration of the Group VI non-metallic compound in the precursor solution is in the range of 0.005-0.1 mol / L.

[0011] Optionally, the preparing the ligand solution includes: dissolving the ligand in a third solvent; Wherein, the metal halide includes at least one of sodium halide, zinc halide, lead halide, cadmium halide, potassium halide, calcium halide, copper halide, silver halide, indium halide, and antimony halide; The ammonium halide includes at least one of ammonium chloride, ammonium bromide, ammonium iodide, and ammonium fluoride; The third solvent includes at least one of methanol, formamide, ethanol, acetonitrile, N-methylformamide, N,N-dimethylformamide, dimethyl sulfoxide, and carbon disulfide; The concentration of the ligand solution in the precursor solution is in the range of 0.001-0.05 mol / L.

[0012] Optionally, before placing the substrate to be grown quantum dots in the precursor solution, the process further comprises: The non-growth area of ​​the substrate is isolated to highlight the growth area of ​​the substrate, and then placed in the precursor solution.

[0013] Optionally, before placing the substrate in the precursor solution, the method further comprises: A seed layer is prepared in a substrate growth area where quantum dots are to be grown, wherein the material of the seed layer comprises at least one of Group IV-VI compounds, Pb, CdSe, ZnO, ZnS, CdS, and ZnSe.

[0014] Optionally, the seed layer is prepared by at least one of thermal evaporation, spin coating, physical vapor deposition, and chemical vapor deposition.

[0015] Optionally, the thickness of the seed layer is not greater than 10 nm. Preferably, the thickness of the seed layer is 2-5 nm.

[0016] In a second aspect, the in-situ grown IV-VI group quantum dot film provided by the present application adopts the following technical solution: The in-situ grown IV-VI group quantum dot film is prepared by using the in-situ grown IV-VI group quantum dot film preparation method.

[0017] In summary, this application includes at least one of the following beneficial technical effects: 1. Through ligand selection and the preparation of mixed Group IV metal compound solution and Group VI non-metallic compound solution, the substrate can be directly placed in the precursor solution, and quantum dot film can be grown in situ in one step at an appropriate temperature. The process is simple, convenient, and can be prepared on a large scale.

[0018] 2. The solvent is preferably set to formamide, N-methylformamide, N,N-dimethylformamide, and dimethyl sulfoxide to improve the quantum dot film formation effect and control the thickness of the generated film.

[0019] 3. The setting of the seed layer improves the generation effect of quantum dot film, especially the control of thickness, while improving the density of the film. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a scanning electron microscope image of the IV-VI group quantum dot film of Example 1 of the present application; Figure 2 The X-ray diffraction pattern and absorption spectrum of the Group IV-VI quantum dot film in Example 1 of the present application; Figure 3 This is a scanning electron microscope image of the IV-VI group quantum dot film of Example 5 of the present application; Figure 4 This is a scanning electron microscope image of the IV-VI group quantum dot film of Example 6 of the present application; Figure 5 This is a scanning electron microscope image of the IV-VI group quantum dot film of Example 7 of the present application; Figure 6 is a scanning electron microscope image of the IV-VI group quantum dot film of Example 11 of the present application; Figure 7 is a scanning electron microscope image of the IV-VI group quantum dot film of Example 12 of the present application; Figure 8 This is a scanning electron microscope image of the IV-VI group quantum dot film of Example 13 of the present application. DETAILED DESCRIPTION

[0021] The main methods for preparing Group IV-VI quantum dot thin films include spin coating, blade coating, inkjet printing, and solution dipping. All of these methods require quantum dot synthesis followed by cleaning, which presents challenges such as demanding experimental conditions, high costs, significant environmental pressures, and time-consuming processes. This application builds on these challenges.

[0022] Reference Figures 1-8 The present invention provides a method for preparing an in-situ grown IV-VI group quantum dot film, comprising the following steps: Step 1: preparing a precursor solution comprising a Group IV metal compound, a Group VI non-metal compound, and a ligand, wherein the ligand comprises at least one of a metal halide and an ammonium halide; Step 2: Place the substrate on which quantum dots are to be grown in the precursor solution and grow at a temperature of 30-110° C. for 2-20 hours.

[0023] In this embodiment, there is no requirement for the order in which the Group IV metal compound, the Group VI non-metallic compound, and the ligand are mixed, and the order in which the substrate is added. As long as the above materials are mixed, any of the following methods can be used: Method 1: Prepare solutions of the Group IV metal compound, the Group VI non-metal compound, and the ligand respectively, mix them, and then place the substrate in the prepared solutions; Method 2: Weigh the Group IV metal compound, Group VI non-metal compound, and ligand together, then add a solvent to dissolve and disperse them, and then place them on the substrate; Method 3: Weigh the Group IV metal compound, the Group VI non-metal compound, and the ligand and put them together, then place them on the substrate, and then add the solution to dissolve and disperse them.

[0024] For step one: In certain embodiments, taking method 1 as an example, the preparation of a precursor solution comprising a Group IV metal compound, a Group VI non-metal compound, and a ligand includes: S1. Prepare a Group IV metal compound solution.

[0025] In this embodiment, a Group IV metal compound is dissolved in a first solvent to obtain a Group IV metal compound solution.

[0026] The Group IV metal in the Group IV metal compound includes germanium (Ge), tin (Sn), and lead (Pb), preferably, lead (Pb). The Group IV metal compound includes at least one of a nitrate, acetate, halide, or halogenate of the Group IV metal; taking lead as an example, exemplary examples include lead nitrate (Pb(NO3)2), lead acetate (CH3COO)2Pb, lead halides (PbCl2, PbI2, etc.), and lead halides (Pb(ClO3)2, Pb(BrO3)2, etc.).

[0027] The first solvent includes at least one of methanol, ethanol, acetonitrile, formamide, N-methylformamide, N,N-dimethylformamide, dimethyl sulfoxide, and carbon disulfide. Preferably, the first solvent includes at least one of formamide, N-methylformamide, N,N-dimethylformamide, and dimethyl sulfoxide, which can finely control the growth rate, particle size, and thickness of the thin film.

[0028] S2. Prepare a Group VI non-metal compound solution.

[0029] In this embodiment, the Group VI non-metallic compound is dissolved in the second solvent to obtain a Group VI non-metallic compound solution.

[0030] The Group VI non-metal compound includes sulfur S, selenium Se, and tellurium Te, preferably, sulfur S and selenium Se, and more preferably, sulfur S. Taking the Group VI non-metal as sulfur S as an example, illustratively, thiourea SC(NH2)2, thiourea derivatives (N,N'-diphenylthiourea, etc.), thiol R-SH, thiophenol , sulfide RSR, disulfide RSSR, sulfide salt (sodium sulfide, etc.), etc., in the above formula, R can be the same structure or different structures; The second solvent includes at least one of methanol, ethanol, acetonitrile, formamide, N-methylformamide, N,N-dimethylformamide, dimethyl sulfoxide, and carbon disulfide. Preferably, the second solvent includes at least one of formamide, N-methylformamide, N,N-dimethylformamide, and dimethyl sulfoxide, which can finely control the growth rate, particle size, and thickness of the thin film.

[0031] S3. Prepare ligand solution.

[0032] In this embodiment, the ligand is dissolved in a third solvent to obtain a ligand solution, and the ligand includes at least one of a metal halide and an ammonium halide, preferably a metal halide.

[0033] Wherein, the metal halide includes at least one of sodium halide, zinc halide, lead halide, cadmium halide, potassium halide, calcium halide, copper halide, silver halide, indium halide, and antimony halide; The ammonium halide includes at least one of ammonium chloride, ammonium bromide, ammonium iodide, and ammonium fluoride; The third solvent includes at least one of methanol, ethanol, acetonitrile, formamide, N-methylformamide, N,N-dimethylformamide, dimethyl sulfoxide, and carbon disulfide. Preferably, the third solvent includes at least one of formamide, N-methylformamide, N,N-dimethylformamide, and dimethyl sulfoxide, which can finely control the growth rate, particle size, and thickness of the thin film.

[0034] In the above solution, the first solvent, the second solvent and the third solvent may be the same solvent or different solvents.

[0035] It should be noted that the serial numbers of the above steps S1, S2, and S3 only represent the steps, not the order.

[0036] S4. Mixing the Group IV metal compound solution, the Group VI non-metal compound solution, and the ligand solution to obtain the precursor solution.

[0037] In this embodiment, the three solutions (the Group IV metal compound solution, the Group VI non-metal compound solution, and the ligand solution) are mixed. During the mixing process, the mixing order of the three solutions is not limited.

[0038] The concentration range of the Group IV metal compound in the precursor solution is 0.005-0.1 mol / L. In one embodiment, the concentration of the Group IV metal compound can be 0.005 mol / L, 0.01 mol / L, or 0.1 mol / L, as long as the set concentration can achieve the effect of in situ growth.

[0039] The concentration of the Group VI non-metallic compound in the precursor solution ranges from 0.005 to 0.1 mol / L. In one embodiment, the concentration of the Group IV metal compound can be 0.005 mol / L, 0.01 mol / L, or 0.1 mol / L, as long as the concentration is sufficient to achieve in situ growth.

[0040] The concentration of the ligand solution in the precursor solution is in the range of 0.001-0.05 mol / L. In one embodiment, the concentration of the Group IV metal compound can be 0.001 mol / L, 0.05 mol / L, or 0.005 mol / L, as long as the concentration can achieve the in situ growth effect.

[0041] For step 2: In some embodiments, the substrate on which the quantum dots are to be grown may be any one of glass, quartz, fluorine-doped indium oxide (FTO), and indium oxide (ITO).

[0042] In some embodiments, the substrate on which quantum dots are to be grown includes a substrate non-growth area and a substrate growth area, wherein the substrate growth area is the area used to grow quantum dot thin films, usually the front side of the substrate; the substrate non-growth area is the area other than the substrate growth area, usually corresponding to the back side of the substrate.

[0043] In certain embodiments, before placing the substrate on which quantum dots are to be grown in the precursor solution, the process includes isolating the non-growth region of the substrate to highlight the growth region, and then placing the substrate in the precursor solution. In this embodiment, isolating the non-growth region of the substrate can be accomplished by applying tape or attaching the substrate to a glass strip or other material to prevent thin film growth on the non-growth region (back surface).

[0044] In some embodiments, placing the substrate in the precursor solution further comprises: A seed layer is prepared in the substrate growth region, wherein the material of the seed layer includes at least one of a Group IV-VI compound (exemplarily, lead sulfide PbS, etc.), Pb, CdSe, ZnO, ZnS, CdS, and ZnSe.

[0045] In one embodiment, the seed layer is prepared by thermal evaporation, spin coating, physical vapor deposition, or chemical vapor deposition.

[0046] In one embodiment, the thickness of the seed layer is not greater than 10 nm, and may be 1 nm, 3 nm, 5 nm, 7 nm, or 9 nm. Preferably, the thickness of the seed layer is 2-5 nm, and may be 2 nm, 4 nm, or 7 nm.

[0047] In some embodiments, the growth temperature may be 30°C, 40°C, 60°C, 80°C, 100°C, or 110°C, as long as the set temperature can achieve in-situ growth; In some embodiments, the growth time can be 2 h, 4 h, 6 h, 8 h, 12 h, 16 h, or 20 h, as long as the set time can meet the in-situ growth requirements.

[0048] Furthermore, embodiments of the present application provide an in-situ grown IV-VI group quantum dot film and an optoelectronic device comprising the in-situ grown IV-VI group quantum dot film.

[0049] The present application is further described in detail below with reference to the accompanying drawings and examples.

[0050] <Example 1> Example 1 of the present application discloses a method for preparing an in-situ grown IV-VI group quantum dot film, comprising the following steps: S1. Prepare a Group IV metal compound solution, specifically: Lead nitrate is dissolved in formamide to prepare a Group IV metal compound solution.

[0051] S2. Prepare a Group VI non-metallic compound solution, specifically: A Group VI non-metal compound solution is prepared by dissolving N,N'-diphenylthiourea in formamide.

[0052] S3. Prepare ligand solution, specifically: The ligand solution was prepared by dissolving zinc iodide in formamide.

[0053] S4. Mix 7.5 mL of the Group IV metal compound solution, 7.5 mL of the Group VI non-metallic compound solution, and 225 μL of the ligand solution to obtain the precursor solution, wherein the concentration of the Group IV metal compound, the concentration of the Group VI non-metallic compound, and the concentration of the ligand in the precursor solution are 0.01 mol / L, 0.01 mol / L, and 0.005 mol / L. When performing the concentration calculation formula, the total volume is calculated as 15 mL, and the volume of the ligand solution is negligible.

[0054] S5. Take the substrate (fluorine-doped indium oxide (FTO) substrate) to be grown quantum dots, with a size of 2.5 cm*2.5 cm, and use tape to protect the non-growth area.

[0055] S6. Prepare a seed layer in the growth area of ​​the substrate. The material of the seed layer is PbS, which is prepared by thermal evaporation. The thickness of the seed layer is limited to 2 nm.

[0056] S7. Then, the substrate with the seed layer is placed in the precursor solution and grown at 60° C. for 5 h.

[0057] <Example 2> Example 2 of the present application discloses a method for preparing an in-situ grown IV-VI group quantum dot film, which is the same as Example 1, except that the first solvent, the second solvent, and the third solvent are not formamide, but are replaced by N-methylformamide.

[0058] <Example 3> Example 3 of the present application discloses a method for preparing an in-situ grown IV-VI group quantum dot film, which is the same as Example 1, except that the first solvent, the second solvent, and the third solvent are not formamide, but are replaced by N,N-dimethylformamide.

[0059] <Example 4> Example 4 of the present application discloses a method for preparing an in-situ grown IV-VI group quantum dot film, which is the same as Example 1, except that the first solvent, the second solvent, and the third solvent are not formamide, but are replaced by methanol.

[0060] <Example 5> Example 5 of the present application discloses a method for preparing an in-situ grown IV-VI group quantum dot film, which is the same as Example 1, except that the first solvent, the second solvent, and the third solvent are not formamide, but are replaced by ethanol + formamide. Specifically, the volume ratio of ethanol and formamide is 1:1.

[0061] <Example 6> Example 6 of the present application discloses a method for preparing an in-situ grown IV-VI group quantum dot film, which is the same as Example 1, except that in step S3, the ligand is not zinc iodide but is replaced by sodium iodide.

[0062] <Example 7> Example 6 of the present application discloses a method for preparing an in-situ grown IV-VI group quantum dot film, which is the same as Example 1, except that in step S3, the ligand is not zinc iodide but is replaced by ammonium iodide.

[0063] <Example 8> Example 8 of the present application discloses a method for preparing an in-situ grown IV-VI group quantum dot film, which is the same as Example 1, except that step S6 is not included. After step S5, the substrate is directly placed in the precursor solution and grown at 60°C for 5 hours.

[0064] <Example 9> Example 9 of the present application discloses a method for preparing an in-situ grown IV-VI group quantum dot film, which is the same as Example 1, except that step S6 specifically includes: A seed layer is prepared in the growth area of ​​the substrate. The material of the seed layer is Pb and is prepared by thermal evaporation. The thickness of the seed layer is limited to 2 nm.

[0065] <Example 10> Example 10 of the present application discloses a method for preparing an in-situ grown IV-VI group quantum dot thin film, which is the same as Example 1, except that step S6 specifically includes: A seed layer is prepared in the substrate growth area. The material of the seed layer is ZnO and is prepared by magnetron sputtering. The thickness of the seed layer is limited to less than 2 nm.

[0066] <Example 11> Example 11 of the present application discloses a method for preparing an in-situ grown IV-VI group quantum dot film, which is the same as Example 1, except that the group IV metal compound is not lead nitrate but is replaced by lead acetate.

[0067] <Example 12> Example 12 of the present application discloses a method for preparing an in-situ grown IV-VI group quantum dot film, which is the same as Example 1, except that the group VI non-metallic compound is not N,N´-diphenylthiourea, but is replaced by thiourea.

[0068] <Example 13> Example 13 of the present application discloses a method for preparing an in-situ grown IV-VI group quantum dot film, which is the same as Example 1, except that the group VI non-metallic compound is not N,N´-diphenylthiourea, but is replaced by N,N´-dimethylselenourea.

[0069] <Example 14> Example 14 of the present application discloses a method for preparing an in-situ grown IV-VI group quantum dot thin film, comprising the following steps: S1. Prepare a Group IV metal compound solution, specifically: Lead nitrate is dissolved in formamide to prepare a Group IV metal compound solution.

[0070] S2. Prepare a Group VI non-metallic compound solution, specifically: A Group VI non-metal compound solution is prepared by dissolving N,N'-diphenylthiourea in formamide.

[0071] S3. Prepare ligand solution, specifically: The ligand solution was prepared by dissolving zinc iodide in formamide.

[0072] S4. Mix 15 mL of the Group IV metal compound solution, 15 mL of the Group VI non-metallic compound solution, and 225 uL of the ligand solution to obtain the precursor solution, wherein in the precursor solution, the concentration of the Group IV metal compound is 0.005 mol / L, the concentration of the Group VI non-metallic compound is 0.005 mol / L, and the concentration of the ligand is 0.001 mol / L. When performing the concentration calculation formula, the total volume is calculated as 30 mL, and the volume of the ligand solution is negligible.

[0073] S5. Take a substrate (glass substrate) on which quantum dots are to be grown, with a size of 2.5 cm*2.5 cm, and use tape to protect the non-growth area. Then, place it in the precursor solution and grow it at 30°C for 2 h.

[0074] <Example 15> Example 15 of the present application discloses a method for preparing an in-situ grown IV-VI group quantum dot thin film, comprising the following steps: S1. Prepare a Group IV metal compound solution, specifically: Lead nitrate is dissolved in formamide to prepare a Group IV metal compound solution.

[0075] S2. Prepare a Group VI non-metallic compound solution, specifically: A Group VI non-metal compound solution is prepared by dissolving N,N'-diphenylthiourea in formamide.

[0076] S3. Prepare ligand solution, specifically: The ligand solution was prepared by dissolving zinc iodide in formamide.

[0077] S4. Mix 15 mL of the Group IV metal compound solution, 15 mL of the Group VI non-metallic compound solution, and 225 uL of the ligand solution to obtain the precursor solution, wherein in the precursor solution, the concentration of the Group IV metal compound is 0.1 mol / L, the concentration of the Group VI non-metallic compound is 0.1 mol / L, and the concentration of the ligand is 0.05 mol / L. When performing the concentration calculation formula, the total volume is calculated as 30 mL, and the volume of the ligand solution is negligible.

[0078] S5. Take a substrate (glass substrate) on which quantum dots are to be grown, with a size of 2.5 cm*2.5 cm, and use tape to protect the non-growth area. Then place it in the precursor solution and grow it at a temperature of 110°C for 2 h.

[0079] Comparative Example 1 Comparative Example 1 of the present application discloses a method for preparing a quantum dot film, which is the same as Example 8, except that in step S3, the ligand is not zinc iodide but is replaced by butylamine.

[0080] Experimental results and discussion (1) PbS quantum dot film product verification The PbS quantum dot film products prepared in Example 1 were tested by scanning electron microscope (SEM) (refer to Figure 1 ), X-ray diffraction pattern (refer to Figure 2 (a) Test, absorption spectrum (refer to Figure 2 (b) Testing. Specifically: Figure 2 (b) is the absorption spectrum of the prepared PbS quantum dot film product. Figure 2 (b) It can be seen that the absorption peak of the absorption spectrum is located at 1155 nm and the cut-off wavelength is at 1650 nm.

[0081] In order to observe the surface morphology of PbS quantum dots, SEM characterization of quantum dots at this wavelength was performed, such as Figure 1 As shown in the figure, it can be seen that the PbS quantum dot film product is evenly distributed without any agglomeration.

[0082] The crystal structure of the synthesized PbS quantum dot film product was further characterized by XRD technology. The results are as follows Figure 2 As shown in (a), the position of the diffraction peak is basically consistent with the standard diffraction peak of the PDF card of PbS material (JCPDS: No.05-0592), and the crystallinity of the quantum dots is good.

[0083] In summary, the prepared product is indeed a PbS quantum dot film.

[0084] Furthermore, lead nitrate was replaced with lead acetate to prepare the SEM image of the PbS quantum dot film product. Figure 6 As shown; replacing N,N'-diphenylthiourea with thiourea, the SEM image of the PbS quantum dot film product is as shown Figure 7 As shown; replacing N,N'-diphenylthiourea with N,N'-dimethylselenourea, the SEM image of the PbSe quantum dot film product is as shown Figure 8 shown.

[0085] (2) About solvents The solvent in the precursor solution is at least one of methanol, formamide, ethanol, acetonitrile, N-methylformamide, N,N-dimethylformamide, dimethyl sulfoxide, and carbon disulfide. A comparison of Examples 1-5, with the exception of different solvents and other growth conditions remaining the same, reveals that, under the same growth conditions, the corresponding quantum dot films produced with formamide, N-methylformamide, and N,N-dimethylformamide (dimethyl sulfoxide) become increasingly thinner. This is likely due to the different coordination binding (solvation effect) between lead and solvent ligands. Controlling the solvent can effectively regulate the growth of quantum dot films.

[0086] (3) About ligands Comparative Example 1 ( Figure 1 )、Example 6( Figure 4 )、Example 7( Figure 5 ), it can be seen from Comparative Example 1: First, Example 1, Example 6, and Example 7 can all achieve in situ thin film growth, among which the growth effects of Example 1 and Example 6 are better than those of Example 7. The scanning electron microscope image of the PbS quantum dot thin film product obtained in Example 7 shows uneven distribution and partial agglomeration. Compared with ammonium halide, metal halide is more suitable for in situ growth of quantum dot thin films; secondly, Comparative Example 1 cannot grow well. During the mixing process of the solution, the color changes quickly and a large amount of insoluble precipitate is generated, indicating that the traditional preferably selected amine ligand is not suitable for use as a ligand for in situ growth.

[0087] (4) About the seed layer Comparing Example 1 with Example 8, it can be seen that the thickness of the seed layer grown in Example 8 is smaller than that in Example 1 within the same time, that is, the setting of the seed layer can improve the generation effect of the quantum dot film, especially the control of the thickness, while improving the density and uniformity of the film.

[0088] The examples of this specific embodiment are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, any equivalent changes made based on the structure, shape, and principle of this application should be included in the scope of protection of this application.

Claims

1. A method for preparing an in-situ grown IV-VI group quantum dot film, characterized in that: The following steps are involved: Preparing a precursor solution comprising a Group IV metal compound, a Group VI non-metal compound, and a ligand, wherein the ligand comprises at least one of a metal halide and an ammonium halide; The substrate on which quantum dots are to be grown is placed in the precursor solution and grown at a temperature of 30-110° C. for 2-20 hours.

2. The method for preparing an in-situ grown IV-VI group quantum dot thin film according to claim 1, characterized in that: The preparation of the precursor solution containing the Group IV metal compound, the Group VI non-metal compound, and the ligand comprises: preparing a Group IV metal compound solution; preparing a Group VI non-metal compound solution; Prepare ligand solution; The precursor solution is obtained by mixing the Group IV metal compound solution, the Group VI non-metal compound solution, and the ligand solution.

3. The method for preparing an in-situ grown IV-VI group quantum dot thin film according to claim 2, characterized in that: The preparation of the Group IV metal compound solution comprises: dissolving the Group IV metal compound in a first solvent; Wherein, the Group IV metal compound comprises at least one of a nitrate, acetate, halide, and halide salt of a Group IV metal; The first solvent includes at least one of methanol, formamide, ethanol, acetonitrile, N-methylformamide, N,N-dimethylformamide, dimethyl sulfoxide, and carbon disulfide; The concentration range of the Group IV metal compound in the precursor solution is 0.005-0.1 mol / L.

4. The method for preparing an in-situ grown IV-VI group quantum dot thin film according to claim 2, wherein: The preparation of the Group VI non-metal compound solution comprises: dissolving the Group VI non-metal compound in a second solvent; The Group VI non-metallic compound includes at least one of thiourea and its derivatives, selenourea and its derivatives, tellurium and its derivatives, thiols, thiophenols, sulfides, disulfides, selenols, selenophene, selenoethers, diselenides, sulfide salts and selenide salts; The second solvent includes at least one of methanol, formamide, ethanol, acetonitrile, N-methylformamide, N,N-dimethylformamide, dimethyl sulfoxide, and carbon disulfide; The concentration range of the Group VI non-metal compound in the precursor solution is 0.005-0.1 mol / L.

5. The method for preparing an in-situ grown IV-VI group quantum dot thin film according to claim 2, wherein: The preparing of the ligand solution comprises: dissolving the ligand in a third solvent; Wherein, the metal halide includes at least one of sodium halide, zinc halide, lead halide, cadmium halide, potassium halide, calcium halide, copper halide, silver halide, indium halide, and antimony halide; The ammonium halide includes at least one of ammonium chloride, ammonium bromide, ammonium iodide, and ammonium fluoride; The third solvent includes at least one of methanol, formamide, ethanol, acetonitrile, N-methylformamide, N,N-dimethylformamide, dimethyl sulfoxide, and carbon disulfide; The concentration of the ligand solution in the precursor solution is in the range of 0.001-0.05 mol / L.

6. The method for preparing an in-situ grown IV-VI group quantum dot thin film according to claim 1, characterized in that: Before placing the substrate to be grown quantum dots in the precursor solution, the method further comprises: The non-growth area of ​​the substrate is isolated to highlight the growth area of ​​the substrate, and then placed in the precursor solution.

7. The method for preparing an in-situ grown IV-VI group quantum dot thin film according to claim 1, wherein: Before placing the substrate on which quantum dots are to be grown into the precursor solution, the method further comprises: A seed layer is prepared in a substrate growth region, wherein the material of the seed layer comprises at least one of Group IV-VI compounds, Pb, CdSe, ZnO, ZnS, CdS, and ZnSe.

8. The method for preparing an in-situ grown IV-VI group quantum dot thin film according to claim 7, characterized in that: The seed layer is prepared by at least one of thermal evaporation, spin coating, physical vapor deposition, and chemical vapor deposition methods.

9. The method for preparing an in-situ grown IV-VI group quantum dot thin film according to claim 7, characterized in that: The thickness of the seed layer is not greater than 10 nm. Preferably, the thickness of the seed layer is 2-5 nm.

10. In-situ grown IV-VI group quantum dot film, characterized in that: The film is prepared by the method for preparing an in-situ grown IV-VI group quantum dot film as described in any one of claims 1 to 9.

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