阅读说明：本技术 一种铅氧族化合物二聚体纳米晶、导电薄膜及制备方法与应用 (Lead-oxygen family compound dimer nanocrystalline, conductive film, preparation method and application ) 是由 马万里 卢坤媛 刘泽柯 于 2020-06-18 设计创作，主要内容包括：本发明公开了一种铅氧族化合物二聚体纳米晶、导电薄膜及制备方法和应用。利用铅试剂、有机酸和1-十八烯制备铅前驱体；利用二(三甲基硅烷基)氧族化合物、1-十八烯与得到的铅前驱体进行反应,对得到的溶液进行冷冻处理后,再通过后处理得到卤素掺杂的铅氧族化合物纳米晶。本发明提供的铅氧族化合物二聚体纳米晶在沉积薄膜过程中能使纳米晶的排列更加无序,避免晶界的形成,可以进一步避免后续配体交换过程中裂缝的形成。利用本发明提供的制备方法,可以大幅简化纳米晶太阳能电池器件的制备工艺。(The invention discloses a lead-oxygen family compound dimer nanocrystal, a conductive film, a preparation method and application. Preparing a lead precursor by using a lead reagent, organic acid and 1-octadecene; reacting a bis (trimethylsilyl) oxide compound and 1-octadecene with the obtained lead precursor, freezing the obtained solution, and performing post-treatment to obtain the halogen-doped lead oxide compound nanocrystal. The lead-oxygen family compound dimer nanocrystalline provided by the invention can enable the arrangement of the nanocrystalline to be more disordered in the process of depositing the film, avoid the formation of crystal boundary, and further avoid the formation of cracks in the subsequent ligand exchange process. By utilizing the preparation method provided by the invention, the preparation process of the nanocrystalline solar cell device can be greatly simplified.)

1. A preparation method of lead-oxygen family compound dimer nanocrystalline is characterized by comprising the following steps:

1) adding a lead reagent, an organic acid and a solvent into a reaction container, wherein the molar ratio of the lead reagent to the organic acid is 1: 2.5-5; stirring and vacuumizing for 1-2 hours until the lead reagent is completely dissolved, and obtaining a lead precursor, wherein the reaction liquid is bubble-free and is clear and transparent;

2) introducing inert gas into a reaction container, uniformly mixing a bis (trimethylsilyl) oxygen compound and 1-octadecene serving as a solvent at the temperature of 60-180 ℃, quickly transferring the mixture into the lead precursor obtained in the step 1), and continuously reacting for 0.5-30 minutes;

3) after the reaction is finished, cooling the reaction liquid to room temperature, adding n-hexane, freezing the reaction liquid, and removing bottom sediment through centrifugation;

4) and precipitating the upper solution by isopropanol and acetone, centrifuging, removing the upper solution, and performing vacuum pumping to obtain the lead-oxygen compound dimer nanocrystal.

2. The method for preparing a lead-oxygen family compound dimer nanocrystal according to claim 1, wherein the method comprises the following steps: the lead reagent in the step 1) is any one of lead oxide, lead acetate, lead chloride, lead bromide and lead iodide; the organic acid is any one of oleic acid, octadecyl acid and hexadecyl acid; the solvent is any one of 1-octadecene, 1-eicosene and diphenyl ether.

3. The method for preparing a lead-oxygen family compound dimer nanocrystal according to claim 1, wherein the method comprises the following steps: the inert gas in the step 2) is any one of nitrogen, helium and neon; the bis (trimethylsilyl) oxygen family compound is any one of bis (trimethylsilyl) sulfide, bis (trimethylsilyl) selenide and bis (trimethylsilyl) telluride.

4. The method for preparing a lead-oxygen family compound dimer nanocrystal according to claim 1, wherein the method comprises the following steps: in the step 1), the organic acid is oleic acid, and the molar ratio of the lead reagent to the oleic acid is 1: 2.5.

5. The method for preparing a lead-oxygen family compound dimer nanocrystal according to claim 1, wherein the method comprises the following steps: the condition of the freezing treatment in the step 3) is that the freezing temperature is 0-5 ℃ and the freezing time is 10-60 minutes.

6. A lead-oxygen family compound dimer nanocrystal obtained by the preparation method of claim 1.

7. A preparation method of a conductive film based on lead-oxygen family compound dimer nanocrystalline is characterized by comprising the following steps:

1) adding a lead reagent, an organic acid and a solvent into a reaction container, wherein the molar ratio of the lead reagent to the organic acid is 1: 2.5-5; stirring and vacuumizing for 1-2 hours until the lead reagent is completely dissolved, and obtaining a lead precursor, wherein the reaction liquid is bubble-free and is clear and transparent;

2) introducing inert gas into a reaction container, uniformly mixing a bis (trimethylsilyl) oxygen compound and 1-octadecene serving as a solvent at the temperature of 60-180 ℃, quickly transferring the mixture into the lead precursor obtained in the step 1), and continuously reacting for 0.5-30 minutes;

3) after the reaction is finished, cooling the reaction liquid to room temperature, adding n-hexane, freezing the reaction liquid, and removing bottom sediment through centrifugation;

4) precipitating the upper layer solution by isopropanol and acetone, centrifuging, removing the upper layer solution, and performing vacuum pumping to obtain lead-oxygen compound dimer nanocrystal;

5) dissolving lead-oxygen family compound dimer nano-crystal in a nonpolar solvent, wherein the concentration of the solution is 10-1000 mg/mL, and depositing the solution on a substrate in a spin coating manner to form a film;

6) dissolving iodide in an alcohol solution, wherein the concentration of the solution is 2-100 mM; and (3) dropwise adding the solution onto the film prepared in the step 5), soaking for 50-300 seconds, then spin-drying, and then washing with isopropanol and acetonitrile to obtain the conductive film.

8. The method for preparing a conductive film based on lead-oxygen family compound dimer nanocrystalline according to claim 7, characterized in that: the nonpolar solvent comprises normal hexane, normal octane, toluene and chloroform; the substrate comprises common glass, transparent conductive glass, a silicon wafer, silicon oxide, quartz and polyethylene terephthalate; the halide comprises formamidine halide, ammonia halide, methylamine halide, tetrabutylammonium halide and tetramethylammonium halide; halogens include chlorine, bromine and iodine.

9. A conductive film based on a lead-oxygen family compound dimer nanocrystal obtained by the preparation method of claim 7.

10. Use of a conductive film based on nanocrystals of lead-oxy group compounds dimers as defined in claim 9 for the preparation of solar cells.

Technical Field

The invention relates to the technical field of functional materials, in particular to a lead-oxygen family compound dimer nanocrystal, a conductive film, a preparation method thereof and application thereof in preparing a solar cell.

Background

PbX of groups IV-VI (X = sulfur, selenium, tellurium) has a large bohr radius, making its quantum confinement effect particularly pronounced. The band gap of the nanocrystalline material can be greatly adjusted through size adjustment, the absorption spectrum of the nanocrystalline material can be well matched with the solar spectrum reaching the earth surface, and meanwhile, the nanocrystalline material has the characteristics of large absorption coefficient, high electron mobility, adjustable energy level and the like, so that the IV-VI group nanocrystalline becomes the most popular photovoltaic nanomaterial at the present stage, and is expected to become a low-cost and high-efficiency solar cell of a new generation of solution process.

At present, most of nanocrystalline materials used in the preparation of PbX nanocrystalline solar cells are synthesized based on a classical thermal injection method, the method needs to use a long-chain organic ligand (oleic acid) to control the growth of nanocrystals, but the long-chain organic ligand enables the nanocrystals to be mutually insulated, and the long-chain organic ligand is exchanged into a short ligand to enhance the conductivity of a nanocrystalline film in the process of preparing a photoelectric device through a ligand exchange step. The ligand exchange step is an extremely important link in the preparation process of the PbS nanocrystalline solar cell, and can be divided into the following two types according to different ligand exchange modes:

(1) solid-state ligand exchange: the method is wide in applicability and is the most widely applied method for early nanocrystalline solar cells. However, in order to ensure sufficient ligand exchange and film compactness in the method, the thickness of each film layer can be controlled to be dozens of nanometers, the process usually needs to be repeated for about 10 times to obtain a photovoltaic active layer with the required thickness, and the preparation process is extremely complicated. And researches show that the solid-state exchange has the problem of uneven exchange, and the surface of the nanocrystal can be damaged by repeated polar solvent washing, so that a defect state is introduced.

(2) Solution phase ligand exchange: to avoid the disadvantages of solid-state ligand exchange, solution phase ligand exchange processes have recently been extensively studied. In the method, PbX nano-crystals synthesized by a thermal injection method are dispersed in a non-polar solvent (n-hexane or n-octane) and stirred with a dimethylformamide solution of lead halide, ligand exchange is completed in a solution phase, surface oleic acid is replaced by lead halide, and then the PbX nano-crystals are dispersed in a butylamine solution to form PbX nano-crystal ink which is directly prepared into a conductive film. Compared with solid-state exchange, the method simplifies the device preparation process and avoids the damage of multiple exchanges to the surface of the nanocrystal. However, the method needs to consume a large amount of expensive lead halide salt and a solvent with high toxicity, and the prepared nanocrystalline ink has poor stability, is not beneficial to large-scale application and still has great limitation.

Disclosure of Invention

In order to solve the problems in the prior art, the invention aims to provide a lead-oxygen compound dimer nanocrystal, a conductive film, a preparation method and application thereof. The device performance of the nanocrystalline prepared by the method in the solar cell is further used for preparing the corresponding solar cell. The method can effectively solve the problems of complex solid ligand exchange and unstable solution phase ligand exchange solution in the prior art, and is expected to provide a new way for the mass production of nanocrystalline solar cells in the future.

In order to achieve the above object, the present invention adopts a technical scheme that a preparation method of a lead-oxygen family compound dimer nanocrystal is provided, which comprises the following steps:

1) adding a lead reagent, an organic acid and a solvent into a reaction container, wherein the molar ratio of the lead reagent to the organic acid is 1: 2.5-5; stirring and vacuumizing for 1-2 hours until the lead reagent is completely dissolved, and obtaining a lead precursor, wherein the reaction liquid is bubble-free and is clear and transparent;

2) introducing inert gas into a reaction container, uniformly mixing a bis (trimethylsilyl) oxygen compound and 1-octadecene serving as a solvent at the temperature of 60-180 ℃, quickly transferring the mixture into the lead precursor obtained in the step 1), and continuously reacting for 0.5-30 minutes;

3) after the reaction is finished, cooling the reaction liquid to room temperature, adding n-hexane, freezing the reaction liquid, and removing bottom sediment through centrifugation;

4) and precipitating the upper solution by isopropanol and acetone, centrifuging, removing the upper solution, and performing vacuum pumping to obtain the lead-oxygen compound dimer nanocrystal.

The preferable scheme of the preparation method of the lead-oxygen family compound dimer nanocrystal is as follows:

the lead reagent in the step 1) is any one of lead oxide, lead acetate, lead chloride, lead bromide and lead iodide; the organic acid is any one of oleic acid, octadecyl acid and hexadecyl acid; the solvent is any one of 1-octadecene, 1-eicosene and diphenyl ether; in the step 1), the organic acid is oleic acid, and the molar ratio of the lead reagent to the oleic acid is 1: 2.5.

The inert gas in the step 2) is any one of nitrogen, helium and neon; the bis (trimethylsilyl) oxy compound is bis (trimethylsilyl) sulfide ((TMS)₂S), bis (trimethylsilyl) selenide ((TMS)₂Se), bis (trimethylsilyl) telluride ((TMS)₂Te) is used.

The condition of the freezing treatment in the step 3) is that the freezing temperature is 0-5 ℃ and the freezing time is 10-60 minutes.

The technical scheme of the invention comprises the lead-oxygen family compound dimer nanocrystalline obtained by the preparation method.

The technical scheme of the invention also provides a preparation method of the conductive film based on the lead-oxygen family compound dimer nanocrystalline, which comprises the following steps:

1) adding a lead reagent, an organic acid and a solvent into a reaction container, wherein the molar ratio of the lead reagent to the organic acid is 1: 2.5-5; stirring and vacuumizing for 1-2 hours until the lead reagent is completely dissolved, and obtaining a lead precursor, wherein the reaction liquid is bubble-free and is clear and transparent;

2) introducing inert gas into a reaction container, uniformly mixing a bis (trimethylsilyl) oxygen compound and 1-octadecene serving as a solvent at the temperature of 60-180 ℃, quickly transferring the mixture into the lead precursor obtained in the step 1), and continuously reacting for 0.5-30 minutes;

3) after the reaction is finished, cooling the reaction liquid to room temperature, adding n-hexane, freezing the reaction liquid, and removing bottom sediment through centrifugation;

4) precipitating the upper layer solution by isopropanol and acetone, centrifuging, removing the upper layer solution, and performing vacuum pumping to obtain lead-oxygen compound dimer nanocrystal;

5) dissolving lead-oxygen family compound dimer nano-crystal in a nonpolar solvent, wherein the concentration of the solution is 10-1000 mg/mL, and depositing the solution on a substrate in a spin coating manner to form a film;

6) dissolving iodide in an alcohol solution, wherein the concentration of the solution is 2-100 mM; and (3) dropwise adding the solution onto the film prepared in the step 5), soaking for 50-300 seconds, then spin-drying, and then washing with isopropanol and acetonitrile to obtain the conductive film.

The preparation method of the conductive film based on the lead-oxygen compound dimer nanocrystal preferably adopts the following scheme: the nonpolar solvent comprises normal hexane, normal octane, toluene and chloroform; the substrate comprises common glass, transparent conductive glass, a silicon wafer, silicon oxide, quartz and polyethylene terephthalate; the halide comprises formamidine halide, ammonia halide, methylamine halide, tetrabutylammonium halide and tetramethylammonium halide; halogens include chlorine, bromine and iodine.

The technical scheme of the invention comprises the conductive film based on the lead-oxygen family compound dimer nanocrystalline obtained by the preparation method.

The technical scheme of the invention provides an application of a conductive film based on a lead-oxygen family compound dimer nanocrystal in preparation of a solar cell.

Compared with the prior art, the invention adopting the technical scheme has the following advantages:

1) the preparation method of the invention provides a simple method for preparing the lead-oxygen family compound dimer nanocrystal;

2) the preparation method is simple and easy to implement, and the lead-oxygen family compound dimer nanocrystalline is used for realizing one-layer ligand exchange through a simple solid-phase ligand exchange method to obtain a conductive nanocrystalline film without cracks so as to prepare the solar cell, and the whole preparation process is greatly simplified compared with the traditional method.

Drawings

Fig. 1 is a projection electron microscope image and a particle size statistical image of a general PbS nanocrystal and a PbS dimer nanocrystal provided by an embodiment of the present invention;

fig. 2 is a top view and a cross-sectional scanning electron microscope image after ligand exchange of a thin film prepared based on a common PbS nanocrystal and a PbS dimer nanocrystal provided by an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a nanocrystalline solar cell device;

FIG. 4 is a graph of current versus voltage for different device structures;

in the figure, 1. a glass substrate; 2. a cathode layer; 3. an electron transport layer; 4. an active layer; a hole transport layer; and 6, anode layer.

Detailed Description

The invention is further described with reference to the following figures and specific embodiments. Unless otherwise specifically indicated, materials, reagents and instruments used in the following examples are commercially available.