阅读说明：本技术 一种高导热性无机铅卤钙钛矿复合薄膜的制备方法 (Preparation method of high-thermal-conductivity inorganic lead-halogen perovskite composite film ) 是由 何海平 陈湛航 叶志镇 于 2020-06-18 设计创作，主要内容包括：本发明公开了一种高导热性无机铅卤钙钛矿复合薄膜的制备方法,该方法利用化学剥离法制备的六方氮化硼纳米片作为导热添加剂,均匀分散在钙钛矿的前驱体溶液中,然后原位地制成复合薄膜。本发明的制备方法简单易行,得到的钙钛矿复合薄膜平整致密、连续性好,六方氮化硼纳米片形成了遍布薄膜的导热通道。本发明方法可以显著缓解钙钛矿薄膜在光照或电流注入时局部的热聚集,提高薄膜的散热性能。(The invention discloses a preparation method of a high-thermal-conductivity inorganic lead-halogen perovskite composite film. The preparation method is simple and feasible, the obtained perovskite composite film is flat and compact and has good continuity, and the hexagonal boron nitride nanosheets form heat conduction channels distributed all over the film. The method can obviously relieve the local heat aggregation of the perovskite film during illumination or current injection, and improve the heat dissipation performance of the film.)

1. A preparation method of a high-thermal-conductivity inorganic lead-halogen perovskite composite film is characterized by comprising the following steps:

1) preparing hexagonal boron nitride nanosheets by adopting a chemical stripping method, and preparing into a dispersion liquid;

2) weighing cesium bromide, lead bromide and octyl ammonium bromide in an inert atmosphere, and adding the cesium bromide, lead bromide and octyl ammonium bromide into the dispersion liquid obtained in the step 1) to prepare a precursor solution; dripping the precursor solution on a substrate, and spin-coating for 90-120 s at 1500-2000 rpm on a spin-coating instrument; and finally, annealing the spin-coated film at 80-120 ℃ for 10-15 min.

2. The method for preparing a highly thermally conductive inorganic lead-halogen perovskite composite thin film as claimed in claim 1, wherein the substrate is sapphire (Al)₂O₃) The substrate is ultrasonically cleaned for 15-30 min at 60 ℃ by acetone, absolute ethyl alcohol and deionized water respectively, soaked in the deionized water and cleaned for 15min by oxygen plasma before use.

3. The method for preparing the highly thermal conductive inorganic lead-halogen perovskite composite thin film according to claim 1, wherein the step (1) is specifically:

(1) grinding and mixing hexagonal boron nitride powder, sodium hydroxide and potassium hydroxide, putting the mixture into a reaction kettle with a polytetrafluoroethylene lining, placing the reaction kettle into an air-blast drying box at 180-200 ℃, preserving heat for 2 hours, and cooling along with the box;

(2) dissolving the mixture treated in the step (1) by adding deionized water, centrifuging at 10000-15000 rpm for 10min, pouring out supernatant, and repeatedly washing precipitates by using the deionized water and absolute ethyl alcohol respectively; finally, drying the mixture in a blast drying oven at the temperature of 60-80 ℃ for 12 hours;

(3) weighing the h-BN nanosheets obtained through the treatment in the step (2) in an inert atmosphere, and preparing the h-BN nanosheets and DMSO into a dispersion liquid of the h-BN nanosheets.

4. The method for preparing a highly thermally conductive inorganic lead-halogen perovskite composite thin film according to claim 3, wherein the particle size of the hexagonal boron nitride powder in the step (1) is 1 to 2 μm.

5. The method for preparing a highly thermal conductive inorganic lead-halogen perovskite composite thin film according to claim 3, wherein the molar ratio of the hexagonal boron nitride powder, the sodium hydroxide and the potassium hydroxide in the step (1) is 1:5: 5.

6. The preparation method of the high thermal conductivity inorganic lead-halogen perovskite composite film as claimed in claim 1, wherein in the step 1), the thickness of the h-BN nano-sheets is less than 30 nm.

7. The method for preparing a highly thermally conductive inorganic lead-halogen perovskite composite thin film according to claim 1, wherein in the step 1),the concentration of the h-BN nano-sheet in the dispersion liquid is 4-10 mg/mL^-1。

8. The preparation method of the high thermal conductivity inorganic lead-halogen perovskite composite film as claimed in claim 1, wherein the molar ratio of cesium bromide, lead bromide and octyl ammonium bromide in the step 2) is n-1: n:2, wherein n is 20-25.

9. The method for preparing the high thermal conductivity inorganic lead-halogen perovskite composite thin film as claimed in claim 1, wherein the mass fraction of the cesium bromide, the lead bromide and the octylammonium bromide in the precursor solution in the step 2) is 10-15 wt%.

10. The method for preparing a highly thermally conductive inorganic lead-halogen perovskite composite thin film as claimed in claim 1, wherein the inert atmosphere in step 2) is achieved by a glove box in which the oxygen content and the water content are less than 0.5 ppm.

Technical Field

The invention relates to a preparation method of an inorganic lead-halogen perovskite composite film, in particular to a preparation method of a high-thermal conductivity inorganic lead-halogen perovskite composite film.

Background

In recent years, inorganic lead-halo perovskites have shown broad application in light sources due to their excellent optical propertiesAnd (4) foreground. The inorganic lead-halogen perovskite has the characteristics of low non-radiative recombination rate, high carrier mobility, long carrier service life, low defect density, tunable band gap and the like. Single crystal methyl ammonium lead halide perovskite (MAPbX)₃X ═ I, Br, Cl) Nanowires (NWs) have laser carrier densities as low as 10¹⁶cm^-3Two orders of magnitude lower than conventional semiconductor nanowires, these excellent properties make lead-halogen perovskites a particularly coherent light source.

In recent years, researchers have succeeded in MAPbI₃Distributed feedback laser and CsPbBr₃Low temperature Continuous Wave (CW) optically pumped lasers are implemented in nanowires, which is a key step in the development to electrically driven laser diodes. Under the condition of high excitation, the temperature of crystal lattice is increased, and the temperature is increased, so that the material threshold is increased, and therefore, the continuous operation of the continuous wave pumping and electrically driven perovskite laser at room temperature is required to be effectively thermally managed.

Two-dimensional materials, particularly hexagonal boron nitride (h-BN), are considered ideal thermal management materials due to their high thermal conductivity and high mechanical flexibility. Researchers used h-BN nanosheet pair CsPbI prepared by mechanical stripping₃The single crystal nano-sheet is packaged, so that CsPbI can be remarkably reduced₃Clear laser behavior can be observed at a high temperature of 75.6 ℃ based on the laser threshold of the NP-h-BN hybrid nano laser.

Unfortunately, h-BN nanosheets prepared based on mechanical exfoliation can only be in surface contact with the target material. For the single crystal nanosheets with micron-sized sizes, the thermal conductivity of the single crystal nanosheets can be obviously improved by the method; however, for a polycrystalline thin film with a larger area and more grain boundaries, the improvement of the thermal conductivity by the method is very limited. In the later device preparation, complex micro-processing processes such as transfer and the like are required, so that the method is not suitable for large-area and large-scale film preparation, and the application of the method on devices is greatly restricted.

Therefore, the method for in-situ preparing the high-thermal-conductivity inorganic lead-halogen perovskite composite film added with the hexagonal boron nitride nanosheets by adopting the liquid phase method is an effective means for solving the problem. The in-situ preparation method can uniformly disperse the h-BN nano-sheets in the lead-halogen perovskite polycrystalline film, thereby greatly increasing the contact area with the lead-halogen perovskite; the h-BN nanosheets can be simultaneously contacted with the lead-halogen perovskite and the heat conducting substrate, and the heat conducting performance of the lead-halogen perovskite is further improved.

Disclosure of Invention

In view of the problems in the prior art, the present invention aims to provide a method for preparing a high thermal conductivity inorganic lead-halogen perovskite composite thin film. The method utilizes a chemical stripping method to prepare h-BN nano-sheets, takes the h-BN nano-sheets as a heat management material, and forms a composite film by one-step spin coating. Local heat collection is avoided when the film works, and high thermal conductivity of the film is realized.

The invention relates to a preparation method of a high-thermal-conductivity inorganic lead-halogen perovskite composite film, which adopts a spin-coating method and specifically comprises the following steps:

1) preparing hexagonal boron nitride nanosheets by adopting a chemical stripping method, and preparing into a dispersion liquid;

2) weighing cesium bromide, lead bromide and octyl ammonium bromide in an inert atmosphere, adding the dispersion liquid obtained in the step 1) and dissolving to prepare a precursor solution. And (3) dripping the precursor solution on a substrate, and spin-coating for 90-120 s at 1500-2000 rpm on a spin-coating instrument. And finally, annealing the spin-coated film at 80-120 ℃ for 10-15 min.

In the above technical solution, further, the substrate is sapphire (Al)₂O₃) The substrate is ultrasonically cleaned for 15-30 min at 60 ℃ by acetone, absolute ethyl alcohol and deionized water respectively, soaked in the deionized water and cleaned for 15min by oxygen plasma before use.

The chemical stripping method in the step 1) is specifically as follows:

(1) grinding and mixing hexagonal boron nitride powder, sodium hydroxide and potassium hydroxide, putting the mixture into a reaction kettle with a polytetrafluoroethylene lining, placing the reaction kettle into an air-blast drying box at 180-200 ℃, preserving heat for 2 hours, and cooling along with the box;

(2) and (2) adding deionized water into the mixture treated in the step (1) for dissolving, centrifuging at 10000-15000 rpm for 10min, pouring out a supernatant, and washing the precipitate for 3 times by using the deionized water and absolute ethyl alcohol respectively. Finally, drying the mixture in a blast drying oven at the temperature of 60-80 ℃ for 12 hours;

(3) weighing the h-BN nanosheets obtained through the treatment in the step (2) in an inert atmosphere, adding the h-BN nanosheets into a screw bottle, and preparing the h-BN nanosheets and DMSO into a dispersion liquid of the h-BN nanosheets.

The inert atmosphere in the step 2) is achieved by a glove box, and the oxygen content and the water content in the glove box are both less than 0.5 ppm.

Preferably, the particle size of the hexagonal boron nitride powder in the step (1) is 1-2 μm.

Preferably, in the step (1), the molar ratio of the hexagonal boron nitride powder to the sodium hydroxide to the potassium hydroxide is 1:5: 5.

Preferably, the thickness of the h-BN nano-sheets in the step 1) is less than 30 nm.

Preferably, the concentration of the h-BN nano-sheets in the dispersion liquid in the step 1) is 4-10 mg/mL^-1。

Preferably, the molar ratio of cesium bromide, lead bromide and octyl ammonium bromide in the step 2) is n-1: n:2, wherein n is 20-25.

Preferably, the mass fraction of cesium bromide, lead bromide and octyl ammonium bromide in the precursor solution in the step 2) is 10-15 wt%.

The prepared final product is an inorganic lead-halogen perovskite composite film added with hexagonal boron nitride nanosheets, and the thickness of the inorganic lead-halogen perovskite composite film is about 100 nm. The h-BN nano-sheets are circular or hexagonal, and each small nano-sheet has an ultrathin thickness of 10-30 nm.

The process used in the process of the invention essentially comprises two steps. The first step is to prepare the ultrathin h-BN nanosheets by a chemical stripping method, and the step is mainly to prepare a large number of ultrathin h-BN nanosheets efficiently by a simple and easy method. The second step is an in-situ preparation process of the composite film, which is a main step of the method, and h-BN nanosheets can be uniformly distributed in the perovskite film without damaging the perovskite film, so that a heat conduction channel extending all over the film is formed, and the heat conduction performance of the film is greatly improved.

In the method, the first step is a process for preparing the ultrathin h-BN nanosheets by a chemical stripping method, and the proportion of alkali and the reaction temperature all have important influence on the shapes of the h-BN nanosheets; the last step is a spin coating process, which greatly influences the appearance of the film, and the spin coating speed, the spin coating time, the precursor concentration and the annealing temperature are all important factors influencing the final product.

The method for preparing the high-thermal-conductivity inorganic lead-halogen perovskite composite film based on the addition of the h-BN nanosheets has low requirements on external environment, equipment and the like, and is very simple and convenient to prepare.

Drawings

FIG. 1 is an Atomic Force Microscope (AFM) photograph and a height distribution graph of an ultrathin h-BN nanosheet prepared by a chemical peeling method.

Fig. 2 is a Scanning Electron Microscope (SEM) photograph of the final composite film.

Detailed Description