Wafer-level ultrathin perovskite single crystal thin film material and preparation method thereof

Abstract

The invention relates to a preparation method of a wafer-level ultrathin perovskite single crystal thin film material. The preparation method comprises the following steps: (a) mixing cesium halide and lead halide powder according to a certain proportion, and putting the mixture into a crucible; putting the crucible into a tubular furnace, and putting a substrate near the crucible; (b) pumping out air in a quartz tube in the tube furnace, setting a tube furnace program, and heating, preserving heat and cooling the quartz tube at a certain rate for a certain time; and after the procedure is finished, when the temperature of the tube furnace is reduced to room temperature, taking out the substrate from the tube furnace, and at the moment, obtaining the perovskite single crystal thin film material with the wafer size. Compared with the prior art, the preparation method of the wafer-level ultrathin perovskite single crystal material has the advantages that the thickness of the obtained perovskite single crystal is 50nm-20mu m by using a high-temperature vapor deposition process, and meanwhile, the size of a film can reach a wafer level (2 inches); and the size and the thickness can meet the processing integration requirements of the current photoelectric devices (such as an LED, a solar cell, a photoelectric detector, a memory and the like).

Description

Technical Field

[0001] The invention belongs to the field of perovskite single crystal thin film materials, and in particular relates to a method for preparing a wafer-level ultra-thin perovskite single crystal thin film material. Background Art

[0002] Perovskite materials have shown great application potential in many fields due to their outstanding optical and electrical properties. From solar cells to detectors, lasers, field-effect transistors and phototransistors, perovskites have shown attractive application prospects. In particular, perovskite single crystal materials have advantages such as long equilibrium carrier diffusion path, high light absorption efficiency, low trapped state density and good mobility, so they have significant competitive advantages in high-performance optoelectronic devices. In the field of LEDs, the application prospects of perovskite materials are also highly anticipated. The characteristics of perovskite single crystals complement the requirements of LED displays, making them an ideal luminescent material with the following significant advantages: (1) Perovskite single crystals have excellent luminescence properties. Due to their excellent optoelectronic properties, perovskite single crystals can produce high-brightness, high-contrast light sources, providing strong optical support for LED displays. This enables LED display screens to present clearer and more delicate images, improving the user's visual experience. (2) Perovskite single crystals have high luminescence efficiency. Compared with traditional luminescent materials, such as organic luminescent materials or inorganic phosphors, perovskite single crystals can more efficiently convert energy into light energy under electronic excitation, which means that LED display screens can achieve brighter display effects at the same power while reducing energy consumption and extending the service life of the device. (3) Perovskite single crystals have excellent color reproduction capabilities. Their wide luminescence spectrum range and adjustable band structure enable perovskite single crystals to achieve a wide color gamut display effect, presenting more realistic and vivid colors. This is especially important for application scenarios such as movies and games that require high color. With the continuous improvement of LED efficiency and performance requirements, it is believed that perovskite single crystals will play an increasingly important role in the future display field, bringing users a better visual experience. Perovskite LEDs are expected to become one of the important innovation directions of the LED industry.

[0003] One of the main disadvantages of single crystal perovskite materials in LED applications is that the bottleneck of single crystal material preparation cannot be broken through. Compared with perovskite polycrystalline films or quantum dots, it is more difficult to obtain high-quality perovskite single crystal materials. The growth process of single crystals is affected by many factors, including nucleation mechanism, crystal growth rate control, impurity control, etc. Therefore, the preparation technology of single crystal perovskite materials is difficult, which limits its wide application in LED, solar cells and other fields. Summary of the invention

[0004] In view of the shortcomings of the existing technology for growing perovskite single crystal thin films, the purpose of the present invention is to provide an effective, low-cost, and excellent performance wafer-level perovskite single crystal thin film material preparation method. The material prepared by this method has the advantages of high efficiency and stability when used as LED and solar cell.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a wafer-level ultra-thin perovskite single crystal film material and a preparation method thereof, which comprises the following steps:

[0006] (a) mixing lead halide and cesium halide powder in a certain ratio and placing them in a crucible, wherein the molar ratio of the lead halide to the cesium halide is (0.1-10):1, the total mass of the lead halide and the cesium halide is 10 mg-100 g, and the halogen species are chlorine, bromine, and iodine, and then placing the crucible in a tube furnace and placing a substrate near the crucible;

[0007] (b) extracting the air in the quartz tube of the tube furnace, setting a program for the tube furnace to heat up, keep warm, and cool down at a certain rate and time; after the program is completed, wait for the temperature of the tube furnace to drop to room temperature, take the substrate out of the tube furnace, and at this time, obtain the wafer-sized perovskite single crystal thin film material.

[0008] Preferably, in step (a), the substrate is mica, sapphire, single crystal silicon, gallium nitride, gallium arsenide single crystal sodium chloride, or single crystal strontium titanate.

[0009] Preferably, in step (a), the crucible is placed in the tube furnace directly below the thermocouple, and the substrate is placed at a position 0-30 cm to the left, right, or top of the crucible.

[0010] Preferably, the air is extracted in step (b) so that the pressure in the tube is 0.5-500 Pa.

[0011] Preferably, in step (b), the programmed temperature control heating rate is 0.5 to 30° C. / min.

[0012] Preferably, in step (b), the programmed temperature control insulation temperature is 300-1500°C.

[0013] Preferably, in step (b), the programmed temperature control insulation time is 0 to 100 hours.

[0014] Preferably, in step (b), the programmed temperature-controlled cooling rate is 0.5 to 50° C. / min.

[0015] Due to the application of the above technical scheme, the present invention has the following advantages compared with the prior art: the present invention provides a method for preparing wafer-level ultra-thin perovskite single crystal materials, by using a high-temperature vapor deposition process, the thickness of the obtained perovskite single crystal is 50nm-20μm, and the film size can reach the wafer level (2 inches), and the size and thickness can meet the processing and integration requirements of current optoelectronic devices (such as LEDs, solar cells, photodetectors, memories, etc.); and the growth process is not selective for the substrate. In principle, as long as the substrate has a flat surface, it can be suitable for growth by this method, which eliminates complex process such as transfer for device processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a photo of the wafer-level ultra-thin perovskite single crystal material prepared in Example 1;

[0017] Figure 2 is a scanning electron microscope (SEM) image of the perovskite material prepared in Example 2;

[0018] Figure 3 is an optical microscope image of the perovskite material prepared in Example 3;

[0019] Figure 4 is an optical microscope image of the perovskite material prepared in Example 4;

[0020] Figure 5 is an optical microscope image of the perovskite material prepared in Example 5;

[0021] Figure 6 is an X-ray diffraction (XRD) pattern of the perovskite material prepared in Example 6;

[0022] Figure 7 is an ultraviolet-visible absorption spectrum (UV-vis) of the perovskite material prepared in Example 7;

[0023] Figure 8 is a photoluminescence spectrum (PL) diagram of the perovskite material prepared in Example 8;

[0024] Fig. 9 is a photoluminescence spectrum (PL) diagram of the perovskite material prepared in Example 9;

[0025] Fig.10 Optical microscope images of the perovskite materials prepared in Comparative Examples 1-4. DETAILED DESCRIPTION

[0026] The invention discloses a wafer-level ultra-thin perovskite single crystal film material and a preparation method thereof. The material comprises the following steps: (a) mixing lead halide and cesium halide powder in a certain proportion and putting them into a crucible, wherein the molar ratio of the lead halide to the cesium halide is (0.1-10):1, the total mass of the two is 10 mg-100 g, and the halogen types are chlorine, bromine and iodine; and then putting the crucible into a tube furnace and placing a substrate near the crucible; (b) extracting the air in the quartz tube in the tube furnace, setting a tube furnace program to heat up, keep warm and cool down at a certain rate and time; after the program is completed, when the temperature of the tube furnace drops to room temperature, taking the substrate out of the tube furnace, and obtaining the wafer-level perovskite single crystal film material.

[0027] In step (a), the substrate is mica, sapphire, single crystal silicon, gallium nitride, gallium arsenide single crystal sodium chloride, single crystal strontium titanate; the crucible is placed in the tube furnace directly below the thermocouple, and the substrate is placed 0-30cm to the left, right, and top of the crucible. The air extraction in step (b) makes the pressure in the tube 300-500Pa; the program temperature control heating rate is 0.5-30℃ / min; the program temperature control insulation temperature is 300℃-1500℃; the program temperature control insulation time is 0-100 hours; the program temperature control cooling rate is 0.5-50℃ / min.

[0028] In order to better explain the present invention and facilitate understanding of the technical solution of the present invention, the present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0029] Example 1

[0030] This embodiment provides a method for preparing a wafer-level ultra-thin perovskite single crystal film material, which comprises the following steps:

[0031] (a) 50 mg of lead bromide and 50 mg of cesium bromide powder were mixed and placed in a crucible; the crucible was placed in a tube furnace, the crucible was placed in the tube furnace directly below the thermocouple, and the base muscovite was placed 10 cm to the left of the crucible.

[0032] (b) The air in the quartz tube in the tube furnace is evacuated to 500 Pa, and the tube furnace program is set to have a heating rate of 10°C / min, a holding temperature of 700°C, a time of 5 hours, and a cooling rate of 10°C / min; after the program is completed, the temperature of the tube furnace is lowered to room temperature, and the substrate is taken out of the tube furnace. At this time, the photo of the wafer-sized perovskite single crystal thin film material is obtained. Figure 1 , it can be seen that the size of the perovskite single crystal thin film material is 2 inches.

[0033] Example 2

[0034] The conditions used in this embodiment are as follows: the substrate is placed at the position 15 cm to the left of the crucible in step (a), and other unmentioned parts are the same as those in Example 1. The surface optical microscopic image of the obtained product is Figure 2 .

[0035] Example 3

[0036] The conditions used in this embodiment are: the halides in step (a) are lead chloride and cesium chloride, and the other parts not mentioned are the same as those in Example 1. The optical microscopic image of the obtained product is Figure 3 .

[0037] Example 4

[0038] The conditions used in this embodiment are: the amounts of lead bromide and cesium bromide in step (a) are 0.1 g and 0.01 g respectively, and the other unmentioned parts are the same as those in Example 1. The optical microscopic image of the obtained product is Figure 4 .

[0039] Example 5

[0040] The conditions used in this embodiment are: the substrate is placed at the position 30 cm to the left of the crucible in step (a), and other unmentioned parts are the same as those in Example 1. The optical microscope image of the obtained product is Figure 5 .

[0041] Example 6

[0042] The conditions used in this example are: the pressure in the tube in step (b) is 300 Pa, and the other unmentioned parts are the same as those in Example 1. The XRD pattern of the obtained product is Figure 6 .

[0043] Example 7

[0044] The conditions used in this example are: the heating rate in step (b) is 30°C / min, and the other conditions not mentioned are the same as those in Example 1. The UV-vis graph of the obtained product is Figure 7 .

[0045] Example 8

[0046] The conditions used in this embodiment are: the holding temperature in step (b) is 1500°C and the holding time is 1 h. Other details not mentioned are the same as those in Example 1. The PL diagram of the obtained product is Figure 8 .

[0047] Example 9

[0048] The conditions used in this example are: the cooling rate in step (b) is 30°C / min, and the other conditions not mentioned are the same as those in Example 1. The PL diagram of the obtained product is Fig. 9 .

[0049] Comparative Example 1

[0050] The conditions used in this comparative example are: no lead halide salt is added in step (a), and the other unmentioned parts are the same as those in Example 1. The final product is random small particles, rather than an ultra-thin single crystal film. The optical microscopic image of the obtained product is Fig.10 a.

[0051] Comparative Example 2

[0052] The conditions used in this comparative example are: the substrate position in step (a) is 40 cm to the left of the crucible, and the other unmentioned parts are the same as those in Example 1. The final product is nanowires, not ultra-thin single crystal films. The optical microscopic image of the obtained product is Fig.10 b.

[0053] Comparative Example 3

[0054] The conditions used in this comparative example are: the holding temperature in step (b) is 150°C, and the other unmentioned parts are the same as those in Example 1, and no product is finally formed on the substrate. The optical microscopic image of the obtained product is Fig.10 c.

[0055] Comparative Example 4

[0056] The conditions used in this comparative example are: the holding time in step (b) is 120 hours, and the other unmentioned parts are the same as those in Example 1, and no product is finally formed on the substrate. The optical microscopic image of the obtained product is Fig.10 d.

[0057] The present invention uses the above-mentioned embodiments to illustrate the detailed process equipment and process flow of the present invention, but the present invention is not limited by the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned detailed process equipment and process flow to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a wafer-level ultra-thin perovskite single crystal film material, characterized in that: The following steps are involved: (a) mixing lead halide and cesium halide powder in a certain ratio and placing them in a crucible, wherein the molar ratio of the lead halide to the cesium halide is (0.1-10):1, the total mass of the lead halide and the cesium halide is 10 mg-100 g, and the halogen species are chlorine, bromine, and iodine, and then placing the crucible in a tube furnace and placing a substrate near the crucible; (b) extracting the air in the quartz tube of the tube furnace, setting a program for the tube furnace to heat up, keep warm, and cool down at a certain rate and time; after the program is completed, wait for the temperature of the tube furnace to drop to room temperature, take the substrate out of the tube furnace, and at this time, obtain the wafer-sized perovskite single crystal thin film material.

2. The method for preparing a wafer-level ultra-thin perovskite single crystal film material according to claim 1, characterized in that: In step (a), the substrate is one of mica, sapphire, single crystal silicon, gallium nitride, gallium arsenide single crystal, sodium chloride, and single crystal strontium titanate.

3. The method for preparing a wafer-level ultra-thin perovskite single crystal film material according to claim 1, characterized in that: In step (a), the crucible is placed in the tube furnace directly below the thermocouple, and the substrate is placed at a position 0 to 30 cm to the left, right, and top of the crucible.

4. The method for preparing a wafer-level ultra-thin perovskite single crystal film material according to claim 1, characterized in that: The air extraction in step (b) makes the pressure in the tube 0.5-500Pa.

5. The method for preparing a wafer-level ultra-thin perovskite single crystal film material according to claim 1, characterized in that: In step (b), the programmed temperature control heating rate is 0.5 to 30° C. / min.

6. The method for preparing a wafer-level ultra-thin perovskite single crystal film material according to claim 1, characterized in that: In step (b), the programmed temperature control and insulation temperature is 300-1500°C.

7. The method for preparing a wafer-level ultra-thin perovskite single crystal film material according to claim 1, characterized in that: In step (b), the programmed temperature control and insulation time is 0 to 100 hours.

8. The method for preparing a wafer-level ultra-thin perovskite single crystal film material according to claim 1, characterized in that: In step (b), the programmed temperature-controlled cooling rate is 0.5 to 50° C. / min.

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