Method for growing thin-layer organic two-dimensional perovskite single crystal at room temperature and application of thin-layer organic two-dimensional perovskite single crystal

Abstract

The invention discloses a method for growing a thin-layer organic two-dimensional perovskite single crystal at room temperature and application, and particularly relates to the field of two-dimensional layered nano materials. Comprising the following steps: preparing a precursor solution from methylamine iodide, ethylamine iodide, lead iodide, hydriodic acid and hypophosphorous acid; dropping the precursor solution on a substrate, covering liquid beads of the substrate with a polydimethylsiloxane film for 1-2 min, dispersing the liquid beads between the surface of the substrate and the polydimethylsiloxane film, and pulling the polydimethylsiloxane film upwards to form perovskite single crystals on the surface of the substrate; wherein the thickness of the perovskite single crystal is 2.8 to 27 nm. Through the method, a large number of uniform thin-layer perovskite single crystals can grow on the growth substrate, the perovskite single crystals are prevented from being damaged in the transfer process, and the product quality is ensured.

Description

Technical Field

[0001] The present application relates to the field of two-dimensional layered nanomaterials, and in particular to a method and application of growing thin-layer organic two-dimensional perovskite single crystals at room temperature. Background Art

[0002] Since the discovery of graphene, research on two-dimensional nanomaterials has achieved numerous breakthroughs, forming a large family of 2D nanomaterials, including graphene, transition metal chalcogenides, black scale and boron nitride, and two-dimensional perovskites. Over the past few decades, halide perovskite semiconductors have attracted significant attention due to their remarkable electrical and optical properties, which are attributed to a variety of intrinsic properties, such as tunable optical band gaps, high carrier mobility, long carrier diffusion lengths, high optical gain, and large oscillation strengths. Compared to first-generation single-crystalline silicon and polycrystalline silicon solar cells, perovskite materials offer advantages as absorber layers in solar cells, such as simple fabrication processes, low cost, and high photoelectric conversion efficiency. They have been hailed as the "new hope in the photovoltaic field." Their high fluorescence quantum yield, high luminescence purity, and tunable wavelength make them suitable materials for light-emitting diodes. Furthermore, perovskite materials have been widely used in photodetectors due to their high photon absorption, compact size, low power consumption, and long lifetime, often serving as dielectric materials for optical communications and optical imaging.

[0003] Two-dimensional perovskite materials better meet the urgent needs of compact, lightweight and high-performance integrated electronic systems. Therefore, the unique electronic properties and high specific surface area of ​​two-dimensional perovskites have unlimited application potential in sensing, catalysis, energy storage and other fields. (HA)2MA2Pb3I 10As a typical representative of two-dimensional perovskites, they have excellent electrical, optical, thermal and mechanical properties and are currently a hot topic in the fields of materials science and condensed matter physics. Currently, most halide perovskite electronic devices are based on polycrystalline perovskite films. Currently, most halide perovskite electronic devices are based on polycrystalline perovskite thin films. This is due to the ease of deposition in the fabrication process. However, polycrystalline films often contain a high density of structural defects, including point defects (e.g., vacancies, interstitial and substitutional atoms), impurities, and dislocations. These defects can lead to degradation of the device's optoelectronic performance, such as non-radiative carrier loss, material degradation, current-voltage hysteresis, and instability. These defects contribute to short lifetimes in perovskite devices, such as solar cells, low brightness in light-emitting diodes, and high thresholds in lasers, hindering further research, development, and commercialization. Single-crystal halide perovskites, due to their ordered lattice arrangement, exhibit a largely suppressed density of these structural defects. The absence of grain boundaries results in lower defect density, higher carrier mobility, and excellent stability, suppressing ion migration and Auger recombination, resulting in superior performance in optoelectronic devices. Perovskite single crystals are of great significance for studying perovskite crystal structures, understanding the intrinsic properties of perovskite materials, and constructing high-performance devices.

[0004] Currently, there are two methods for preparing thin-layer perovskites: mechanical exfoliation and liquid-phase transfer. Mechanical exfoliation results in small perovskite samples and a low yield due to high randomness. Furthermore, stress can cause lattice distortion, leading to a high number of product defects. Liquid-phase transfer, on the other hand, is complex and prone to various defects during the transfer process, resulting in high randomness and poor sample crystal quality. Summary of the Invention

[0005] The main purpose of this application is to provide a method and application for growing thin-layer organic two-dimensional perovskite single crystals at room temperature, aiming to solve the problem of poor product quality in existing methods for preparing thin-layer perovskites.

[0006] To achieve the above-mentioned objectives, the present application provides a method for growing a thin layer of organic two-dimensional perovskite single crystal at room temperature, comprising: preparing a precursor solution using methylamine iodide, ethylamine iodide, lead iodide, hydroiodic acid and hypophosphorous acid; dropping the precursor solution on a substrate, covering the liquid droplets on the substrate with a polydimethylsiloxane film for 1-2 minutes, allowing the liquid droplets to disperse between the substrate surface and the polydimethylsiloxane film, and pulling the polydimethylsiloxane film upward to form a perovskite single crystal on the substrate surface; wherein the thickness of the perovskite single crystal is 2.8-27 nm.

[0007] Optionally, in the raw materials of the precursor solution, the content of ethylammonium iodide is 0.083 mol / L, the content of methylammonium iodide is 0.417 mol / L, the content of lead iodide is 0.5 mol / L, and the volume ratio of hydroiodic acid to hypophosphorous acid is 10:1.

[0008] Optionally, the preparation method of the precursor solution includes: mixing methylamine iodide, ethylamine iodide, lead iodide, hydroiodic acid and hypophosphorous acid, reacting at 120°C-140°C for 15-20 minutes to obtain a dark yellow highly saturated precursor solution; cooling the highly saturated precursor solution to 30-35°C to obtain a light yellow supersaturated precursor solution.

[0009] Optionally, the substrate includes a sapphire substrate, a quartz substrate, a mica substrate, or a silicon substrate coated with silicon dioxide.

[0010] To achieve the above objectives, the present application also provides an organic two-dimensional perovskite single crystal, which is prepared by the above method.

[0011] To achieve the above objectives, the present application also provides an application of the above-mentioned organic two-dimensional perovskite single crystal in a perovskite device.

[0012] Optionally, the perovskite device comprises a solar cell, a light emitting diode or a laser.

[0013] Compared with the prior art, the present invention has the following advantages: The method of growing thin-layer organic two-dimensional perovskite single crystals at room temperature of the present invention covers a polydimethylsiloxane film on a precursor liquid bead, and by a rapid "pulling" method, most of the thick-layer single crystals in the precursor solution are adhered and carried away, forming many dispersed supersaturated precursor liquid beads on the substrate. A large number of uniform thin-layer perovskite single crystals can be grown on the growth substrate without transfer, thus avoiding damage to the perovskite single crystals during the transfer process and ensuring product quality. There is no randomness in the preparation process, so the product yield is high. The thickness of the single-layer perovskite single crystal can reach 2.8 nm. The growth of thin-layer perovskite single crystals at room temperature avoids a vacuum environment, reduces the difficulty of preparation, and reduces the number of process steps. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of a process for preparing a precursor solution in a method for growing a thin layer of organic two-dimensional perovskite single crystal at room temperature in the present application; Figure 2 This is a schematic diagram of a process for growing a thin layer of organic two-dimensional perovskite single crystal at room temperature in a method for growing a thin layer of organic two-dimensional perovskite single crystal at room temperature in the present application; Figure 3 This is an optical image of the thin-layer perovskite single crystal obtained in Example 1; Figure 4X-ray polycrystalline diffraction of the thin-layer perovskite single crystal obtained in Example 1; Figure 5 Atomic force microscope imaging of the single-layer perovskite single crystal obtained in Example 1; Figure 6 Atomic force microscope imaging of 1-4 layers of perovskite single crystal obtained in Example 2; Figure 7 Atomic force microscope imaging of the single-layer perovskite single crystal obtained in Example 2; Figure 8 Atomic force microscope imaging of a single layer of perovskite single crystal obtained in Example 3; Figure 9 This is a schematic structural diagram of the vertical cavity surface laser emitter obtained in Example 3; Figure 10 Characterization diagram of the perovskite and cavity in the vertical cavity surface laser emitter obtained in Example 3; Figure 11 This is a laser power characterization diagram of the vertical cavity surface laser emitter obtained in Example 3.

[0015] The realization of the objectives, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0016] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions of this application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0017] The first embodiment of the present invention provides a method for growing a thin layer of organic two-dimensional perovskite single crystal at room temperature, such as Figure 1 As shown, the specific steps include: Step S1: Prepare a precursor solution using methylamine iodide, ethylamine iodide, lead iodide, hydroiodic acid, and hypophosphorous acid. The precursor solution comprises the following raw materials: lead iodide having a purity of 99.999%, methylamine iodide having a purity of 98%, and ethylamine iodide having a purity of 99%. The ethylamine iodide content is 0.083 mol / L, the methylamine iodide content is 0.417 mol / L, and the lead iodide content is 0.5 mol / L. The volume ratio of hydroiodic acid to hypophosphorous acid is 10:1. Furthermore, the mass ratio of lead iodide, methylamine iodide, and ethylamine iodide is 6:(1-1.1):(1-1.2).

[0018] Specifically, methylamine iodide, ethylamine iodide, lead iodide, hydroiodic acid and hypophosphorous acid are mixed in a pressure-resistant bottle, and the mixture is reacted in an oil bath at a stirring speed of 500 r / min and a temperature of 120°C-140°C for 15-20 minutes to obtain a dark yellow highly saturated precursor solution; the highly saturated precursor solution is cooled to 30-35°C to obtain a light yellow supersaturated precursor solution.

[0019] In this example, the precursor solution has higher solubility at higher temperatures, allowing it to dissolve more solute atoms. However, when the precursor solution is removed from a 30-35°C environment and placed at room temperature (25°C), the temperature difference remains. At room temperature, the solubility of the solution is lower, leading to the precipitation of excess solute atoms and the formation of crystal nuclei.

[0020] In step S2, the precursor solution is dropped onto the substrate using a pipette. A polydimethylsiloxane film is placed over the liquid droplet on the substrate for 1-2 minutes, dispersing the liquid droplet between the substrate surface and the polydimethylsiloxane film. The polydimethylsiloxane film is then rapidly pulled upward to form a perovskite single crystal on the substrate surface. The perovskite single crystal has a thickness of 2.8-27 nm. The substrate may include a sapphire substrate, a quartz substrate, a mica substrate, or a silicon substrate coated with 300 nm of single-side polished silicon dioxide.

[0021] Based on the above preparation method, in order to ensure a uniform temperature within the pressure bottle, this embodiment places the entire solution portion of the pressure bottle in an oil bath, with the solution interface 3-5 cm from the oil bath opening. Opening the bottle mouth during heating prevents excessive pressure buildup in the pressure bottle during the heating process. Closing the bottle mouth after heating prevents the risk of excessive condensation of water vapor in the air and subsequent condensation onto the bottle wall during the cooling process, which can impact the precursor solution. Furthermore, the pipette should be used to remove the solution along the edge of the pressure bottle, as the supersaturated solution in the pressure bottle will preferentially crystallize at the solution-air interface during cooling. This is because the air / precursor solution interface has the lowest temperature and the greatest nucleation driving force, making it easier to obtain thin perovskite single crystals by removing the precursor solution from the edge.

[0022] In this embodiment, due to the hydrophobicity of the polydimethylsiloxane film, it adheres to most of the thick single crystals in the solution, forming numerous dispersed, supersaturated precursor droplets on the substrate. At room temperature, these droplets slowly crystallize to form high-quality, large-area, thin perovskite single crystals with controllable layer thickness. Different layers of perovskite single crystals form on the substrate, with a single layer thickness reaching 2.8 nm. Using a "pulling" method, tiny, supersaturated droplets are dropped onto the growth substrate. These droplets are cooled from 30°C to room temperature, achieving the required supercooling to provide the driving force for nucleation. Due to the low number of droplets, high-quality, thin perovskite single crystals are formed. By controlling the duration of the polydimethylsiloxane coating on the precursor solution, the saturation level of the remaining solution can be controlled, thereby controlling the thickness of the growing crystals. In this embodiment, the coating time is 1-2 minutes, which can control the thickness of the grown layer to the desired value. If the coating time is too short, high saturation will easily form a thick layer. If the coating time is too long, the solution saturation will be too low, which is not conducive to crystallization.

[0023] A second embodiment of the present invention provides an organic two-dimensional perovskite single crystal, which is prepared by the above method.

[0024] A third embodiment of the present invention provides an application of the above-mentioned organic two-dimensional perovskite single crystal in a perovskite device, wherein the perovskite device includes a solar cell, a light-emitting diode, and a laser.

[0025] Example 1 Step 1. Add 507 mg of lead iodide with a purity of 99.999%, 145.8 mg of methylamine iodide with a purity of 98%, 41.84 mg of ethylamine iodide with a purity of 99%, 10 ml of 50% hypophosphorous acid, and 200 ml of 57% hydroiodic acid into the pressure bottle in sequence; and add a 3 cm x 5 cm (length x width) magnetic stirring bar into the pressure bottle; use a clamp to fix the pressure bottle in an oil bath at a temperature of 130 ° C and a speed of 500 r / min, and open the bottle cap of the pressure bottle. The oil bath in the magnetic stirrer should completely cover the mixed solution in the pressure bottle, and the oil bath interface should be 3 cm away from the solution interface in the pressure bottle. Allow the mixed solution in the pressure bottle to be fully heated and heated evenly; after heating for 15 minutes, set the temperature of the magnetic stirrer to 30 ° C, turn off the magnetic stirring, and cover the pressure bottle cap. Figure 1 ; Step 2: Take a single-surface silica / silicon substrate (300nm of silica coated on a silicon substrate, (8.0cm×1.5cm, length×width)), blow the substrate surface clean with a clean balloon or high-purity nitrogen; use a 10ml pipette to take 3ml of solution from the edge of a pressure-resistant bottle and drop it on the clean substrate. Immediately cover the liquid droplets on the substrate with a 1cmx1cm (length×width) polydimethylsiloxane film, wait for 1 minute, and then quickly pull up the polydimethylsiloxane film. At room temperature, the small liquid droplets scattered on the substrate begin to grow a thin layer of perovskite single crystal. Figure 2 The perovskite single crystal obtained in this example was tested as follows.

[0026] Using an optical microscope, we can observe single-layer perovskite crystals with no surface defects, good quality, and large area. Figure 3 The single layer perovskite crystal was tested by X-ray diffractometer, and the results are shown in Figure 4 From the figure, we can observe that the single crystal has narrow, sharp and equally spaced X-ray diffraction peaks, without other miscellaneous peaks, indicating that the grown sample has high crystallinity and uniform arrangement. Figure 5 As shown, atomic force microscopy can be used to observe that the thickness of a single-layer perovskite sample is only 2.8nm.

[0027] Example 2 Step 1. Add 507 mg of 99.999% pure lead iodide, 145.8 mg of 98% pure methylamine iodide, 41.84 mg of 99% pure ethylamine iodide, 10 ml of 50% hypophosphorous acid, and 200 ml of 57% hydroiodic acid to the pressure bottle in sequence; and add a 3 cm x 5 cm (length x width) magnetic stirring bar to the pressure bottle; fix the pressure bottle in an oil bath at a temperature of 130°C with a clamp and a speed of 500 r / min, and open the cap of the pressure bottle. The oil bath in the magnetic stirrer should completely cover the mixed solution in the pressure bottle, and the oil bath interface should be 3 cm away from the solution interface in the pressure bottle. Allow the mixed solution in the pressure bottle to be fully heated and heated evenly; after heating for 15 minutes, set the temperature of the magnetic stirrer to 30°C, turn off the magnetic stirring, and cover the pressure bottle. In step 2, a single-polished silica / silicon substrate (silicon substrate coated with 300nm of silica, 8.0cm×1.5cm, length×width) was prepared. The substrate surface was cleaned with a clean balloon or high-purity nitrogen. A 10ml pipette was used to remove 3ml of the solution from the edge of a pressure-resistant bottle and droplet was placed on the clean substrate. The liquid droplet on the substrate was immediately gently covered with a 1cm×1cm (length×width) polydimethylsiloxane film. After waiting for 30 seconds, the polydimethylsiloxane film was rapidly pulled upward. At room temperature, the small liquid droplets dispersed on the substrate began to grow into a thin layer of perovskite single crystal. The perovskite single crystal obtained in this example was tested as follows.

[0028] Using an optical microscope, we can observe single-layer perovskite crystals with no surface defects, good quality, and large area. Figure 6 .like Figure 7 As shown, atomic force microscopy can be used to observe different layers of perovskite single crystals with no surface defects, good quality, and large area. The thickness between each layer is 2.8nm, which is a single layer of perovskite, indicating that the prepared perovskite material is strictly grown layer by layer.

[0029] The difference between Example 1 and Example 2 lies in the different adsorption times of the polydimethylsiloxane film on the liquid bead, resulting in different saturation levels in the dispersed liquid bead. The shorter the adsorption time, the fewer crystals precipitate from the liquid bead and adhere to the polydimethylsiloxane. The remaining liquid bead has a higher supersaturation level, making it easier to precipitate thick crystals. The longer the adsorption time in Example 1 than in Example 2, the thinner the perovskite single crystals in Example 1 are.

[0030] Example 3: A vertical cavity surface laser emitter (VCSEL) is prepared. The VCSEL includes a bottom DBR substrate and a top DBR substrate, and a gain medium thin layer perovskite single crystal (8.6 nm) located between the bottom DBR (B-DBR) substrate and the top DBR (T-DBR) substrate.

[0031] Step 1: Place a standard silicon wafer (500 μm thick) in the vacuum chamber of a high vacuum electron beam evaporator and pump the vacuum to 10 -4 Torr; turn on the electron beam evaporation equipment, first evaporate a layer of SiO2 (thickness of 110μm, evaporation rate of 0.6nm / min) on the surface of the silicon wafer, then evaporate a layer of TiO2 (thickness of 70μm, evaporation rate of 0.6nm / min) on the surface of the SiO2, repeat the above SiO2 and TiO2 evaporation steps, and evaporate a total of 12.5 pairs of SiO2 / TiO2 dielectric films on the silicon substrate. During this period, the temperature in the vacuum chamber is controlled at 80℃; after the evaporation is completed, the silicon wafer is taken out to obtain the bottom DBR substrate.

[0032] Step 2: Use a clean balloon or high-purity nitrogen to blow clean the surface of the bottom DBR substrate, and prepare the precursor solution using the method of step 1 of Example 1; use a 10ml pipette to take out 3ml of the solution from the edge of the pressure bottle and drop it on the clean substrate, and immediately cover the liquid droplets on the substrate lightly with 1cmx1cm (length x width) polydimethylsiloxane, wait for 1 minute, and then quickly uncover the polydimethylsiloxane on the substrate. At room temperature, the small liquid droplets scattered on the substrate begin to grow a thin layer of perovskite single crystal, as shown. Figure 8 , as can be seen from the figure, its thickness is 15nm.

[0033] Step 3: Place the bottom DBR with the thin layer of perovskite sample in the vacuum chamber of a high vacuum electron beam evaporator and pump the vacuum degree to 10 -4 Torr; start the electron beam evaporation equipment, first evaporate a layer of SiO2 (thickness of 110μm, evaporation rate of 0.6nm / min) on the bottom DBR surface, then evaporate a layer of TiO2 (thickness of 70μm, evaporation rate of 0.6nm / min) on the SiO2 surface, repeat the above SiO2 and TiO2 evaporation steps, and evaporate a total of 4.5 pairs of SiO2 / TiO2 dielectric films on the silicon substrate. During this period, the temperature in the vacuum chamber is controlled at 80℃; after the evaporation is completed, a vertical cavity surface laser emitter (VCSEL) is obtained, see Figure 9 .

[0034] The performance of the vertical cavity surface laser emitter obtained in this embodiment was tested. The vertical cavity surface laser emitter was placed under the 100x lens of the angle-resolved spectrometer to characterize the perovskite and cavity respectively. Figure 10 As shown. Figure 10 As can be seen in (a), the thin layer perovskite and the cavity photons are strongly coupled, showing the Rabi splitting phenomenon. Figure 10 (b) is the angle-resolved reflectance spectrum of a pure cavity without a sample. Figure 10 Figures (a) and (b) illustrate that the thin-layer laser in this example has only one mode, while the thick layer has multiple modes. Single-mode laser emitters offer high beam quality, a small divergence angle, a circular spot shape, and uniform energy distribution. This small divergence angle makes them easy to collimate and focus. For example, they excel in scenarios requiring high spatial coherence, such as holography, interferometry, and optical sensing. Multimode VCSELs, due to their low spatial coherence, may not be suitable for such high-precision applications.

[0035] The vertical cavity surface laser emitter was tested for angle-resolved fluorescence at 0.34 μJ / cm 2 , 0.39μJ / cm 2 and 0.42 μJ / cm 2 The characterization was performed under the laser power of Figure 11 As shown, from Figure 11 (a)-(c) As the laser power increases, the divergence angle of the laser emitter decreases, and the exciton exciton undergoes a red shift. This phenomenon is not achieved with a thick-layer laser under the same conditions (room temperature, the same excitation power, and a 532nm pump laser).

[0036] The above are only preferred embodiments of the present application and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for growing thin organic two-dimensional perovskite single crystals at room temperature, characterized in that: include: A precursor solution is prepared using methylammonium iodide, ethylammonium iodide, lead iodide, hydroiodic acid and hypophosphorous acid; Dropping the precursor solution on the substrate, covering the liquid droplets on the substrate with a polydimethylsiloxane film for 1-2 minutes, allowing the liquid droplets to disperse between the substrate surface and the polydimethylsiloxane film, and pulling the polydimethylsiloxane film upward to form a perovskite single crystal on the substrate surface; Wherein, the thickness of the perovskite single crystal is 2.8-27 nm.

2. The method for growing thin-layer organic two-dimensional perovskite single crystals at room temperature according to claim 1, characterized in that: The raw materials of the precursor solution include 0.083 mol / L of ethylamine iodide, 0.417 mol / L of methylamine iodide, 0.5 mol / L of lead iodide, and a volume ratio of hydroiodic acid to hypophosphorous acid of 10:

1.

3. The method for growing thin-layer organic two-dimensional perovskite single crystals at room temperature according to claim 1, characterized in that: The preparation method of the precursor solution comprises: Mixing the methylamine iodide, ethylamine iodide, lead iodide, hydroiodic acid, and hypophosphorous acid, and reacting at 120° C. to 140° C. for 15 to 20 minutes to obtain a deep yellow highly saturated precursor solution; The highly saturated precursor solution was cooled to 30-35° C. to obtain a light yellow supersaturated precursor solution.

4. The method for growing thin-layer organic two-dimensional perovskite single crystals at room temperature according to claim 1, characterized in that: The substrate includes a sapphire substrate, a quartz substrate, a mica substrate, or a silicon substrate coated with silicon dioxide.

5. An organic two-dimensional perovskite single crystal, characterized in that: It is prepared by the method according to any one of claims 1 to 4.

6. Use of the organic two-dimensional perovskite single crystal according to claim 5 in a perovskite device.

7. Use of the organic two-dimensional perovskite single crystal in a perovskite device according to claim 6, characterized in that: The perovskite device includes a solar cell, a light emitting diode or a laser.

Images