A surface polishing method of a perovskite crystal material and a perovskite crystal material

Abstract

The disclosure provides a surface polishing method of a perovskite crystal material, comprising: performing hot mounting treatment on a perovskite single crystal to be polished to obtain a perovskite single crystal sample; fixing the perovskite single crystal sample on a polishing table and performing rough polishing on the perovskite single crystal sample; and performing fine polishing on the rough-polished perovskite single crystal sample to obtain a polished perovskite single crystal sample, wherein the process of fine polishing comprises: using artificial leather polishing cloth and performing first drop processing using anhydrous ethanol as a polishing liquid; and after a preset time interval elapses after the first drop processing, replacing the anhydrous ethanol with a suspension of dimethyl sulfoxide and anhydrous ethanol for second drop processing.

Description

Technical Field

[0001] This disclosure relates to the field of nuclear radiation detectors, and particularly to surface polishing and processing technology for semiconductor perovskite materials. More specifically, it relates to a surface polishing method for perovskite crystal materials and perovskite crystal materials. Background Technology

[0002] Perovskite single crystals are widely used in photovoltaic devices, photodetectors and lasers due to their excellent performance in photoelectric conversion efficiency, stability and tunable bandgap.

[0003] The surface quality of perovskite single crystals directly affects their photoelectric properties. Due to their brittleness, they are prone to cracks and fissures. However, traditional polishing methods typically rely on hard abrasive particles such as diamond and alumina. These methods easily create micro-scratches on the crystal surface during polishing, which are difficult to completely remove, thus forming defects on the crystal surface. These surface defects become non-radiative recombination centers, leading to increased carrier recombination and reduced device efficiency and stability.

[0004] It should be noted that the information disclosed in this section is only used for understanding the background of the inventive concept of this disclosure. Therefore, the above information may include information that does not constitute prior art. Summary of the Invention

[0005] In view of this, the present disclosure provides a surface polishing method for perovskite crystal materials and perovskite crystal materials, which aims to achieve chemical passivation of the crystal surface during polishing, reduce surface roughness, reduce surface defects, and improve crystal transmittance and electrical stability.

[0006] One aspect of this disclosure provides a surface polishing method for a perovskite crystal material, comprising: hot-mounting a perovskite single crystal to be polished to obtain a perovskite single crystal sample; fixing the perovskite single crystal sample on a polishing table and performing coarse grinding and polishing on the perovskite single crystal sample; and performing fine grinding and polishing on the coarsely ground perovskite single crystal sample to obtain a polished perovskite single crystal sample, wherein the fine grinding and polishing process includes: using an artificial leather polishing cloth and using anhydrous ethanol as a polishing liquid for a first droplet addition treatment; after a preset time interval following the first droplet addition treatment, replacing the anhydrous ethanol with a suspension of dimethyl sulfoxide and anhydrous ethanol for a second droplet addition treatment.

[0007] According to embodiments of this disclosure, in the suspension of dimethyl sulfoxide and anhydrous ethanol, the volume ratio of dimethyl sulfoxide to anhydrous ethanol is 1:1 to 3:1.

[0008] According to an embodiment of this disclosure, the hot mounting process specifically includes: using paraffin wax to hot mount the perovskite single crystal to be polished to obtain the perovskite single crystal sample, wherein the size of the perovskite single crystal sample obtained by hot mounting is adapted to the size of the sample fixing stage in the polishing table.

[0009] According to embodiments of this disclosure, the perovskite single crystal sample is coarsely ground and polished sequentially using silicon carbide sandpaper with mesh sizes ranging from 300-500 mesh, 700-900 mesh, 1000-1300 mesh, and 1800-2200 mesh.

[0010] According to embodiments of this disclosure, the sample fixing pressure during the rough grinding and polishing process is set to 0.1-0.2 MPa, the rotation speed of the turntable on the polishing table is set to 40-60 rpm, the rotation speed of the turntable under the polishing table is set to 70-90 rpm, and the rough grinding and polishing time for silicon carbide abrasive paper of different mesh sizes is set to 2-5 min.

[0011] According to an embodiment of this disclosure, during the coarse grinding and polishing process, anhydrous ethanol is added as a third drop, and the flow rate of the third drop is set to 8-20 mL / min.

[0012] According to an embodiment of this disclosure, after the rough grinding process is completed, the silicon carbide sandpaper is replaced with artificial leather polishing cloth, the fiber diameter of which is less than 1µm.

[0013] According to embodiments of this disclosure, the artificial leather polishing cloth comprises polyurethane resin and viscose fiber.

[0014] According to embodiments of this disclosure, the sample fixation pressure during the fine grinding and polishing process is set to 0.3-0.4 MPa, the flow rate of the first droplet treatment is set to 10-30 mL / min, the rotation speed of the turntable on the polishing table is set to 40-60 rpm, the rotation speed of the turntable under the polishing table is set to 80-150 rpm, and the preset time interval of the first droplet treatment is set to 20-40 min.

[0015] According to embodiments of this disclosure, the flow rate of the second droplet addition process is set to 8-20 mL / min, the rotation speed of the turntable on the polishing stage is set to 40-60 rpm, the rotation speed of the turntable under the polishing stage is set to 80-150 rpm, and the time of the second droplet addition process is set to 4-7 min.

[0016] According to embodiments of this disclosure, the purity of the anhydrous ethanol is greater than or equal to 99.99%.

[0017] Another aspect of this disclosure provides a perovskite crystal, which is surface-treated using the surface polishing method described above for perovskite crystal materials.

[0018] According to embodiments of this disclosure, by using artificial leather polishing cloth and anhydrous ethanol, as well as a suspension of dimethyl sulfoxide and anhydrous ethanol, for dropwise treatment during fine grinding and polishing, chemical passivation of the crystal surface can be achieved simultaneously with polishing, reducing surface roughness, minimizing surface defects, and improving crystal transmittance and electrical stability. This disclosure achieves nanoscale roughness polishing without the presence of abrasive particles such as diamond oxide by using specific artificial leather polishing cloth, ethanol, and a polishing slurry prepared from ethanol and dimethyl sulfoxide. Simultaneously, dimethyl sulfoxide can dissolve dangling bonds on the single crystal surface, passivating the crystal surface, effectively reducing the dark current of the single crystal, and improving the detection performance of the single crystal. Attached Figure Description

[0019] The above and other objects, features and advantages of this disclosure will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0020] Figure 1 A flowchart illustrating a surface polishing method for perovskite crystal materials according to an embodiment of the present disclosure is shown schematically.

[0021] Figure 2 The illustration shows a comparison of the morphology and transparency of samples before and after polishing according to embodiments of the present disclosure;

[0022] Figure 3 The diagram schematically illustrates the perovskite crystal roughness test results of samples before and after polishing according to embodiments of the present disclosure;

[0023] Figures 4A to 4C The diagram schematically illustrates the IV curves and laser response results of samples before and after polishing according to embodiments of the present disclosure, wherein... Figure 4A The IV curve is for the unpolished sample; Figure 4B The IV curve and laser response of the sample after the first drop of treatment; Figure 4C The IV curve and laser response of the sample after the second drop treatment are shown. Detailed Implementation

[0024] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0025] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0026] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0027] When using expressions such as "at least one of A, B and C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B and C, etc.).

[0028] Perovskite single crystals, especially cesium lead bromide perovskite single crystals, have shown great potential in applications such as solar cells, photodetectors, and light-emitting diodes due to their unique electronic and optical properties, such as high carrier mobility, long carrier lifetime, and wide bandgap. However, the surface quality of perovskite single crystals directly affects their photoelectric performance. Surface defects often become non-radiative recombination centers, leading to increased carrier recombination and reduced device efficiency and stability. Therefore, optimizing the surface treatment methods for perovskite single crystals to reduce surface defects and improve surface quality is crucial for enhancing their performance in optoelectronic devices.

[0029] The applicant's research revealed that traditional polishing methods typically rely on hard abrasive particles such as diamond and alumina, but these methods have certain limitations. Hard particles like diamond and alumina easily leave micro-scratches on the surface of perovskite single crystals, and these scratches are difficult to completely remove, leading to surface defects. These surface defects not only affect the photoelectric properties of perovskite single crystals but may also cause stability issues during long-term use. Furthermore, traditional polishing methods can damage the crystal surface structure, especially affecting dangling bonds, which may exacerbate dark currents in the material, thus impacting detection performance.

[0030] The applicant's research also found that some existing technologies use polishing cloths, polishing liquids and mechanical polishing machines for polishing. Although this can further improve the surface smoothness, the pressure and heat applied during mechanical polishing may cause uneven treatment on the surface of perovskite single crystals. Especially in the absence of chemical passivation, this may have adverse effects on the surface, such as stress concentration or deterioration of electrical properties.

[0031] Based on this, embodiments of this disclosure provide a surface polishing method for perovskite crystal materials, comprising: hot-mounting a perovskite single crystal to be polished to obtain a perovskite single crystal sample; fixing the perovskite single crystal sample on a polishing table and performing coarse grinding and polishing on the perovskite single crystal sample; and performing fine grinding and polishing on the coarsely ground perovskite single crystal sample to obtain a polished perovskite single crystal sample, wherein the fine grinding and polishing process includes: using an artificial leather polishing cloth and anhydrous ethanol as the polishing liquid for a first drop-addition treatment; after a preset time interval following the first drop-addition treatment, replacing the anhydrous ethanol with a suspension of dimethyl sulfoxide and anhydrous ethanol for a second drop-addition treatment. In this embodiment, by using an artificial leather polishing cloth and anhydrous ethanol and a suspension of dimethyl sulfoxide and anhydrous ethanol for drop-addition treatment during the fine grinding and polishing process, chemical passivation of the crystal surface can be achieved simultaneously with polishing, reducing surface roughness, reducing surface defects, and improving crystal transmittance and electrical stability. This disclosure achieves nanoscale roughness polishing without the presence of abrasive particles such as diamond oxide by using a specific artificial leather polishing cloth, ethanol, and a polishing slurry prepared from ethanol and dimethyl sulfoxide. Simultaneously, dimethyl sulfoxide can dissolve dangling bonds on the single crystal surface, passivating the crystal surface, effectively reducing the dark current of the single crystal, and improving its detection performance.

[0032] More advantageously, the above embodiments of this disclosure provide an environmentally friendly and low-cost polishing process that reduces the impact on the environment and operators while ensuring good performance. Unlike traditional chemical polishing slurries, this disclosure uses environmentally friendly solvents such as ethanol and dimethyl sulfoxide in combination with artificial leather polishing cloth for polishing, avoiding the use of traditional chemical polishing slurries containing harmful chemicals, thereby greatly reducing environmental pollution during the polishing process and protecting the health of operators. In addition, this disclosure has a significant cost advantage; the preparation cost of artificial leather polishing cloth and environmentally friendly solvents is much lower than that of traditional chemical polishing slurries. This not only reduces production costs but also reduces reliance on safety measures, making the overall process more economical and practical.

[0033] Figure 1 A flowchart illustrating a surface polishing method for perovskite crystal materials according to an embodiment of the present disclosure is shown.

[0034] Reference Figure 1 The surface polishing method 100 for perovskite crystal material in this embodiment includes operations S110 to S130.

[0035] In operation S110, the perovskite single crystal to be polished is hot-mounted to obtain a perovskite single crystal sample.

[0036] In the embodiments of this disclosure, paraffin wax can be used as the hot-setting material in the hot-setting process. Specifically, paraffin wax can be heated to melt it, and the perovskite single crystal sample can be immersed in the molten paraffin wax. After cooling, the paraffin wax solidifies and encapsulates the perovskite single crystal sample, forming a stable support structure. The encapsulation of paraffin wax can effectively fix the perovskite single crystal sample, preventing the sample from cracking or deforming due to unstable or uneven stress during subsequent polishing, thus helping to maintain the integrity of the crystal.

[0037] In embodiments of this disclosure, the size of the perovskite single crystal sample should be adapted to the size of the polishing stage. Exemplarily, the diameter of the formed cylindrical paraffin sample can be less than 25 mm and the height less than 30 mm.

[0038] It should be noted that existing polishing methods generally use cold mounting. While this process can fix the crystal sample, it may lead to sample instability, thereby increasing instability during processing, especially during high-precision polishing. This disclosure uses hot mounting, encapsulating the perovskite single crystal sample with paraffin wax, to ensure that the sample can be stably fixed on the polishing stage, avoiding the instability problem caused by the cold mounting method.

[0039] In operation S120, the perovskite single crystal sample is fixed on the polishing table and coarsely polished.

[0040] A polishing table uses rotation and friction to finely process the sample surface, achieving a smooth and flat finish. The polishing table allows adjustment of the turntable's rotation speed, pressure, and polishing time to meet different process requirements, ensuring uniformity and precision in surface treatment. By controlling the rotation speed, the polishing table can influence the polishing rate, thus achieving different stages of rough or fine grinding. Pressure control helps adjust the polishing intensity, ensuring appropriate pressure is applied to the sample surface and avoiding excessive wear or insufficient polishing.

[0041] A polishing table typically consists of an upper turntable, a lower turntable, a drive system, and an adjustment system. The upper turntable is used to hold the sample to be polished, and its rotation speed and pressure significantly affect the polishing effect. The lower turntable provides the friction required for polishing through its relative movement with the upper turntable, and it is usually equipped with an independent speed adjustment function to adapt to different polishing needs. The drive system uses a motor to drive the rotation of the upper and lower turntables, ensuring smooth rotation, and provides different operating speeds through adjustable speed functions to meet the needs of different polishing stages such as rough grinding and fine grinding. The adjustment system is used to adjust parameters such as polishing pressure, turntable speed, and time to optimize the polishing process and ensure the best surface treatment effect for different materials.

[0042] According to embodiments of this disclosure, during the coarse grinding process, silicon carbide abrasive paper with mesh sizes ranging from 300-500, 700-900, 1000-1300, and 1800-2200 can be selected and coarsely ground and polished sequentially. Each mesh size corresponds to a different polishing stage, starting with coarser abrasive paper and gradually using finer abrasive paper for refinement, ensuring a progressively smooth and even surface. During the coarse grinding and polishing process, the sample is fixed on the polishing table, and the fixing pressure can be set to 0.1-0.2 MPa to ensure appropriate contact force between the sample and the abrasive paper during polishing, avoiding excessive wear or damage to the sample surface. The rotation speed of the upper rotary table can be set to 40-60 rpm, while the rotation speed of the lower rotary table can be set between 70-90 rpm to ensure a uniform polishing effect. The polishing time for each stage can be set to 2-5 minutes depending on the mesh size of the abrasive paper to accommodate the polishing requirements of different mesh sizes.

[0043] In the embodiments of this disclosure, silicon carbide sandpaper possesses high hardness and sharpness, making it suitable for processing materials with high hardness. Its main component is silicon carbide, whose hardness is second only to diamond, thus effectively removing irregularities and rough parts from surfaces. Silicon carbide sandpaper ranges from coarse to fine; the smaller the grit number, the coarser the particles and the stronger the abrasive force, making it suitable for removing larger imperfections. Higher grit sandpaper is used for fine polishing and improving surface smoothness.

[0044] Furthermore, during the rough grinding and polishing process, to ensure polishing precision and surface quality, anhydrous ethanol can be dripped into the contact area between the polishing surface and the sandpaper at a uniform flow rate throughout the process for a third drip treatment. The purpose of this third drip treatment is to allow an appropriate amount of anhydrous ethanol to flow into the polishing area to remove grinding heat and abrasive particles, helping to clean and lubricate the polishing surface, reducing heat accumulation caused by friction during polishing, and preventing the accumulation of particles and impurities, thereby optimizing the rough grinding effect.

[0045] For example, the flow rate of the third droplet addition process can be set to 8-20 mL / min. For instance, the flow rate of the third droplet addition process can be set to 10 mL / min to ensure that the added anhydrous ethanol can slowly penetrate during the process, maintain proper lubrication, and prevent excessive friction and surface overheating.

[0046] In operation S130, the coarsely ground perovskite single crystal sample is finely ground and polished to obtain a polished perovskite single crystal sample. The fine grinding and polishing process includes: using artificial leather polishing cloth and anhydrous ethanol as polishing liquid for the first drop treatment; after the first drop treatment has passed a preset time interval, the anhydrous ethanol is replaced with a suspension of dimethyl sulfoxide and anhydrous ethanol, and the finely ground perovskite single crystal sample is subjected to a second drop treatment.

[0047] In the embodiments of this disclosure, after the coarse grinding and polishing process is completed, the fine grinding and polishing stage begins. To further improve the smoothness and uniformity of the sample surface, the coarse sandpaper on the turntable under the polishing table can be replaced with artificial leather polishing cloth.

[0048] Specifically, artificial leather polishing cloths with fiber diameters less than 1µm can be used. These tiny fibers can make better contact with the sample surface, and because they do not come into contact with solid particles, they reduce abrasive wear and scratches on the sample surface. Compared to traditional polishing cloths with higher roughness, the tiny fibers can apply uniform pressure to the crystal surface during polishing, reducing localized wear and effectively lowering the roughness of the sample surface. This helps the sample surface achieve nanoscale smoothness, resulting in a smoother and more uniform surface condition, improved surface quality, reduced potential microcracks and defects, and ultimately, enhanced photoelectric properties of the crystal.

[0049] Furthermore, the components of the artificial leather polishing cloth may include polyurethane resin and viscose fiber to provide good elasticity and toughness, effectively meeting the needs for fine surface treatment during fine grinding.

[0050] During fine grinding and polishing, the sample fixing pressure can be set to 0.3-0.4 MPa. This pressure range ensures sufficient contact force between the polishing cloth and the sample surface, thus ensuring a fine polishing effect without damaging the sample surface due to excessive pressure. The upper rotary table speed can be set to 40-60 rpm to ensure that the polishing cloth can make uniform contact with the sample surface and continuously polish it, while avoiding excessive friction or surface unevenness caused by excessive speed. The lower rotary table speed can be set to 80-150 rpm, which helps to increase the rotation trajectory of the sample on the polishing cloth, further ensuring the uniformity and stability of fine grinding and polishing.

[0051] Simultaneously, during the fine grinding and polishing process, anhydrous ethanol can be used as the polishing solution for the first drop addition. Similar to the third drop addition, anhydrous ethanol has good lubrication and cleaning properties, effectively reducing friction and heat generation during polishing, and maintaining the smoothness and uniformity of the sample surface. Furthermore, the first drop addition helps remove tiny particles generated during polishing, preventing these particles from affecting the polishing effect or causing secondary scratches on the sample surface. The flow rate and preset time interval of the first drop addition can be adjusted according to process requirements to ensure that anhydrous ethanol can uniformly penetrate between the sample and the polishing cloth, maintaining a continuous lubricating effect and reducing surface scratches and particle accumulation.

[0052] For example, the flow rate of the first droplet addition process can be set to 10-30 mL / min. For instance, the flow rate of the first droplet addition process can be set to 20 mL / min to ensure that the lubricant used in the polishing process can be evenly and stably distributed between the sample surface and the polishing cloth. The preset time interval of the first droplet addition process can be set to 20-40 min to ensure that the polishing liquid penetrates evenly and continues to play a role throughout the polishing process, so that the polishing process at each stage can maintain stable conditions.

[0053] Furthermore, after a preset time interval, the first droplet addition process is completed, and anhydrous ethanol can be replaced with a suspension of dimethyl sulfoxide (DMSO) and anhydrous ethanol for the second droplet addition process.

[0054] In the embodiments of this disclosure, the use of a suspension composed of DMSO and anhydrous ethanol as the polishing solution gives this disclosure a unique advantage. Ethanol and dimethyl sulfoxide each have specific chemical properties and solubility, and their combination can play a synergistic role in the fine grinding and polishing process, effectively solving various challenges in crystal surface treatment.

[0055] Specifically, anhydrous ethanol is a widely used organic solvent with strong dissolving power, particularly effective at dissolving organic impurities. It not only removes minute organic contaminants from crystal surfaces but also effectively dissolves some insoluble substances on the crystal surface, thus preventing uneven or incomplete polishing caused by surface impurities. Due to its high volatility, ethanol evaporates rapidly during use, preventing long-term corrosion of the crystal. Therefore, ethanol provides the necessary lubrication and cleaning functions during fine polishing, helping to improve the polishing effect and protect the crystal surface.

[0056] On the other hand, DMSO is a polar solvent with extremely strong dissolving power, especially when mixed with water or other solvents, it can enhance the ability to dissolve other chemicals. Adding DMSO to a suspension allows for the removal of stubborn impurities from crystal surfaces, particularly metal oxides or other harmful substances, utilizing its excellent polarity and dissolving power. More importantly, DMSO has a chemical passivation effect; it can form a thin film on the crystal surface. This passivation film reduces surface defects and lowers dark current caused by surface activity, thereby improving the electrical stability of the crystal. Therefore, adding the specific chemical DMSO to a suspension can achieve both polishing and passivation of the crystal surface in the process, reducing surface defects, further improving the photoelectric properties of the crystal surface, and effectively extending the lifespan of optoelectronic devices.

[0057] In the embodiments of this disclosure, for the suspension prepared from DMSO and anhydrous ethanol, the anhydrous ethanol plays a role in dissolving and removing impurities that may be generated during the chemical passivation process of DMSO, ensuring that impurities in the passivation solution are removed in a timely manner, and maintaining the sample surface at the high quality level at the end of fine polishing. Because anhydrous ethanol has the characteristics of rapid dissolution and removal of impurities, it can effectively avoid the generation of unnecessary residues during the passivation process, thereby ensuring the stability and uniformity of the surface passivation film. Therefore, by combining the polishing steps of anhydrous ethanol and dimethyl sulfoxide, this disclosure can achieve surface passivation simultaneously with polishing, maintaining the high quality of the crystal surface and avoiding the surface inhomogeneity or chemical instability problems that may occur in traditional passivation processes.

[0058] In the embodiments of this disclosure, the volume ratio of dimethyl sulfoxide to anhydrous ethanol in the suspension of dimethyl sulfoxide and anhydrous ethanol can be 1:1 to 3:1.

[0059] Furthermore, through numerous experiments, the applicant discovered that preparing a suspension of ethanol and DMSO at a 1:1 volume ratio allows the advantages of both to be fully complemented and utilized. Specifically, this ensures that the suspension possesses sufficient cleanliness while avoiding excessive corrosion or damage to the crystal surface. The chemical passivation effect of DMSO and the physical lubrication effect of ethanol work synergistically to guarantee the uniformity and stability of the crystal surface during polishing, thereby minimizing surface defects and loss of crystal properties while ensuring the polishing effect.

[0060] Therefore, another major advantage of this disclosure is its ease of operation. By integrating polishing and passivation, it simplifies the traditional process flow. In traditional processes, polishing and passivation are usually performed separately, increasing process complexity and production time. The integrated polishing and passivation design of this disclosure not only simplifies the process flow but also improves production efficiency.

[0061] For example, the flow rate of the second droplet addition process can be set to 8-20 mL / min, preferably 10 mL / min, and the time of the second droplet addition process can be set to 4-7 min.

[0062] In the embodiments of this disclosure, the anhydrous ethanol used in the coarse and fine grinding processes can be of a purity of 99.99% or higher. High-purity ethanol is free of water and impurities, thus preventing the introduction of any additional water or harmful substances when dissolving organic impurities, particles, or contaminants on the crystal surface, and avoiding reactions that may adversely affect the crystal surface.

[0063] Furthermore, using high-purity anhydrous ethanol as the polishing fluid ensures that the liquid contains virtually no water or impurities, avoiding chemical reactions and corrosion caused by moisture. Simultaneously, the volatility of anhydrous ethanol allows it to evaporate rapidly during polishing, preventing unevenness on the sample surface caused by liquid residue. The rapid evaporation of anhydrous ethanol effectively removes the heat generated during polishing, preventing thermal deformation or cracking of the sample due to overheating. This characteristic is particularly important when processing brittle perovskite samples. The brittleness of perovskite materials makes them susceptible to thermal stress in traditional polishing methods, leading to cracks or damage. This disclosure effectively avoids this problem through the volatility of anhydrous ethanol.

[0064] According to embodiments of this disclosure, by using high-purity anhydrous ethanol as the polishing fluid, the introduction of moisture and impurities can be effectively avoided, thus preventing the corrosive effects that may arise from traditional polishing fluids. The volatility of anhydrous ethanol allows it to evaporate rapidly during polishing, promptly carrying away the heat generated by friction between the sample and the polishing cloth, effectively preventing thermal deformation and cracking of the sample surface due to overheating, thereby improving the integrity and stability of the sample. Secondly, using a synthetic fiber polishing cloth with a fiber diameter of less than 1µm provides a more uniform polishing effect, avoiding scratches and uneven wear caused by larger particles in traditional methods. The fine polishing cloth effectively reduces the roughness of the sample surface, ultimately achieving a nanoscale smooth effect, improving the surface quality of the sample, and providing a high-quality surface foundation for subsequent photoelectric performance testing. In the fine polishing step, this disclosure further optimizes the surface state of the sample by using a combined suspension of anhydrous ethanol and dimethyl sulfoxide. Anhydrous ethanol effectively removes impurities generated during the dimethyl sulfoxide passivation process, ensuring a more uniform and stable passivation film formation, thereby improving the electrical stability of the sample. Passivation treatment of dimethyl sulfoxide helps reduce defects on the crystal surface, prevents non-radiative recombination, and significantly improves the photoelectric properties of the sample.

[0065] In the embodiments of this disclosure, the above-described method can be used to process perovskite crystal materials to obtain perovskite crystal materials with excellent surface smoothness, low roughness, and better photoelectric properties.

[0066] The embodiments of this disclosure will be described below through several examples. However, those skilled in the art should understand that these embodiments are merely illustrative and not intended to limit the scope of this disclosure. Those skilled in the art can refer to the content of this document to appropriately modify the process parameters. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included within this application. As for reagents or equipment that do not specify a brand or manufacturer, they are standard products readily available on the market.

[0067] Example 1

[0068] The paraffin wax sample containing cesium lead bromine single crystals was mounted in the sample fixing hole of the polishing table, with the sample fixing pressure set to 0.1-0.2 MPa. Next, 400-grit, 800-grit, 1200-grit, and 2000-grit silicon carbide abrasive paper were used sequentially to coarsely grind the sample to remove cutting marks introduced by wire cutting on the surface of the cesium lead bromine crystals. The coarse grinding time for each abrasive grit was set to 3 minutes. Throughout the process, anhydrous ethanol was dripped at a rate of 10 mL / min to remove heat and particles generated during grinding, ensuring the stability of the polishing effect. The upper rotary table speed was set to 50 rpm, and the lower rotary table speed was set to 80 rpm to ensure uniformity and effectiveness during the grinding process.

[0069] Example 2

[0070] Based on Example 1, the coarse sandpaper on the polishing table's lower turntable was replaced with a synthetic leather polishing cloth with a fiber diameter of less than 1µm, and fine polishing of the sample was initiated. The sample fixation pressure was set to 0.3-0.4 MPa to ensure full contact between the polishing cloth and the sample surface. The drop rate of anhydrous ethanol was set to 20 mL / min to continuously remove heat and particles generated during polishing. The rotation speed of the upper turntable was set to 50 rpm, and the rotation speed of the lower turntable was set between 80-150 rpm to ensure the uniformity and stability of the polishing process. The total time for the first drop of anhydrous ethanol was set to 30 min to ensure that the surface treatment achieved the desired flatness and smoothness.

[0071] Example 3

[0072] A suspension was prepared by mixing dimethyl sulfoxide and anhydrous ethanol in a 1:1 volume ratio. The anhydrous ethanol used in Example 2 was replaced with the prepared suspension for further sample processing. The sample fixation pressure was set to 0.3-0.4 MPa, the drop rate of the suspension was set to 10 mL / min, the upper turntable speed was set to 50 rpm, and the lower turntable speed was adjusted to between 80-150 rpm to ensure uniform polishing. The second drop of suspension was added over a period of 5 minutes to ensure effective passivation.

[0073] Example 4

[0074] The photoelectric properties of the cesium lead bromide perovskite single crystal samples after coarse and fine grinding and polishing treatments in Examples 1-3 were tested to verify the changes in their detection performance. The tests included the crystal's dark current, laser response, and surface roughness, as improvements in these parameters directly reflect improvements in the crystal's surface quality.

[0075] Figure 2 A comparison diagram of the morphology and transparency of a sample before and after polishing, according to an embodiment of this disclosure, is shown. Figure 2 As shown, a distinct grid background is used as an auxiliary tool for comparative analysis. The sample before polishing (left) has a relatively rough or irregular texture, resulting in low overall smoothness and low transparency; while the crystal after polishing according to Examples 1-3 of this disclosure (right) has a smoother surface with almost no obvious roughness, and the transparency of the sample is improved, showing a clear grid background.

[0076] The increased transparency indicates that the polishing process removed some minor imperfections and irregularities on the surface, thereby enhancing light transmission. The uniformity of the sample surface was also significantly improved, resulting in a more consistent visual appearance.

[0077] Figure 3 The diagram schematically illustrates the surface roughness test results of perovskite crystal samples before and after polishing according to embodiments of the present disclosure. Specifically, the roughness of the samples before and after polishing was tested using atomic force microscopy (AFM). The roughness of the perovskite sample (left) before polishing was 0.09 µm, while the roughness of the sample (right) after polishing decreased to 0.89 nm. It can be seen that by using the surface polishing methods of embodiments 1-3 of the present disclosure, the surface roughness of the perovskite crystal decreased by more than 100 times.

[0078] Furthermore, IV characteristics and laser response tests were performed on the samples before polishing, after polishing, and after surface passivation. The laser used was a 27µW violet laser with a wavelength of 405 nm, and the laser was irradiated from a distance of 5 cm from the side of the sample. 100 nm thick gold (Au) and indium (In) metal electrodes were deposited on the upper and lower surfaces of the test sample, respectively, to ensure good electrical contact and facilitate signal extraction.

[0079] Figures 4A-4C The diagram schematically illustrates the IV curves and laser response results of samples before and after polishing according to embodiments of the present disclosure. Figure 4A The image shows the IV curve of the unpolished sample. The dark current is 9.8µA under a bias voltage of 100 V. Due to the large dark current, the signal generated by the laser is overwhelmed, resulting in no response when the laser irradiates the sample. Figure 4B The image shows the IV curve and laser response of the sample after the first droplet treatment. The dark current of the sample after the first droplet treatment was 0.1 nA under a bias voltage of 100 V, indicating that the treatment significantly reduced the dark current of the sample by four orders of magnitude. Furthermore, the maximum laser response of this sample was 2.7 × 10⁻⁶. 3 times; Figure 4CThe image shows the IV curve and laser response of the sample after the second droplet treatment. It can be seen that the second droplet treatment process described in this disclosure can annihilate the Pb dangling bonds on the sample surface, enabling the sample to form an ohmic contact with the metal electrode. Under +100 V and -100 V bias conditions, the laser responses are 5.2 × 10⁻⁶ and 5.2 × 10⁻⁶, respectively. 3 The sum is 5.7 × 10 3 times.

[0080] The embodiments of this disclosure have been described above; however, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A surface polishing method for perovskite crystal materials, characterized in that, The method includes: The perovskite single crystal to be polished is subjected to a hot mounting process to obtain a perovskite single crystal sample. The perovskite single crystal sample was fixed on a polishing table and subjected to rough grinding and polishing; and The coarsely ground perovskite single crystal sample was then finely ground and polished to obtain the polished perovskite single crystal sample. The fine polishing process includes: using an artificial leather polishing cloth and anhydrous ethanol as the polishing liquid for the first droplet addition treatment; after a preset time interval has elapsed in the first droplet addition treatment, the anhydrous ethanol is replaced with a suspension of dimethyl sulfoxide and anhydrous ethanol for the second droplet addition treatment.

2. The method according to claim 1, characterized in that, In the suspension of dimethyl sulfoxide and anhydrous ethanol, the volume ratio of dimethyl sulfoxide to anhydrous ethanol is 1:1 to 3:

1.

3. The method according to claim 1, characterized in that, The hot mounting process specifically includes: using paraffin wax to hot mount the perovskite single crystal to be polished to obtain the perovskite single crystal sample, wherein the size of the perovskite single crystal sample obtained by hot mounting is adapted to the size of the sample fixing stage in the polishing table.

4. The method according to claim 1, characterized in that, The perovskite single crystal sample was coarsely ground and polished sequentially using silicon carbide sandpaper with mesh sizes ranging from 300-500 mesh, 700-900 mesh, 1000-1300 mesh, and 1800-2200 mesh.

5. The method according to claim 4, characterized in that, The sample fixing pressure during the rough grinding and polishing process was set to 0.1-0.2 MPa, the rotation speed of the turntable on the polishing table was set to 40-60 rpm, the rotation speed of the turntable under the polishing table was set to 70-90 rpm, and the rough grinding and polishing time for silicon carbide abrasive paper of different mesh sizes was set to 2-5 min.

6. The method according to claim 4, characterized in that, During the coarse grinding and polishing process, anhydrous ethanol was added as a third drop, with the flow rate set to 8-20 mL / min.

7. The method according to any one of claims 4-6, characterized in that, After the rough grinding process is completed, the silicon carbide sandpaper is replaced with artificial leather polishing cloth, the fiber diameter of which is less than 1µm.

8. The method according to claim 7, characterized in that, The artificial leather polishing cloth is composed of polyurethane resin and viscose fiber.

9. The method according to claim 1, characterized in that, The sample fixation pressure during the fine grinding and polishing process was set to 0.3-0.4 MPa, the flow rate of the first droplet addition was set to 10-30 mL / min, the rotation speed of the turntable on the polishing stage was set to 40-60 rpm, the rotation speed of the turntable under the polishing stage was set to 80-150 rpm, and the preset time interval of the first droplet addition was set to 20-40 min.

10. The method according to claim 1, characterized in that, The flow rate for the second droplet addition was set to 8-20 mL / min, the rotation speed of the turntable on the polishing stage was set to 40-60 rpm, the rotation speed of the turntable under the polishing stage was set to 80-150 rpm, and the time for the second droplet addition was set to 4-7 min.

11. The method according to claim 1 or 6, characterized in that, The purity of the anhydrous ethanol is greater than or equal to 99.99%.

12. A perovskite crystal, characterized in that, The perovskite crystal is obtained by surface treatment using the surface polishing method for perovskite crystal materials as described in any one of claims 1-11.

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