Perovskite photodetector and preparation method thereof

Abstract

The present application provides a perovskite photodetector and a method for preparing the same. The perovskite photodetector comprises a polyvinyl alcohol-nanometallic particle layer and a perovskite layer which are stacked; there is a cavity between the polyvinyl alcohol-nanometallic particle layer and the perovskite layer. The method for preparing the perovskite photodetector comprises: forming the polyvinyl alcohol-nanometallic particle layer on a first substrate using a polyvinyl alcohol solution containing metal nanoparticles; coating a PbX solution on a second substrate to obtain a PbX film, then reacting the PbX film with a YX solution to obtain a perovskite polycrystalline film, and annealing to obtain a perovskite layer; and laminating the polyvinyl alcohol-nanometallic particle layer and the perovskite layer to obtain a perovskite photodetector. The perovskite photodetector provided in the present application achieves the control of the distance between the metal nanoparticles and the perovskite through the cavity between the polyvinyl alcohol-nanometallic particle layer and the perovskite layer, thereby achieving an LSPR enhancement effect.

Description

Technical Field

[0001] The present application relates to the field of materials, and in particular to a perovskite photodetector and a method for preparing the same. Background Art

[0002] All-inorganic halide perovskite materials have attracted a lot of attention due to their excellent photoelectric conversion performance and high carrier mobility. The excellent photoelectric performance makes perovskite materials have good application prospects in devices such as light-emitting diodes, photodetectors, and solar cells. Among them, photodetectors refer to devices that convert light signals into electrical signals. They are important devices in the fields of optical communication, image sensing, digital imaging, chemical and biological monitoring, etc. According to different working mechanisms, photodetectors are divided into photoconductive type and photovoltaic type. Photoconductive type detectors are photoexcited electrons that cause the conductivity to increase under an external bias, and current signals appear. Photovoltaic type detectors are mainly based on the photovoltaic effect of pn junctions. The photoexcited electron holes enter the p region and n region respectively, causing a potential difference, thereby generating a voltage or current signal in the outside world. The performance of photodetectors is described mainly through several aspects, including responsivity, detection rate, response time, etc.

[0003] In order to improve the performance of perovskite photodetectors, people have proposed many methods to improve the responsiveness, including oxide film coating, optimization of perovskite growth conditions, rare earth ion doping, etc. On the other hand, due to the needs of military detection and other aspects, instant imaging, fast optical communication and high-speed dynamic monitoring are very necessary for ultrafast response photodetectors. Since metal nanoparticles have local surface plasma resonance (LSPR) effect, metal nanoparticles interact with excitons to produce fluorescence, accelerate the radiation decay rate of nearby excitons, thereby reducing the possibility of quenching by non-radiative conformation, and can enhance light absorption and emission. Therefore, introducing metal nanoparticles into the surface of perovskite can enhance the responsiveness of the detector and significantly reduce the response time.

[0004] There are several common methods for applying metal nanoparticles to perovskite photodetectors. These methods include direct contact with metal nanoparticles, dissolving metal nanoparticles in the hole transport layer, and separating metal nanoparticles from perovskite through an insulating layer. Generally speaking, the closer the distance between the metal nanoparticles and the semiconductor, the greater the coupling coefficient of the LSPR, and the greater the enhancement of the detector's responsiveness. Therefore, direct contact between metal nanoparticles and perovskite will have the best responsiveness enhancement effect. However, when metal nanoparticles are close to the semiconductor surface, in addition to the LSPR effect, there may be a process in which the semiconductor's hot electrons are directly transferred to the metal nanoparticles, resulting in the quenching of the semiconductor. Even if there is a small distance in between, the performance of the semiconductor will be negatively affected by the tunneling of electrons. In order to prevent the loss of hot electrons from the surface of perovskite, a spacer layer is usually introduced between the metal nanoparticles and the perovskite. The material is SiO, polymethyl methacrylate, etc. The spacer layer provides a huge barrier between the metal nanoparticles and the perovskite to prevent the transfer of hot electrons. However, the stability of the perovskite material is poor. The growth process of the spacer layer on the surface will have a negative impact on the performance of the perovskite. In addition, the insulating layer in the structure separates the perovskite layer from the electron transport layer, which also has a negative impact on the design of the overall detector structure. Dissolving metal nanoparticles in the hole transport layer can avoid direct contact with the perovskite layer, but the distance between the metal nanoparticles and the perovskite cannot be specifically controlled. Too close will lead to the transfer of hot electrons in the perovskite, and too far will lead to a lower LSPR coupling coefficient. Summary of the invention

[0005] The purpose of this application is to provide a perovskite photodetector and a preparation method thereof to solve the above problems.

[0006] To achieve the above objectives, this application adopts the following technical solutions:

[0007] A perovskite photodetector comprises a polyvinyl alcohol-nanometallic particle layer and a perovskite layer stacked in layers;

[0008] There is a cavity between the polyvinyl alcohol-nanometallic particle layer and the perovskite layer.

[0009] Preferably, the nano-metal ions in the polyvinyl alcohol-nano-metal particle layer include one or more of nano-gold particles, nano-silver particles and nano-indium particles.

[0010] Preferably, the perovskite in the perovskite layer is polycrystalline perovskite, and the polycrystalline perovskite includes one or more of CsPbBr3, CsPbI3, CsPbCl3 and MAPbBr3.

[0011] Preferably, the thickness of the polyvinyl alcohol-nanometallic particle layer is 100nm-800nm.

[0012] Preferably, the thickness of the perovskite layer is 500nm-5000nm.

[0013] Preferably, the cavity includes a gas, and the gas includes one or more of air, nitrogen, carbon dioxide, and a rare gas;

[0014] Preferably, the depth of the cavity is 100nm-1000nm.

[0015] The present application also provides a method for preparing the perovskite photodetector, comprising:

[0016] Forming the polyvinyl alcohol-nanometallic particle layer on the first substrate with a polyvinyl alcohol solution containing metal nanoparticles;

[0017] Coating a PbX solution on a second substrate to obtain a PbX film, then reacting the PbX film with a YX solution to obtain a perovskite polycrystalline film, and annealing to obtain the perovskite layer; wherein X is selected from any one of Cl, Br, and I, and Y is selected from Cs or MA;

[0018] The polyvinyl alcohol-nanometallic particle layer and the perovskite layer are bonded together to obtain the perovskite photodetector.

[0019] Preferably, the annealing temperature is 150°C-350°C.

[0020] Preferably, the first substrate comprises glass, and the second substrate comprises a conductive substrate;

[0021] Preferably, the first substrate is quartz glass, and the conductive substrate is ITO glass.

[0022] Preferably, the first substrate and the second substrate are cleaned before use;

[0023] Preferably, the cleaning comprises: ultrasonic treatment using acetone, ethanol and deionized water;

[0024] Preferably, the first substrate further includes plasma hydrophilic treatment before use;

[0025] Preferably, the coating is spin coating, and the spin rate is 1500rpm-3000rpm.

[0026] Compared with the prior art, the beneficial effects of this application include:

[0027] The perovskite photodetector provided in the present application, by setting a cavity between the polyvinyl alcohol-nanometallic particle layer and the perovskite layer, cooperates with polyvinyl alcohol to control the distance between the metal nanoparticles and the perovskite, avoids the loss of thermal electrons caused by direct contact, and thereby realizes the regulation of the localized surface plasma co-effect of the metal nanoparticles, reduces the possibility of quenching by non-radiative conformation, enhances the absorption and emission of light, enhances the responsiveness of the detector, and greatly reduces the response time.

[0028] The preparation method of the perovskite photodetector provided in the present application forms grains and holes of different heights on the surface of the perovskite polycrystalline film by annealing the perovskite polycrystalline film, thereby forming a cavity between the two after laminating with the polyvinyl alcohol-nanometallic particle layer; the perovskite photodetector prepared by this method has a controllable cavity depth, thereby making the distance between the metal nanoparticles and the perovskite controllable; because the method does not directly grow a film on the surface of the perovskite, it avoids the contact between various solvents and the perovskite film during the new growth process, thereby maintaining good film morphology and performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope of the present application.

[0030] Figure 1 A schematic diagram of the structure and principle of the CsPbBr3 thin film detector provided in Example 1 of the present application;

[0031] Figure 2 This is a SEM photo of the perovskite polycrystalline thin film obtained in Example 1;

[0032] Figure 3 This is a SEM photo of the perovskite polycrystalline thin film obtained in Example 2;

[0033] Figure 4 This is a SEM photo of the perovskite polycrystalline thin film obtained in Example 3;

[0034] Figure 5 Response curves corresponding to the perovskite photodetector obtained in Example 1 and the perovskite film in Comparative Example 1;

[0035] Figure 6 Response curves corresponding to the perovskite photodetector obtained in Example 2 and the perovskite film in Comparative Example 2;

[0036] Figure 7 Response curves corresponding to the perovskite photodetector obtained in Example 3 and the perovskite film in Comparative Example 3;

[0037] Figure 8 The response curves of the perovskite photodetector and the perovskite film prepared in this application;

[0038] Fig. 9 is the corresponding curve of gold nanoparticles;

[0039] Fig.10 Response curves of the perovskite photodetector and the perovskite film obtained in Comparative Example 4. DETAILED DESCRIPTION

[0040] As used herein:

[0041] "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0042] The conjunction "consisting of excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed-ended so that it does not include materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0043] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described in this article, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0044] In these examples, parts and percentages are by mass unless otherwise indicated.

[0045] "Parts by mass" refers to the basic unit of measurement for expressing the mass ratio of multiple components. 1 part can represent any unit mass, such as 1g or 2.689g. If we say that the mass of component A is a parts and the mass of component B is b parts, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it means that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number, indicating a multiple factor). It should not be misunderstood that, unlike the mass parts, the sum of the mass of all components is not limited to 100 parts.

[0046] "And / or" is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0047] A perovskite photodetector comprises a polyvinyl alcohol-nanometallic particle layer and a perovskite layer stacked in layers;

[0048] There is a cavity between the polyvinyl alcohol-nanometallic particle layer and the perovskite layer.

[0049] In an optional embodiment, the nano-metal ions in the polyvinyl alcohol-nano-metal particle layer include one or more of nano-gold particles, nano-silver particles and nano-indium particles.

[0050] In an optional embodiment, the perovskite in the perovskite layer is a polycrystalline perovskite, and the polycrystalline perovskite includes one or more of CsPbBr3, CsPbI3, CsPbCl3 and MAPbBr3.

[0051] It should be noted that, in the compounds provided in this application, MA refers to CH3NH3-.

[0052] In an optional embodiment, the thickness of the polyvinyl alcohol-nanometallic particle layer is 100 nm-800 nm.

[0053] Optionally, the thickness of the polyvinyl alcohol-nanometallic particle layer may be 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm or any value between 100 nm and 800 nm.

[0054] In an optional embodiment, the thickness of the perovskite layer is 500nm-5000nm.

[0055] Optionally, the thickness of the perovskite layer may be 500 nm, 1000 nm, 2000 nm, 3000 nm, 4000 nm, 5000 nm or any value between 500 nm and 5000 nm.

[0056] In an optional embodiment, the cavity includes a gas, and the gas includes one or more of air, nitrogen, carbon dioxide, and a rare gas;

[0057] In an optional embodiment, the depth of the cavity is 100nm-1000nm.

[0058] In general use scenarios, the gas in the cavity is air. The gas environment around the device can also be controlled by first evacuating the cavity to a vacuum and then filling it with the target gas to achieve the purpose of controlling the gas in different cavities.

[0059] Optionally, the depth of the cavity may be 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm or any value between 100 nm and 1000 nm.

[0060] The present application also provides a method for preparing the perovskite photodetector, comprising:

[0061] Forming the polyvinyl alcohol-nanometallic particle layer on the first substrate with a polyvinyl alcohol solution containing metal nanoparticles;

[0062] Coating a PbX solution on a second substrate to obtain a PbX film, then reacting the PbX film with a YX solution to obtain a perovskite polycrystalline film, and annealing to obtain the perovskite layer; wherein X is selected from any one of Cl, Br, and I, and Y is selected from Cs or MA;

[0063] The polyvinyl alcohol-nanometallic particle layer and the perovskite layer are bonded together to obtain the perovskite photodetector.

[0064] In an optional embodiment, the annealing temperature is 150°C-350°C.

[0065] The control of annealing temperature can control the roughness of the surface of the perovskite film, thereby controlling the depth (thickness) of the cavity between the polyvinyl alcohol-nanometallic particle layer and the perovskite layer, and achieving the purpose of controlling the distance between the nanometallic particles and the surface of the perovskite film.

[0066] Optionally, the annealing temperature may be 150°C, 200°C, 250°C, 300°C, 350°C or any value between 150°C and 350°C.

[0067] In an optional embodiment, the first substrate comprises glass, and the second substrate comprises a conductive substrate;

[0068] In an optional embodiment, the first substrate is quartz glass, and the conductive substrate is ITO glass.

[0069] In an optional embodiment, the first substrate and the second substrate are both cleaned before use;

[0070] In an optional embodiment, the cleaning comprises: ultrasonic treatment using acetone, ethanol and deionized water;

[0071] In an optional embodiment, the first substrate further includes a plasma hydrophilic treatment before use;

[0072] In order to prepare a PVA film, it is necessary to make the PVA aqueous solution adhere to the glass surface. Plasma treatment of the substrate can improve the hydrophilicity of the substrate surface and make the final synthesized film of better quality.

[0073] In an optional embodiment, the coating is spin coating, and the spin rate is 1500 rpm-3000 rpm.

[0074] Optionally, the rotation rate may be 1500 rpm, 2000 rpm, 2500 rpm, 3000 rpm or any value between 1500 rpm and 3000 rpm.

[0075] The embodiments of the present application will be described in detail below in conjunction with specific examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If specific conditions are not specified in the examples, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0076] Example 1

[0077] The present application provides a perovskite photodetector, comprising a polyvinyl alcohol-nanometallic particle layer and a perovskite layer stacked in layers; a cavity is provided between the polyvinyl alcohol-nanometallic particle layer and the perovskite layer. In the polyvinyl alcohol-nanometallic particle layer, the nanometallic particles are gold nanoparticles, and the thickness of the polyvinyl alcohol-nanometallic particle layer is 100nm. In the perovskite layer, the perovskite is CsPbBr3, and the thickness of the perovskite layer is 500nm. The depth of the cavity is 100nm, and the cavity is filled with air.

[0078] The specific preparation method is as follows:

[0079] 1. Preparation of Au Nanoparticle Solution

[0080] The PVA powder was stirred and poured into an aqueous solution of Au particles of different concentrations (0.005 mg / ml, 0.01 mg / ml, 0.05 mg / ml), placed on a 70°C hot plate to accelerate the dissolution of the PVA, and then cooled at room temperature. After the solution was completely clear, a 0.05 g / ml PVA solution was prepared.

[0081] 2. Preparation of Au nanoparticle film (polyvinyl alcohol-nanometallic particle layer)

[0082] First, clean the quartz substrate, ultrasonically clean it with acetone, ethanol, and deionized water for 10 minutes each, and then perform plasma hydrophilic treatment on the quartz substrate for 30 minutes. Drop 75ul of the prepared Au particle solution on the quartz substrate, place it in an oven at 80℃, and evaporate the solvent.

[0083] 3. Preparation of polycrystalline perovskite films

[0084] The CsPbBr3 polycrystalline film was synthesized using a two-step method. 1.2cm*1.2cm ITO glass was cleaned according to the cleaning method in step 2 above and used as the substrate for the CsPbBr3 film. 0.367g PbBr was dissolved in 1ml N,N-dimethylformamide (DMF) at 75℃. 100ul PbBr was spin-coated on the ITO glass at 2000rpm for 30s, and then placed on an 80℃ hot stage for 30 minutes to evaporate the DMF. 0.15g CsBr was dissolved in 10ml methanol and stirred on a 50℃ hot stage to dissolve. Then the prepared PbBr film was immersed in the CsBr solution, reacted for 5 minutes, and then taken out and the sample was cleaned with isopropanol to prevent methanol from dissolving CsPbBr. Finally, it was placed on a 150℃ hot stage and annealed for 5 minutes to obtain a polycrystalline film of CsPbBr3.

[0085] 4. Preparation of CsPbBr3 thin film detector

[0086] The PVA film containing gold nanoparticles is closely attached to the CsPbBr3 thin film detector to obtain the CsPbBr3 thin film detector.

[0087] like Figure 1 As shown, when light is incident from one side of the PVA film, the light response of the detector can be enhanced.

[0088] When light is incident, it first passes through the side of the PVA film containing gold nanoparticles, stimulating the LSPR effect, and then propagates into the air. Due to the uneven surface of CsPbBr3, there is an air cavity between the PVA corrugation and the CsPbBr3 surface. The LSPR-enhanced light propagates a distance of several hundred nanometers in the air cavity, and then propagates to the CsPbBr3 surface to stimulate photogenerated carriers.

[0089] Example 2

[0090] Different from Example 1, the annealing temperature is 250°C.

[0091] Example 3

[0092] Different from Example 1, the annealing temperature is 350°C.

[0093] Figure 2 , Figure 3 and Figure 4 The SEM images of the perovskite polycrystalline thin films obtained in Example 1, Example 2 and Example 3 are shown respectively. The upper image in each figure is a surface SEM image of the perovskite polycrystalline thin film, and the lower image is a cross-sectional SEM image of the perovskite polycrystalline thin film.

[0094] Depend on Figure 2 , Figure 3 and Figure 4 It can be seen that the surface roughness of the perovskite polycrystalline films treated at different annealing temperatures is different, and thus the depth of the cavity formed after the perovskite polycrystalline films are combined with the polyvinyl alcohol-nanometallic particle layer is also different.

[0095] Example 4

[0096] The difference from Example 1 is that nano silver particles are used as plasma enhanced nano metal particles.

[0097] The main difference is that the absorption peak of silver particles is at 430nm, which is suitable for enhancing the detector response spectrum near 430nm, that is, it can enhance the detector's detection ability for purple.

[0098] Comparative Examples 1-3

[0099] The pure perovskite films after annealing in Example 1, Example 2 and Example 3 were used as controls.

[0100] Figure 5 , Figure 6 , Figure 7 The response curves of the perovskite photodetectors obtained in Examples 1-3 and the perovskite films in Comparative Examples 1-3 are shown respectively.

[0101] Depend on Figure 5 , Figure 6 , Figure 7 It can be seen that at the same annealing temperature, the structure provided in the present application can obtain a significant light response enhancement effect; at different annealing temperatures, due to different surface roughness and different air cavity depths, the light response enhancement effect caused by LSPR is different.

[0102] Comparative Example 4

[0103] Different from Example 1, the thickness of the polyvinyl alcohol-nanometallic particle layer is 10 μm.

[0104] Figure 8 The response curves of the perovskite photodetector and the perovskite film prepared in this application. Fig. 9 is the corresponding curve of gold nanoparticles. Figure 8 It can be seen that the perovskite photodetector obtained in this application has a significantly enhanced response curve compared to the perovskite film; Fig. 9 By comparison, it can be seen that the enhancement effect is brought about by gold nanoparticles.

[0105] Fig.10 Response curves of the perovskite photodetector and the perovskite film obtained in Comparative Example 4. Fig.10 It can be seen that if the thickness of the polyvinyl alcohol-nanometallic particle layer is too large, the original response ability of the perovskite will be reduced.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0107] In addition, those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the above claims, any one of the claimed embodiments may be used in any combination. The information disclosed in this background technology section is intended only to deepen the understanding of the overall background technology of the present application and should not be regarded as an admission or in any form of implication that the information constitutes prior art known to those skilled in the art.

Claims

1. A perovskite photodetector, characterized in that: It includes a polyvinyl alcohol-nanometallic particle layer and a perovskite layer which are stacked; There is a cavity between the polyvinyl alcohol-nanometallic particle layer and the perovskite layer; The nano-metal particles in the polyvinyl alcohol-nano-metal particle layer include one or more of nano-gold particles, nano-silver particles and nano-indium particles; The perovskite in the perovskite layer is polycrystalline perovskite, and the polycrystalline perovskite includes one or more of CsPbBr3, CsPbI3, CsPbCl3 and MAPbBr3; The thickness of the polyvinyl alcohol-nanometallic particle layer is 100nm-800nm; The thickness of the perovskite layer is 500nm-5000nm; The cavity includes a gas, and the gas includes one or more of air, nitrogen, carbon dioxide, and a rare gas; The depth of the cavity is 100nm-1000nm.

2. A method for preparing the perovskite photodetector according to claim 1, characterized in that: include: Forming the polyvinyl alcohol-nanometallic particle layer on the first substrate with a polyvinyl alcohol solution containing metal nanoparticles; Coating a PbX solution on a second substrate to obtain a PbX film, then reacting the PbX film with a YX solution to obtain a perovskite polycrystalline film, and annealing to obtain the perovskite layer; wherein X is selected from any one of Cl, Br, and I, and Y is selected from Cs or MA; The polyvinyl alcohol-nanometallic particle layer and the perovskite layer are bonded together to obtain the perovskite photodetector.

3. The method for preparing a perovskite photodetector according to claim 2, characterized in that: The annealing temperature is 150°C-350°C.

4. The method for preparing a perovskite photodetector according to claim 2, characterized in that: The first substrate includes glass, and the second substrate includes a conductive substrate.

5. The method for preparing a perovskite photodetector according to claim 4, characterized in that: The first substrate is quartz glass, and the conductive substrate is ITO glass.

6. The method for preparing a perovskite photodetector according to any one of claims 2 to 5, characterized in that: The first substrate and the second substrate are both cleaned before use.

7. The method for preparing a perovskite photodetector according to claim 6, characterized in that: The cleaning comprises: performing ultrasonic treatment using acetone, ethanol and deionized water.

8. The method for preparing a perovskite photodetector according to any one of claims 2 to 5, characterized in that: The first substrate is further subjected to plasma hydrophilic treatment before use.

9. The method for preparing a perovskite photodetector according to any one of claims 2 to 5, characterized in that: The coating is performed by spin coating, and the spin rate is 1500 rpm-3000 rpm.

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