A perovskite single crystal array photodetector and its preparation method

Abstract

The present invention belongs to the field of photoelectric detection technology, specifically a perovskite single crystal array photodetector and a method for preparing the same. The method for preparing the perovskite single crystal array photodetector comprises: preparing perovskite precursor solutions of varying concentrations; preparing a clean substrate; using a low-concentration perovskite precursor solution to form a thin, dense polycrystalline film on the substrate; forming patterned electrodes on the polycrystalline film; placing the device in a high-concentration perovskite precursor solution to grow a single crystal array; and removing the device, cleaning, and drying it. This preparation method can directly produce a photodetector with a perovskite single crystal array, and is simple, convenient, and cost-effective.

Description

Technical Field

[0001] The present invention belongs to the technical field of photoelectric detection, and in particular relates to a perovskite single crystal array photoelectric detector and a preparation method thereof. Background Art

[0002] Semiconductor arrays are widely used in many fields of optoelectronics due to their versatility and large-scale integration. Metal halide perovskites, due to their outstanding optoelectronic properties, have become prime candidates for next-generation optoelectronic devices. However, current research on metal halide perovskites focuses on the preparation of polycrystalline thin films and the growth of large single crystals, while the preparation of single crystal arrays remains challenging.

[0003] Currently, metal halide perovskite single crystal arrays are typically fabricated using a spatial confinement method. The use of molds not only increases costs but also complicates the fabrication process. Furthermore, the resulting single crystal arrays often require further processing before being combined with electrodes to form a complete photodetector. Therefore, this area of technology still requires further improvement and development. Summary of the Invention

[0004] In view of the above-mentioned deficiencies in the prior art, an object of the present invention is to provide a perovskite single crystal array photodetector and a preparation method thereof with simple process and reduced cost.

[0005] The method for preparing the perovskite single crystal array photodetector provided by the present invention comprises the following specific steps:

[0006] S1, prepare perovskite precursor solutions with lower concentration and near saturation concentration respectively;

[0007] S2. Prepare a clean substrate;

[0008] S3, using a lower concentration of perovskite precursor solution to prepare a thin and dense perovskite polycrystalline film on a substrate;

[0009] S4, preparing an electrode with a certain pattern on the perovskite polycrystalline film;

[0010] S5, placing the device in a near-saturated concentration of a perovskite precursor solution, and slowly evaporating the solution under heating to form a perovskite single crystal array;

[0011] S6. Take out the device, clean it, and dry it.

[0012] In step S1 of the present invention, a perovskite precursor solution is prepared, using lead halide and methylamine halide or cesium halide as solutes, N,N-dimethylformamide and / or dimethyl sulfoxide mixture as solvent, and the molar ratio of lead halide to methylamine halide or cesium halide is 1:1;

[0013] When preparing a lower concentration of perovskite precursor solution, the solvent is a mixture of N, N-dimethylformamide and dimethyl sulfoxide, and the concentration of the perovskite precursor solution is 0.7-1.0 mol / L;

[0014] When preparing a near-saturation concentration perovskite precursor solution, the solvent is N,N-dimethylformamide or a dimethyl sulfoxide mixture, and the concentration of the perovskite precursor solution is 1.4-1.6 mol / L;

[0015] Wherein, the lead halide is one of lead iodide, lead bromide and lead chloride; the methylamine halide is one of methylamine iodide, methylamine bromide and methylamine chloride; and the cesium halide is one of cesium iodide, cesium bromide and cesium chloride.

[0016] In step S2 of the present invention, the substrate is a glass substrate or a flexible substrate, etc., and the substrate is cleaned with deionized water, ethanol, acetone, and isopropyl alcohol in sequence, and blown dry with a nitrogen gun; and then treated with ultraviolet light for 10-15 minutes.

[0017] In step S3 of the present invention, the perovskite polycrystalline thin film is prepared by any one of a one-step spin coating method, a two-step spin coating method, a doctor blade method, a spray coating method, an inkjet method, and a roll-to-roll method. The thickness of the polycrystalline thin film is 100-150 nm.

[0018] When using the one-step spin coating method, the settings of the spin coating station are:

[0019] Initial speed and time: 1500-2500 rpm and 10s;

[0020] Final speed and time: 5000-6000 rpm and 20 s.

[0021] In step S4 of the present invention, the distance between the electrodes is between 1-10 μm, and the thickness of the electrodes is between 50-150 nm.

[0022] In step S5 of the present invention, the solution is slowly evaporated under heating, the heating temperature is 50-100° C., and the evaporation time is 8-24 hours.

[0023] Specifically, the mixture can be placed in a container, sealed with aluminum foil, and several holes can be opened on it to reduce the evaporation rate of the solution.

[0024] In step S6 of the present invention, the cleaning is to use a solvent such as chlorobenzene or toluene to clean the surface of the device, and the drying is to use a heating platform to remove the residual organic solvent.

[0025] The present invention also provides a perovskite single crystal array photoelectric detector obtained by the above preparation method.

[0026] In the method of the present invention, a polycrystalline perovskite film is first deposited on a substrate, followed by patterned electrodes, and finally, single crystal arrays are grown. The electrodes control the locations where the single crystals grow to form the array structure, while the polycrystalline film serves as a substrate for epitaxial single crystal growth.

[0027] Compared with the prior art, the preparation method provided by the present invention has the following advantages:

[0028] (1) Simple process and convenient operation;

[0029] (2) The perovskite single crystal is in contact with the electrode during growth and can be directly used for photoelectric detection without the need for subsequent processing such as substrate transfer, which simplifies the process and saves costs;

[0030] (3) Perovskite has a variety of components, which can fully utilize the advantage of the controllable perovskite components;

[0031] (4) The electrode pattern is not unique, and devices with complex patterns can be prepared according to actual needs;

[0032] (5) It can be used as a preparatory step for the preparation of large-area photodetector modules. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a flow chart of the method of the present invention.

[0034] Numbers in the figure: 1-substrate, 2-perovskite polycrystalline film, 3-electrode, 4-beaker, 5-perovskite nearly saturated precursor solution, 6-heating stage, 7-perovskite single crystal. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments. The embodiments shown here are only part of the various possible embodiments of the present invention and do not represent all embodiments.

[0036] The present invention provides a method for preparing a perovskite single crystal array photodetector, comprising the following steps:

[0037] S1. Prepare perovskite precursor solutions with lower concentration and near saturation concentration respectively. The two perovskite precursor solutions with different concentrations are prepared for subsequent polycrystalline thin film and single crystal growth respectively.

[0038] S2. Prepare a clean substrate. A clean substrate is a prerequisite for preparing high-performance devices.

[0039] S3, using a relatively low concentration of perovskite precursor solution to prepare a very thin but dense perovskite polycrystalline film on a substrate;

[0040] S4, preparing electrodes with a certain pattern on the perovskite polycrystalline film to control the growth position of the perovskite single crystal and form a desired ordered array;

[0041] S5. Placing the device in a near-saturated concentration of a perovskite precursor solution, and slowly evaporating the solution under heating to form a perovskite single crystal array. Specifically, placing the device after step S4 in a preheated container filled with a near-saturated precursor solution, completely immersing the device, and then properly sealing the container mouth to achieve an appropriate solvent evaporation rate;

[0042] S6. Take out the device, clean and dry it to obtain a complete photodetector, and then test and apply it.

[0043] Step S1 includes the following sub-steps:

[0044] S11. When preparing a low-concentration perovskite precursor solution, the molar mass ratio of lead halide to methylamine halide or cesium halide is 1:1, and a mixture of N,N-dimethylformamide and dimethyl sulfoxide is selected as the solvent. For example, methylamine bromide and lead bromide powder are mixed in a molar ratio of 1:1 and dissolved in a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 5:1, with a concentration of 0.7-1.0 mol / L;

[0045] S12. When preparing a perovskite precursor solution with a near-saturated concentration, the molar mass ratio of lead halide and methylamine halide or cesium halide is 1:1, and one of N,N-dimethylformamide or dimethyl sulfoxide is selected as the solvent. For example, methylamine bromide and lead bromide powder are mixed in a molar ratio of 1:1 and dissolved in N,N-dimethylformamide solvent.

[0046] The mixed solvent is selected in step S11 to prepare a polycrystalline thin film with larger grains and greater density, while the single solvent is selected in step S12 to better control the growth of the single crystal.

[0047] Step S2 includes the following sub-steps:

[0048] S21, the substrate is cleaned in sequence using deionized water, ethanol, acetone, and isopropanol, wherein the cleaning process can be performed by ultrasonically treating the substrate in each solvent for 20 minutes;

[0049] S22. Use a nitrogen gun to blow dry the cleaned substrate. Using a nitrogen gun to blow dry can effectively prevent dust particles from adhering to the substrate during drying.

[0050] S23. The dried substrate is treated with ultraviolet light for 10-15 minutes to eliminate various chemical substances and groups adsorbed on the surface of the substrate, thereby improving the wettability of the substrate with the perovskite precursor solution and facilitating the formation of a dense polycrystalline film.

[0051] The substrate selected above may be a glass substrate or a flexible substrate.

[0052] In certain preferred embodiments, the preparation of the polycrystalline thin film in step S3 uses a perovskite precursor solution with a relatively low concentration, and can be performed using any of one-step spin coating, two-step spin coating, doctor blade coating, spray coating, inkjet coating, and roll-to-roll methods. Specifically, taking the one-step spin coating method as an example, 50-65 μL of the perovskite precursor solution is drawn onto the substrate, and after setting the spin coating table parameters, spin coating is started. After approximately 15 seconds, 150-250 μL of the antisolvent is continuously and rapidly added dropwise. After the spin coating is completed, the device is transferred to a heating table for annealing, thereby achieving the effect of the first step shown in the accompanying drawings.

[0053] The spin coating parameters should be set as follows: initial speed and time: 1500-2500 rpm and 10 seconds; final speed and time: 5000-6000 rpm and 20 seconds. The initial speed should not be too low to reduce the thickness of the polycrystalline film.

[0054] Among them, the anti-solvent can be chlorobenzene, toluene and ethyl acetate.

[0055] The annealing temperature is 100-270° C. and the annealing time is 10-120 min. The specific parameters depend on the composition of the selected perovskite.

[0056] The metal electrode in step S4 can be prepared by methods such as evaporation or magnetron sputtering. In addition, transparent electrodes such as silver nanowires, carbon nanotubes, indium tin oxide, etc. can also be used. The final effect is shown in step 2 in the accompanying figure.

[0057] The spacing between the electrodes is between 1-10 μm, and the spacing should not be too large to ensure that many irregular single crystals are not formed between each spacing. The thickness of the electrode is 50-150 nm.

[0058] Among them, the structure of the metal electrode can be realized by designing different styles of masks, while transparent electrodes such as silver nanowires, carbon nanotubes, and indium tin oxide can realize different patterns through photolithography technology after preparation.

[0059] In certain preferred embodiments, step S5 is as shown in step three in the accompanying drawings. Specifically, the nearly saturated perovskite precursor solution is first transferred to a beaker and placed on a heating table for preheating. After reaching the required temperature, the device after step S4 is completed is placed in the beaker so that the solution completely immerses the device. Then, the beaker mouth is wrapped with aluminum foil and the edges are sealed with sealing film. Then, a syringe is used to open several small holes on the aluminum foil to achieve the purpose of controlling the evaporation rate of the solution. After a period of time, the device is taken out and the single crystal array growth is completed, as shown in step four in the accompanying drawings.

[0060] The temperature of the heating stage is 50-100° C., and the heating time is 8-24 hours.

[0061] Before placing the device into the solution, the back of the device should be wiped clean with ethanol and blown dry to avoid introducing too much impurities and contaminating the experiment.

[0062] Among them, the perovskite single crystal is first constrained by the electrodes and grows between the electrodes. When the height of the single crystal exceeds the thickness of the electrode, the width of the single crystal will exceed the electrode spacing and cover it.

[0063] In certain preferred embodiments, the cleaning process in step S6 includes cleaning the perovskite single crystal array and the back of the device. The perovskite single crystal array surface can be cleaned using solvents such as chlorobenzene or toluene. These solvents can effectively remove organic solvents attached to the surface without destroying the array structure, while the back of the device can be wiped clean with N,N-dimethylformamide, and then dried to obtain a complete perovskite single crystal array photodetector.

[0064] The preparation method of the perovskite single crystal array photodetector provided by the present invention can be summarized as follows: first, a polycrystalline thin film and an electrode structure are prepared, and then a single crystal array is grown. Among them, the preparation of the polycrystalline thin film and the electrode structure are both indispensable. If there is only a polycrystalline thin film without an electrode structure, the perovskite single crystal will grow irregularly in various places on the film; if there is only an electrode structure without a polycrystalline thin film, the growth of the single crystal lacks a suitable epitaxial substrate, the points of single crystal growth will be sparse, unable to form the required array, and the contact between the single crystal and the substrate is not firm and is easy to fall off.

[0065] The preparation method provided by the present invention is generally simple to operate and cost-effective. The prepared single crystal array directly forms a photodetector with an electrode without further processing. It fully utilizes the advantage of the controllable perovskite composition and meets the requirements of pattern diversification and large-area modules.

[0066] Example embodiment:

[0067] S1. Dissolve methylammonium bromide and lead bromide in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 5:1 at a molar mass ratio to prepare a 0.7 mol / L lower concentration perovskite precursor solution. Dissolve methylammonium bromide and lead bromide in an N,N-dimethylformamide solution in a molar mass ratio of 1:1 to prepare a 1.4 mol / L nearly saturated perovskite precursor solution.

[0068] S2. Ultrasonic cleaning of the glass substrate in deionized water, ethanol, acetone, and isopropanol for 20 minutes, followed by drying with a nitrogen gun, and finally irradiation with ultraviolet light for 15 minutes.

[0069] S3. Spread 50 μl of a lower-concentration perovskite precursor solution on a glass substrate. Set the spin-coating parameters as follows: initial speed and time are 1500 rpm and 10 s, and final speed is 5000 rpm and 20 s. Start the spin-coating station and flush 250 μl of chlorobenzene with a pipette after 15 s. After spin coating, anneal on a heating plate at 100°C for 10 min.

[0070] S4, using an evaporation process to prepare a patterned gold electrode on the polycrystalline film with the help of a mask, the electrode thickness is 100 nm;

[0071] S5. Take a 50ml beaker, add 5ml of nearly saturated perovskite precursor solution, place it on a heating table at 100℃ to preheat for 5 minutes, then place the gold-deposited device into it, ensuring that it is completely immersed in the solution. Then wrap the mouth of the beaker with aluminum foil and seal the edges with parafilm. Use a syringe to make three small holes in the aluminum foil. After standing for 6 hours, remove the device;

[0072] S6. Soak the removed device in a chlorobenzene solution to remove the organic solvent attached to the surface, then place it on a heating table to dry, and wipe the back of the device with N,N-dimethylformamide to finally obtain a perovskite single crystal array photodetector.

[0073] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, they can make improvements or changes based on the above description, but all these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing a perovskite single crystal array photodetector, characterized in that: The specific steps are as follows: S1, prepare perovskite precursor solutions with lower concentration and near saturation concentration respectively; S2. Prepare a clean substrate; S3, using a lower concentration of perovskite precursor solution to prepare a dense perovskite polycrystalline film on a substrate; S4, preparing an electrode with a certain pattern on the perovskite polycrystalline film; S5, placing the device in a near-saturated concentration of a perovskite precursor solution, and slowly evaporating the solution under heating to form a perovskite single crystal array; S6. Take out the device, clean it, and dry it; In step S1, a perovskite precursor solution is prepared, using lead halide and methylamine halide or cesium halide as solutes, N,N-dimethylformamide and / or dimethyl sulfoxide mixture as solvent, and the molar ratio of lead halide to methylamine halide or cesium halide is 1:1; When preparing a lower concentration of perovskite precursor solution, the solvent is a mixture of N, N-dimethylformamide and dimethyl sulfoxide, and the concentration of the perovskite precursor solution is 0.7-1.0 mol / L; When preparing a perovskite precursor solution with a near-saturation concentration, the solvent is N,N-dimethylformamide or a dimethyl sulfoxide mixture, and the concentration of the perovskite precursor solution is 1.4-1.6 mol / L.

2. The preparation method according to claim 1, characterized in that In step S1, the lead halide is one of lead iodide, lead bromide, and lead chloride, the methylamine halide is one of methylamine iodide, methylamine bromide, and methylamine chloride, and the cesium halide is one of cesium iodide, cesium bromide, and cesium chloride.

3. The preparation method according to claim 1, characterized in that In step S2, the substrate is a glass substrate or a flexible substrate; the substrate is cleaned with deionized water, ethanol, acetone, and isopropyl alcohol in sequence, and blown dry with a nitrogen gun; and then treated with ultraviolet light for 10-15 minutes.

4. The preparation method according to claim 1, characterized in that In step S3, the perovskite polycrystalline thin film is prepared by any one of a one-step spin coating method, a two-step spin coating method, a doctor blade method, a spray coating method, an inkjet method, and a roll-to-roll method; the thickness of the polycrystalline thin film is 100-150 nm.

5. The preparation method according to claim 4, characterized in that In step S3, when a one-step spin coating method is used, the settings of the spin coating station are: initial speed and time: 1500-2500 rpm and 10 s; final speed and time: 5000-6000 rpm and 20 s.

6. The preparation method according to claim 4, characterized in that In step S4, the distance between the electrodes is 1-10 μm, and the thickness of the electrodes is 50-150 nm.

7. The preparation method according to claim 4, characterized in that In step S5, the solution is slowly evaporated under heating, the heating temperature is 50-100° C., and the evaporation time is 8-24 hours.

8. The preparation method according to claim 4, characterized in that In step S6, the cleaning is to use chlorobenzene or toluene solvent to clean the device surface, and the drying is to use a heating platform to remove the residual organic solvent.

9. A perovskite single crystal array photodetector obtained by the preparation method according to any one of claims 1 to 8.

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