Low-temperature PS preparation method of height-controllable all-inorganic perovskite thin film array

Abstract

The invention discloses a low-temperature PS preparation method of a height-controllable all-inorganic perovskite thin film array, and belongs to the technical field of all-inorganic perovskite polycrystalline thin film array growth. The method comprises the following steps of: covering a layer of photoresist with a target array pattern on a substrate through a photoetching method; vertically placing the substrate in a tubular furnace, and keeping a distance from the substrate to the quartz boat filled with the PbI2 medicine; cleaning with acetone to remove the photoresist covering the surface of the substrate to obtain a patterned PbI2 film array; and spin-coating a methanol solution of CsBr added with cesium acetate on the PbI2 thin film array, converting to obtain a CsPbI3-xBrx thin film array, and annealing at 135 DEG C for 15 minutes to improve the crystallinity of the thin film. The prepared perovskite polycrystalline thin film is compact and flat in surface, good in crystallinity, accurate in position of each pixel point of an array, uniform in thickness and size, controllable in morphology, thickness and height and good in quality, and has good universality and universality.

Description

Technical Field

[0001] The invention belongs to the technical field of all-inorganic perovskite polycrystalline thin film array growth, and specifically relates to a low-temperature PS preparation method for a highly controllable all-inorganic perovskite thin film array. Background Art

[0002] Simulating the human visual system and developing flexible photodetector (PD) arrays with wide field of view, high resolution, color resolution and adaptability to optical environments are the key to realizing bionic eyes and bionic robots. Compared with organic-inorganic hybrid perovskites, all-inorganic perovskite materials show better environmental stability, and also have the characteristics of long carrier lifetime, diffusion length, adjustable band gap and high absorption coefficient. They are the preferred materials for manufacturing large-scale, high-performance PD arrays. From previous studies on the preparation of high-resolution all-inorganic perovskite film arrays on flexible substrates, it is difficult to obtain continuous, flat, high-quality perovskite films due to the fast crystallization process of the solution method. Although chemical vapor deposition (CVD) can obtain high-quality polycrystalline films, it is also difficult to obtain high-resolution flexible PD arrays due to the high deposition temperature, which exceeds the temperature tolerance range of photoresist and flexible substrates. Therefore, it is urgent to develop an all-inorganic perovskite film array growth technology that is compatible with photolithography and flexible substrates and can regulate the morphology and thickness of film materials. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a low-temperature PS preparation method for a highly controllable all-inorganic perovskite thin film array. The perovskite thin film array prepared by this method has good quality and highly controllable morphology and thickness, and has good universality and versatility.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0005] A low-temperature PS preparation method for a highly controllable all-inorganic perovskite film array comprises the following steps:

[0006] (1) Covering the substrate with a layer of photoresist having a target array pattern by photolithography;

[0007] (2) Place the substrate prepared in step (1) vertically in a tube furnace and place it in a tube furnace filled with PbI 2 The quartz boats of medicines are kept at a certain distance;

[0008] (3) Cleaning with acetone solution to remove the photoresist covering the substrate surface to obtain patterned PbI 2 Thin film arrays;

[0009] (4) In step (3), PbI 2The film array was spin-coated with a methanol solution of CsBr with cesium acetate added, and then spin-coated to obtain CsPbI 3-x Br x The film array was prepared and annealed at 135 °C for 15 min to improve the crystallinity of the film, wherein x is not greater than 3.

[0010] Furthermore, the substrate in step (1) is a rigid substrate and a flexible substrate, and the flexible substrate includes p-xylene-C and polydimethylsiloxane.

[0011] Furthermore, in step (2), the distance between the substrate and the quartz boat is 11 cm.

[0012] Furthermore, in step (2), the reaction temperature of the tubular furnace is 320°C, and the heating rate is 15°C / min.

[0013] Furthermore, in the step (3), the PVD time is controlled to be 30-80 min.

[0014] Furthermore, in the step (4), the spin coating speed is 4000 rpm and the time is 1 min.

[0015] Furthermore, the concentration of cesium acetate in step (4) is 1.75 mg / mL.

[0016] Furthermore, in step (4), x is 1.

[0017] Furthermore, any of the above-mentioned low-temperature PS preparation methods for highly controllable all-inorganic perovskite thin film arrays can prepare highly controllable all-inorganic perovskite thin film arrays.

[0018] Furthermore, the highly controllable all-inorganic perovskite thin film array is used in the preparation of photodetectors.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] (1) The preparation method of the present invention is compatible with the photolithography process. The surface of the prepared perovskite polycrystalline film is dense and flat, with good crystallinity. The pixel points of the array are precisely positioned, and the thickness and size are uniform.

[0021] (2) The annealing temperature in the present invention is reduced from the traditional 260°C or above to 120°C, realizing a preparation method compatible with a variety of flexible substrates.

[0022] (3) The preparation method of the present invention can prepare thin film arrays with complex patterns including rectangles, circles and letters by changing the mask pattern in the photolithography process; by controlling the PVD time, the thickness of the precursor film can be controlled, thereby controlling the thickness of the converted perovskite film; by controlling the distance between the substrate and the drug source in the tubular furnace, the surface morphology of the precursor can be controlled, and the morphology of the converted perovskite polycrystalline film can be further controlled.

[0023] (4) The preparation method of the present invention can grow perovskite thin film arrays with controllable morphology, thickness and height and good quality on rigid substrates such as glass and flexible substrates such as PMDS (polydimethylsiloxane) and Parylence-C (paraxylene-C), and has good universality and versatility. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The CsPbI prepared by the present invention 3-x Br x The synthesis process of perovskite arrays;

[0025] Figure 2 It is CsPbI prepared in Example 1 of the present invention 3-x Br x XRD patterns of polycrystalline thin films;

[0026] Figure 3 It is PbI prepared in Example 1 of the present invention 2 SEM image of polycrystalline thin film;

[0027] Figure 4 It is CsPbI prepared in Example 1 of the present invention 3-x Br x SEM image of polycrystalline thin film;

[0028] Figure 5 It is CsPbI of different geometric shapes and patterns in Example 1 of the present invention 3-x Br x Thin film array images;

[0029] Figure 6 The PbI prepared by different substrate and chemical source spacing in the PVD process of Example 1 of the present invention is 2 and CsPbI 3-x Br x Surface morphology comparison of polycrystalline thin films;

[0030] Figure 7 The PbI obtained in Examples 1-3 of the present invention at different PVD times 2 Thin films and CsPbI 3-x Br x Film thickness comparison chart;

[0031] Figure 8 The PVD time and the obtained PbI 2 Thin films and CsPbI 3-x Br x Film thickness curve relationship diagram;

[0032] Fig. 9 The corresponding CsPbI when different concentrations of cesium acetate are added to the CsBr solution in Examples 1, 4 and 5 of the present invention 3- x Br x Crystal phase transition temperature diagram;

[0033] Fig.10 The corresponding CsPbI when different concentrations of cesium acetate are added to the CsBr solution in Examples 1, 4 and 5 of the present invention 3- x Br x Graph of the change in crystal photocurrent. DETAILED DESCRIPTION

[0034] The present invention is further illustrated below in conjunction with specific examples. The examples are implemented based on the technical solutions of the present invention. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0035] In the following examples, CsPbI 3-x Br x The x in the perovskite array represents the specific number of spin coating, x=1.

[0036] Figure 1 To prepare CsPbI 3-x Br x The synthesis process of the perovskite array, the synthesis route is:

[0037] (1) Covering the substrate with a layer of photoresist having a target array pattern by photolithography;

[0038] (2) Place the substrate prepared in step (1) vertically in a tube furnace and place it in a tube furnace filled with PbI 2 The quartz boats of medicines are kept at a certain distance;

[0039] (3) Cleaning with acetone solution to remove the photoresist covering the substrate surface to obtain patterned PbI 2 Thin film arrays;

[0040] (4) In step (3), PbI 2 The film array was spin-coated with a methanol solution of CsBr with cesium acetate added, and then spin-coated to obtain CsPbI 3-x Br xThe film arrays were annealed at 135 °C for 15 min to improve the crystallinity of the films.

[0041] Example 1

[0042] A layer of photoresist with a target array pattern was covered on a glass rigid substrate by photolithography, and then placed vertically in a tube furnace and calcined at 320 °C with a heating rate of 15 °C / min and kept warm for 30 min. 2 The source was kept at 11 cm, and a layer of PbI with a thickness of about 190 nm was grown on the substrate by PVD (physical vapor deposition) for 30 min. 2 Polycrystalline film. After removing the photoresist covering the substrate surface with acetone solution, the patterned PbI 2 Thin film array. In this PbI 2 The film array was spin-coated with a methanol solution of CsBr with 1.75 mg / mL cesium acetate added for 1 min at a speed of 4000 rpm to obtain CsPbI 3-x Br x The film array was then annealed at 135 °C for 15 minutes to obtain a 180 nm CsPbI 3-x Br x Thin film array.

[0043] Figure 2 For the preparation of CsPbI 3-x Br x The XRD pattern shows two strong characteristic diffraction peaks at 14.8° and 29.8°, which are consistent with CsPbI 3-x Br x The (110) and (220) cubic phase perovskite structures are consistent, indicating that the perovskite arrays prepared by the PS method have good crystallinity.

[0044] Figure 3 PbI prepared by PVD 2 SEM image of the film, the image shows PbI 2 The film surface is tight, the crystal shape is regular and uniform, and the edges are clear.

[0045] Figure 4 The converted CsPbI 3-x Br x SEM image of polycrystalline perovskite film. The image shows that the film surface is uniform and flat. Figure 3 It can be seen that the surface morphology of the perovskite polycrystalline film prepared by the PS method proposed in the present invention is dense, flat and controllable.

[0046] Figure 5 CsPbI with different geometric shapes and patterns 3-xBr x The thin film array image can realize arrays of different geometric shapes, including more complex patterns such as rectangles, circles and letters, by changing the mask pattern in the photolithography process, which shows that the PS preparation method proposed in the present invention is feasible and universal.

[0047] Figure 6 PbI prepared by different substrate and chemical source spacing in the PVD process of the present invention 2 and CsPbI 3-x Br x Surface morphology comparison of polycrystalline films. When the substrate is in the proper position (the distance between the two is 9.5-10.5 cm), PbI 2 The surface morphology of polycrystalline films becomes controllable. When close to the drug source, PbI 2 The crystal grows perpendicular to the substrate surface. The farther away from the drug source, the 2 The smoother and more regular the surface morphology of the crystal, the better the PbI 2 The crystal morphology and surface morphology of the film will directly affect the converted CsPbI 3-x Br x Perovskite film morphology. This shows that PbI can be tuned by precisely controlling the location of the source and substrate. 2 The growth direction of the thin film crystals can be precisely controlled to precisely regulate the surface morphology of the converted perovskite film.

[0048] Example 2

[0049] A layer of photoresist with a target array pattern was covered on a glass rigid substrate by photolithography, and then placed vertically in a tube furnace and calcined at 320 °C with a heating rate of 15 °C / min and kept warm for 30 min. 2 The source was kept at 11 cm, and a layer of PbI with a thickness of about 510 nm was grown on the substrate by PVD (physical vapor deposition) for 60 min. 2 Polycrystalline film. After removing the photoresist covering the substrate surface with acetone solution, the patterned PbI 2 Thin film array. In this PbI 2 The film array was spin-coated with a methanol solution of CsBr with 1.75 mg / mL cesium acetate added for 1 min at 4000 rpm to obtain CsPbI with a particle size of 508 nm. 3-x Br x The film array was then annealed at 135 °C for 15 minutes to obtain CsPbI 3-x Br x Thin film array.

[0050] Example 3

[0051] A layer of photoresist with a target array pattern was covered on a glass rigid substrate by photolithography, and then placed vertically in a tube furnace and calcined at 320 °C with a heating rate of 15 °C / min and kept warm for 30 min. 2 The source was kept at 11 cm, and a layer of PbI with a thickness of about 750 nm was grown on the substrate by PVD (physical vapor deposition) for 80 min. 2 Polycrystalline film. After removing the photoresist covering the substrate surface with acetone solution, the patterned PbI 2 Thin film array. In this PbI 2 The film array was spin-coated with a methanol solution of CsBr with 1.75 mg / mL cesium acetate added for 1 min at 4000 rpm to obtain CsPbI with a particle size of 730 nm. 3-x Br x The film array was then annealed at 135 °C for 15 minutes to obtain CsPbI 3-x Br x Thin film array.

[0052] Figure 7 PbI obtained by different PVD times in Examples 1-3 2 Thin films and CsPbI 3-x Br x Film thickness comparison chart, as PVD deposition time increases, PbI 2 Thin films and CsPbI 3-x Br x The film thickness increases, indicating that the PbI 2 The thickness of the film can be adjusted to adjust the converted CsPbI 3-x Br x Thickness of the perovskite film.

[0053] Figure 8 is the PVD deposition time, PbI 2 Film thickness and converted CsPbI 3-x Br x Relationship between the thickness of perovskite films and PbI prepared with the same PVD deposition time 2 Film thickness and converted CsPbI 3-x Br x The film thickness is almost the same, which further proves that PbI can be adjusted by controlling the PVD time. 2 The thickness of the film can be adjusted to adjust the converted CsPbI 3-x Br x Thickness of the perovskite film.

[0054] Example 4

[0055] A layer of photoresist with a target array pattern was covered on a glass rigid substrate by photolithography, and then placed vertically in a tube furnace and calcined at 320 °C with a heating rate of 15 °C / min and kept warm for 30 min. 2 The source was kept at 11 cm, and a layer of PbI with a thickness of about 190 nm was grown on the substrate by PVD (physical vapor deposition) for 30 min. 2 Polycrystalline film. After removing the photoresist covering the substrate surface with acetone solution, the patterned PbI 2 Thin film array. In this PbI 2 The film array was spin-coated with a methanol solution of CsBr with 1.0 mg / mL cesium acetate added for 1 min at a speed of 4000 rpm to obtain CsPbI 3-x Br x The film array was then annealed at 135 °C for 15 minutes to obtain a 180 nm CsPbI 3-x Br x Thin film array. Example 5

[0056] A layer of photoresist with a target array pattern was covered on a glass rigid substrate by photolithography, and then placed vertically in a tube furnace and calcined at 320 °C with a heating rate of 15 °C / min and kept warm for 30 min. 2 The source was kept at 11 cm, and a layer of PbI with a thickness of about 190 nm was grown on the substrate by PVD for 30 min. 2 Polycrystalline film. After removing the photoresist covering the substrate surface with acetone solution, the patterned PbI 2 Thin film array. In this PbI 2 The film array was spin-coated with a methanol solution of CsBr with 3.0 mg / mL cesium acetate added for 1 min at a speed of 4000 rpm to obtain CsPbI 3-x Br x The film array was then annealed at 135 °C for 15 minutes to obtain a 180 nm CsPbI 3-x Br x Thin film array.

[0057] Fig. 9 The corresponding CsPbI when different concentrations of cesium acetate are added to the CsBr solution in Examples 1, 4, and 5 3-x Br x Crystal phase transition temperature, without adding cesium acetate, CsPbI 3-x Br xThe crystal phase transition temperature is as high as 320 °C. When 0.75, 1, 1.25, 1.5, 1.75, 2 and 3 mg / mL of cesium acetate are added to the CsBr solution, the phase transition temperature decreases to 280 °C, 220 °C, 180 °C, 150 °C, 135 °C and 120 °C, respectively, indicating that adding cesium acetate to the methanol solution of CsBr during the spin coating step can effectively reduce the phase transition temperature of CsPbI 3-x Br x Annealing temperature of perovskite films.

[0058] Fig.10 The corresponding CsPbI when different concentrations of cesium acetate are added to the CsBr solution in Examples 1, 4, and 5 3-x Br x The change diagram of crystal photocurrent shows that when the concentration of cesium acetate is 0-2 mg / mL, the photoelectric properties of the material are tested and it is found that the photocurrent does not change significantly compared with that without adding cesium acetate. When the concentration exceeds 2 mg / mL, it will cause CsPbI 3- x Br x Severe degradation of the optoelectronic properties of the crystal.

[0059] Example 6

[0060] First, a Parylene-C (para-xylene-C) flexible substrate was deposited on a silicon wafer with a conductivity of less than 0.1 S / cm, and then a metal electrode array was deposited on the surface of the Parylene-C (para-xylene-C) substrate. Then, a layer of photoresist with a target array pattern was covered on the substrate with the electrode deposited by photolithography. The substrate was placed vertically in a tube furnace and calcined at 320 °C with a heating rate of 15 °C / min for 30 min. 2 The quartz boats of the drugs were separated by 11 cm, and a layer of PbI with a thickness of about 200 nm was grown on the substrate by PVD (physical vapor deposition) for 30 min. 2 Polycrystalline film. The photoresist covering the substrate surface is removed by cleaning with acetone solution to obtain a patterned PbI 2 Then on the above PbI 2 The film array was spin-coated with a methanol solution of CsBr with 1.75 mg / mL cesium acetate added for 1 min at 4000 rpm to obtain 180 nm CsPbI 3-x Br x The thin film array was annealed at 135 °C for 15 minutes. After the photosensitive layer of the PD (photodetector) array was prepared by the above PS growth method, Parylene-C (paraxylene-C) was used for encapsulation, and the PD array device was peeled off from the silicon wafer by an electrochemical method.

[0061] Example 7

[0062] First, a PDMS (polydimethylsiloxane) flexible substrate was deposited on a glass sheet, and then a metal electrode array was deposited on the surface of the PDMS (polydimethylsiloxane) substrate. Then, a layer of photoresist with a target array pattern was covered on the substrate with the electrode deposited by photolithography. The substrate was placed vertically in a tube furnace and calcined at 320 °C with a heating rate of 15 °C / min for 30 min. 2 The quartz boats of the drugs were separated by 11 cm, and a layer of PbI with a thickness of about 200 nm was grown on the substrate by PVD (physical vapor deposition) for 30 min. 2 Polycrystalline film. The photoresist covering the substrate surface is removed by cleaning with acetone solution to obtain a patterned PbI 2 Then on the above PbI 2 The film array was spin-coated with a methanol solution of CsBr with 1.75 mg / mL cesium acetate added for 1 min at 4000 rpm to obtain 180 nm CsPbI 3-x Br x The film array was annealed at 135 °C for 15 minutes. After the photosensitive layer of the PD (photodetector) array was prepared by the above PS growth method, it was encapsulated using PDMS (polydimethylsiloxane), and the PD array device was peeled off from the glass sheet by an electrochemical method.

[0063] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A low-temperature PS preparation method for a highly controllable all-inorganic perovskite film array, characterized in that: The following steps are involved: (1) Covering the substrate with a layer of photoresist having a target array pattern by photolithography; (2) placing the substrate of step (1) vertically in a tube furnace, keeping a certain distance from the quartz boat containing PbI2 chemical; (3) Cleaning with acetone solution to remove the photoresist covering the surface of the substrate to obtain a patterned PbI2 thin film array; (4) Spin-coat a methanol solution of CsBr with cesium acetate added on the PbI2 thin film array of step (3) to obtain CsPbI 3-x Br x The film array was prepared and annealed at 135 °C for 15 min to improve the crystallinity of the film, wherein x is not greater than 3.

2. The low-temperature PS preparation method of highly controllable all-inorganic perovskite thin film array according to claim 1, characterized in that: The substrate in step (1) is a rigid substrate and a flexible substrate, and the flexible substrate includes p-xylene-C and polydimethylsiloxane.

3. The low-temperature PS preparation method of highly controllable all-inorganic perovskite thin film array according to claim 1, characterized in that: In the step (2), the distance between the substrate and the quartz boat is 11 cm.

4. The low-temperature PS preparation method of highly controllable all-inorganic perovskite thin film array according to claim 1, characterized in that: In the step (2), the reaction temperature of the tubular furnace is 320°C, and the heating rate is 15°C / min.

5. The low-temperature PS preparation method of highly controllable all-inorganic perovskite thin film array according to claim 1, characterized in that: The PVD time in step (3) is controlled to be 30-80 min.

6. The low-temperature PS preparation method of highly controllable all-inorganic perovskite thin film array according to claim 1, characterized in that: The spin coating speed in step (4) is 4000 rpm and the time is 1 min.

7. The low-temperature PS preparation method of highly controllable all-inorganic perovskite thin film array according to claim 1, characterized in that: The concentration of cesium acetate in step (4) is 1.75 mg / mL.

8. The low-temperature PS preparation method of highly controllable all-inorganic perovskite thin film array according to claim 1, characterized in that: In the step (4), x is 1.

9. According to the low-temperature PS preparation method of a highly controllable all-inorganic perovskite thin film array according to any one of claims 1 to 7, a highly controllable all-inorganic perovskite thin film array is prepared.

10. Use of the highly controllable all-inorganic perovskite thin film array according to claim 8 in the preparation of photodetectors.

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