Lipss-based perovskite single crystal thin film and preparation method and application thereof
By using vertically polarized femtosecond laser double pulses to process the substrate and surface in a perovskite photodetector, LIPSS perovskite single-crystal thin films were prepared, solving the problem of poor light absorption of perovskite thin films and improving quantum efficiency and responsivity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- YANGTZE DEITA GRADUATE SCHOOI OF BEIJING INST OF TECH (JIAXING)
- Filing Date
- 2023-04-14
- Publication Date
- 2026-07-14
AI Technical Summary
Existing perovskite thin films exhibit poor light absorption, low quantum efficiency and responsivity in photodetectors, with approximately 14% of the incident light being reflected by the surface, thus limiting device performance.
LIPSS-based perovskite single-crystal thin films were fabricated by processing the substrate and perovskite single-crystal surface using vertically polarized femtosecond laser dual-pulse technology. By inducing periodic micro- and nano-structures on the substrate and active layer surfaces, light absorption was enhanced and reflection was reduced.
This improves the light absorption efficiency of perovskite thin films, reduces surface reflectivity by at least 5%, enhances photogenerated carrier collection, and improves the performance of photodetectors.
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Figure CN116367679B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of perovskite photodetector technology, specifically to a LIPSS-based perovskite single-crystal thin film, its preparation method, and its application. Background Technology
[0002] In recent years, organic-inorganic hybrid perovskites have attracted widespread attention due to their advantages such as high light absorption coefficient, wide absorption range, long carrier diffusion length, and tunable band gap. Because of these unique photoelectric properties, perovskites are widely used in photodetectors, light-emitting diodes, lasers, and solar cells. Commonly used organic-inorganic hybrid perovskite materials have the chemical formula ABX3, where A represents a monovalent organic cation, such as methylamine cation (CH3NH3). + ), Methylimide cation (H2CH=NH + ) and ethylamine cation (CH3CH2NH3) + ) etc., B refers to inorganic metal cations, such as lead ions (Pb). 2+ ) and tin ions (Sn 2+ ) etc., where X refers to a halide anion, such as chloride ion (Cl... - ), bromide ions (Br) - ) and iodide ions (I - )wait.
[0003] As the absorber layer of optoelectronic devices, the quality of perovskite often determines the performance of these devices. Perovskite thin films are classified into single-crystal and polycrystalline films. Although polycrystalline perovskite films are currently the mainstream absorber layer for optoelectronic devices, they have a defect density at least four orders of magnitude higher than that of single-crystal perovskite. However, due to the high nucleation energy barrier, single-crystal perovskite is difficult to grow uniformly on smooth substrates, and its thickness is difficult to control. With continuous optimization and development of fabrication processes, single-crystal perovskite films with a thickness of a few micrometers can now be fabricated, and single-crystal perovskite films have great potential in the field of optoelectronic devices in the future. However, in perovskite photodetectors, approximately 14% of the incident light is reflected by the perovskite surface, which to some extent limits its quantum efficiency and responsivity. Summary of the Invention
[0004] To address the aforementioned technical problems, the present invention aims to provide a LIPSS-based perovskite single-crystal thin film, its preparation method, and its application, thereby solving the problems of poor light absorption, low quantum efficiency, and low responsivity of existing perovskite thin films.
[0005] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A method for preparing LIPSS perovskite single-crystal thin films is provided, comprising the following steps:
[0006] (1) A periodic surface structure is induced on the surface of a pretreated substrate by a vertically polarized femtosecond laser double pulse to obtain a processed substrate;
[0007] (2) A perovskite precursor solution was dropped onto the processed substrate obtained in step (1), a PDMS substrate was covered and gently pressed, and then heated to obtain a perovskite single crystal.
[0008] (3) On the perovskite single crystal surface obtained in step (2), a periodic structure is induced by a vertically polarized femtosecond laser double pulse to obtain a LIPSS-based perovskite single crystal thin film.
[0009] The beneficial effects of this invention are as follows: In perovskite photodetectors, approximately 14% of the incident light is reflected by the perovskite surface, which to some extent limits its quantum efficiency and responsivity. Fabricating micro / nano structures can extend the optical path, couple incident photons into the perovskite active layer, generate standing waves within the photoactive layer, enhance light absorption, and simultaneously reduce the diffusion length of local charge carriers, increase the contact area with the transport layer, and enhance the collection of photogenerated charge carriers. Femtosecond lasers have advantages such as high processing precision, low thermal effect, processing flexibility, and strong material adaptability. Utilizing femtosecond lasers to induce periodic micro / nano structures on the surface of a perovskite single crystal can reduce surface reflectivity by at least 5%, and is low-cost and simple to process, offering unparalleled advantages in the field of photodetection.
[0010] This invention employs a vertically polarized femtosecond laser dual-pulse scanning process. By controlling the direction of the excited SPPs (Special Purpose Particles) to always align with the scanning direction, periodic energy deposition occurs along the SPP direction. This ensures that the arrangement direction of the periodic structure is always perpendicular to the scanning direction, overcoming the traditional phenomenon in single-pulse processing where the arrangement direction of the periodic surface structure is perpendicular to the incident laser polarization direction. Furthermore, it overcomes the problem of significant fluctuations in the periodic structure across different scanning directions in traditional single-pulse processing, resulting in smoother and more regular micro / nano-scale periodic structures, which is beneficial for the subsequent uniform deposition of perovskite.
[0011] This invention utilizes vertically polarized femtosecond laser double pulses to fabricate surface periodic structures (LIPSS), i.e., trench shapes on a micro-nano scale, on a substrate. Then, a perovskite single crystal with a millimeter-scale size and micrometer-scale thickness is prepared using a spatial confinement growth method. Finally, a femtosecond laser is used again to fabricate the surface periodic structure on the perovskite single crystal surface. The first use of the femtosecond laser leverages the confinement effect of microchannels to prepare a large-area, appropriately thick, and higher-quality perovskite single crystal. The second use of the femtosecond laser induces periodic micro-nano structures, which minimize reflection on the perovskite single crystal surface and improve its absorption efficiency. Optoelectronic devices fabricated using the perovskite single crystal thin film of this invention not only possess superior optoelectronic performance but also feature simple fabrication and low cost.
[0012] Based on the above technical solution, the present invention can be further improved as follows:
[0013] Further, in step (1), the pretreated substrate is prepared by the following method: the substrate is ultrasonically cleaned with deionized water and anhydrous ethanol for 20-40 min respectively, then vacuum dried, and then treated with ultraviolet-ozone for 10-20 min to obtain the pretreated substrate.
[0014] Furthermore, in step (1), the substrate material is tin-doped indium oxide or fluorine-doped tin oxide.
[0015] Furthermore, in steps (1) and (3), the vertically polarized femtosecond laser double pulse is formed by the following method: a Michelson interferometer is used to convert the femtosecond laser single pulse into a femtosecond laser double pulse, and then a quarter-wave plate is used to change the polarization direction, thereby forming a vertically polarized femtosecond laser double pulse.
[0016] Furthermore, the center wavelength of the femtosecond laser is 800-1030nm, the repetition frequency is 900-1100Hz, and the pulse width is 50-270fs.
[0017] Furthermore, the femtosecond laser has a center wavelength of 1030 nm, a repetition frequency of 1000 Hz, and a pulse width of 270 fs.
[0018] Furthermore, in step (2), the concentration of the perovskite precursor solution is 0.08-0.12 mol / L.
[0019] Furthermore, in step (2), the concentration of the perovskite precursor solution is 0.1 mol / L.
[0020] Furthermore, the perovskite precursor is MAPbBr3.
[0021] Furthermore, in step (2), the perovskite precursor solution is prepared by the following method: MABr and PbBr2 are dissolved in DMF to obtain solution one and solution two, which are then mixed and shaken to obtain the perovskite precursor solution.
[0022] Furthermore, in step (2), heating is performed at 50-80°C.
[0023] Furthermore, the heating rate is 5-10℃ / min.
[0024] The present invention also provides LIPSS perovskite single crystal thin films prepared by the above method.
[0025] The present invention also provides the application of the above-mentioned LIPSS perovskite single crystal thin film in the fabrication of photodetectors.
[0026] The present invention has the following beneficial effects:
[0027] This invention combines femtosecond laser-induced periodic structure technology with spatial confinement growth method. By utilizing the confinement effect of the prepared periodic trenches, the transport of perovskite solute is stabilized, enabling uniform deposition of perovskite single-crystal thin films, improving crystal quality, and growing perovskite single-crystal thin films with millimeter-scale dimensions and micrometer-scale thicknesses, thereby improving carrier lifetime and mobility. On the other hand, by again inducing LIPSS on the perovskite surface using femtosecond laser, the optical path can be extended, coupling incident photons into the perovskite active layer, generating standing waves within the photoactive layer, enhancing light absorption, and simultaneously reducing the local carrier diffusion length, increasing the contact area with the transport layer, and enhancing the collection of photogenerated carriers. Attached Figure Description
[0028] Figure 1 This is a schematic diagram of the optical path of a vertically polarized femtosecond laser dual pulse.
[0029] Figure 2 This is an optical microscope image of the perovskite single crystal obtained in Example 1;
[0030] Figure 3 This is a model diagram of the absorption enhancement of the perovskite single crystal thin film prepared in Example 1;
[0031] Figure 4 The absorption enhancement curve of the perovskite single crystal thin film prepared in Example 1 is shown.
[0032] Figure 5 This is a schematic diagram illustrating the principle of enhanced absorption of the perovskite single-crystal thin film prepared in Example 1. Detailed Implementation
[0033] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.
[0034] Example 1:
[0035] A LIPSS-based perovskite single-crystal thin film is prepared by the following steps:
[0036] (1) The substrate ITO (tin-doped indium oxide) film was ultrasonically cleaned with deionized water and anhydrous ethanol for 30 min, vacuum dried, and treated with ultraviolet-ozone for 15 min to obtain a pretreated substrate. Then, it was placed on a femtosecond laser processing platform, and the delay platform of the Michelson interferometer was adjusted so that the delay between the two sub-pulses was 1 ps. The angle of the quarter-wave plate was rotated to 45° to obtain a vertically polarized femtosecond laser double pulse sequence. A 100 mm plano-convex lens (NA = 0.058) was used to focus the focal point on the ITO surface. The average power of the femtosecond laser was controlled to be 0.54 mw using an attenuator. The displacement speed of the translation stage was controlled by computer to be 1.1 mm / s, the scanning interval was 6 μm, the center wavelength of the femtosecond laser was 1030 nm, the repetition frequency was 1000 Hz, and the pulse width was 270 fs. Using the above method, a periodic structure was induced on the surface of the substrate by vertically polarized femtosecond laser double pulse to obtain the processed substrate.
[0037] (2) Using a balance of 0.001 mol, MABr and PbBr2 were obtained respectively and dissolved in 5 mL of DMF solvent to obtain solution one and solution two. The two solutions were mixed and shaken thoroughly until a transparent solution was obtained to prepare a perovskite precursor solution with a concentration of 0.1 mol / L. The perovskite precursor solution was dropped onto the processed substrate obtained in step (1), and a PDMS substrate was covered and gently pressed to make the solution spread evenly on the ITO surface and remove the air bubbles. The solution was heated at 60°C at a heating rate of 8°C / min until the solvent was completely evaporated and crystals precipitated to obtain a perovskite single crystal.
[0038] (3) On the perovskite single crystal surface obtained in step (2), the same method as in step (1) is used to induce the formation of a periodic structure on the surface by using a vertically polarized femtosecond laser double pulse to obtain a perovskite single crystal thin film based on LIPSS.
[0039] Example 2:
[0040] A LIPSS-based perovskite single-crystal thin film is prepared by the following steps:
[0041] (1) The substrate ITO (tin-doped indium oxide) film was ultrasonically cleaned with deionized water and anhydrous ethanol for 20 min, vacuum dried, and treated with ultraviolet-ozone for 10 min to obtain a pretreated substrate. Then, it was placed on a femtosecond laser processing platform, and the delay platform of the Michelson interferometer was adjusted so that the delay between the two sub-pulses was 1 ps. The angle of the quarter-wave plate was rotated to 45° to obtain a vertically polarized femtosecond laser double pulse sequence. A 100 mm plano-convex lens (NA = 0.058) was used to focus the focal point on the ITO surface. The average power of the femtosecond laser was controlled to be 0.54 mw using an attenuator. The displacement speed of the translation stage was controlled by computer to be 1.1 mm / s, the scanning interval was 6 μm, the center wavelength of the femtosecond laser was 800 nm, the repetition frequency was 900 Hz, and the pulse width was 50 fs. Using the above method, a periodic structure was induced on the surface of the substrate by vertically polarized femtosecond laser double pulse to obtain the processed substrate.
[0042] (2) Using a balance of 0.001 mol MABr and PbBr2, respectively, they were dissolved in 5 mL DMF solvent to obtain solution one and solution two. After mixing the two solutions, they were shaken thoroughly until a transparent solution was obtained to prepare a perovskite precursor solution with a concentration of 0.1 mol / L. The perovskite precursor solution was dropped onto the processed substrate obtained in step (1), and a PDMS substrate was covered and gently pressed to make the solution spread evenly on the ITO surface and remove the air bubbles. The solution was heated at 50°C with a heating rate of 5°C / min until the solvent was completely evaporated and crystals precipitated to obtain a perovskite single crystal.
[0043] (3) On the perovskite single crystal surface obtained in step (2), the same method as in step (1) is used to induce the formation of a periodic structure on the surface by using a vertically polarized femtosecond laser double pulse to obtain a perovskite single crystal thin film based on LIPSS.
[0044] Example 3:
[0045] A LIPSS-based perovskite single-crystal thin film is prepared by the following steps:
[0046] (1) The substrate ITO (tin-doped indium oxide) film was ultrasonically cleaned with deionized water and anhydrous ethanol for 40 min each, vacuum dried, and treated with ultraviolet-ozone for 20 min to obtain a pretreated substrate. Then, it was placed on a femtosecond laser processing platform, and the delay platform of the Michelson interferometer was adjusted to make the delay between the two sub-pulses 1 ps. The angle of the quarter-wave plate was rotated to 45° to obtain a vertically polarized femtosecond laser double pulse sequence. A 100 mm plano-convex lens (NA = 0.058) was used to focus the focal point on the ITO surface. The average power of the femtosecond laser was controlled to be 0.54 mW using an attenuator. The displacement speed of the translation stage was controlled by computer to be 1.1 mm / s, the scanning interval was 6 μm, the center wavelength of the femtosecond laser was 1030 nm, the repetition frequency was 1100 Hz, and the pulse width was 270 fs. The above method (see the optical path diagram) was used. Figure 1 A periodic surface structure is induced on the substrate surface using vertically polarized femtosecond laser double pulses to obtain the processed substrate;
[0047] (2) Using a balance of 0.001 mol, MABr and PbBr2 were obtained respectively and dissolved in 5 mL of DMF solvent to obtain solution one and solution two. The two solutions were mixed and shaken thoroughly until a transparent solution was obtained to prepare a perovskite precursor solution with a concentration of 0.1 mol / L. The perovskite precursor solution was dropped onto the processed substrate obtained in step (1), and a PDMS substrate was covered and gently pressed to make the solution spread evenly on the ITO surface and remove the air bubbles. The solution was heated at 80°C at a heating rate of 5°C / min until the solvent was completely evaporated and crystals precipitated to obtain a perovskite single crystal.
[0048] (3) On the perovskite single crystal surface obtained in step (2), the same method as in step (1) is used to induce the formation of a periodic structure on the surface by using a vertically polarized femtosecond laser double pulse to obtain a perovskite single crystal thin film based on LIPSS.
[0049] Comparative Example 1:
[0050] A LIPSS-based perovskite single-crystal thin film is prepared by the following steps:
[0051] Step (3) is excluded; the rest is the same as in Example 1.
[0052] Test case
[0053] I. The perovskite single crystal obtained in Example 1 was examined using an optical microscope. The results are shown in the figure. Figure 2 .
[0054] Depend on Figure 2 As can be seen under an optical microscope, the prepared perovskite crystals are uniformly distributed on the substrate, indicating that the film quality is good.
[0055] II. Using the LIPSS perovskite single-crystal thin film and the ITO planar structure of the substrate obtained in Example 1 and Comparative Example 1, the LIPSS structure simulation model and simulation results were obtained based on FDTD simulation. The results are shown in […]. Figure 3-4 ( Figure 4 In the diagram, at the horizontal axis of 450 nm, from top to bottom, are Example 1, Comparative Example 1, and a planar structure.
[0056] Depend on Figure 3-4 It is known that when LIPSS structures are fabricated only on the surface of the ITO layer, the MAPbBr3 absorbance only increases slightly at around 400-530 nm. Therefore, the main function of fabricating LIPSS on the ITO layer is to utilize the confinement effect of the prepared periodic trenches to stabilize the transport of perovskite solutes, achieve uniform deposition of perovskite single-crystal thin films, improve crystal quality, grow perovskite single-crystal thin films with millimeter-scale dimensions and micrometer-scale thickness, and improve carrier lifetime and mobility. However, when LIPSS structures are fabricated simultaneously on both the ITO and MAPbBr3 layers using the method of this invention, the absorbance of perovskite at 400-530 nm can be increased by 6-8%.
[0057] The mechanism for achieving absorption optimization by fabricating LIPSS structures in MAPbBr3 layers is as follows: Figure 5 When incident light reaches the LIPSS structure, it is trapped inside the structure and undergoes multiple internal reflections, thereby achieving maximum absorption of incident light by MAPbBr3.
[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing LIPSS perovskite single-crystal thin films, characterized in that, Includes the following steps: (1) A periodic surface structure is induced on the surface of the pretreated substrate by a vertically polarized femtosecond laser double pulse to obtain the processed substrate; (2) A perovskite precursor solution is dropped onto the processed substrate obtained in step (1), a PDMS substrate is covered and lightly pressed, and heated. The perovskite single crystal is obtained by utilizing the confinement effect of the surface periodic structure. (3) On the perovskite single crystal surface obtained in step (2), a periodic structure is induced by vertically polarized femtosecond laser double pulse to obtain a perovskite single crystal thin film based on LIPSS. The process employs a vertically polarized femtosecond laser dual-pulse sequence scanning. By controlling the direction of the excited SPPs to always be along the scanning direction, periodic energy deposition occurs along the direction of the SPPs, ensuring that the arrangement direction of the periodic structure is always perpendicular to the scanning direction.
2. The method for preparing LIPSS-based perovskite single-crystal thin films according to claim 1, characterized in that, In step (1), the pretreated substrate is prepared by the following method: the substrate is ultrasonically cleaned with deionized water and anhydrous ethanol for 20-40 min respectively, then vacuum dried, and then treated with ultraviolet-ozone for 10-20 min to obtain the pretreated substrate.
3. The method for preparing LIPSS-based perovskite single-crystal thin films according to claim 1 or 2, characterized in that, In step (1), the substrate material is tin-doped indium oxide or fluorine-doped tin oxide.
4. The method for preparing LIPSS-based perovskite single-crystal thin films according to claim 1, characterized in that, In steps (1) and (3), the vertically polarized femtosecond laser double pulse is formed by the following method: a Michelson interferometer is used to convert the femtosecond laser single pulse into a femtosecond laser double pulse, and then a quarter-wave plate is used to change the polarization direction, thereby forming a vertically polarized femtosecond laser double pulse.
5. The method for preparing LIPSS-based perovskite single-crystal thin films according to claim 4, characterized in that, The center wavelength of a femtosecond laser is 800-1030nm, the repetition frequency is 900-1100Hz, and the pulse width is 50-270fs.
6. The method for preparing LIPSS-based perovskite single-crystal thin films according to claim 1, characterized in that, In step (2), the concentration of the perovskite precursor solution is 0.08-0.12 mol / L.
7. The method for preparing LIPSS-based perovskite single-crystal thin films according to claim 1, characterized in that, In step (2), the perovskite precursor solution is prepared by the following method: MABr and PbBr2 are dissolved in DMF to obtain solution one and solution two, which are then mixed and shaken to obtain the perovskite precursor solution.
8. The method for preparing LIPSS-based perovskite single-crystal thin films according to claim 1, characterized in that, In step (2), heating is carried out at 50-80℃.
9. A LIPSS-based perovskite single crystal thin film prepared by the method according to any one of claims 1-8.
10. An application of the LIPSS perovskite single-crystal thin film according to claim 9 in the fabrication of photodetectors.