A method for enhancing nonlinear optical performance of SnS2 nanosheets by electrostatic doping
By electrostatically doping SnS2 nanosheets with hydrogen ions, the performance limitations of two-dimensional semiconductor materials in nonlinear optical applications are addressed, achieving a significant improvement in the material's efficient nonlinear optical performance, making it suitable for rapid recognition tasks in optical neural networks.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TONGJI UNIV
- Filing Date
- 2025-10-13
- Publication Date
- 2026-06-05
AI Technical Summary
Existing two-dimensional semiconductor materials suffer from problems such as weak performance, difficulty in large-area uniform growth, and complex fabrication in nonlinear optical applications, which limit their practical application in devices.
SnS2 nanosheets were prepared by chemical vapor deposition and hydrogen ions were inserted into an FTO substrate by electrochemical intercalation. Electrostatic doping was used to enhance their nonlinear optical properties, and the built-in electric field was controlled by adjusting the hydrogen ion concentration and the applied voltage.
This significantly improves the nonlinear optical properties of SnS2 nanosheets, enhancing both saturable and antisaturable absorption, making them suitable for rapid recognition tasks in optical neural networks and providing a design basis for high-performance nonlinear absorption materials.
Smart Images
Figure CN122144780A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the fields of electrochemical technology and nonlinear optics, and relates to a method for enhancing the nonlinear optical properties of SnS2 nanosheets through electrostatic doping. Background Technology
[0002] In recent years, information and communication technologies have developed rapidly. Integrated optical neural networks rely on nonlinear optical materials to perform complex nonlinear matrix operations. Therefore, exploring materials with strong optical nonlinear responses and ease of fabrication is crucial. Two-dimensional semiconductors have shown great potential in nonlinear optical applications and are easy to integrate into devices. However, in addition to their relatively weak performance, the practical application of two-dimensional semiconductors in devices is hindered by their inherent limitations, especially thin two-dimensional semiconductors, which exhibit shallow modulation depths due to the relatively small length of light-matter interaction. Therefore, finding effective strategies to advance the development of high-performance nonlinear optical materials is essential.
[0003] Existing control strategies still face several challenges, including difficulty in ensuring uniform growth during the large-area fabrication of few-layer two-dimensional materials; the complexity and time-consuming nature of heterojunction fabrication; and the high cost and difficulty in large-scale production due to reliance on complex nanotechnology for plasma coupling. Therefore, effectively improving the nonlinear optical properties of materials through simple and controllable methods is an important research direction in the field of nonlinear optics.
[0004] Electrostatic doping, involving proton insertion between two-dimensional material layers, provides a general, effective, and novel strategy for improving nonlinear optical absorption performance. This method involves a simple and rapid electrochemical intercalation process to insert hydrogen ions into the interlayer of a two-dimensional material. Due to electrostatic doping, electrons are injected into the conduction band, reducing its capacity to accommodate carriers generated by photons and enhancing the Pauli blockade effect, thereby improving saturable absorption. Furthermore, the strong internal electric field induced by electrostatic doping enhances the material's antisaturable absorption. Summary of the Invention
[0005] The purpose of this invention is to provide a method for enhancing the nonlinear optical properties of SnS2 nanosheets through electrostatic doping, thereby achieving enhanced nonlinear optical properties of the material under laser excitation at different wavelengths.
[0006] The objective of this invention can be achieved through the following technical solutions:
[0007] In one aspect, this invention provides a method for enhancing the nonlinear optical properties of SnS2 nanosheets through electrostatic doping. First, SnS2 nanosheets are prepared on an FTO substrate using chemical vapor deposition. Then, hydrogen-ion-intercalated SnS2-H nanosheets are prepared using an electrochemical intercalation method. +The nonlinear optical properties of the material are enhanced by bandgap shrinkage induced by electrostatic doping and a strong built-in electric field.
[0008] Furthermore, the electrolyte used in the electrochemical intercalation method is a dilute aqueous solution of H2SO4.
[0009] Furthermore, the electrochemical intercalation process is as follows:
[0010] Electrochemical intercalation was performed in a three-electrode system using Pt as the reference electrode, SnS2 grown on an FTO substrate as the working electrode, and Pt as the auxiliary electrode, with dilute H2SO4 aqueous solution as the electrolyte. By applying a negative voltage using an electrochemical workstation, SnS2-H ions with varying degrees of hydrogen ion intercalation were obtained in H2SO4 aqueous solutions of different concentrations. + Material.
[0011] Furthermore, the concentration of the H2SO4 aqueous solution is 2.5 mM to 5 mM.
[0012] Furthermore, the applied voltage is -1.2 to -1.5V.
[0013] Furthermore, the voltage is applied for 15 to 20 seconds.
[0014] Furthermore, the substrate used for growing SnS2 is FTO.
[0015] Specifically, during the electrochemical intercalation process, a voltage of -1.5V was applied for 20 seconds.
[0016] Compared with the prior art, the present invention has the following advantages:
[0017] 1. A series of hydrogen-intercalated tin disulfide thin film materials were prepared using a simple and controllable electrochemical method, demonstrating the electrostatically doped SnS2-H with a built-in electric field. + It has great potential in the field of nonlinear optics.
[0018] 2. The magnitude of the built-in electric field can be adjusted by changing the hydrogen ion intercalation concentration. This result provides new insights for the structural design and exploration of high-performance nonlinear absorbing materials.
[0019] 3. The hydrogen ion intercalation method can be extended to other acid-resistant layered two-dimensional materials, and has a wide range of applications. Attached Figure Description
[0020] Figure 1 This is an illustration for the abstract of the instruction manual.
[0021] Figure 2 Electrostatically doped SnS2-H was prepared by electrochemical intercalation in Examples 1-2. + A device for materials.
[0022] Figure 3 The images are X-ray powder diffraction (XRD) images of the products obtained in Examples 1-2.
[0023] Figure 4 These are scanning electron microscope (SEM) images of the products obtained in Examples 1-2.
[0024] Figure 5 The images show X-ray photoelectron spectroscopy (XPS) images of the products obtained in Examples 1-2.
[0025] Figure 6 The absorption spectra of the products obtained in Examples 1-2 are shown.
[0026] Figure 7 The T products were obtained under laser excitation at 515, 800 and 1550 nm, respectively. NL Summary of Z-plots and nonlinear absorption coefficients.
[0027] Figure 8 The saturated absorption of the product obtained in Example 2 is used as a nonlinear activation function to apply the recognition results of an optical neural network after training for 10 cycles in the MNIST dataset handwritten digit recognition task. Detailed Implementation
[0028] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.
[0029] In the following embodiments, unless otherwise specified, the raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art.
[0030] Example 1:
[0031] SnS2-2.5H thin film material was prepared by electrochemical intercalation. SnS2 grown on FTO was used as the working electrode and immersed in 2.5 mM H2SO4 aqueous solution. A voltage of -1.5 V was applied for 20 s to obtain SnS2-2.5H.
[0032] SnS2 was prepared by vapor deposition (for details, please refer to the literature: YTKe, H.Li, MGHumphrey, B.Zhang, J.Wang, YLLiu, R.D.Cong, C.Zhang, ZPHuang, Prominent enhancement of nonlinear optical absorption in SnS2 nanosheets through controllable electrodeposition of porphyrins. Adv. Opt. Mater. 2024, 12, 2401286).
[0033] The nonlinear response of the material was tested under a single-beam nonlinear transmittance setting.
[0034] The results of single-beam nonlinear transmittance evaluation of the SnS2-2.5H nonlinear response in an open-aperture Z-scan system show that its nonlinear absorption coefficient is improved under 515 nm laser excitation, and its value β eff =–(1377±31)cmGW -1 The β of the original SnS2 eff =–(638±39)cm GW -1 .
[0035] Example 2:
[0036] SnS2-5H thin film material was prepared by electrochemical intercalation. SnS2 grown on FTO was used as the working electrode and immersed in 5 mM H2SO4 aqueous solution. A voltage of -1.5 V was applied for 20 s to obtain SnS2-5H.
[0037] SnS2 was prepared by vapor deposition (same as in Example 1).
[0038] The nonlinear response of the material was tested under a single-beam nonlinear transmittance setting.
[0039] The results of single-beam nonlinear transmittance evaluation of the ele-30s nonlinear response in an open-aperture Z-scan system show that its nonlinear absorption coefficient is improved, and its value β eff =–(3045±55)cm GW -1 .
[0040] Figure 2 The electrochemical intercalation device demonstrates that electrostatically doped materials can be prepared in a simple three-electrode system.
[0041] Figure 3SnS2-H in X-ray powder diffraction (XRD) images + All samples showed sharp diffraction peaks, which were unchanged from those of the original SnS2, indicating that SnS2 did not undergo structural changes or redox processes after modification and maintained high crystallinity.
[0042] Figure 4 The scanning electron microscope (SEM) images show SnS2-H + It still retains the morphology of SnS2 hexagonal nanosheets, with a clean, flat, and smooth surface, and no acid corrosion has occurred.
[0043] Figure 5 The X-ray photoelectron spectroscopy (XPS) images showed that the material underwent only electrostatic doping, and no redox reactions occurred in the S and Sn elements. For the pristine SnS2, the SnS2-H after hydrogen ion intercalation... + The S and Sn elements did not generate new valence states. The shift in binding energy and peak splitting are attributed to the effect of charge injection: the accumulation of negative charge causes the peak to shift to a lower binding energy. This proves that hydrogen ion intercalation did not cause a redox reaction in SnS2, but only led to charge accumulation.
[0044] Figure 6 The absorption spectra show that the absorption edge of SnS2 redshifts after intercalation with different hydrogen ion concentrations, which is consistent with the band gap contraction caused by the strong built-in electric field.
[0045] Figure 7 Images (a)-(c) show the T values of SnS2-2.5H and SnS2-5H obtained in Examples 1-2 under different nanolaser excitations. NL -Z patterns all exhibit enhanced nonlinear absorption behavior. (d)-(f) are a summary of the nonlinear absorption coefficients of the products obtained in Examples 1-2.
[0046] Figure 8 The saturated absorption data of SnS2-5H obtained in Example 2 is shown as a nonlinear activation function applied to an optical neural network. The recognition results after training for 10 cycles on the MNIST dataset handwritten digit recognition task show a high accuracy of 97.46%, demonstrating the application potential for rapid recognition.
[0047] Reply: No error.
[0048] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.
Claims
1. A method for enhancing the nonlinear optical properties of SnS2 nanosheets through electrostatic doping, characterized in that, First, SnS2 nanosheets were prepared on a fluorine-doped tin oxide (FTO) substrate using chemical vapor deposition, and then SnS2-H nanosheets were prepared by electrochemical intercalation. + Electrostatic doping leads to band gap contraction and generates a strong built-in electric field, which promotes the enhancement of the material's nonlinear optical properties.
2. The method for enhancing the nonlinear optical properties of SnS2 nanosheets by electrostatic doping according to claim 1, characterized in that, Electrostatic doping is achieved through electrochemical intercalation.
3. The method for enhancing the nonlinear optical properties of SnS2 nanosheets by electrostatic doping according to claim 1, characterized in that, The electrochemical intercalation process is as follows: Using Pt as the reference electrode, SnS2 grown on an FTO substrate as the working electrode, and Pt as the auxiliary electrode, electrochemical intercalation was performed in a three-electrode system using dilute H2SO4 aqueous solutions of different concentrations as the electrolyte. By applying a negative voltage for a period of time using an electrochemical workstation, SnS2-H ions with varying degrees of hydrogen ion intercalation were obtained. + Electrostatic doped materials.
4. The method for enhancing the nonlinear optical properties of SnS2 nanosheets by electrostatic doping according to claim 3, characterized in that, The dilute H2SO4 aqueous solution is 2.5mM to 5mM.
5. The method for enhancing the nonlinear optical properties of SnS2 nanosheets by electrostatic doping according to claim 3, characterized in that, The applied voltage is -1.2 to -1.5V.
6. The method for enhancing the nonlinear optical properties of SnS2 nanosheets by electrostatic doping according to claim 3, characterized in that, The voltage is applied for 15 to 20 seconds.
7. The method for enhancing the nonlinear optical properties of SnS2 nanosheets by electrostatic doping according to claim 1, characterized in that, The substrate used for growing SnS2 is FTO.
8. The method for enhancing the nonlinear optical properties of SnS2 nanosheets by electrostatic doping according to claim 1, characterized in that, The specific synthesis process using chemical vapor deposition is as follows: Sublimed sulfur was used as the sulfur source, and stannous chloride was used as the tin source, with a stannous chloride to sublimed sulfur ratio of 0.5 g: 1 g. The reaction was carried out under nitrogen atmosphere, heated, and cooled to room temperature to obtain SnS2.
9. The method for preparing SnS2 nanosheets according to claim 8, characterized in that, The temperature for the heating reaction is 350–500℃.
10. The method for preparing SnS2 nanosheets according to claim 8, characterized in that, The heating reaction time is 5 to 30 minutes.