Controllable preparation method of high-uniformity laser-induced graphene

Abstract

The invention relates to the technical field of graphene preparation, and particularly discloses a controllable preparation method of high-uniformity laser-induced graphene, which comprises the following steps of: acting a main processing light beam, an annealing auxiliary light beam and a quenching auxiliary light beam on the same processing area of a substrate in a space-time synergistic manner, the main processing light beam is used for inducing the substrate to generate graphitization to form an sp2 carbon network; the annealing auxiliary light beam is triggered by a pulse of a preset delay time relative to the main processing light beam and is used for carrying out in-situ annealing on the processing area so as to repair defects in the sp2 carbon network; and the quenching auxiliary light beam is used for generating a plasma sheath layer in the processing area to isolate air and prevent oxidation. Through a three-beam space-time cooperative processing mechanism of main processing beam induced graphitization-annealing auxiliary beam in-situ annealing-quenching auxiliary beam plasma quenching, the problems of uneven interlayer structure and high defect density caused by a heat accumulation effect in traditional single-beam laser processing are solved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of graphene preparation, in particular to a controllable preparation method of high-uniformity laser-induced graphene. BACKGROUND

[0002] Laser-induced graphene (LIG) technology is a processing method that realizes local carbonization and graphitization by irradiating carbon precursor materials (such as polyimide) with a laser beam. Due to its high efficiency, non-contact, and strong patterning capability, it has shown wide application prospects in the fields of flexible electronics, sensors, and energy devices.

[0003] Currently, mainstream LIG technology usually uses a single-wavelength laser beam (commonly 1064 nm or 10.6 μm) for processing. However, this method has a significant heat accumulation effect, resulting in poor uniformity of the graphene structure formed in the interlayer distribution. Specifically, the surface layer of the material forms a high-defect-density carbon structure due to insufficient heat diffusion, while the bottom layer undergoes excessive carbonization or even disordering due to continuous heat, causing the electrical conductivity to fluctuate greatly at different depths, which seriously affects the consistency of device performance. To improve uniformity, existing technologies attempt to use gas protection or pre-coat functional layers on the surface of the precursor, but these methods still cannot accurately control the cross-scale thermal behavior and fundamentally solve the heat management problem.

[0004] To further suppress thermal damage, some studies have turned to using ultrafast lasers or multi-pass scanning strategies. Ultrafast lasers can control the heat-affected zone to some extent, but their excessively high peak power can easily lead to out-of-control ablation thresholds and narrow processing windows. Multi-pass scanning significantly reduces processing efficiency and is difficult to meet the needs of large-area and continuous preparation. Some studies have proposed using a dual-beam collaborative processing method, such as combining infrared and ultraviolet lasers, but their mechanisms are mostly limited to surface cleaning or activation treatment and do not repair defects in the bulk structure. In particular, they lack the ability to control the timing of in-situ annealing and active oxygen quenching during graphene growth, resulting in limited improvement in material performance. SUMMARY

[0005] To improve the interlayer uniformity of graphene caused by heat accumulation of a single beam, the application provides a controllable preparation method of high-uniformity laser-induced graphene.

[0006] The controllable preparation method of high-uniformity laser-induced graphene provided by the application adopts the following technical scheme: A controllable preparation method of high-uniformity laser-induced graphene, comprising the following steps: The same processing region of the substrate is acted on by at least three laser beams in space-time coordination, the three laser beams including a main processing beam, an annealing auxiliary beam and a quenching auxiliary beam; The main processing beam is used for inducing graphitization of the substrate to form sp 2 carbon network; The annealing auxiliary beam is triggered with a preset delay time relative to the pulse trigger of the main processing beam, and is used for in-situ annealing of the processing region to repair defects in the sp 2 carbon network; The quenching auxiliary beam is triggered synchronously with the main processing beam, and is used for generating a plasma sheath layer in the processing region to isolate air to prevent oxidation.

[0007] Further, the wavelength of the main processing beam > the wavelength of the annealing auxiliary beam > the wavelength of the quenching auxiliary beam.

[0008] Preferably, the main processing beam is a nanosecond pulsed laser with a wavelength of 1064 nm, the annealing auxiliary beam is a nanosecond pulsed laser with a wavelength of 532 nm, and the quenching auxiliary beam is a nanosecond pulsed laser with a wavelength of 355 nm.

[0009] Preferably, the pulse width of the main processing beam is 50-100 ns, the single pulse energy is 1-5 mJ, and the repetition frequency is 1-20 kHz; the pulse width of the annealing auxiliary beam is 30-80 ns, the single pulse energy is 0.15-1 mJ, and the repetition frequency is synchronized with the main beam; the pulse width of the quenching auxiliary beam is 10-30 ns, the single pulse energy is 0.1 mJ, and the repetition frequency is 10 kHz.

[0010] In the three-beam synergistic processing stage, the main processing beam first irradiates the surface of the substrate, induces carbonization thereof through photo-thermal effect, and preliminarily forms sp 2 carbon network; after the preset delay time, the annealing auxiliary beam acts on the same region, the local temperature is raised to 600℃±50℃ through the resonance effect of 2.33eV photons and carbon lattice phonons, and the carbon atoms are rearranged to repair defects; the quenching auxiliary beam triggered synchronously with the main processing beam generates a 250μm±30μm thick O2 + / e - plasma sheath layer through four-photon ionization, which isolates the processing region from air contact to avoid oxidation; the substrate is scanned at a preset speed along a preset path, and the above synergistic action is repeated to obtain large-area high-uniformity laser-induced graphene.

[0011] The above processing does not require an inert gas atmosphere and is directly carried out in air, and the plasma sheath layer generated in real time by the quenching auxiliary beam can achieve effective oxidation protection, simplifying the process complexity.

[0012] Further, the pulse energy of the annealing auxiliary light beam is 15%-20% of the pulse energy of the main machining light beam.

[0013] When the power ratio of the annealing auxiliary light beam is less than 15%, the annealing temperature is less than 500℃, the carbon atom migration energy is not enough, and the defect repair effect is weak. When the power ratio is higher than 20%, the temperature will exceed 700℃, which will lead to sp 2 Local ablation of carbon network.

[0014] Further, the preset delay time is 50±10 ns.

[0015] Further, the preset delay time is dynamically adjusted according to the pulse width of the main machining light beam, the scanning speed and / or the thickness of the substrate.

[0016] The applicable range of the delay time of 50±5 ns is related to the pulse width of the main machining light beam, the scanning speed and the thickness of the substrate. When the main machining light beam is a 100 ns long pulse, the preset delay time can be relaxed to 55 ns. When the main machining light beam is a 50 ns short pulse, the preset delay time is tightened to 45 ns. When the scanning speed is greater than 5 mm / s, the preset delay time is shortened to 40-45 ns to avoid spatial misplacement. When the scanning speed is less than 0.5 mm / s, the preset delay time can be extended to 55-60 ns to match the heat diffusion rhythm. When the thickness of the substrate is greater than 125 μm, the preset delay time is slightly increased to match the deep graphitization process.

[0017] Further, the annealing auxiliary light beam adopts a flat-top pulse.

[0018] Further, the quenching auxiliary light beam adopts a Gaussian pulse.

[0019] The pulse shape significantly affects the preparation effect: the annealing auxiliary light beam adopts a flat-top pulse (achieved by an acousto-optic modulator) to avoid temperature sudden change caused by energy fluctuation, and the quenching auxiliary light beam adopts a Gaussian pulse to ensure the uniform thickness of the plasma sheath layer and prevent local protection failure.

[0020] The application also provides a three-beam time-space coordinated laser processing system for implementing a controllable preparation method of high-uniformity laser-induced graphene, which comprises: A laser generation module for generating the main machining light beam, the annealing auxiliary light beam and the quenching auxiliary light beam; An optical path coupling module for coaxially combining and focusing the three beams of laser on the same machining focal point; A precision motion module for carrying and moving the substrate to realize scanning of a preset path; A control system for controlling the trigger timing, pulse parameters of the three beams of laser and the motion parameters of the precision motion module.

[0021] Further, the light path coupling module comprises at least two dichroic mirrors configured to have high transmission and / or high reflection characteristics for specific wavelengths of laser light to achieve coaxial beam combination of three beams.

[0022] Further, the control system comprises a synchronous pulse generator for controlling the trigger delay between the annealing auxiliary beam and the main processing beam.

[0023] In summary, the present application has the following beneficial technical effects: The present application improves the problems of uneven layer structure, high defect density, and large conductivity fluctuation caused by thermal accumulation effect in traditional single-beam laser processing by using a three-beam spatiotemporal synergistic processing mechanism of main processing beam-induced graphitization-annealing auxiliary beam in-situ annealing-quenching auxiliary beam plasma quenching. High-quality graphene can be prepared in one step in an air environment without inert gas protection by precisely controlling the beam parameters and timing. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 FIG. 1 is a structural schematic diagram of a multi-light-path laser in a three-beam spatiotemporal synergistic laser processing system in an embodiment of the present application.

[0025] The reference signs are as follows: 1, housing; 2, first light-emitting unit; 3, second light-emitting unit; 4, third light-emitting unit; 5, first collimating lens; 6, second collimating lens; 7, third collimating lens; 8, first dichroic mirror; 9, second dichroic mirror; 10, third dichroic mirror; 11, polarization beam combination module; 12, focusing lens; 13, light path turning piece; 14, reflecting part; 15, absorbing part; 16, output optical fiber. DETAILED DESCRIPTION

[0026] The present application will be further described below in conjunction with the accompanying drawings. Figure 1 The present application will be further described below in conjunction with the accompanying drawings.

[0027] An embodiment of the present application discloses a three-beam spatiotemporal synergistic laser processing system, comprising a multi-light-path laser, a precision motion module, and a control system. The multi-light-path laser comprises a laser generation module and a light path coupling module. The laser generation module is used to generate a main processing beam, an annealing auxiliary beam, and a quenching auxiliary beam. The light path coupling module is used to coaxially combine and focus the three beams of laser light on the same processing focal point. The precision motion module is used to carry and move the substrate to realize scanning of a preset path. The control system is used to control the trigger timing, pulse parameters of the three beams of laser light, and the motion parameters of the precision motion module. The control system comprises a synchronous pulse generator for controlling the trigger delay between the annealing auxiliary beam and the main processing beam.

[0028] Specifically, referring to Figure 1 , the laser generating module and the optical path coupling module are arranged in the shell 1 of the multi-optical path laser, the laser generating module includes a first light emitting unit 2, a second light emitting unit 3 and a third light emitting unit 4, which are respectively used to generate nanosecond pulse laser of 1064 nm wavelength (main machining light beam), nanosecond pulse laser of 532 nm wavelength (annealing auxiliary light beam) and nanosecond pulse laser of 355 nm wavelength (quenching auxiliary light beam).

[0029] Referring to Figure 1 , the optical path coupling module includes a first collimating lens 5, a second collimating lens 6 and a third collimating lens 7 corresponding to the three groups of light emitting units one by one, and the exit ends of the first collimating lens 5, the second collimating lens 6 and the third collimating lens 7 are respectively provided with a first dichroic mirror 8 (1064 nm high reflection), a second dichroic mirror 9 (1064 nm high transmission, 532 nm high reflection) and a third dichroic mirror 10 (355 nm high reflection).

[0030] Further, referring to Figure 1 , the optical path coupling module further includes a polarization beam combining module 11 for realizing coaxial beam combining of three beams; the main machining light beam, the annealing auxiliary light beam and the quenching auxiliary light beam directly enter the polarization beam combining module 11, or enter the polarization beam combining module 11 after being reflected by the optical path turning piece 13. The exit end of the polarization beam combining module 11 is provided with a focusing lens 12 (focal length 100 mm, numerical aperture 0.3, focal point diameter 50-100 μm, spatial coincidence degree controlled within ±5 μm), and a precision translation stage (positioning accuracy ±1 μm) and a piezoelectric focusing mirror connected in series in the optical path can compensate the focal point deviation in real time during scanning (response speed <1 ms). The three beams after beam combining and focusing are output through the output optical fiber 16 on the shell 1. The shell 1 is also provided with a reflecting part 14 and an absorbing part 15 for reflecting and absorbing stray light respectively.

[0031] The precision motion module is arranged at the exit end of the output optical fiber 16, including an XY axis electric translation stage (stroke 300 mm x 300 mm, positioning accuracy ±2 μm, maximum scanning speed 10 mm / s) and a sample clamp, which is used to carry the sample and realize programmable path scanning.

[0032] A controllable preparation method of high uniformity laser-induced graphene is implemented by using the above three-beam space-time coordinated laser processing system, which includes the following steps: Step 1, sample pretreatment: an aromatic polyimide film with a thickness of 25-125 μm (preferably 50 μm) is used as a substrate, cut to a predetermined size and fixed on the sample clamp, and cleaned with alcohol to remove surface impurities.

[0033] Step 2, system parameter debugging: adjust the power density of the 1064 nm main machining light beam to 5-20 kW / cm 2 , single pulse energy 1-3 mJ, repetition frequency 10 kHz, pulse width 50 ns to ensure effective graphitization; set the 532 nm annealing auxiliary light beam power to 15%-20% of the main machining light beam (real-time monitoring by a power meter), single pulse energy 0.15-1 mJ, repetition frequency 10 kHz, pulse width 50 ns, pulse shape flat-top pulse, delay time 50 ns relative to the pulse start point (rising edge) of the main machining light beam; at the same time, set the 355 nm quenching auxiliary light beam single pulse energy to 0.1 mJ, repetition frequency 10 kHz, pulse width 20 ns, pulse shape Gaussian pulse.

[0034] Step 3, three-beam synergistic machining: the main machining light beam first irradiates the polyimide surface, inducing carbonization through photothermal effect and initially forming an sp 2 carbon network; after a delay of 50 ns, the annealing auxiliary light beam acts on the same region (spatial deviation <5 μm), the local temperature is raised to 600℃±50℃ and maintained for 250 μs through the resonance effect of 2.33 eV photons and carbon lattice phonons, prompting the rearrangement of carbon atoms to repair defects; the quenching auxiliary light beam triggered synchronously with the main machining light beam generates a 250 μm±30 μm thick O2 + / e - plasma sheath layer, isolating the machining area from air contact to avoid oxidation; at the same time, the XY translation stage carrying the polyimide substrate scans at a speed of 0.5-5 mm / s along the preset path, repeating the above synergistic effect to obtain large-area high-uniformity laser-induced graphene.

[0035] The laser-induced graphene prepared by the above method has an ID / IG ratio reduced to 0.7-0.8 (the ID / IG ratio is the ratio of the intensity of the D peak to the intensity of the G peak in the Raman spectrum, i.e. the ratio of defect or disordered structure to ordered structure in the carbon lattice, used to characterize the structural order and defect density of carbon materials), indicating that the laser-induced graphene prepared by the method has lower defect density and higher crystalline quality.

[0036] In addition, the machining method provided by the present application does not require an inert gas atmosphere and is directly carried out in air, and the plasma sheath layer generated in real time by the quenching auxiliary light beam can achieve effective oxidation protection, simplifying the process complexity.

[0037] The above are preferred embodiments of the present application, which do not limit the protection scope of the present application, therefore: any equivalent changes made on the basis of the structure, shape, principle of the present application shall be covered within the protection scope of the present application.

Claims

1. A controllable preparation method for highly uniform laser-induced graphene, characterized in that: Includes the following steps: At least three laser beams are used to act on the same processing area of ​​the substrate in a spatiotemporal coordinated manner. The three laser beams include a main processing beam, an annealing auxiliary beam, and a quenching auxiliary beam. The main processing beam is used to induce graphitization in the substrate, forming sp. 2 Carbon networks; The annealing auxiliary beam is pulse-triggered with a preset delay time relative to the main machining beam, and is used to perform in-situ annealing on the machining area to repair the sp 2 Defects in carbon networks; The quenching auxiliary beam is triggered synchronously with the main processing beam to generate a plasma sheath in the processing area to isolate it from air and prevent oxidation.

2. The controllable preparation method for highly uniform laser-induced graphene according to claim 1, characterized in that: The wavelength of the main machining beam is greater than the wavelength of the annealing auxiliary beam, which is greater than the wavelength of the quenching auxiliary beam.

3. The controllable preparation method for highly uniform laser-induced graphene according to claim 2, characterized in that: The pulse energy of the annealing auxiliary beam is 15%-20% of the pulse energy of the main machining beam.

4. A controllable preparation method for highly uniform laser-induced graphene according to claim 1, characterized in that: The preset delay time is 50±10 ns.

5. The controllable preparation method for highly uniform laser-induced graphene according to claim 4, characterized in that: The preset delay time is dynamically adjusted based on the pulse width of the main processing beam, the scanning speed, and / or the thickness of the substrate.

6. The controllable preparation method for highly uniform laser-induced graphene according to claim 2, characterized in that: The annealing auxiliary beam uses a flat-top pulse.

7. The controllable preparation method for highly uniform laser-induced graphene according to claim 2, characterized in that: The quenching auxiliary beam uses a Gaussian pulse.

8. A three-beam spatiotemporal coordinated laser processing system for implementing the method of any one of claims 1-7, characterized in that: include: A laser generating module is used to generate the main processing beam, the annealing auxiliary beam, and the quenching auxiliary beam; The optical path coupling module is used to coaxially combine three laser beams and focus them onto the same processing focal point; The precision motion module is used to support and move the substrate to achieve scanning along a preset path; The control system is used to control the triggering timing, pulse parameters, and motion parameters of the precision motion module of the three laser beams.

9. A three-beam spatiotemporal coordinated laser processing system according to claim 8, characterized in that: The optical path coupling module includes at least two dichroic mirrors, which are configured to have high transmittance and / or high reflectivity for lasers of a specific wavelength, so as to achieve coaxial beam combining of three beams.

10. A three-beam spatiotemporal coordinated laser processing system according to claim 8, characterized in that: The control system includes a synchronous pulse generator for controlling the trigger delay between the annealing auxiliary beam and the main machining beam.

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