Flexible infrared display panel based on CVD graphene

Abstract

The invention belongs to the field of infrared display of the modern equipment manufacturing industry, and particularly relates to a flexible infrared display panel based on CVD graphene. The flexible infrared display panel based on CVD graphene comprises a flexible PCB and a graphene film, electrode pairs are prefabricated on the flexible PCB, the electrode pairs are arranged in an array to form an electrode matrix, each electrode pair comprises a positive electrode and a negative electrode, the graphene film covers the electrode matrix, and the graphene film covers the flexible PCB. Input interfaces for controlling on-off of the electrode pairs in the electrode matrix are further reserved in the flexible PCB, and the input interfaces are divided into a positive electrode interface and a negative electrode interface. According to the flexible infrared display panel, the graphene film is transferred to the flexible PCB to prepare the flexible infrared display panel, the panel can be freely / repeatedly bent within the range of 0-150 degrees, the display characteristic is kept stable, the light-emitting area can be controlled, and the flexible infrared display panel has excellent low-energy-consumption performance.

Description

Technical Field

[0001] The present invention belongs to the infrared display field of modern equipment manufacturing industry, and specifically is a flexible infrared display panel based on CVD graphene. Background Art

[0002] Infrared light sources are widely used in infrared imaging, security monitoring, medical diagnosis, non-destructive testing and other fields. They can effectively improve the accuracy and efficiency of detection and monitoring, and have important economic and technical value. At present, LED infrared light sources face multiple challenges in terms of flexibility and luminous area control. First, the traditional LED structure is relatively rigid and difficult to adapt to the bending and deformation of flexible substrates, resulting in limited application in flexible electronic devices. Secondly, it is difficult to control the luminous area, especially when the luminous area is precisely adjusted, it is easy to have problems of non-uniform luminescence or reduced efficiency. In addition, in the manufacturing process of flexible LEDs, material compatibility, heat dissipation management and stability after long-term use are also urgent issues to be solved. Therefore, it is urgent to develop flexible infrared emitters with controllable infrared emission area and good stability. Graphene is a zero-bandgap material whose electrons have a linear dispersion relationship, which makes it have good photoelectric response in infrared light bands of different frequencies. Since the carriers of graphene can be adjusted by an external electric field or doping, the emission wavelength of infrared light can be precisely controlled. In addition, the high electron mobility and low light absorption loss of graphene ensure its application potential in efficient infrared emission. Its two-dimensional structure also supports high surface area and close integration with materials, further improving its performance as an infrared light source. Summary of the invention

[0003] In order to solve the problems of limited luminous area, difficulty in flexibility and poor stability after long-term use of infrared light source LED infrared emitters at the current stage, the present invention provides a flexible infrared display panel based on CVD graphene. The present invention combines CVD graphene as a sensitive material of the flexible infrared display panel with a flexible PCB board, and prepares a flexible infrared display panel by utilizing the principle that infrared radiation is generated by scattering between sound and electrons when CVD graphene on the flexible PCB board is powered on.

[0004] The present invention is implemented by adopting the following technical scheme: a flexible infrared display panel based on CVD graphene, including a flexible PCB board and a graphene film, an electrode pair is prefabricated on the flexible PCB board, the electrode pair is arranged in an array to form an electrode matrix, each pair of electrode pairs includes a positive electrode and a negative electrode, the graphene film is covered on the electrode matrix, and an input interface for controlling the power on and off of the electrode pairs in the electrode matrix is ​​also reserved on the flexible PCB board, and the input interface is divided into a positive electrode interface and a negative electrode interface. The present invention transfers the graphene film to a flexible PCB board prepared with a metal electrode pair, and the whole piece of graphene film covers the electrode array on the flexible PCB board, and different electrode pairs can be independently powered on / off. An electrode pair negative control switch is installed on the negative electrode interface, and an electrode pair positive control switch is installed on the positive electrode interface. The negative electrodes of all electrode pairs are connected together, and a DC power supply and a control switch are used to control the power on and off of the electrode pairs. Different positions on the graphene film will generate different infrared radiations, and the flexible infrared display panel can display different infrared patterns by controlling the power on and off of the electrode pairs and the magnitude of the applied voltage.

[0005] The above-mentioned flexible infrared display panel based on CVD graphene has the following preparation process: S1: designing a flexible PCB board, on which an electrode matrix and an input interface for controlling the on and off power of the electrode pairs are prefabricated; S2: preparing a flexible PCB board, and conducting an electrical inspection on the prepared flexible PCB board to ensure that before the graphene film is transferred, the electrode pairs in the electrode matrix are not conductive to each other; S3: preparing a graphene film, and placing the copper-based graphene with a spin-coated sacrificial layer of PMMA into a copper sulfate solution for corrosion, and leaving a sacrificial layer after the copper base is completely corroded. A layer of PMMA graphene film is prepared, and the graphene film is transferred to deionized water and allowed to stand; S4: the graphene film processed in step S3 is transferred to the flexible PCB board prepared in step S2, and the next test is performed after the graphene film is naturally dried; S5: the conductivity and uniformity are tested. After the graphene film is transferred to the flexible PCB board and dried, the resistance between each pair of electrodes is tested. The resistance between each pair of electrodes should fluctuate between 1kΩ-1.5kΩ, otherwise it is regarded as an unqualified sample; S6: the sample is optically characterized, and it can be used after confirming that the graphene film is intact.

[0006] In the above-mentioned flexible infrared display panel based on CVD graphene, in each pair of electrodes, the spacing between the positive electrode and the negative electrode is 3 mm, and the positive electrode and the negative electrode are square electrodes with a side length of 3 mm.

[0007] The distance between the positive and negative electrodes includes but is not limited to 3mm. The distance between the electrodes is positively correlated with the side length of the electrodes. In essence, it is sufficient to ensure that the electric field generated by the electrode size and distance setting according to the present invention is consistent with the preset electric field. The greater the electric field intensity, the stronger the infrared radiation intensity of the graphene film, and the larger the controllable range of the electric field, the larger the adjustable range of the infrared radiation of the graphene film. For the flexible infrared display panel of the present invention, the intensity and range of the electric field are jointly determined by the side length of the electrodes, the electrode distance and the applied power supply voltage.

[0008] The present invention transfers the graphene film to a flexible PCB board to prepare a flexible infrared display panel. The panel can be bent freely / repeatedly in the range of 0-150 degrees and the display characteristics remain stable. The luminous area can also be controlled, and the flexible infrared display panel has excellent low energy consumption performance. In addition, the flexible infrared display panel has good stability and can still maintain a stable display after continuous use for 15 hours; after the flexible infrared display panel is stored in the air for 200 days, its display performance can still remain stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic diagram of the structure of the flexible PCB board of the present invention.

[0010] Figure 2 It is a schematic structural diagram of the flexible infrared display panel of the present invention.

[0011] Figure 3 This is the emissivity test result of the flexible infrared display panel in the near-infrared band.

[0012] Figure 4 This is the infrared radiation temperature response test result of the flexible infrared display panel.

[0013] Figure 5 This is the current response test result diagram of the flexible infrared display panel.

[0014] Figure 6 This is a graph showing the current stability test results of the flexible infrared display panel.

[0015] In the figure: 1-flexible PCB board, 2-positive electrode, 3-negative electrode, 4-electrode matrix, 5-graphene film, 6-electrode to negative electrode control switch, 7-electrode to positive electrode control switch. DETAILED DESCRIPTION

[0016] A flexible infrared display panel based on CVD graphene includes a flexible PCB board 1 and a graphene film 5. Electrode pairs are prefabricated on the flexible PCB board 1. The electrode pairs are arranged in an array to form an electrode matrix 4. Each pair of electrode pairs includes a positive electrode 2 and a negative electrode 3. The graphene film 5 covers the electrode matrix 4. An input interface for controlling the power on and off of the electrode pairs in the electrode matrix 4 is also reserved on the flexible PCB board 1. The input interface is divided into a positive electrode interface and a negative electrode interface. The negative electrode interface is used to install an electrode pair negative electrode control switch 6, and the positive electrode interface is used to install an electrode pair positive electrode control switch 7.

[0017] Working principle of flexible infrared display panel: Before testing, the device needs to be lead packaged, and the flexible infrared display panel is connected to the DC power supply through a 16-way control switch. Voltage is applied to different electrode pairs according to the display rules, and then the flexible infrared display panel is observed using an infrared camera. The image displayed by the flexible infrared display panel will be displayed on the external screen of the infrared camera. By changing the electrode pairs to which the voltage is applied and the size of the applied voltage, different infrared patterns and infrared patterns with different infrared radiation intensities can be displayed.

[0018] The present invention transfers the graphene film 5 to the flexible PCB board 1 to prepare a flexible infrared display panel. The panel can be bent freely / repeatedly within the range of 0-150° and the display characteristics remain stable, thus solving the problem of difficulty in making the LED infrared emitter flexible.

[0019] The present invention uses the graphene film 5 and the flexible PCB board 1 to realize the preparation of a flexible infrared display panel with controllable area, solving the bottleneck problem of the small light-emitting area of ​​the LED infrared emitter.

[0020] The distance between the electrode pairs of the present invention is 3mm, and the average resistance between the electrode pairs after the graphene film 5 is transferred is 1kΩ. Combined with the high conductivity of the graphene film 5, the working voltage of the flexible infrared display panel is 10V, the working current is less than 0.01A, and the energy consumption of the flexible infrared display panel is less than 0.1W, which is at the same order of magnitude as the energy consumption of the LED infrared emitter; the flexible infrared display panel has excellent low energy consumption performance. In addition, the infrared display of the flexible infrared display panel designed by the present invention is controllable, and the current controllable range is 0.3mm to 10cm, that is, under the same voltage, the diameter of the infrared pattern can be changed between 0.3mm and 10cm by changing the electrode pairs. At the same time, the flexible infrared display panel has good stability and can maintain a radiation temperature of 60°C for more than 15 hours. After the flexible infrared display panel is placed in the air for 200 days, it can still maintain stable display performance.

[0021] The present invention adopts a flexible PCB board (FPC for short, which is a printed circuit board made of polyimide or polyester film as a substrate with high reliability and excellent flexibility) 1 as a substrate material, which effectively reduces the influence of the substrate scattering on the infrared display of the graphene film 5. Combined with the excellent infrared display characteristics of the graphene film 5, a high-efficiency flexible infrared display panel can be prepared.

[0022] The present invention transfers the graphene film 5 onto the flexible PCB board 1 by adopting a CVD graphene (chemical vapor deposition graphene) wet transfer process. The processes involved are all very mature technologies in the MEMS (micro-electromechanical systems) field, with low process difficulty and high yield rate; the process cost is relatively stable.

[0023] The graphene film 5 used in the present invention retains the sacrificial layer PMMA (polymethyl methacrylate: [CH 2 C(CH 3 )(COOCH 3 )] n ), while effectively ensuring the integrity and flatness of the graphene film 5, it also protects the graphene film 5 from oxidation during the infrared display process.

[0024] Device preparation: S1: Use Altium Designer software to design a flexible PCB board 1 that meets the requirements. The flexible PCB board 1 is designed with a 4×4 electrode matrix consisting of electrode pairs and an input interface for controlling the electrode pairs. The input interface includes 16 positive electrode interfaces and one negative electrode interface (the negative electrodes of all electrode pairs are connected together). In each pair of electrodes, the spacing between the positive and negative electrodes is 3 mm. The positive and negative electrodes are square electrodes with a side length of 3 mm (such as Figure 1 As shown). S2: The design data of the flexible PCB board 1 is handed over to a third-party manufacturer for preparation. The completed flexible PCB board 1 needs to be electrically checked with a multimeter to ensure that before the graphene film 5 is transferred, the electrode pairs in the electrode matrix 4 are not conductive to each other. S3: Prepare the graphene film, divide the copper-based graphene with the sacrificial layer PMMA spin-coated into a shape compatible with the PCB substrate, put it into a copper sulfate solution for corrosion, and after the copper base is completely corroded, the graphene film 5 is left, and the graphene film 5 is transferred to deionized water and allowed to stand. S4: Transfer the graphene film 5 processed in step S3 to the substrate prepared in step S2 (as shown). Figure 2As shown), after the graphene film 5 is naturally dried, the sample is tested in the next step. S5: Test the conductivity and uniformity of the sample. After the graphene film 5 is transferred to the flexible PCB board 1 and dried, the resistance between each pair of electrodes is tested. Considering the uniformity of the graphene film 5, the resistance between each pair of electrodes should fluctuate between 1kΩ-1.5kΩ, otherwise it is considered as an unqualified sample. S6: Perform optical characterization on the sample. After confirming that the graphene film 5 is intact, it can be used.

[0025] Device test: The test system consists of a power supply module, an electrical data acquisition module, and an infrared signal acquisition module. The power supply module consists of a Keithley 2602B source meter and a 16-bit one-on-one-control switch array. This module is mainly used to provide different voltages for the four pairs of electrode matrices; the electrical data acquisition module consists of a Keithley 2612B source meter and software installed with Keithley KickStart. This system is mainly used to monitor the resistance and current on the flexible infrared display panel in real time during power-on; the infrared signal acquisition module consists of a FLIR T540 infrared camera and a laptop computer installed with FLIR Tool software. This module is mainly used to monitor the infrared emission signal of the flexible infrared display panel in real time during power-on. The specific test process is as follows: (1) Place the packaged flexible infrared display panel on the observation platform of the infrared camera, and connect the flexible infrared display panel to the power supply module and the electrical data acquisition module through an one-on-one-control switch. (2) Turn on the infrared signal acquisition module and calibrate and focus so that the sample is directly below the infrared camera. The distance between the sample and the infrared camera lens should be between 20cm and 30cm. (3) Turn on the power supply module and the electrical data acquisition module, select different electrode pairs, apply voltage to observe the infrared display of the flexible infrared display panel, and then switch to different voltages to observe the infrared display of the flexible infrared display panel again. (4) Use the electrical data acquisition module and the infrared signal acquisition module to record the current change process and infrared signal response process of the flexible infrared display panel under different voltages. (5) Test the emissivity of the flexible infrared display panel in the near-infrared band of 1-3.5μm at a voltage of 10V. The results are shown in Figure 2. Figure 3 The emissivity test results show that the flexible infrared display panel has infrared emission in the 1-3.5μm band. (6) A power module is used to input a 2V-12V step voltage signal with a step length of 2V to the flexible infrared display panel. The electrical data acquisition module and the infrared signal acquisition module are used to measure the current response of the flexible infrared display panel (see the results). Figure 5 ) and infrared radiation temperature response (results see Figure 4 ) for recording. Figure 4 The response of mid-infrared radiation temperature under voltage step signal shows that the infrared radiation temperature of flexible infrared display panel has a great influence on the Figure 5The current response trend in the figure has a certain followability. It also shows that the power supply voltage can dynamically control the infrared radiation temperature. Figure 5 The response results of the current under different voltage step signals show that the resistance of the flexible infrared display panel has good stability under different voltages. (7) The power module is used to apply a voltage matrix signal to the flexible infrared display panel to test the current stability of the flexible infrared display panel after 10,000 cycles. The results are shown in Figure 6 The stability test results show that the flexible infrared display panel has good stability in 10,000 cycle tests. (8) Analyze the relevant data and evaluate the performance of the flexible infrared display panel.

Claims

1. A flexible infrared display panel based on CVD graphene, characterized in that: The invention comprises a flexible PCB board (1) and a graphene film (5). The flexible PCB board (1) is prefabricated with electrode pairs, which are arranged in an array to form an electrode matrix (4). Each electrode pair comprises a positive electrode (2) and a negative electrode (3). The graphene film (5) covers the electrode matrix (4). The flexible PCB board (1) is also pre-reserved with an input interface for controlling the on / off of the electrode pairs in the electrode matrix (4). The input interface is divided into a positive electrode interface and a negative electrode interface.

2. The flexible infrared display panel based on CVD graphene according to claim 1, characterized in that: The preparation process of the flexible infrared display panel is as follows: S1: designing a flexible PCB board (1), on which an electrode matrix (4) and an input interface for controlling the on and off of power to the electrode pairs are prefabricated; S2: preparing a flexible PCB (1), and conducting an electrical inspection on the prepared flexible PCB (1) to ensure that before being transferred to the graphene film (5), the electrode pairs in the electrode matrix (4) are not electrically connected to each other; S3: preparing a graphene film (5), placing the copper-based graphene with the sacrificial layer PMMA spin-coated in a copper sulfate solution for corrosion, and leaving the graphene film (5) with the sacrificial layer PMMA after the copper base is completely corroded, and transferring the graphene film (5) to deionized water for standing; S4: transferring the graphene film (5) processed in step S3 to the flexible PCB (1) prepared in step S2, and conducting the next test after the graphene film (5) is naturally dried; S5: testing the conductivity and uniformity, and after the graphene film (5) is transferred to the flexible PCB (1) and dried, testing the resistance between each pair of electrodes, and the resistance between each pair of electrodes should fluctuate between 1 kΩ and 1.5 kΩ, otherwise it is regarded as an unqualified sample; S6: Perform optical characterization on the sample and confirm that the graphene film (5) is intact before use.

3. The flexible infrared display panel based on CVD graphene according to claim 1 or 2, characterized in that: In each pair of electrodes, the distance between the positive electrode (2) and the negative electrode (3) is 3 mm, and the positive electrode (2) and the negative electrode (3) are square electrodes, each with a side length of 3 mm.

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