A method for preparing nitrogen-doped non-benzene graphene nanoribbons with a wide bandgap.

Abstract

This invention relates to a method for preparing nitrogen-doped non-benzene graphene nanoribbons with a wide bandgap, belonging to the field of surface synthesis technology. The invention utilizes a strategy of intramolecular dehalogenation coupling and cyclization dehydrogenation of 1,8-dibromo-9H-carbazole precursor molecules under the catalysis of a gold substrate. The 1,8-dibromo-9H-carbazole precursor molecules are deposited on the surface of a gold substrate and held at 200°C for 20-40 minutes. The sample is then cooled to room temperature to obtain a one-dimensional polymer chain. This one-dimensional molecular chain sample is then held at 400°C for 20-40 minutes to obtain nitrogen-doped non-benzene graphene nanoribbons. The prepared nitrogen-doped non-benzene graphene nanoribbons have a bandgap of 3.55 eV, belonging to the wide-bandgap semiconductor category.

Description

Technical Field

[0001] This invention relates to a method for preparing nitrogen-doped non-benzene graphene nanoribbons with a wide bandgap, belonging to the field of surface synthesis technology. Background Technology

[0002] In recent decades, with the development of surface science and technology, scanning tunneling microscopy (STM) has become one of the most effective tools for observing and analyzing surface reactions. It can obtain real-time three-dimensional images of the sample surface in real space, and can be used to study surface structures with or without periodicity. Furthermore, combined with scanning tunneling spectroscopy, information about the surface's electronic structure can be obtained. With the precise imaging capabilities and powerful spectroscopic functions of STM, we can gain a more intuitive understanding of the entire reaction pathway and mechanism of surface reactions.

[0003] One-dimensional graphene nanoribbons have attracted widespread attention over the past decade due to their intriguing electronic properties and potential applications in nanoelectronic devices. To achieve graphene nanoribbons with precisely defined widths and edge structures (i.e., armchair, zigzag, or concave edges), two bottom-up synthetic strategies have been developed: surface synthesis and solution synthesis. Compared to solution-based synthesis methods, surface synthesis based on scanning tunneling microscopy has shown substantial advantages in characterization, such as identification of chemical structures and measurement of electronic structures in real space.

[0004] Most synthesized graphene nanoribbons currently available focus on all-benzene structures, with limited research on non-benzene graphene nanoribbons and their doping. Theoretical studies indicate that non-benzene graphene nanoribbons possess properties distinct from all-benzene types, showing great promise for applications in optoelectronics, transport, and sensing. However, experimental research on non-benzene graphene nanoribbons is extremely scarce, primarily due to the significant difficulty in achieving atomically precise growth. Summary of the Invention

[0005] To address the problems and shortcomings of the existing technology, this invention provides a wide-bandgap nitrogen-doped non-benzene graphene nanoribbon and its preparation method. This invention utilizes two strategies: 1. A 1,8-dibromo-9H-carbazole precursor undergoes a Ullmann reaction on the surface of a gold single crystal to form a polymer chain; 2. The polymer chain undergoes a dehydrogenation cyclization reaction at high temperature to form nitrogen-doped non-benzene graphene nanoribbons. This invention is achieved through the following technical solutions.

[0006] A method for preparing wide-bandgap nitrogen-doped non-benzene graphene nanoribbons, the specific steps of which include:

[0007] Step 1: Prepare a gold single crystal substrate;

[0008] Step 2: The 1,8-dibromo-9H-carbazole precursor molecule is evaporated and deposited on the gold single crystal substrate of Step 1 to obtain the substrate and the assembled structure deposited on the substrate. The deposition process controls the temperature on the substrate to be 25-30℃.

[0009] Step 3: The substrate from Step 2 and the assembled structure deposited on the substrate are subjected to a first heating and heat preservation treatment to obtain a one-dimensional nitrogen-doped polymer chain.

[0010] Step 4: The polymer chain sample from Step 3 is subjected to a second heating and holding treatment to obtain one-dimensional nitrogen-doped non-benzene graphene nanoribbons.

[0011] The preparation process of the gold single crystal substrate is as follows:

[0012] Step 1.1: In an ultra-high vacuum chamber, the gold substrate is subjected to argon ion sputtering to obtain a gold substrate;

[0013] Step 1.2: Heat the gold substrate obtained in Step 1.1 to 430℃ and hold for 10-30 minutes to obtain a gold single crystal substrate.

[0014] In step 2, the evaporation temperature of the 1,8-dibromo-9H-carbazole precursor molecule is 50℃-60℃, and the deposition time is 2 minutes-5 minutes.

[0015] The step-by-step heating process in steps 3 and 4 involves first heating to 200°C and holding for 20-40 minutes; then heating to 400°C and holding for 20-40 minutes.

[0016] The beneficial effects of this invention are:

[0017] (1) The present invention can prepare one-dimensional nitrogen-doped graphene polymer chains;

[0018] (2) The one-dimensional nitrogen-doped non-benzene graphene nanoribbons prepared by the present invention;

[0019] (3) The nitrogen-doped non-benzene graphene nanoribbon prepared in this invention is a wide bandgap semiconductor with a bandgap of about 3.55 electron volts. Attached Figure Description

[0020] Figure 1 This is a scanning tunneling microscope image of the self-assembled structure prepared in Example 1 of the present invention;

[0021] Figure 2 This is a scanning tunneling microscope image of the one-dimensional nitrogen-doped polymer chain prepared in this invention;

[0022] Figure 3This is a scanning tunneling microscope image of one-dimensional nitrogen-doped non-benzene graphene nanoribbons prepared with atomic-level precision according to the present invention.

[0023] Figure 4 This is a scanning tunneling microscopy image of one-dimensional nitrogen-doped non-benzene graphene nanoribbons prepared with atomic precision according to the present invention.

[0024] Figure 5 This is a schematic diagram illustrating the preparation principle of the present invention. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0026] Test instruments and equipment:

[0027] Cryogenic scanning tunneling microscope: purchased from Omicron GmbH, Germany.

[0028] K-cell molecular evaporation source: purchased from Omicron, Germany.

[0029] Argon ion gun: purchased from Omicron, Germany.

[0030] raw material:

[0031] 1,8-Dibromo-9H-carbazole precursor molecule, purchased from Bid Pharmaceuticals, purity 99.9%.

[0032] Gold single crystal: purchased from MaTecK, purity 99.999%.

[0033] Example 1

[0034] A method for preparing wide-bandgap nitrogen-doped non-benzene graphene nanoribbons, the specific steps of which include:

[0035] Step 1: Preparation of gold single crystal substrate; The preparation process of the gold single crystal substrate is as follows:

[0036] Step 1.1: In an ultra-high vacuum chamber, the gold substrate is subjected to argon ion sputtering to obtain a gold substrate;

[0037] Step 1.2: Heat the gold substrate obtained in Step 1.1 to 430℃ and hold for 10 minutes to obtain a gold single crystal substrate;

[0038] Step 2: 50 mg of 1,8-dibromo-9H-carbazole precursor molecules were evaporated and deposited on the 50 g gold single crystal substrate from Step 1 using a thermally resistive K-cell molecular evaporation source at an evaporation temperature of 55 °C. This yielded the substrate and the self-assembled structure of the 1,8-dibromo-9H-carbazole precursor molecules deposited on the substrate. The deposition process controlled the temperature of the gold single crystal substrate at 30 °C and the deposition time at 5 minutes.

[0039] Step 3: The substrate from Step 2 and the self-assembly deposited on the substrate are subjected to a first heating to the growth temperature and held at that temperature to obtain a one-dimensional nitrogen-doped polymer chain; the growth temperature is 250℃ and the holding time is 30 minutes.

[0040] Step 4: Then, the substrate from Step 3 and the one-dimensional nitrogen-doped graphene polymer chains deposited on the substrate are subjected to a second heating to the growth temperature and held at 350°C for 30 minutes.

[0041] Step 5: Characterize the electrical properties of the nitrogen-doped non-benzene graphene nanoribbons obtained in Step 4, and measure their broadband semiconductor electronic structure.

[0042] The scanning tunneling microscope image of the self-assembled structure of the 1,8-dibromo-9H-carbazole molecule prepared in this embodiment is shown below. Figure 1 As shown, from Figure 1 It can be seen that it is a high-quality, neatly arranged self-assembly structure.

[0043] The scanning tunneling microscope image of the one-dimensional nitrogen-doped polymer chain prepared in this embodiment is shown below. Figure 2 As shown.

[0044] The scanning tunneling microscope image of the nitrogen-doped non-benzene graphene nanoribbons prepared in this embodiment is shown below. Figure 3 As shown.

[0045] The scanning tunneling microscopy (STM) spectra of the nitrogen-doped non-benzene graphene nanoribbons prepared in this embodiment are as follows: Figure 4 As shown.

[0046] Example 2

[0047] A method for preparing wide-bandgap nitrogen-doped non-benzene graphene nanoribbons, the specific steps of which include:

[0048] Step 1: Preparation of gold single crystal substrate; The preparation process of the gold single crystal substrate is as follows:

[0049] Step 1.1: In an ultra-high vacuum chamber, the gold substrate is subjected to argon ion sputtering to obtain a gold substrate;

[0050] Step 1.2: Heat the gold substrate obtained in Step 1.1 to 430℃ and hold for 10 minutes to obtain a gold single crystal substrate;

[0051] Step 2: 50 mg of 1,8-dibromo-9H-carbazole precursor molecules were evaporated and deposited on the 50 g gold single crystal substrate from Step 1 using a thermally resistive K-cell molecular evaporation source at an evaporation temperature of 60 °C. This yielded the substrate and the self-assembled structure of the 1,8-dibromo-9H-carbazole precursor molecules deposited on the substrate. The deposition process controlled the temperature of the gold single crystal substrate at 30 °C and the deposition time at 2 minutes.

[0052] Step 3: The substrate from Step 2 and the self-assembly deposited on the substrate are subjected to a first heating to the growth temperature and held at that temperature to obtain a one-dimensional nitrogen-doped polymer chain; the growth temperature is 250℃ and the holding time is 30 minutes.

[0053] Step 4: Then, the substrate from Step 3 and the one-dimensional nitrogen-doped polymer chains deposited on the substrate are subjected to a second heating to the growth temperature and held at 350°C for 30 minutes.

[0054] Step 5: Characterize the electrical properties of the nitrogen-doped non-benzene graphene nanoribbons obtained in Step 4 and measure their broadband semiconductor electronic structure.

[0055] Example 3

[0056] A method for preparing wide-bandgap nitrogen-doped non-benzene graphene nanoribbons, the specific steps of which include:

[0057] Step 1: Preparation of gold single crystal substrate; The preparation process of the gold single crystal substrate is as follows:

[0058] Step 1.1: In an ultra-high vacuum chamber, the gold substrate is subjected to argon ion sputtering to obtain a gold substrate;

[0059] Step 1.2: Heat the gold substrate obtained in Step 1.1 to 430℃ and hold for 10 minutes to obtain a gold single crystal substrate;

[0060] Step 2: 50 mg of 1,8-dibromo-9H-carbazole precursor molecules were evaporated and deposited on the 50 g gold single crystal substrate from Step 1 using a thermally resistive K-cell molecular evaporation source at an evaporation temperature of 50 °C. This yielded the substrate and the self-assembled structure of the 1,8-dibromo-9H-carbazole precursor molecules deposited on the substrate. The deposition process controlled the temperature of the gold single crystal substrate at 30 °C and the deposition time at 20 minutes.

[0061] Step 3: The substrate from Step 2 and the self-assembly deposited on the substrate are subjected to a first heating to the growth temperature and held at that temperature to obtain a one-dimensional nitrogen-doped polymer chain; the growth temperature is 250℃ and the holding time is 30 minutes.

[0062] Step 4: Then, the substrate from Step 3 and the one-dimensional nitrogen-doped polymer chains deposited on the substrate are subjected to a second heating to the growth temperature and held at 350°C for 30 minutes.

[0063] Step 5: Characterize the electrical properties of the nitrogen-doped non-benzene graphene nanoribbons obtained in Step 4 and measure their broadband semiconductor electronic structure.

[0064] The specific embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for preparing wide-bandgap nitrogen-doped non-benzene graphene nanoribbons, characterized by the following steps: include: Step 1: Prepare a gold single crystal substrate; Step 2: The 1,8-dibromo-9H-carbazole precursor molecule is deposited onto a gold single crystal substrate maintained at room temperature using molecular beam epitaxy. The temperature is then raised to 200°C and held for 20-40 minutes to obtain a one-dimensional polymer chain. Step 3: Heat the one-dimensional polymer chain sample obtained in Step 2 to 400℃ and hold for 20-40 minutes to obtain nitrogen-doped non-benzene graphene nanoribbons.

2. The method for preparing a wide-bandgap nitrogen-doped non-benzene graphene nanoribbon according to claim 1, characterized in that... The specific preparation process of the gold single crystal substrate is as follows: Step 1.1: In an ultra-high vacuum chamber, the gold substrate is subjected to argon ion sputtering to obtain a gold substrate; Step 1.2: Heat the gold substrate obtained in Step 1.1 to 480°C and hold for 20-30 minutes to obtain a clean gold single crystal substrate.

3. The method for preparing a wide-bandgap nitrogen-doped non-benzene graphene nanoribbon according to claim 1, characterized in that: In step 2, the evaporation temperature of the 1,8-dibromo-9H-carbazole precursor molecule is 50℃-60℃, and the deposition time is 2 minutes-5 minutes.

4. The method for preparing a wide-bandgap nitrogen-doped non-benzene graphene nanoribbon according to claim 1, characterized in that: The nitrogen-doped non-benzene graphene nanoribbons have a band gap of 3.55 electron volts.

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