Condensed ring imide room temperature organic ferromagnetic semiconductor film and preparation method thereof

Abstract

The invention belongs to the technical field of ferromagnetic semiconductor materials, and discloses a fused ring imide room temperature organic ferromagnetic semiconductor film and a preparation method thereof. The method comprises the following steps: depositing a condensed ring imide compound to prepare a thin film, and then performing vapor phase reduction to obtain the condensed ring imide room-temperature organic ferromagnetic semiconductor thin film, the condensed ring imide compound has a structure as shown in a formula III. The method is simple, and the prepared film has high saturation magnetization, high Curie temperature and excellent electrical properties, and is an organic ferromagnetic semiconductor film. # imgabs0 #

Description

Technical Field

[0001] The present invention belongs to the field of ferromagnetic semiconductor materials, and particularly relates to polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin film materials and a preparation method thereof. Background Art

[0002] Ferromagnetic semiconductors show important application prospects in breaking through the limitations of Moore's Law through the collaborative regulation of electron charge and spin, and can effectively achieve the deep integration of spintronics and traditional electronics. Such materials have significant advantages in improving energy efficiency, data storage capacity, and information processing capabilities, providing important technical support for the development of new-generation electronic devices. Currently, ferromagnetic semiconductors mainly rely on inorganic materials. People dope high-spin metal atoms (Mn) into traditional inorganic semiconductor materials (InAs, GaAs, etc.), and ferromagnetic coupling is induced between the spins of manganese atoms through hole carriers in the semiconductor, thereby endowing the semiconductor with ferromagnetism. However, due to the huge difference in atomic sizes, doping is difficult and the doping degree is low, which leads to difficulties in preparing inorganic ferromagnetic semiconductor materials, low saturation magnetization intensity, and low Curie temperature. Recently, some researchers have also prepared ferromagnetic semiconductors based on metal-organic framework materials, providing spins through metal ions and regulating the spacing of metal ions through organic linkers to obtain ferromagnetic coupling. Although such materials can obtain high saturation magnetization intensity and Curie temperature, their electrical properties are poor. At the same time, future device applications require thin film materials. Therefore, currently, preparing ferromagnetic semiconductor thin films with high saturation magnetization intensity, high Curie temperature, and excellent electrical properties is still a huge challenge. Summary of the Invention

[0003] In order to overcome the disadvantages and deficiencies of the prior art, the purpose of the present invention is to provide a polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin film and a preparation method thereof. The present invention can obtain a ferromagnetic semiconductor thin film with high saturation magnetization intensity, high Curie temperature, and excellent electrical properties by a process of first evaporating and then reducing the polycyclic imide-based compound.

[0004] The present invention is realized through the following technical solutions:

[0005] A preparation method of a polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin film, comprising the following steps:

[0006] Deposit a polycyclic imide-based compound to form a thin film, and then perform gas-phase reduction to obtain a polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin film;

[0007] The polycyclic imide-based compound has the following structure:

[0008]

[0009] Wherein: n = 1, 2, 3; R1 and R2 are each independently at least one of H, alkyl, amino, carboxyl, hydroxyl, hydrazino (NH-NH2), pyridyl (2-substituted pyridine, 3-substituted pyridine, 4-substituted pyridine);

[0010] X1 - X4 are each independently an electron-withdrawing group, specifically H, F, Cl, Br, CN, NO2 group.

[0011] After reduction, the polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin film includes a polycyclic imide-based ionic material;

[0012] The polycyclic imide-based ionic material is one or more of the following structural formulas;

[0013]

[0014] In Formula I or II: n = 1, 2, 3; R1 and R2 are each independently at least one of H, alkyl, amino, carboxyl, hydroxyl, hydrazino (NH-NH2), pyridyl (2-substituted pyridine, 3-substituted pyridine, 4-substituted pyridine);

[0015] X1 - X4 are each independently an electron-withdrawing group, specifically H, F, Cl, Br, CN, NO2 group.

[0016] The deposition is thermal evaporation deposition; the reduction is gas-phase reduction.

[0017] The polycyclic imide-based compound thin film is obtained by the following method:

[0018] During the thermal evaporation coating process, the vacuum degree ≤ 1×10 -4 Pa (that is, the chamber pressure during the thermal evaporation coating process is maintained below 1×10 -4 Pa), the evaporation source temperature is 100 - 500 °C, the substrate temperature is 25 - 250 °C, and the evaporation rate is To obtain a polycyclic imide-based compound thin film. The thickness of the polycyclic imide-based compound thin film is 20 - 300 nm.

[0019] During thermal evaporation coating, the polycyclic imide-based compound is evaporated onto the substrate. The substrate is a single-crystalline silicon wafer, a quartz wafer, or a single-crystalline silicon wafer coated with silicon dioxide. The substrate is placed on the substrate.

[0020] The gas-phase reduction refers to: in a protective atmosphere, the reducing agent solution is placed in a closed space, volatilized or evaporated in the closed space, and then the polycyclic imide-based compound thin film evaporated on the substrate is placed therein to undergo a reduction reaction to obtain a polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin film.

[0021] Volatilize or evaporate in the closed space for 30 - 120 min, and then add the polycyclic imide-based compound thin film.

[0022] The time of the reduction reaction is 1 - 48 h.

[0023] The reducing agent solution refers to a mixture of a reducing agent and an organic solvent;

[0024] The reducing agent for gas-phase reduction is one or more of hydrazine hydrate, ammonia water, alkali metal, sodium dithionite, sodium sulfide, potassium sulfide, and polyethyleneimine.

[0025] The organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran, chloroform, dichloromethane, toluene, chlorobenzene, o-dichlorobenzene, ethyl acetate, methanol, acetone, acetonitrile, ethylene glycol dimethyl ether, 1,2-dichloroethane, dioxane, pyridine, or 2-methylpyrrolidone.

[0026] The volume ratio of the reducing agent to the organic solvent is 1:(0 - 10), preferably 1:(0.1 - 8), and more preferably 1:(0.5 - 5).

[0027] Volatilization or evaporation in a closed space means that the reducing agent solution is left standing at 10 - 200 °C for 30 - 120 min. The temperature is preferably 20 - 35 °C.

[0028] Specifically, the reducing agent solution is placed in a closed space, left standing for 30 - 120 min, the thin film is placed above the reducing agent solution (i.e., placed on a reduction table, the reduction table is located in the center of the reducing agent solution, and the upper surface of the reduction table is higher than the reducing agent solution), and sealed and left standing for 1 - 48 h.

[0029] The polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin film of the present invention has room-temperature ferromagnetism and semiconductor properties and is used as an organic ferromagnetic semiconductor thin film.

[0030] In the polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin film of the present invention, the anion after reduction of the polycyclic imide compound is a monovalent anion and / or a divalent anion.

[0031] The thin film of the present invention used as an organic ferromagnetic semiconductor has good performance. The presence of four carbonyl groups with electron-withdrawing ability in the structure of the polycyclic imide material selected in the present invention enables such molecules to form stable monovalent and divalent anion species. At the same time, this type of compound has a large conjugated planar structure, with ordered intermolecular packing and a small intermolecular distance, so the interaction is strong, the free radicals are ordered and arranged to form a magnetic moment, showing a ferromagnetic order close to room temperature. The Curie temperature (T c > 300 K) of the ferromagnetic transition is significantly higher than that of the reported ferromagnetic semiconductors. The saturation magnetization intensity reaches 10.6 emu / g, the coercive force at room temperature is close to 200 Oe, the conductivity is greater than 1 S / cm, and the band gap is about 2 eV.

[0032] The present invention provides an organic ferromagnetic semiconductor thin film with high saturation magnetization, high Curie temperature and excellent electrical properties, which has broad application prospects in pure organic magnetic materials and devices.

[0033] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0034] (1) The polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin film of the present invention has ferromagnetism and excellent electrical properties, and its Curie temperature exceeds room temperature. It is a room-temperature pure organic magnetic semiconductor material with broad application prospects;

[0035] (2) The present invention adopts thermal evaporation deposition and gas-phase reduction, and the preparation process is simple and the manufacturing cost is low. Description of the Drawings

[0036] Figure 1 Schematic diagram of the device used for the preparation of the polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin film in the examples;

[0037] Figure 2 Ultraviolet spectra of the thin film before and after reduction in Example 1;

[0038] Figure 3 Room-temperature and low-temperature hysteresis loops of the thin film in Example 1;

[0039] Figure 4 Temperature-dependent resistance curve of the thin film in Example 1;

[0040] Figure 5 Room-temperature and low-temperature hysteresis loops of the thin film in Example 2;

[0041] Figure 6 Temperature-dependent resistance curve of the thin film in Example 2. Detailed Description of the Invention

[0042] The following combines examples and drawings to further elaborate on the present invention in detail, but the implementation manners of the present invention are not limited thereto. The polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin film of the present invention contains the anion after reduction of the polycyclic imide-based compound, and also contains a cation that counteracts the anion.

[0043] Figure 1Schematic diagram of the device used for the preparation of polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin films in the examples. It includes a housing with a cavity (i.e., an empty bottle), a reduction platform (such as a cylinder) is provided at the bottom of the housing. The maximum horizontal distance of the reduction platform is less than the minimum horizontal distance of the bottom of the housing, and the vertical height of the reduction platform is less than the vertical height of the internal cavity of the housing (for example, the vertical height of the reduction platform is 1 / 5 or 1 / 3 of the vertical height of the internal cavity of the housing). The reducing agent solution is placed in the device, the thin film is placed on the reduction platform, and the reduction platform is located in the center of the reducing agent solution.

[0044] Example 1

[0045] The polycyclic imide compound (1,8:4,5-naphthalenetetracarboxylic diimide) in this example has the following structure:

[0046]

[0047] Soak a single-crystalline silicon wafer in piranha solution (a mixture of 40 mL of concentrated sulfuric acid and 20 mL of 30% hydrogen peroxide) for 12 h. After taking it out, ultrasonically treat it with deionized water, ethanol, dichloromethane, and isopropanol for 30 min in sequence, and then place it in an oven at 80 °C and let it stand for 6 h to dry for later use.

[0048] Place the single-crystalline silicon on the substrate in the evaporation chamber, keep the vacuum degree of the evaporation chamber below 1×10 -4 Pa, the substrate temperature is 25 °C, and the evaporation rate is controlled at Deposit a naphthalimide thin film with a thickness of 100 nm.

[0049] In the N2 glove box, mix 1.5 mL of hydrazine hydrate and 1.5 mL of dimethyl sulfoxide and place them in the bottle shown in Device I and let it stand for 30 min. Place the naphthalimide thin film evaporated on the single-crystalline silicon on the sample reduction platform and seal the device, and let it stand for 6 h to obtain a room-temperature organic ferromagnetic semiconductor thin film. The spectra of the original thin film and the reduced thin film are as Figure 2 shown, and the hysteresis loops at 300 K and 10 K are as Figure 3 shown. The saturation magnetization intensity is 10.6 emu / g, and the Curie temperature is greater than 300 K. Its temperature-dependent resistance is as Figure 4 shown, showing the characteristics of a semiconductor, and the room-temperature conductivity is 2.87 S / cm.

[0050] Example 2

[0051] The polycyclic imide compound (3,4:9,10-perylenetetracarboxylic diimide) in this example has the following structure:

[0052]

[0053] Immerse the monocrystalline silicon wafer in piranha solution (a mixture of 40 mL concentrated sulfuric acid and 20 mL 30% hydrogen peroxide) for 12 h. After taking it out, successively perform ultrasonic treatment with deionized water, ethanol, dichloromethane, and isopropanol for 30 min, and then place it in an oven at 80 °C and let it stand for 6 h to dry for standby.

[0054] Keep the vacuum degree of the evaporation chamber below 1×10 -4 Pa, the substrate temperature is 25 °C, and the evaporation rate is controlled at Deposit a perylene diimide thin film with a thickness of 100 nm.

[0055] In an N2 glove box, mix 1.5 mL of hydrazine hydrate and 1.5 mL of dimethyl sulfoxide and place them in the bottle shown in Device I and let it stand for 30 min. Place the monocrystalline silicon coated with the perylene diimide thin film on the sample reduction stage and seal the device, and let it stand for 6 h to obtain a room-temperature organic ferromagnetic semiconductor thin film. The hysteresis loops of the room-temperature organic ferromagnetic semiconductor thin film in this example at 300 K and 10 K are as Figure 5 shown, the saturation magnetization intensity is 10.5 emu / g, and the Curie temperature is greater than 300 K. Its temperature-dependent resistance is as Figure 6 shown, showing the characteristics of a semiconductor, and the room-temperature conductivity is 1.05 S / cm.

[0056] Comparative Example 1

[0057] Reduce the polycyclic imide compound provided in Example 2 into an anion solution through hydrazine hydrate, and then drop-coat and dry the anion solution to prepare a thin film. The saturation magnetization intensity of the thin film is 1.2 emu / g, the Curie temperature is greater than 400 K, and the conductivity is 0.62 S / cm.

[0058] Comparative Example 3

[0059] Change the reduction time in Example 2 to 50 h, then an antiferromagnetic thin film is obtained.

[0060] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A preparation method of a polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin film, characterized in that: It includes the following steps: Deposit a polycyclic imide compound to prepare a thin film, and then perform gas-phase reduction to obtain a polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin film; The polycyclic imide compound has the following structure: In the formula: n = 1, 2, 3; R1 and R2 are each independently at least one of H, alkyl, amino, carboxyl, hydroxyl, hydrazino NH-NH2, and pyridyl; X1-X4 are each independently an electron-withdrawing group; After reduction, the polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin film includes a polycyclic imide-based ionic material; The polycyclic imide-based ionic material is one or more of the following structural formulas; In Formula I or II: n = 1, 2, 3; R1 and R2 are each independently at least one of H, alkyl, amino, carboxyl, hydroxyl, hydrazino NH-NH2, and pyridyl; X1-X4 are each independently an electron-withdrawing group.

2. The method for preparing a polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin film according to claim 1, wherein: The pyridyl is at least one of 2-substituted pyridine, 3-substituted pyridine, or 4-substituted pyridine; X1-X4 are each independently a group of H, F, Cl, Br, CN, or NO2; The deposition is thermal evaporation deposition; the reduction is gas-phase reduction.

3. The preparation method of the polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin film according to claim 2, wherein: The thermal evaporation deposition means that the polycyclic imide compound thin film is obtained by the following method: During the thermal evaporation coating process, the vacuum degree ≤ 1×10 -4 Pa, the evaporation source temperature is 100 - 500 °C, the substrate temperature is 25 - 250 °C, and the evaporation rate is A polycyclic imide compound thin film is obtained.

4. The preparation method of the polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin film according to claim 2, wherein: The gas-phase reduction refers to: in a protective atmosphere, the reducing agent solution is placed in a closed space, volatilized or evaporated in the closed space, and then the polycyclic imide compound thin film is placed therein to undergo a reduction reaction to obtain a polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin film.

5. The preparation method of the polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin film according to claim 4, wherein: Volatilize or evaporate in the closed space for 30-120 min, and then add the polycyclic imide compound thin film; The time of the reduction reaction is 1-48 h; The reducing agent solution refers to a mixture of a reducing agent and an organic solvent; The reducing agent for the gas-phase reduction is one or more of hydrazine hydrate, ammonia water, alkali metal, sodium dithionite, sodium sulfide, potassium sulfide, and polyethyleneimine; The organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran, chloroform, dichloromethane, toluene, chlorobenzene, o-dichlorobenzene, ethyl acetate, methanol, acetone, acetonitrile, ethylene glycol dimethyl ether, 1,2-dichloroethane, dioxane, pyridine, or 2-methylpyrrolidone.

6. The preparation method of the polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin film according to claim 5, characterized in that: The volume ratio of the reducing agent to the organic solvent is 1:(0-10); Volatilizing or evaporating in the closed space means that the reducing agent solution stands at 10-200 °C for 30-120 min; The time of the reduction reaction is 4-15 h.

7. The preparation method of the polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin film according to claim 6, wherein: The volume ratio of the reducing agent to the organic solvent is 1:(0.1-8); Volatilizing or evaporating in the closed space means that the reducing agent solution stands at 20-35 °C for 30-120 min.

8. The preparation method of the polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin film according to claim 5, characterized in that: The gas-phase reduction refers to placing the reducing agent solution in a closed space, standing for 30-120 min, placing the thin film above the reducing agent solution, and sealing and standing for 1-48 h.

9. A polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin film obtained by the preparation method according to any one of claims 1-8.

10. Use of the polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin film according to claim 9, characterized in that: The polycyclic imide-based room-temperature organic ferromagnetic semiconductor thin film is used in organic solar cells, electroluminescent devices, field-effect transistors, spin valves, spin field-effect transistors, self-assembly, and bio-fluorescence detectors.

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