A class of benzodithiophene derivatives and their preparation and application
By using benzodithiophene derivatives and triisopropylethynyl silicon as charge trapping layers, the high operating voltage, slow reading and writing speed and poor tolerance of organic field effect transistor memory is solved. Problem, high performance stable and high-density storage is achieved, suitable for flexible storage devices and display applications.
Patent Information
- Application Number
- CN202310209593.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-03-07
- Publication Date
- 2024-12-06
- Estimated Expiration
- 2043-03-07
AI Technical Summary
The existing airport effect transistor memory has problems such as high operating voltage, slow reading and writing speed, poor tolerance, unclear relationship between storage mechanism and molecular structure, and complex device structure increases cost and processing technology requirements, affecting material performance and stability. .
Using benzodithiophene derivatives as charge capture layer material, molecular films are prepared through simple and low-cost process methods, used for OFET memory devices, and synthesized with triisopropylethynyl silicon to form high-performance D-A conjugated polymerization optimize device structure and process flow.
Improves the performance stability and storage density of memory devices, enhances charge capture capabilities, reduces charge leakage, improves the storage performance and tolerance of devices, is suitable for flexible large-area preparation, suitable for non-volatile storage devices and flexibility Display and other applications.
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Figure CN116199707B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of organic storage and information technology, and in particular to a class of benzodithiophene derivatives and a preparation method thereof and application thereof in an organic field effect transistor memory. Background Art
[0002] The development and transformation of human society cannot be separated from the continuous exploration and application of advanced materials and technologies. The 20th century experienced a transition from silicon chemistry to the information age. We are currently in the era of mobile Internet and big data with explosive growth of information, and will gradually enter the era of consciousness of artificial intelligence and machine services.
[0003] As the home of data, memory is an indispensable element in the era of information technology and artificial intelligence. In order to cope with the explosive growth of data, memory is not only required to have faster read and write speeds, smaller size, higher storage density and simpler preparation process, but also to be flexible, lightweight and easy to carry. Compared with traditional silicon technology, non-volatile memory based on organic field effect transistor (OFET) is more suitable for application on large-area flexible substrates to create low-cost electronic devices. It can be processed and prepared using relatively inexpensive solutions without the need for photolithography processes used in the traditional semiconductor industry. It can greatly reduce production costs and achieve low-cost, low-energy green processing. It is expected to become a mainstream alternative for the new generation of memory, showing broad application prospects in memory chips, flexible integrated circuits and flexible displays.
[0004] Organic electronics has developed a rich array of electrical storage matrices and endowed them with a series of novel storage mechanisms under the action of electric fields, such as charge trapping, ion migration, conformational transitions, and filamentary conductance. The development of novel optoelectronic behaviors of organic semiconductors, such as multi-level storage, multiple intelligent responses, and information encryption, has made this field more vibrant. In recent years, important progress has also been made in the optimization of processing technology, high-density and multi-dimensional device integration of organic memory. However, the performance and stability data of organic information materials have not yet met people's expectations, and their electronic action mechanisms, energy level regulation, and carrier transport characteristics need to be further revealed. In addition, the complex device structure is not only not conducive to reducing costs, but also puts higher requirements on the material processing technology, and the device efficiency and lifespan need to be further improved.
[0005] Compared with traditional organic field effect transistors, organic field effect transistor memory adds a carrier trapping layer between the semiconductor layer and the gate. The trapping layer can be divided into three types according to the different trapping characteristics: ferroelectric, floating gate, and electret. Organic electret OFET memory is a dielectric that can semi-permanently maintain the polarization state without the action of an external electric field. It captures and stably stores charges, and has storage characteristics and insulation properties. However, there are problems such as excessively high operating voltage, slow read and write speeds, poor tolerance, and unclear relationship between storage mechanism and molecular structure.
[0006] Chinese patent CN111875616A discloses a method of utilizing the special chemical and physical properties of spiro derivative molecules to provide a simple and low-cost process to prepare different molecular films, and apply them to OFET memories to serve as charge trapping layers of memories. The resulting field effect memory device exhibits the advantages of organic memories such as flexibility, large area, and low process cost. It can be seen that using compound materials with special physical and chemical properties as raw materials for charge trapping layers is beneficial to improving the performance of field effect transistors. Therefore, in order to better explore the relationship between storage mechanism and molecular structure, it is necessary to explore more and better performance capture layer materials, which can not only solve the key problems of the device itself, but also effectively expand the source of materials and provide new ideas for the development of this field.
[0007] The benzodithiophene ring has the advantages of a large conjugated surface and conjugated length, good π-π stacking performance and high charge transfer efficiency, which is conducive to the synthesis of DA-type conjugated polymers with excellent performance. Studies have shown that polymer solar cell devices prepared from benzodithiophene derivatives have relatively good photovoltaic performance. Hou and Yang et al. (L. Dou, J. You, J. Yang, et al. Tandem polymer solar cells featuring aspectrally matched low-bandgap polymer. Nat. Photonics, 2012, 6 (3): 180-185.) have synthesized a series of narrow-bandgap conjugated polymers based on benzodithiophene. The energy conversion efficiency of solar cells based on this type of polymer has reached 5.63%-8.4%. This type of compound has excellent physical and chemical properties, but it is mostly used in solar photovoltaic devices. There is no technical solution for applying benzothiophene derivatives to field effect transistors. Summary of the invention
[0008] The purpose of the present invention is to disclose a class of benzodithiophene derivatives and their preparation and application. The main purpose is to utilize the special chemical and physical properties of benzodithiophene derivative molecules to prepare a molecular film that can be used in OFET memory and act as a charge trapping layer of the memory device through simple and low-cost process means. It is expected that by improving the capture layer, a high-performance memory device with stable performance and high storage density can be obtained, and the relationship between the storage mechanism and the molecular structure can be further explored.
[0009] In order to achieve the above technical purpose, the present invention is implemented by the following technical scheme: a class of benzodithiophene derivatives, whose general structural formula is as follows:
[0010]
[0011] Wherein, X is one of N, O, S, Se, and Ge, and Y and Z are selected from any one of the following structures: H- * ,
[0012] The synthetic route of the above-mentioned benzodithiophene derivatives is as follows:
[0013]
[0014] The synthesis steps of the above-mentioned benzodithiophene derivatives are as follows: under oxygen-free conditions, trifluoromethanesulfonate benzodithiophene compound a, triisopropylethynylsilane, Pd(PPh 3 ) 2 Cl 2 The copper iodide is dissolved in a mixed solution of DMF and diisopropylamine, and the temperature is raised to 90-100°C for reaction for 10-12 hours; HCl is added to terminate the reaction, the organic phase is extracted, the organic phases are combined, dried, filtered, the solvent is removed, and column chromatography is performed to obtain the product.
[0015] An organic field effect transistor comprises, from top to bottom, a source-drain electrode, an organic semiconductor layer, a charge trapping layer, a gate insulating layer, a substrate and a gate electrode formed on the substrate, wherein the charge trapping layer can be made from the above-mentioned benzodithiophene derivative.
[0016] Furthermore, the thickness of the source-drain electrode and the gate electrode is 50-100 nm, the thickness of the organic semiconductor layer is 30-50 nm, the thickness of the gate insulating layer is 50-300 nm, and the thickness of the charge trapping layer is 10-30 nm.
[0017] The preparation method of the above-mentioned organic field effect transistor is as follows:
[0018] (1) dissolving a benzodithiophene derivative in a solvent;
[0019] (2) using the substrate material as a substrate, forming a gate electrode and a gate insulating layer on the substrate, ultrasonically cleaning with acetone, ethanol, and deionized water in sequence, purging with nitrogen, and drying;
[0020] (3) treating the dried clean substrate with ultraviolet ozone;
[0021] (4) spin coating the solution prepared in step (1) on the surface of the substrate, annealing, and removing the solvent;
[0022] (5) forming an organic semiconductor layer on the substrate prepared in step (4) by a thermal vacuum evaporation film forming method or a solution spin coating method, preferably a vacuum evaporation film forming method;
[0023] (6) Taking out the substrate, and preparing source and drain electrodes on the substrate by magnetron sputtering, inkjet printing or vacuum evaporation, preferably preparing the source and drain electrodes by vacuum evaporation.
[0024] Furthermore, in step (1), the solvent used is chloroform or toluene, and the concentration of the obtained benzodithiophene derivative solution is 3 to 10 mg / mL.
[0025] Furthermore, in step (4), the spin coating process is carried out in air, the air humidity is controlled below 40%, and the temperature is controlled at room temperature.
[0026] Furthermore, in step (5), the conditions for vacuum evaporation of the organic semiconductor layer are: the evaporation rate is The vacuum degree is controlled at 6×10 -5 pa~6×10 -4 pa.
[0027] Furthermore, in step (6), the conditions for vacuum evaporation of the source and drain electrodes are: the evaporation rate The vacuum degree is controlled at 6×10 -5 pa~6×10 -4 pa.
[0028] The beneficial effects of the present invention are:
[0029] 1. The present application discloses a class of benzodithiophene derivatives and a preparation method thereof. The preparation process is simple, and the obtained compound has a large conjugated plane and charge cloud density, and is suitable for the preparation of organic field effect transistor memory;
[0030] 2. The OFET memory prepared using a class of benzodithiophene derivatives disclosed in the present application as a charge trapping layer has a simple structure. Since the benzodithiophene structure has charge trapping sites, when a voltage is applied to the device, electrons or holes tunnel from the semiconductor layer into the storage layer under the action of the electric field and are more easily captured, which helps to improve the storage performance of the device;
[0031] 3. Since the benzodithiophene ring has a large conjugated surface and good π-π stacking properties, it can further inhibit charge leakage and block the loss of carriers after combining with triisopropylethynyl silicon, thereby effectively improving the storage stability and tolerance of the charge and improving the storage performance of the device;
[0032] 4. Since the performance of the organic field-effect transistor memory prepared in the present application is effectively improved, and the memory is easy to process and integrate, and is suitable for flexible and large-area preparation, the memory device can be used to prepare non-volatile storage devices, such as solid-state hard drives, portable USB flash drives, etc.; at the same time, it can also be used in flexible storage devices, such as flexible display screens, electronic skin, wearable devices, etc. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] Figure 1 is a schematic diagram of the planar structure of the organic field effect transistor memory prepared in Application Example 1;
[0034] Figure 2 is the hydrogen nuclear magnetic resonance spectrum of compound 1 prepared in Example 1;
[0035] Figure 3 The output curve of the organic field effect transistor memory prepared in Application Example 1;
[0036] Figure 4 The transfer curve of the organic field effect transistor memory prepared in Application Example 1;
[0037] Figure 5 Positive and negative storage window characteristic curves of the organic field effect transistor memory prepared for the test application example 1;
[0038] Figure 6 The read-write-erase cycle curve of the organic field effect transistor memory prepared in Application Example 1;
[0039] Figure 7 The stability curve of the organic field effect transistor memory prepared in Application Example 1 is shown in FIG.
[0040] Figure 8 The hydrogen nuclear magnetic resonance spectrum of compound 3 prepared in Example 2;
[0041] Fig. 9 The output curve of the organic field effect transistor memory prepared in Application Example 2;
[0042] Fig.10 The transfer curve of the organic field effect transistor memory prepared in Application Example 2;
[0043] Fig.11Positive and negative storage window characteristic curves of the organic field effect transistor memory prepared for the test application example 2;
[0044] Fig.12 This is the maintenance time stability curve of the organic field effect transistor memory prepared in Application Example 2. DETAILED DESCRIPTION
[0045] The following examples further illustrate the content of the present invention, but should not be construed as limiting the present invention. Without departing from the essence of the present invention, modifications and substitutions made to the methods, steps or conditions of the present invention all fall within the scope of the present invention.
[0046] Example 1: Preparation of a benzodithiophene derivative
[0047] The specific synthesis route is as follows
[0048]
[0049] The specific preparation method is:
[0050] Under oxygen-free conditions, trifluoromethanesulfonate benzodithiophene (200 mg, 0.41 mmol), triisopropylethynylsilane (0.17 mL, 1.2 mmol), Pd(PPh 3 ) 2 Cl 2 (57 mg, 0.04 mmol, 10 mol%) and cuprous iodide (30 mg, 0.08 mmol, 20 mol%) were dissolved in a mixed solution of DMF (7 mL, nitrogen to remove oxygen) and diisopropylamine (7 mL, nitrogen to remove oxygen), and the temperature was raised to 100°C for reaction for 12 hours. HCl (100 mL, 1 M) was added to terminate the reaction, and the organic phase was extracted with ethyl acetate. The organic phases were combined, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed by rotary evaporator. The crude product was separated by column chromatography and eluted with n-hexane to obtain yellow solid compound 1.
[0051] 1 HNMR (400MHz, CDCl 3 ): δ (ppm) 7.61-7.55 (t, J = 8.8Hz, 2H), 7.54-7.26 (d, J = 113.2Hz, 2H), 1.22 (m, 42H).
[0052] Figure 2 This is the H NMR spectrum of compound 1. The H NMR spectrum shows obvious characteristic peaks, which are consistent with the material structure. The number of hydrogen is consistent with the material, and there is no impurity peak, so it is confirmed to be the product.
[0053] Example 2: Preparation of a benzodithiophene derivative
[0054] The specific synthesis route is as follows
[0055]
[0056] The specific preparation method is:
[0057] Under oxygen-free conditions, trifluoromethanesulfonate triisopropylethynylsilylbenzodithiophene (353 mg, 0.41 mmol), triisopropylethynylsilyl (0.17 mL, 1.2 mmol), Pd(PPh 3 ) 2 Cl 2 (57 mg, 0.04 mmol, 10 mol%) and cuprous iodide (30 mg, 0.08 mmol, 20 mol%) were dissolved in a mixed solution of DMF (7 mL, nitrogen to remove oxygen) and diisopropylamine (7 mL, nitrogen to remove oxygen), and the temperature was raised to 100°C for reaction for 12 hours. HCl (100 mL, 1 M) was added to terminate the reaction, and the organic phase was extracted with ethyl acetate, combined, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed by rotary evaporator. The crude product was separated by column chromatography and eluted with n-hexane to obtain yellow solid compound 2.
[0058] 1 HNMR (400MHz, CDCl 3 ): δ (ppm) 7.64 (s, 2H), 1.21 (m, 42H), 1.16 (m, 42H).
[0059] Figure 8 This is the H NMR spectrum of compound 2. The H NMR spectrum shows obvious characteristic peaks, which are consistent with the material structure. The number of hydrogen is consistent with the material, and there are no impurity peaks, so it is confirmed to be the product.
[0060] Application Example 1: Preparation of an OFET memory
[0061] The memory structure is as follows Figure 1 As shown, from bottom to top, it mainly includes substrate, gate electrode, gate insulating layer, charge trapping layer, organic semiconductor layer and source and drain electrodes on both sides of the channel on the surface of the organic semiconductor layer. The substrate is generally made of highly doped silicon wafer, glass sheet or PET plastic.
[0062] In this application example, heavily doped silicon is used as the substrate and gate electrode, 50 to 300 nm thick silicon dioxide is used as the gate insulating layer, 10 to 30 nm thick benzodithiophene derivative (i.e., compound 1) prepared in Example 1 is used as the charge trapping layer, 30 to 50 nm thick pentacene is used as the organic semiconductor layer, and copper is evaporated on the organic semiconductor layer as the source and drain electrodes.
[0063] During preparation, the laboratory temperature was maintained at about 25°C and the humidity was 40%.
[0064] The specific preparation steps are as follows:
[0065] (1) The benzodithiophene derivative prepared in Example 1 was dissolved in toluene, heated or ultrasonicated to fully dissolve it, and allowed to stand for 24 hours to disperse it evenly. The concentration of the resulting solution was 3 mg / mL;
[0066] (2) ultrasonically cleaning the substrate (heavily doped silicon with 50 nm of silicon dioxide on the surface) with acetone, ethanol, and deionized water for 10 min in sequence, with an ultrasonic frequency of 100 kHz, and then blowing the surface of the substrate dry with high-purity nitrogen to ensure that the substrate surface is clean, and then placing the substrate in an oven at 120° C. to dry;
[0067] (3) Place the dried substrate in a UV ozone machine for 10 minutes;
[0068] (4) The experiment was carried out in an air environment with a humidity of 40%. The solution prepared in step (1) was spin-coated on the treated substrate surface at a speed of 3000 r / min for 30 s. The spin-coated substrate was placed in a vacuum drying oven at 80° C. and annealed for 30 min to obtain a charge trapping layer.
[0069] (5) Vacuum evaporation of pentacene as an organic semiconductor layer on the surface of the charge trapping layer at a rate of The vacuum degree is 5×10 -4 Pa or less, the thickness of pentacene is 30nm; then take it out and add the mask plate for multiple batches of processing, vacuum evaporation copper as the source and drain electrodes, the evaporation rate The vacuum degree is 5×10 -4 The electrode thickness is about 60nm; the mask template controls the channel width and length of a single group to be 2000μm and 100μm respectively.
[0070] Figure 3 The output curve of the organic field effect transistor memory is obtained from Figure 3 It can be seen that the threshold voltage of the device is 8.22V and the field effect mobility is 0.2366cm 2 / Vs; current switching ratio is 8.0*10 4 ;
[0071] Figure 4 The transfer curve of the obtained organic field effect transistor memory shows that the device has good field effect;
[0072] Figure 5 The positive and negative storage window characteristic curves of the tested organic field effect transistor memory. Under 80V voltage stimulation, the storage window of the device reaches 50.7V.
[0073] Figure 6 The read-write-erase cycle curve of the organic field effect transistor memory. After 100 read-write-erase cycles, the switching ratio of the device is still 10 2 Magnitude;
[0074] Figure 7 This is the holding time stability curve of the organic field effect transistor memory. After a holding time of 10,000 seconds, the current state of the device can still remain stable.
[0075] Application Example 2: Preparation of an OFET memory
[0076] The only difference between Application Example 2 and Application Example 1 is that the charge trapping layer in this application example is prepared by using the benzodithiophene derivative prepared in Example 2 (i.e., Compound 2) instead of Compound 1. The structure of the prepared memory is the same as that in Application Example 1, and the preparation steps are also the same.
[0077] Fig. 9 The output curve of the organic field effect transistor memory is obtained from Fig. 9 It can be seen that the threshold voltage of the device is -2.29V and the field effect mobility is 0.1620cm 2 / Vs; current switching ratio is 1.22*10 5 ;
[0078] Fig.10 The transfer curve of the obtained organic field effect transistor memory shows that the device has good field effect;
[0079] Fig.11 The positive and negative storage window characteristic curves of the tested organic field effect transistor memory. Under 80V voltage stimulation, the storage window of the device reaches 45.6V, and under -80V voltage stimulation, the storage window of the device reaches 18.7V.
[0080] Fig.12 This is the holding time stability curve of the organic field effect transistor memory. After a holding time of 10,000 seconds, the current state of the device can still remain stable.
[0081] The above shows and describes the basic principles, main features and advantages of the present invention. However, the above is only a specific embodiment of the present invention, and the technical features of the present invention are not limited thereto. Any other implementation methods derived by any technician in the field without departing from the technical solution of the present invention should be included in the patent scope of the present invention.
Claims
1. An organic field effect transistor memory, comprising, from top to bottom, a source-drain electrode, an organic semiconductor layer, a charge trapping layer, a gate insulating layer, a substrate, and a gate electrode formed on the substrate, characterized in that: The charge trapping layer is prepared based on a class of benzodithiophene derivatives, and the general structural formula of the benzodithiophene derivatives is as follows: Wherein, X is one of N, O, S, Se, and Ge, and Y and Z are selected from the following structures: H- * , 2. An organic field effect transistor memory as claimed in claim 1, characterized in that: The thickness of the source-drain electrode and the gate electrode is 50-100 nm, the thickness of the organic semiconductor layer is 30-50 nm, the thickness of the gate insulating layer is 50-300 nm, and the thickness of the charge trapping layer is 10-30 nm.
3. A method for preparing an organic field effect transistor memory according to any one of claims 1 to 2, characterized in that: The steps include: (1) dissolving a benzodithiophene derivative in a solvent; (2) using the substrate material as a substrate, forming a gate electrode and a gate insulating layer on the substrate, ultrasonic cleaning, nitrogen purging and drying; (3) UV-ozone treatment of the dried substrate; (4) spin coating the solution prepared in step (1) on the surface of the substrate, annealing, and removing the solvent; (5) vacuum evaporating an organic semiconductor layer on the substrate prepared in step (4); (6) Take out the substrate and vacuum evaporate the source and drain electrodes on the substrate.
4. The method for preparing an organic field effect transistor memory according to claim 3, characterized in that: In step (1), the solvent used is chloroform or toluene, and the concentration of the obtained benzodithiophene derivative solution is 3 to 10 mg / mL.
5. The method for preparing an organic field effect transistor memory according to claim 3, characterized in that: In step (4), the spin coating process is carried out in an air environment, the air humidity is controlled at 40%, and the temperature is controlled at room temperature.
6. The method for preparing an organic field effect transistor memory according to claim 3, characterized in that: In step (5), the conditions for vacuum evaporation of the organic semiconductor layer are: the evaporation rate is The vacuum degree is controlled at 6×10 -5 pa~6×10 -4 pa.
7. The method for preparing an organic field effect transistor memory according to claim 3, characterized in that: In step (6), the conditions for vacuum evaporation of source and drain electrodes are: evaporation rate The vacuum degree is controlled at 6×10 -5 pa~6×10 - 4 pa.