N2200-based top gate bottom contact polymer field effect transistor
By employing a top-gate bottom contact structure and a spin-coating method to form the encapsulation layer in organic field-effect transistors, the problem of insufficient water and oxygen stability is solved, electrical performance is improved, and the encapsulation process is simplified, making it suitable for flexible electronic devices.
Patent Information
- Application Number
- CN202422356062.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-26
- Publication Date
- 2026-02-13
- Estimated Expiration
- 2034-09-26
AI Technical Summary
Existing organic field-effect transistors (OTFTs) are not stable enough in water and oxygen environments, especially since N-type semiconductor materials are easily corroded, affecting electrical performance. Furthermore, existing packaging methods may damage the semiconductor layer or increase complexity.
The N2200-based top-gate bottom-contact polymer field-effect transistor structure is adopted, and polymethyl methacrylate (PMMA), polydimethylsiloxane (PDMS) or polyethylene glycol (PEG) is used as the encapsulation layer. A barrier film is formed on the transistor surface by spin coating to protect the semiconductor layer from water and oxygen corrosion.
It effectively reduces water and oxygen permeability, improves the degradation rate of transistors in the environment, maintains electrical characteristics such as mobility, threshold voltage and on/off ratio, simplifies the packaging process, and facilitates mass production.
Smart Images
Figure CN223912817U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model belongs to the technical field of electronic material and device, especially relates to a top gate bottom contact polymer field effect transistor based on N2200. BACKGROUND
[0002] Organic field effect transistors have become the core component of flexible electronic products due to its low cost, environmental protection and large area preparation. The conjugated polymer represented by the newly developed donor-acceptor copolymer has great application potential due to its solution processability, natural softness and high bipolar performance.
[0003] Organic thin film transistors (OTFTs) are generally used in wearable technology, flexible electronic devices and medical devices due to their flexibility and bendability. Although this technology has broad prospects, it is still necessary to further improve the electrical performance stability of these organic field effect transistors, especially to improve the N-type semiconductor material which is easily affected by water and oxygen erosion, because they are usually located at a lower LUMO (lowest unoccupied molecular orbital) energy level, and the transmission of electrons occurs at the oxidation-reduction potential close to the oxygen and water existing in the ambient air. Although developing higher performance and more stable N-type materials has become the focus of research in recent years, the materials available on the market still need to be improved for large-scale production of device preparation. Although it is a good choice to select the material of the semiconductor layer itself to improve the reliability, it is more economical and convenient to improve the environmental water and oxygen stability by encapsulating the top layer of the device, which accelerates the commercialization of OTFT-based applications. The encapsulation barrier film can isolate water and oxygen, mainly due to the following two factors: ① modify the surface of the film to increase the water contact angle, and modify the hydrophilic surface to a hydrophobic surface. ② Increasing the thickness will reduce the permeability, because the molecular diffusion takes a long time. The effective path length of the diffusion molecules from one side of the barrier to the other side is related to the thickness of the barrier film and its internal structure. However, as a protective layer, encapsulation should not interfere with the basic characteristics of the device, therefore, the encapsulation material must be flexible, easy to operate, light in weight, optically transparent and economical.
[0004] In order to effectively improve the water and oxygen stability of organic field effect transistors and slow down the degradation rate in a particular environment, spin-coating a barrier blocking film for encapsulation is one of the effective methods to achieve this purpose. Although device encapsulation can quickly achieve air stability of the device, if the solvent is not properly selected, it will damage the semiconductor layer.
[0005] Based on this, we have developed a top gate bottom contact polymer field effect transistor based on N2200. Utility model content
[0006] The utility model discloses a top gate bottom contact polymer field effect transistor based on N2200.
[0007] In order to solve above technical problem, the utility model discloses a top gate bottom contact polymer field effect transistor based on N2200, including substrate and the organic semiconductor layer, polymer dielectric layer and polymer encapsulation layer made by N2200 that are sequentially arranged on substrate,
[0008] One end of organic semiconductor layer is electrically connected with source electrode, and the other end is electrically connected with drain electrode.
[0009] Gate is equipped between polymer dielectric layer and polymer encapsulation layer, and gate and polymer dielectric layer are electrically connected together.
[0010] Among them, the material of organic semiconductor layer is poly naphthalene diimine - bithiophene P (DNI2OD-T2), namely N2200, and the corresponding CAS number is 1100243-40-0.
[0011] Among them, the encapsulation material of polymer encapsulation layer is one or more of polymethyl methacrylate (PMMA), polydimethylsiloxane (PDMS) or polyethylene glycol (PEG).
[0012] Among them, the polymer encapsulation layer adopts spin coating method.
[0013] The preparation method of polymer field effect transistor, specifically includes the following steps:
[0014] S1. select substrate and carry out cleaning;
[0015] S2. the source electrode and drain electrode are prepared on the substrate obtained in S1 using vacuum thermal evaporation method;
[0016] S3. spin coating semiconductor solution on the substrate after S2 processing and annealing treatment to prepare organic semiconductor layer;
[0017] S4. spin coating polymer dielectric layer solution on the organic semiconductor layer obtained in S3 and annealing treatment to prepare polymer dielectric layer;
[0018] S5. the gate is prepared on the polymer dielectric layer prepared in S4 using vacuum thermal evaporation method;
[0019] S6. the polymer encapsulation layer solution is added on the surface of gate and polymer dielectric layer using drop coating method or spin coating method and annealing treatment to prepare polymer encapsulation layer, and the polymer field effect transistor is obtained.
[0020] The source and the drain in the S2 use nickel and gold as the material; the side of the source and the drain in contact with the substrate is nickel, and gold is on the nickel; the thickness of the nickel in the source and the drain is 5 nm, and the thickness of the gold is 50 nm; the channel length of the source and the drain is 150 μm, 300 μm and 500 μm respectively, and the width is 1200 μm.
[0021] The thermal evaporation current of the nickel in the source and the drain is 130-150 A, and the evaporation rate is 0.005-0.01 nm / s; the evaporation current of the gold in the source and the drain is 130-150 A, and the evaporation rate is 0.01-0.03 nm / s.
[0022] The semiconductor solution in the S3 is a dichlorobenzene solution of poly (naphthalene diimine-bithiophene) P (DNI2OD-T2) ; the mass-volume ratio of the dichlorobenzene solution of poly (naphthalene diimine-bithiophene) P (DNI2OD-T2) is 6-8 mg / ml; the parameters of the spin coating are first uniform coating at a speed of 400-600 rpm for 4-6 seconds, and then uniform coating at a speed of 1800-2200 rpm for 45-70 seconds.
[0023] Preferably, in the S3, the mass-volume ratio of the dichlorobenzene solution of poly (naphthalene diimine-bithiophene) P (DNI2OD-T2) is 7 mg / ml; the parameters of the spin coating are first uniform coating at a speed of 500 rpm for 5 seconds, and then uniform coating at a speed of 2000 rpm for 60 seconds.
[0024] The polymer dielectric layer solution in the S4 is a butyl acetate solution of polymethyl methacrylate; the mass-volume ratio of the butyl acetate solution of polymethyl methacrylate is 100 mg / ml; the parameters of the spin coating are first uniform coating at a speed of 400-600 rpm for 4-6 seconds, and then uniform coating at a speed of 1800-2200 rpm for 45-70 seconds.
[0025] Preferably, in the S4, the parameters of the spin coating are first uniform coating at a speed of 500 rpm for 5 seconds, and then uniform coating at a speed of 2000 rpm for 60 seconds.
[0026] The polymer encapsulating layer solution in the S6 includes one of a polymethyl methacrylate solution, a polydimethylsiloxane solution or a polyethylene glycol solution; the solvent of the polymethyl methacrylate solution is butyl acetate, and the mass-volume ratio is 14-16 mg / mL; the polydimethylsiloxane solution contains pure polydimethylsiloxane and a curing agent, and the volume ratio of the pure polydimethylsiloxane to the curing agent is (8-12) : 1; the solvent of the polyethylene glycol solution is dimethyl sulfoxide, and the mass-volume ratio is 14-16 mg / mL.
[0027] Preferably, in S6, the solvent of the polymethyl methacrylate solution is butyl acetate, the mass / volume ratio is 15mg / mL; the polysiloxane solution contains pure polysiloxane and curing agent, the volume ratio of the pure polysiloxane to the curing agent is 10:1; the solvent of the polyethylene glycol solution is dimethyl sulfoxide, the mass / volume ratio is 15mg / mL.
[0028] Preferably, in S6, the spin coating parameters of the polymethyl methacrylate solution are as follows: first, uniform coating at a rotation speed of 400-600rpm for 4-6 seconds, and then uniform coating at a rotation speed of 1800-3500rpm for 45-70 seconds; the spin coating parameters of the polysiloxane solution are as follows: first, uniform coating at a rotation speed of 400-600rpm for 4-6 seconds, and then uniform coating at a rotation speed of 800-1000rpm for 45-70 seconds; the spin coating parameters of the polyethylene glycol solution are as follows: first, uniform coating at a rotation speed of 400-600rpm for 4-6 seconds, and then uniform coating at a rotation speed of 2800-4200rpm for 45-70 seconds.
[0029] Preferably, in S6, the spin coating parameters of the polymethyl methacrylate solution are as follows: first, uniform coating at a rotation speed of 400-600rpm for 4-6 seconds, and then uniform coating at a rotation speed of 1800-2200rpm for 45-70 seconds; the spin coating parameters of the polysiloxane solution are as follows: first, uniform coating at a rotation speed of 400-600rpm for 4-6 seconds, and then uniform coating at a rotation speed of 800-1200rpm for 45-70 seconds; the spin coating parameters of the polyethylene glycol solution are as follows: first, uniform coating at a rotation speed of 400-600rpm for 4-6 seconds, and then uniform coating at a rotation speed of 2800-3200rpm for 45-70 seconds.
[0030] More preferably, in S6, the spin coating parameters of the polymethyl methacrylate solution are as follows: first, uniform coating at a rotation speed of 500rpm for 5 seconds, and then uniform coating at a rotation speed of 2000rpm for 60 seconds; the spin coating parameters of the polysiloxane solution are as follows: first, uniform coating at a rotation speed of 500rpm for 5 seconds, and then uniform coating at a rotation speed of 1000rpm for 60 seconds; the spin coating parameters of the polyethylene glycol solution are as follows: first, uniform coating at a rotation speed of 500rpm for 5 seconds, and then uniform coating at a rotation speed of 3000rpm for 60 seconds.
[0031] Beneficial effects:
[0032] 1. The utility model discloses a high-performance transistor of top gate bottom contact is prepared by using N2200 as organic semiconductor layer, evaporating nickel and gold on the substrate as source and drain electrode, adopting polymethyl methacrylate as dielectric layer, simultaneously adding the encapsulation layer on the surface of organic field effect transistor by simple spin coating method, can effectively reduce the surface defect of encapsulation film, and the spin coating method is simple to operate, and the complexity is reduced, can be prepared on a large scale, and this has great application prospect in flexible, wearable electronics.
[0033] 2、The packaging material selected in the utility model can effectively block water and oxygen environment, reduce the permeability of water and oxygen in the air to the device, thereby improving the degradation of the field effect transistor in the environment, and can ensure that the electrical characteristics such as mobility, threshold voltage and on-off ratio are far superior to the field effect transistor without packaging within a certain time range. BRIEF DESCRIPTION OF DRAWINGS
[0034] The above and / or other aspects of the utility model will become more apparent by describing in detail some embodiments thereof, with reference made to the accompanying drawings.
[0035] Figure 1 is the structure diagram of the thin film transistor prepared based on different kinds of packaging layers in the embodiment of the utility model;
[0036] Figure 2 is the structure diagram of the organic field effect transistor without the upper packaging layer prepared in the comparative example of the utility model;
[0037] Figure 3 is the saturation region transfer characteristic curve of the organic field effect transistor with or without the packaging layer after the device prepared by the best spin coating parameter in the embodiment of the utility model degrades for three days in a specific environment (25 DEG C, 60 RH);
[0038] Figure 4 is the mean value statistical diagram of the mobility of the organic field effect transistor with or without the packaging layer after the device prepared by the best spin coating parameter in the embodiment of the utility model degrades for three days in a specific environment (25 DEG C, 60 RH);
[0039] Figure 5 is the mean value statistical diagram of the threshold voltage of the organic field effect transistor with or without the packaging layer after the device prepared by the best spin coating parameter in the embodiment of the utility model degrades for three days in a specific environment (25 DEG C, 60 RH);
[0040] Figure 6 is the mean value statistical diagram of the on-off ratio of the organic field effect transistor with or without the packaging layer after the device prepared by the best spin coating parameter in the embodiment of the utility model degrades for three days in a specific environment (25 DEG C, 60 RH);
[0041] Wherein, 1 is a substrate, 2 is a source, 3 is an organic semiconductor layer, 4 is a polymer dielectric layer, 5 is a gate, 6 is a polymer packaging layer, and 7 is a drain. DETAILED DESCRIPTION
[0042] In order to make the purpose, technical scheme and advantages of the utility model more clear and obvious, the utility model will be further described in detail below by combining with the drawings and embodiments, obviously, the described embodiments are only a part of the embodiments of the utility model, not all the embodiments.
[0043] Referring to Figures 1-2 The utility model discloses a kind of top gate bottom contact polymer field effect transistor based on N2200, including substrate, and sequentially arranged on substrate organic semiconductor layer made of N2200, polymer dielectric layer and polymer encapsulation layer;
[0044] The organic semiconductor layer is electrically connected with source electrode at one end, and is electrically connected with drain electrode at the other end.
[0045] The gate is provided between the polymer dielectric layer and the polymer encapsulation layer, and the gate and the polymer dielectric layer are electrically connected together.
[0046] The material of the organic semiconductor layer is poly (naphthalene diimide) -bithiophene P (DNI2OD-T2).
[0047] Poly (naphthalene diimide) -bithiophene P (DNI2OD-T2) is N2200, and the corresponding CAS number is 1100243-40-0, which has the following formula structure:
[0048]
[0049] The encapsulation material of the polymer encapsulation layer is one or more of polymethyl methacrylate (PMMA), polydimethylsiloxane (PDMS) or polyethylene glycol (PEG).
[0050] Further, the source electrode and the drain electrode are in contact with the substrate on one side, and gold is on the nickel, the thickness of the nickel in the source electrode and the drain electrode is 5 nm, the thickness of the gold is 50 nm, the channel length of the source electrode and the drain electrode is 150 μm, 300 μm and 500 μm respectively, and the width is 1200 μm.
[0051] Further, the polymer encapsulation layer is added by spin coating method.
[0052] Embodiment 1: The embodiment provides a preparation method for improving top gate bottom contact polymer field effect transistor based on N2200 by encapsulation, the field effect transistor structure is the same before the encapsulation layer, but the encapsulation layer solution is different, and the best spin coating parameters are selected, so as to form three different field effect transistor devices, mainly including the following steps:
[0053] 1) The preparation method of the semiconductor solution is as follows: dissolve the semiconductor material N2200 in the high-boiling organic solvent dichlorobenzene (DCB), and the solution concentration is 7 mg / ml. Place the prepared semiconductor solution on the heating table and stand still until completely dissolved without precipitation.
[0054] Preparation of polymer dielectric layer solution: the polymer material polymethyl methacrylate (PMMA) is dissolved in butyl acetate (NBA) at a mass-volume ratio of 100 mg / ml to obtain a polymer dielectric layer solution, and the prepared polymer dielectric layer solution is placed on a heating table at 80°C for dissolution for one week;
[0055] 2) The glass sheet with a size of about 1.5*1.5 cm is cleaned by ultrasonic cleaning with ethanol and deionized water respectively, and then ultrasonic cleaning with ethanol, and then dried with a nitrogen gun; after nitrogen drying, it is used as a substrate;
[0056] 3) The source and drain electrodes are prepared by vacuum thermal evaporation method with a suitable evaporation rate using a stainless steel mask on the substrate, the channel length of the electrodes evaporated on the substrate is 150 μm, 300 μm and 500 μm respectively, and the width is 1200 μm, the nickel is in direct contact with the substrate, and the gold is on the nickel; the thickness of the nickel layer is 5 nm, and the thickness of the gold layer is 50 nm;
[0057] 4) The prepared N2200 solution is spin-coated, and the prepared semiconductor solution is spread on the surface of the substrate by a pipette, and the spin-coating process is as follows: first, uniform glue at a speed of 500 rpm for 5 seconds, and then uniform glue at a speed of 2000 rpm for 60 seconds. After spin-coating, the sample is placed on a heating table to anneal in a pure nitrogen atmosphere to ensure that the prepared semiconductor thin film is uniform in thickness;
[0058] 5) The prepared polymer dielectric layer solution is spin-coated, and the spin-coating process is as follows: first, uniform glue at a speed of 500 rpm for 5 seconds, and then uniform glue at a speed of 2000 rpm for 60 seconds. After spin-coating, the sample is placed on a heating table to anneal;
[0059] 6) The gate electrode is prepared by vacuum thermal evaporation method combined with mask method and accurate alignment with the deposited nickel-gold source and drain electrodes, and then 100 nm thick aluminum is evaporated on the dielectric layer as a gate electrode at a suitable evaporation rate;
[0060] 7) PMMA, PDMS and PEG encapsulation layer solutions are prepared respectively, wherein PMMA is dissolved in butyl acetate (NBA) at a mass-volume ratio of 15 mg / mL to obtain a PMMA encapsulation layer solution; PDMS and curing agent are mixed at a volume ratio of 10:1 to obtain a PDMS encapsulation layer solution; and PEG is dissolved in dimethyl sulfoxide (DMSO) at a mass-volume ratio of 15 mg / mL to obtain a PEG encapsulation layer solution;
[0061] 8) The PMMA encapsulation layer solution is spin-coated, and the spin-coating process of polymethyl methacrylate (PMMA) is as follows: first, uniform glue at a speed of 500 rpm for 5 seconds, and then uniform glue at a speed of 2000 rpm for 60 seconds. After spin-coating, the sample is placed on a heating table to anneal to form an encapsulation layer, and thus the complete organic field effect transistor is obtained.
[0062] 9) The PDMS encapsulation layer solution is spin-coated. The spin-coating process of the polydimethylsiloxane polymer (PDMS) is first uniform coating at a speed of 500 rpm for 5 seconds, and then uniform coating at a speed of 1000 rpm for 60 seconds. After spin-coating is completed, the sample is placed on a heating table for annealing to form an encapsulation layer. Thus, the complete organic field effect transistor is obtained;
[0063] 10) The PEG encapsulation layer solution is spin-coated. The spin-coating process of the polyethylene glycol polymer (PEG) is first uniform coating at a speed of 500 rpm for 5 seconds, and then uniform coating at a speed of 3000 rpm for 60 seconds. After spin-coating is completed, the sample is placed on a heating table for annealing to form an encapsulation layer. Thus, the N2200-based top-gate bottom-contact structure organic field effect transistor with an encapsulation layer is prepared.
[0064] 7), 8) and 9) The spin-coated solutions are different, and three independent and different organic field effect transistor devices are formed.
[0065] Example 2: This example provides a preparation method for improving a N2200-based top-gate bottom-contact polymer field effect transistor by encapsulation. The difference is that the spin-coating speed of the encapsulation layer solution is different from that of Example 1. The method mainly includes the following steps:
[0066] 1) The preparation method of the semiconductor solution is as follows: the semiconductor material N2200 is dissolved in the high-boiling organic solvent dichlorobenzene (DCB). The prepared semiconductor solution is placed on a heating table for standing and dissolving until complete dissolution without precipitation;
[0067] Preparation of the polymer dielectric layer solution: the polymer material polymethyl methacrylate (PMMA) is dissolved in butyl acetate (NBA) at a mass-volume ratio of 100 mg / ml to obtain a polymer dielectric layer solution. The prepared polymer dielectric layer solution is placed on a heating table at 80°C for standing and dissolving for one week;
[0068] 2) A glass sheet with a size of about 1.5*1.5 cm is ultrasonically cleaned with ethanol and deionized water, respectively, and then ultrasonically cleaned with ethanol again, and then dried with a nitrogen gun. After being dried with nitrogen, the glass sheet is used as a substrate;
[0069] 3) A vacuum thermal evaporation method is used to evaporate nickel and gold as source and drain electrodes on the substrate using a stainless steel mask at a suitable evaporation rate. The channel length of the electrode evaporated on the substrate is 150 μm, 300 μm and 500 μm, respectively, and the width is 1200 μm. The nickel is in direct contact with the substrate, and the gold is on the nickel. The thickness of the nickel layer is 5 nm, and the thickness of the gold layer is 50 nm;
[0070] 4) spin-coat the prepared N2200 solution, the prepared semiconductor solution is spread on the surface of the substrate by the pipette, the spin-coating process is: first spin at 500 rpm for 5 seconds, then spin at 2000 rpm for 60 seconds. After spin-coating, the sample is placed on the heating stage to anneal in a pure nitrogen atmosphere to ensure that the prepared semiconductor thin film is uniform in thickness;
[0071] 5) spin-coat the prepared polymer dielectric layer solution, the spin-coating process is: first spin at 500 rpm for 5 seconds, then spin at 2000 rpm for 60 seconds. After spin-coating, the sample is placed on the heating stage to anneal;
[0072] 6) after precise alignment with the deposited nickel-gold source and drain electrodes using the vacuum thermal evaporation method combined with a mask method, 100 nm thick aluminum is evaporated as a gate electrode on the dielectric layer at a suitable evaporation rate;
[0073] 7) prepare PMMA, PDMS and PEG encapsulation layer solutions respectively, wherein PMMA is dissolved in butyl acetate (NBA) at a mass-volume ratio of 15 mg / mL to obtain a PMMA encapsulation layer solution; PDMS is mixed with a curing agent at a volume ratio of 10:1 to obtain a PDMS encapsulation layer solution; PEG is dissolved in dimethyl sulfoxide (DMSO) at a mass-volume ratio of 15 mg / mL to obtain a PEG encapsulation layer solution;
[0074] 8) spin-coat the PMMA encapsulation layer solution, the poly(methyl methacrylate) (PMMA) spin-coating process is: first spin at 500 rpm for 5 seconds, then spin at 3000 rpm for 60 seconds, after spin-coating, the sample is placed on the heating stage to anneal to form an encapsulation layer, thus obtaining the complete organic field effect transistor;
[0075] 9) directly drop the PDMS polymer solution to form an encapsulation layer, and then place the sample on the heating stage to anneal, thus obtaining the complete organic field effect transistor;
[0076] 10) spin-coat the PEG encapsulation layer solution, the polyethylene glycol (PEG) spin-coating process is: first spin at 500 rpm for 5 seconds, then spin at 4000 rpm for 60 seconds, after spin-coating, the sample is placed on the heating stage to anneal to form an encapsulation layer, thus the N2200-based top-gate bottom-contact structure organic field effect transistor with an encapsulation layer is prepared.
[0077] 7), 8) and 9) are different spin-coating solutions, and three independent organic field effect transistor devices are formed.
[0078] Comparative Example 1: The field effect transistor structure prepared in this comparative example differs from the field effect transistors prepared in Example 1 and Example 2 in that there is no encapsulating layer film on the uppermost layer.
[0079] 1) The semiconductor solution was prepared as follows: semiconductor material N2200 was dissolved in high-boiling organic solvent dichlorobenzene (DCB), and the prepared semiconductor solution was placed on a heating table to stand and dissolve until completely dissolved without precipitation;
[0080] Preparation of the polymer dielectric layer solution: the polymer material polymethyl methacrylate (PMMA) was dissolved in butyl acetate (NBA) to prepare the dielectric layer solution, and the prepared dielectric layer solution was placed on a heating table to stand and dissolve for one week;
[0081] 2) The glass sheet with a size of about 1.5 x 1.5 cm was cleaned by ultrasonic cleaning with ethanol, deionized water, and then ultrasonic cleaning with ethanol again, and then dried with a nitrogen gun; after nitrogen drying, it was used as a substrate;
[0082] 3) A vacuum thermal evaporation method was used to evaporate nickel and gold as source and drain electrodes on the substrate using a stainless steel mask with a suitable evaporation rate, the channel length of the electrode evaporated on the substrate was 150 μm, 300 μm and 500 μm, and the width was 1200 μm, the nickel was in direct contact with the substrate, and the gold was on the nickel; the thickness of the nickel layer was 5 nm, and the thickness of the gold layer was 50 nm;
[0083] 4) The prepared N2200 solution was spin-coated, and the prepared semiconductor solution was spread on the surface of the substrate with a pipette, the spin-coating process was: first spin-coating at a speed of 500 rpm for 5 seconds, and then spin-coating at a speed of 2000 rpm for 60 seconds. After spin-coating, the sample was placed on a heating table to anneal in a pure nitrogen atmosphere to ensure that the prepared semiconductor thin film was uniform in thickness;
[0084] 5) The prepared polymethyl methacrylate polymer (PMMA) solution was spin-coated, and the spin-coating process was: first spin-coating at a speed of 500 rpm for 5 seconds, and then spin-coating at a speed of 2000 rpm for 60 seconds. After spin-coating, the sample was placed on a heating table to anneal;
[0085] 6) A vacuum thermal evaporation method was used to evaporate 100 nm thick aluminum as a gate electrode on the dielectric layer with a suitable evaporation rate after precise alignment with the deposited nickel-gold source and drain electrodes using a mask method; thus, the complete organic field effect transistor was obtained; thus, a high-performance top-gate bottom-contact structure organic field effect transistor has been prepared.
[0086] Conclusion: All three encapsulation materials in Embodiment 1 of this utility model can effectively improve the water and oxygen stability of field-effect transistors. The optimized electrical characteristics of organic field-effect transistors with the best spin-coating parameters are as follows: After 3 days, the mobility, threshold voltage, on / off ratio, and subthreshold swing of the unencapsulated device increased by 0.11 cm⁻¹. 2 v -1 s -1 Reduced to 0.037cm 2 v -1 s -1 The voltage increased from 1.778V to 4.778V, and from 7.768 × 10⁻⁶V to 4.778V. 5 Reduced to 7.433×10 4 The value increased from 1.81 to 3.04; with the implementation of PMMA packaging, the mobility, threshold voltage, on / off ratio, and subthreshold swing of the packaged device after 3 days were 0.078 cm. 2 v -1 s -1 2.505V, 8.11×10 4 The values of 2.198 and 111% represent improvements of 111% and 47% respectively compared to unpackaged devices, while the values of 47% and 28% represent improvements of 9% and 28% respectively. With PDMS packaging, the packaged device achieved a mobility, threshold voltage, on / off ratio, and subthreshold swing of 0.054 cm⁻¹ after 3 days. 2 v -1 s -1 3.47V, 9.87×10 4 The values of PEG encapsulation and PEG-encapsulated devices were 2.183, representing improvements of 46% and reductions of 27% and 33% respectively compared to unencapsulated devices, respectively. After 3 days, the encapsulated device exhibited 0.086 cm⁻¹ mobility, threshold voltage, on / off ratio, and subthreshold swing. 2 v -1 s -1 2.67V, 6.96×10 4 The encapsulation efficiency of PMMA and PEG is 2.191, which represents an improvement of 132%, a reduction of 44%, a reduction of 6%, and a reduction of 27.9% respectively compared to unencapsulated devices. The encapsulation effect of PMMA and PEG is better than that of PDMS. This is mainly because after PDMS is formed, it solidifies into a tough and transparent elastomer. The film is thicker and the adhesion between the film and the glass surface is weaker. Water and oxygen can enter from the side of the glass sheet, resulting in device performance degradation.
[0087] The optimized electrical characteristics of the organic field-effect transistor with the better spin-coating parameters in Embodiment 2 of this utility model are as follows: After 3 days, the mobility, threshold voltage, on / off ratio, and subthreshold swing of the unpackaged device increased from 0.11 cm⁻¹ to 0.11 cm⁻¹. 2 v -1 s -1 Reduced to 0.037cm2 v -1 s -1 , from 1.778 V to 4.778 V, from 7.768 x 10 5 to 7.433 x 10 4 , from 1.81 to 3.04; PMMA encapsulated implementation, the mobility, threshold voltage, on / off ratio, subthreshold swing of the encapsulated device after 3 days are 0.063 cm 2 v -1 s -1 , 3.54 V, 1.23 x 10 5 , 2.16, which are increased by 70%, decreased by 26%, increased by 65%, decreased by 29% respectively compared to the unencapsulated device. PDMS encapsulated implementation, the mobility, threshold voltage, on / off ratio, subthreshold swing of the encapsulated device after 3 days are 0.047 cm 2 v -1 s -1 , 3.74 V, 9.18 x 10 4 , 1.89, which are increased by 65%, decreased by 22%, increased by 23.5%, decreased by 38% respectively compared to the unencapsulated device. PEG encapsulated implementation, the mobility, threshold voltage, on / off ratio, subthreshold swing of the encapsulated device after 3 days are 0.057 cm 2 v -1 s -1 , 2.84 V, 5.04 x 10 4 , 2.22, which are increased by 54%, decreased by 41%, decreased by 32%, decreased by 27% respectively compared to the unencapsulated device.
[0088] From the comparative examples, it can be seen that the encapsulation layer plays a crucial role in the water-oxygen stability of the top-gate bottom-contact polymer field effect transistor based on N2200. The electrical properties of the encapsulated organic field effect transistor are superior to the unencapsulated device in terms of threshold voltage, mobility and on / off ratio. The solvent used in the selected encapsulation material does not affect the film formation quality of the lower semiconductor layer, and the spin coating process using appropriate process parameters does not adversely affect the device performance and can effectively improve the degradation of the semiconductor layer caused by water and oxygen contained in the air. The spin coating process is simple and easy to operate, which is more conducive to repeated experiments and further commercialization.
[0089] The above description of the embodiments is for facilitating the ordinary skilled in the art to understand and use the present application, and the person skilled in the art can easily make various modifications to the embodiments, and apply the general principles described herein to other embodiments without creative labor, therefore, the present application is not limited to the above embodiments, the improvements and modifications made by the person skilled in the art according to the disclosure of the present application without departing from the scope of the present application should be within the protection scope of the present application.
Claims
1. An N2200-based top-gate bottom-contact polymer field effect transistor, characterized by: The application relates to a substrate and an organic semiconductor layer made of N2200, a polymer dielectric layer and a polymer encapsulation layer arranged on the substrate in sequence. The organic semiconductor layer is electrically connected with a source electrode at one end and a drain electrode at the other end. A gate electrode is arranged between the polymer dielectric layer and the polymer encapsulation layer, and the gate electrode and the polymer dielectric layer are electrically connected together. The material of the organic semiconductor layer is polyimide-bithiophene P(DNI2OD-T2), namely N2200. The encapsulation material of the polymer encapsulation layer is one of polymethyl methacrylate, polydimethylsiloxane and polyethylene glycol. The material of the source electrode and the drain electrode is nickel and gold.
2. The N2200-based top-gate bottom-contact polymer field effect transistor according to claim 1, wherein: The source electrode and the drain electrode are in contact with the substrate on one side, and the source electrode and the drain electrode are made of nickel and gold. The channel length of the source electrode and the drain electrode is 150 mu m, 300 mu m and 500 mu m respectively, and the width is 1200 mu m.