CN104900518A - Method for enhancing carbon nanotube thin-film transistor uniformity and phase inverter - Google Patents

Abstract

The present application discloses a method for improving the uniformity of carbon nanotube thin film transistors, including: s1, preparing a carbon nanotube solution; s2, performing plasma etching on the substrate to make it modified and have certain wettability; s3, The carbon nanotube solution is positioned between the channels of the substrate by printing to obtain a plurality of carbon nanotube thin film transistors with uniform properties. The present invention treats the surface of the substrate through short-time oxygen plasma etching, and the surface of the substrate has obvious hydrophilization effect and good wettability. On this basis, the performance of the constructed carbon nanotube thin film transistor device is good, and multiple transistors with high uniformity can be fabricated on the modified substrate. The preparation method has the advantages of simple process, environmental friendliness, convenient operation and low cost, so it is expected to be applied to large-scale commercial production of high-performance large-area printed independent carbon nanotube transistor devices.

Description

A method for improving the uniformity of a carbon nanotube thin film transistor and an inverter

technical field

The application belongs to the field of printed nanoelectronics, and in particular relates to a method for improving the uniformity of a carbon nanotube thin film transistor, a method for manufacturing a carbon nanotube thin film transistor and an inverter.

Background technique

Printed electronics technology is an emerging technology and industry field that has only flourished in the world in recent years. According to experts' prediction, the total value of printed electronics products in the world will reach 330 billion US dollars in 2017. Therefore, the development of printed electronics technology has been favored by people all over the world. Widely concerned, it has become a multidisciplinary and comprehensive frontier research hotspot. Although the performance of printed electronic devices is not as good as that of silicon-based semiconductor microelectronic devices, due to its simple printing process and non-selectivity to substrate materials, it has great potential in the application of large-area, flexible, and low-cost electronic devices. Incomparable advantages of semiconductor microelectronic electronic devices. In order to achieve large-area, high-volume, and low-cost production, the uniform performance of devices is a key element that must be guaranteed. Semiconducting carbon nanotubes have many superior properties. Compared with other semiconductor materials, they are not only small in size, excellent in electrical properties, and stable in physical and chemical properties, but also electronic components such as transistors constructed of carbon nanotubes have less heat generation and lower operating frequency. At the same time, carbon nanotubes are easy to achieve solution, and the separated and purified semiconducting carbon nanotube printing ink can build high-performance printed carbon nanotube thin film transistor devices. One of the most ideal semiconductor materials for devices.

However, during the preparation of the device, impurities such as surfactants and polymers introduced due to the dispersion and separation of carbon tubes will directly affect the performance of the device, and are usually removed by cleaning or annealing. However, due to the poor binding force between the substrate without any treatment and the carbon nanotubes, cleaning will lead to a decrease in the density of the carbon tubes, and the performance of the device cannot be improved well, and the decrease in the density of the carbon tubes will lead to poor uniformity of the device. Difference. However, substrates that are functionalized with polymers such as APTES can better enrich carbon nanotubes on the surface of the substrate to a certain extent, but the scope of application is limited.

Contents of the invention

The purpose of the present invention is to provide a method for improving the uniformity of carbon nanotube thin film transistors, a method for manufacturing carbon nanotube thin film transistors, and an inverter, which solves the problem of poor device performance and the bonding force between the substrate and carbon nanotubes in the prior art. Poor and technical issues with limited scope.

To achieve the above object, the present invention provides the following technical solutions:

The present application discloses a method for improving the uniformity of carbon nanotube thin film transistors, including:

s1, preparing a carbon nanotube solution;

s2. Perform plasma etching treatment on the substrate to make it modified and have certain wettability;

s3. Positioning the carbon nanotube solution between the channels of the substrate by printing to obtain a plurality of carbon nanotube thin film transistors with uniform performance.

Preferably, in the above-mentioned method for improving the uniformity of a carbon nanotube thin film transistor, in the step s2, the substrate is subjected to oxygen plasma etching treatment.

Preferably, in the above-mentioned method for improving the uniformity of a carbon nanotube thin film transistor, in the step s2, the time for performing oxygen plasma etching treatment on the substrate is 1 min to 10 min.

Preferably, in the above-mentioned method for improving the uniformity of a carbon nanotube thin film transistor, in the step s2, the discharge power for oxygen plasma etching treatment on the substrate is 80-120W.

Preferably, in the above-mentioned method for improving the uniformity of carbon nanotube thin film transistors, in the step s1, a solution enriched in semiconducting carbon nanotubes is obtained by separating and combining carbon nanotubes with polymers.

Preferably, in the above-mentioned method for improving the uniformity of carbon nanotube thin film transistors, the polymer is selected from polythiophene derivatives, polyfluorene, polyfluorene derivatives, polyphenylene vinylene derivatives, polycarbazole derivatives and One or more combinations of polypyridine derivatives.

Preferably, in the above method for improving the uniformity of carbon nanotube thin film transistors, the diameter of the carbon nanotubes is 0.6nm-2nm, and the obtained carbon nanotube solution is a single-wall semiconducting carbon nanotube solution.

Preferably, in the above-mentioned method for improving the uniformity of carbon nanotube thin film transistors, the substrate is selected from PET, PI, glass, silicon wafer or quartz; in the step s3, the printing method includes inkjet printing or gas Sol printing.

The application also discloses a method for manufacturing a carbon nanotube thin film transistor, comprising:

s1, preparing a carbon nanotube solution;

s2. Perform plasma etching treatment on the substrate to make it modified and have certain wettability;

s3. Positioning the carbon nanotube solution between the channels of the substrate by printing to obtain a carbon nanotube thin film transistor.

Correspondingly, the present application also discloses an inverter, including the carbon nanotube thin film transistor manufactured by the above method.

Compared with the prior art, the present invention has the advantages that: the surface of the substrate is treated by short-time oxygen plasma etching, the surface of the substrate is hydrophilized and has good wettability. On this basis, the performance of the constructed carbon nanotube thin film transistor device is good, and multiple transistors with high uniformity can be fabricated on the modified substrate. The preparation method has the advantages of simple process, environmental friendliness, convenient operation and low cost, so it is expected to be applied to large-scale commercial production of high-performance large-area printed independent carbon nanotube transistor devices.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments described in this application. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Figure 1 is a side view of the contact angle of the substrate in Example 1 of the present invention, wherein, a) is the test of the contact angle of the substrate after oxygen plasma treatment; b) is a test chart of a blank substrate without any treatment; c ) is the contact angle test of the substrate treated under vacuum at 200°C for 1 hour;

Figure 2 is the electrical performance test diagram of the thin film transistor prepared in Example 1 of the present invention, wherein, a) and b) are the transfer and output curves of the hydrophilized substrate device after plasma etching, and c) is the substrate without The transfer curve of any treated substrate device, d) is the transfer curve of the hydrophobized substrate device after vacuum treatment;

Fig. 3 is the electrical performance test diagram (a, b) and the statistical distribution diagram (d) of mobility (c) and switch ratio data of 200 thin film transistors prepared in Example 1 of the present invention.

Detailed ways

In view of the deficiencies of the existing methods for preparing carbon nanotube thin film transistors, such as the need for additional introduction of functionalized polymers, long processing time, complicated methods, poor adhesion, etc., devices constructed on rough surface substrates Performance is often poor or not working properly. An embodiment of the present invention provides a method for improving the uniformity of a carbon nanotube thin film transistor, including:

s1, preparing a carbon nanotube solution;

s2. Perform plasma etching treatment on the substrate to make it modified and have certain wettability;

s3. Positioning the carbon nanotube solution between the channels of the substrate by printing to obtain a plurality of carbon nanotube thin film transistors with uniform performance.

In the above step s1, it is necessary to coat the carbon nanotubes with a polymer to functionalize the surface of the carbon nanotubes. The surface functionalization of carbon nanotubes refers to the selection of specific polymers in a certain organic solvent through ultrasonic centrifugation, etc., to promote the interaction between polymers and semiconducting carbon nanotubes, and finally selectively separate and enrich the semiconducting carbon nanotubes with surface functionalization. nanotube solution. The polymer is preferably selected from one or more combinations of polythiophene derivatives, polyfluorenes, polyfluorene derivatives, polym-phenylene vinylene derivatives, polycarbazole derivatives and polypyridine derivatives.

The carbon nanotubes are any one of commercially available CoMoCat 65, CoMoCat76, CG200, HiPCO, CG100 and Arc discharge (such as P2); the diameter range of the carbon nanotubes is between 0.6 and 2nm . The obtained carbon nanotube solution is a single-wall semiconducting carbon nanotube solution.

In the above step s2, the wettability modification of the substrate is through oxygen plasma etching for a certain period of time, so that the surface of the substrate is modified to be hydrophilic, so that it has a certain degree of wettability, which can better and function bonded carbon nanotubes. The time for the oxygen plasma etching treatment is preferably 1 min˜10 min, more preferably 1 min. The discharge power for performing the oxygen plasma etching treatment on the substrate is preferably 80-120W. The material of the substrate can be rigid or flexible, the flexible substrate is preferably selected from PET (polyethylene terephthalate) or PI (polyimide), and the rigid substrate is glass, silicon wafer, quartz, etc.

In the above step s3, the printing method includes inkjet printing or aerosol printing and the like.

In the above step s3, it is necessary to clean the surface of the device 2-4 times with a solvent when the printing solution is completed, to remove unnecessary impurities on the surface and promote the device to have a higher on-off ratio value.

The embodiment of the invention also discloses an inverter, which adopts the carbon nanotube thin film transistor obtained by the above manufacturing method.

In order to make the object, technical solution and advantages of the present invention clearer, the specific implementation manners of the present invention will be described in detail below in conjunction with the accompanying drawings. Examples of these preferred embodiments are illustrated in the accompanying drawings. The embodiments of the invention shown in and described with reference to the drawings are merely exemplary, and the invention is not limited to these embodiments.

Here, it should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only the structures and/or processing steps closely related to the solution according to the present invention are shown in the drawings, and the related Other details are not relevant to the invention.

Example 1

The fabrication method of carbon nanotube thin film transistor comprises:

1. Preparation of semiconducting carbon nanotube ink

Under the condition of temperature ≤ 0℃, the commercial large-diameter arc discharge carbon tubes (P2 carbon tubes) with a tube diameter of 1.4nm were dispersed in poly[(9,9-dioctylfluorenyl-2,7- In the organic solution of diyl)-co-1,4-benzo-2,1,3-thiadiazole] (PFOBT), a uniformly dispersed carbon nanotube solution is obtained; and, the carbon nanotube solution is centrifuged , the centrifugation speed is 15000g, the centrifugation time is 60min, and the supernatant is separated. It is confirmed by ultraviolet and Raman characterization that there is no metallic carbon nanotube in the supernatant, thus obtaining a solution enriched in semiconducting carbon nanotube.

2. Construction and electrical performance testing of carbon nanotube thin film transistors

The first is the treatment of the substrate. The substrate is placed in the chamber of the device, treated in an atmosphere of oxygen plasma discharge for 1 min, and the discharge power is adjusted to 80w. In addition, as a comparative test, another substrate was treated at 200 ^o C for 1 hour under the condition of vacuum and high temperature. Figure 1 is a test of the contact angle for the above two different conditions and a blank substrate without any treatment. The results confirmed that the minimum contact angle after oxygen plasma treatment was 15.4 ^o , which was smaller than that of untreated 43.5 ^o and vacuum treated 68.1 ^o . It also shows that the surface of the substrate after plasma treatment becomes hydrophilic and has wettability, while the surface after vacuum treatment becomes hydrophobic. Carbon nanotube thin film transistor devices were constructed by printing using standard devices, in which silicon was used as the gate, silicon dioxide was used as the dielectric layer, Si/SiO ₂ (100 nm/300 nm), and gold with a thickness of 100 nm was deposited by electron beam ( Au) as the source-drain electrodes.

FIG. 2 is a graph showing electrical performance tests of transistors prepared by different processing methods. It can be seen from the figure that under the same working voltage, both of which are 1V, the mobility of the transistor constructed on the plasma-treated substrate reaches 17.3 cm ² V ^-1 s ^-1 , which is much higher than that of the untreated substrate and vacuum Processed substrate device performance.

Figure 3 shows the construction of 200 carbon nanotube thin film transistor devices on the substrate treated by oxygen plasma etching by printing. The performance test data shows that the mobility of more than 85% of the devices is concentrated in the 12-20 cm ² V ^-1 s ^-1 , among which 179 devices have switching ratios distributed between 105-108. It can be seen that, through the method of plasma etching, a carbon nanotube thin film transistor device with good uniformity can be prepared quickly and conveniently.

In addition, as an auxiliary experiment, in order to verify the strong adhesion and bonding force between the functionalized carbon nanotubes and the surface of the hydrophilic substrate, the prepared carbon nanotube thin film transistor device was subjected to ultrasonic treatment for 45 minutes under ultrasonic conditions with a power of 40W. , the test results confirmed that the performance of the device was basically unchanged. Therefore, the bond between the surface of the substrate etched by oxygen plasma and the functionalized carbon nanotubes is stronger, so that the uniformity of the device can be better improved.

The carbon nanotube thin film transistor with good performance prepared by the above-mentioned substrate modification was used to construct an inverter, and when the working voltage was 5V, a gain of 17 was obtained.

Example 2

The fabrication method of carbon nanotube thin film transistor comprises:

Under the condition of temperature ≤ 0℃, commercial carbon nanotubes CG200 with a diameter of 0.8nm were dispersed in poly[(2,7-9,9-dioctylfluorenyl)-alt-4,7-bis In the organic solution of (thiophen-2-yl)benzo-2,1,3-thiadiazole] (PFODBT), a uniformly dispersed carbon nanotube solution is obtained; and, the carbon nanotube solution is centrifuged, and the centrifugal speed is was 12000g, the centrifugation time was 90min, and the supernatant was separated to obtain a solution enriched in semiconducting carbon nanotubes. Next, the substrate is processed. The substrate is placed in the chamber of the device, and treated in an atmosphere of oxygen plasma discharge for 10 minutes, and the discharge power is adjusted to 100w. And the carbon nanotube solution was printed between the channels on the substrate through the printing method, and the electrical performance test results of the device confirmed that the performance of the device was good, and the uniformity of multiple transistors was also very good.

Example 3

The fabrication method of carbon nanotube thin film transistor comprises:

Under the condition of temperature ≤ 0℃, commercial carbon nanotubes CoMoCAT 76 with a diameter of 0.6nm were dispersed in poly[(9,9-dioctylfluorenyl-2,7-diyl)-co- Thiophene] (F8T2) in the organic solution to obtain a uniformly dispersed carbon nanotube solution; Set of semiconducting carbon nanotubes in solution. Next, the substrate is processed. The substrate is placed in the chamber of the device, treated in an atmosphere of oxygen plasma discharge for 5 minutes, and the discharge power is adjusted to 120w. And the carbon nanotube solution was printed between the channels on the substrate through the printing method, and the electrical performance test results of the device confirmed that the performance of the device was good, and the uniformity of multiple transistors was also very good.

In summary, the present invention proposes a method for manufacturing carbon nanotube thin film transistors. The substrate is etched with oxygen plasma. The test data show that the mobility and switching ratio of the device are concentrated and relatively high. The later cleaning and long-term Neither time of sonication affected the performance of the device. The preparation method has the advantages of simple process operation, rapidity, environmental friendliness, high performance without introducing other impurity molecules, and is suitable for rigid and flexible substrates.

Finally, it should also be noted that the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article or apparatus comprising a set of elements includes not only those elements, but also Other elements not expressly listed, or inherent to the process, method, article, or apparatus are also included.

Claims (10)

1. A method for improving the uniformity of carbon nanotube thin film transistors, characterized in that, comprising: s1, preparing a carbon nanotube solution; s2. Perform plasma etching treatment on the substrate to make it modified and have certain wettability; s3. Positioning the carbon nanotube solution between the channels of the substrate by printing to obtain a plurality of carbon nanotube thin film transistors with uniform performance. 2. The method for improving the uniformity of a carbon nanotube thin film transistor according to claim 1, characterized in that: in the step s2, the substrate is subjected to oxygen plasma etching treatment. 3. The method for improving the uniformity of a carbon nanotube thin film transistor according to claim 2, characterized in that: in the step s2, the time for performing oxygen plasma etching treatment on the substrate is 1 min to 10 min. 4. The method for improving the uniformity of a carbon nanotube thin film transistor according to claim 2, characterized in that: in the step s2, the discharge power for oxygen plasma etching treatment on the substrate is 80-120W. 5. The method for improving the uniformity of carbon nanotube thin film transistors according to claim 1, characterized in that: in the step s1, the carbon nanotubes enriched in semiconductor carbon nanometer tube of solution. 6. The method for improving the uniformity of carbon nanotube thin film transistors according to claim 5, characterized in that: said polymer is selected from the group consisting of polythiophene derivatives, polyfluorenes, polyfluorene derivatives, polym-phenylene vinylene derivatives, A combination of one or more of polycarbazole derivatives and polypyridine derivatives. 7. The method for improving the uniformity of carbon nanotube thin film transistors according to claim 5, characterized in that: the diameter of the carbon nanotubes is 0.6nm ~ 2nm, and the obtained carbon nanotube solution is single-wall semiconducting carbon nanotube solution. 8. The method for improving the uniformity of carbon nanotube thin film transistors according to claim 1, characterized in that: the substrate is selected from PET, PI, glass, silicon wafer or quartz; in the step s3, the printing method Including inkjet printing or aerosol printing. 9. A method for manufacturing a carbon nanotube thin film transistor, comprising: s1, preparing a carbon nanotube solution; s2. Perform plasma etching treatment on the substrate to make it modified and have certain wettability; s3. Positioning the carbon nanotube solution between the channels of the substrate by printing to obtain a carbon nanotube thin film transistor. 10. An inverter, characterized in that it comprises the carbon nanotube thin film transistor produced by the method of claim 9.