KR20150052546A - Method of measuring resistance of transparent electrodes - Google Patents

Abstract

The present invention provides a method to measure resistance of transparent electrodes which includes a step to manufacture transparent electrodes formed with networks by making use of nanowire; a step to create electrodes by using a conductive tape on the transparent electrodes; and a step to measure resistance of the transparent electrodes. For this reason, the repeated measurement of resistance on network-formed transparent electrodes can be realized and the resistance of transparent electrodes can be measured without damaging the transparent electrodes.

Description

TECHNICAL FIELD The present invention relates to a method of measuring the resistance of a transparent electrode,

The present invention relates to a method of measuring the electrical conductivity of an electrode, and more particularly to a method of measuring the resistance of a transparent electrode in which a nanowire is formed in a network.

With the development of semiconductor technology, nano-level thin film forming technology is being developed. Among them, transparent electrode is replacing opaque conductor such as copper with transparency of 80% or more and conductivity of 500 Ω / sqm or less. In particular, transparent electrodes are widely used in electronic fields such as LCD front electrodes, OLED electrodes, displays, touch screens, solar cells, and optoelectronic devices. Because ITO electrode material applied to existing touch screen panel (TSP) is difficult to use in flexible display with flexible or curved surface, it can be used as next generation new material to replace ITO film. Graphene, carbon nanotube CNT), and silver nano wire (Ag Nano Wire).

Silver nanoparticles are used as materials for electrodes with high conductivity and electrical conductivity. Using such properties, the possibility of application as a transparent electrode such as a touch screen, a display, an OLED, and a solar cell is increasing. Such electrodes may be manufactured in the form of dense films using conductive polymers or ITO, but they are also manufactured as transparent electrodes through network formation as in the case of carbon nanotubes or metal nanowires.

1 is a schematic view showing a 4-point probe method for measuring resistance of a conventional electrode. In general, the sheet resistance is expressed in units of ohm / sq. Here, sq is also expressed as □, and it is generally interpreted as an infinite area as a separate unit rather than a metric method (such as cm ² ). The line resistance measures the resistance to a certain distance with two probes, but the four probes with the same interval measure the sheet resistance. In this case, the probe used is a 4-point probe. In general, the probe is a probe arranged in a line at intervals of 1 mm, and the current and voltage are measured with four probes. Apply a correction factor (CF) to calculate. To calculate the sheet resistance value, the correction factor should be applied to the resistance value (ohm) measured by the 4-point probe. The correction factor is calculated by using three coefficients from the sample size to the thickness of the thin film and the temperature during the measurement. The sample size factor is 4.532 for a sample with a diameter of 40 mm or more and the thin film thickness coefficient is 1 when the thin film thickness is about 400 탆 or less and the temperature varies slightly depending on the temperature coefficient of the sample, 1 is close. It is desirable to measure the resistivity of the thin film or the dense sample after measuring the sheet resistance and then measuring the resistivity using the thickness of the thin film.

Korean Patent Laid-Open Publication No. 10-2010-0077808, as an embodiment of the above-mentioned sheet resistance measuring method, relates to a probe conditioning system of a sheet resistance measuring instrument, and more particularly, A probe conditioning system of a sheet resistance measuring instrument is disclosed. A probe conditioning system of a sheet resistance measuring apparatus of the present invention includes a wafer stage on which a wafer to be measured is placed and changes the position of the wafer; A probe having a plurality of probe needles to contact the wafer to supply current and to measure a voltage; A probe driving shaft for vertically driving the probe; And a disc-shaped conditioning plate inserted into the center surface of the wafer stage.

According to the probe conditioning system of the sheet resistance measuring apparatus according to the present invention, the conditioning plate is provided on the surface of the wafer stage and the probe conditioning operation is automatically performed, thereby improving the measurement accuracy and the equipment operation rate.

However, in the case of a transparent electrode by network formation, a commonly used 4-point probe method is difficult to measure the resistance when the probe is not in contact with the network portion, It's happening, and it's hard to get a reproducible value.

Therefore, in the case of an electrode formed by network formation, conduction is performed by percolation, so that a reproducible resistance measuring method or measuring instrument for the electrode is still required.

It is an object of the present invention to provide a method and a measuring apparatus capable of measuring resistance without damaging a transparent electrode even in the case of a transparent electrode having a network, which has reproducibility even in repetitive resistance measurement.

The present invention provides a method of manufacturing a transparent electrode, comprising: fabricating a transparent electrode in which a network is formed using nanowires; Forming an electrode on the transparent electrode using a conductive tape; And a step of measuring a resistance of the electrode.

The nanowire may be any one selected from the group consisting of metal nanowires, metal nanorods, electrically conductive fibers, and carbon nanotubes.

In addition, the transparent electrode may be characterized in that a network is formed using the nanowire by a sputtering method or an electric vapor deposition method.

Also, the conductive tape may be any one selected from the group consisting of copper, silver, and aluminum.

In addition, the conductive tape may have an adhesive layer formed on one surface thereof, adhered to the transparent electrode, and electrically conductive with the transparent electrode.

According to the method for measuring the resistance of the transparent electrode according to the present invention, the resistance of the transparent electrode can be measured without repairs of the transparent electrode, with the reproducibility of the resistance measurement in the repeated resistance measurement of the transparent electrode formed with the network.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing a conventional four-point probe for measuring the resistance of an electrode;
FIG. 2 is a schematic diagram illustrating a method of measuring a resistance of a transparent electrode formed with a network according to an embodiment of the present invention. FIG.
FIG. 3 is a schematic view showing a process of measuring the resistance measurement method shown in FIG. 2,
4 is a photograph of a conductive tape adhered to a transparent electrode according to an embodiment of the present invention.

The present invention provides a method of fabricating a transparent electrode, comprising: fabricating a transparent electrode having a network formed using nanowires; Forming an electrode on the transparent electrode using a conductive tape; And a step of measuring a resistance of the electrode.

Transparent electrodes can replace opaque conductors such as copper with a transparency of 80% or more and a conductivity of 500? / Sqm or less. In general, when the network is formed by using the nanowires as described above, the conventional four-point probe method, which is a resistance measuring method, measures the resistance when the wire is not in contact with the network portion It is difficult to measure the reproducible resistance value because the transparent electrode is damaged after the probe is contacted.

Therefore, it is possible to manufacture the transparent electrode, to measure the resistance of the transparent electrode by adhering the conductive tape on the both side end faces of the transparent electrode, electrically conducting the electric field, and applying an electric signal. When the resistance is measured through the conductive tape, the transparent electrode is not damaged, and a reproducible resistance value can be obtained.

The step of fabricating the transparent electrode having the network using the nanowire may include preparing a substrate and coating the substrate using the nanowire-containing ink.

The nanowire may be any one selected from the group consisting of a metal nanowire, a nitrogen nano rod, an electrically conductive fiber, and a carbon nanotube.

The metal nanowires may include silver (Ag) complexes. The metal nanowires are not limited to silver complexes, but may be formed by growing conductive metal particles and forming conductive metal particles.

The transparent electrode may be formed of a network using the nanowire by a sputtering method or an electric vapor deposition method.

The nanowire may be formed by spin coating, roll coating, spray coating, dip coating, flow coating, doctor blade and dispensing, inkjet printing, , Screen printing, pad printing, gravure printing, flexography printing, stencil printing, imprinting, xerography, and lithography.

Also, the conductive tape may be any one selected from the group consisting of copper, silver, and aluminum.

Here, the conductive tape may be a metal foil having self-supportability and exhibiting electrical conductivity, and may be made of nickel, iron, and alloys thereof as well as copper, silver, and aluminum. Among them, copper is preferably used from the viewpoints of conductivity, cost and workability.

The conductive tape may have a pressure-sensitive adhesive layer on one surface thereof and may be adhered to the transparent electrode, and may be electrically connected to the transparent electrode.

The pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer is not particularly limited, but may be an acrylic pressure-sensitive adhesive, a rubber pressure-sensitive adhesive, a vinyl alkyl ether pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, a polyester pressure-sensitive adhesive, a polyamide pressure-sensitive adhesive, a urethane pressure-sensitive adhesive, Mixtures of these may be used.

The conductive tape may be provided with a conductive portion having a terminal portion at a front end thereof. The resistance value of the transparent electrode may be measured using a capacitor, a resistor, and an RC circuit connected to the conductive portion.

The present invention also provides a transparent electrode resistance measuring apparatus manufactured by the above method.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the scope of the present invention is not limited to the following examples.

< Example 1 > Transparent electrode manufacturing

1. Manufacture of transparent electrode

A substrate was prepared to prepare a transparent electrode. A silver nano wire having a solid content of 1 wt% on an optical PET (polyethylene terephthalate) film prepared as a base material was sprayed with silver nano wire to the optical PET using a spray equipment (type of equipment, purchase place and conditions of use) Respectively.

A transparent electrode of Sample 1, Sample 2 and Sample 3 was prepared, gradually increasing the concentration of the silver nano ink.

A silver nano wire layer was formed and dried at room temperature for 30 minutes to prepare a transparent electrode having a network formed using nanowires.

2. The above- On the substrate Conductive tape  Adhesion and resistance measurement

A pressure sensitive adhesive solution was applied to the release paper coated with silicone on the above-mentioned pressure-sensitive adhesive, and the pressure-sensitive adhesive solution was adhered to the copper foil, and this was rolled up to prepare a conductive tape. A commercially available conductive tape having an adhesive applied to the copper foil was also used.

The resistance value of the transparent electrode was measured by applying a voltage or a current to a capacitor, a resistor and an RC circuit connected to the terminal portion of the conductive tape at the tip of the conductive tape.

< Experimental Example  1> Measurement of resistance of transparent electrode

FIG. 2 is a schematic view illustrating a method of measuring a resistance of a transparent electrode formed with a network according to an embodiment of the present invention. FIG. 3 is a schematic view illustrating a method of measuring resistance according to the present invention, FIG. 4 is a photograph of a conductive tape adhered to a transparent electrode according to an embodiment of the present invention.

Table 1 shows resistance values measured by applying a current or voltage to capacitors, resistors, and RC circuits on the conductive tape adhered to both sides of the transparent electrode prepared in Example 1.

Sample 1, Sample 2 and Sample 3 increased the amount of silver nano ink, and the content of silver nano-ray was higher toward Sample 3. As the content of silver nano wire increases, the resistance value decreases. When the conventional method is used, the transparent electrode is damaged, and the reproducibility of the resistance measurement is decreased due to the increase of the resistance value at the part where no network is formed Respectively.

In the present invention, it was possible to measure a similar resistance value without damaging the electrodes even in a large number of measurements.

Number of measurements One 2 3 4 5 6 7 8 9 10 Sample 1 40.4 41.5 35.1 23.6 27.5 44.1 56.4 39.8 45.9 37.9 Sample 2 34.4 28.8 26.5 25.7 27.4 31.7 24.5 19.4 22.3 26.2 Sample 3 16.3 18.5 28.7 17.2 17.7 18.3 15.2 16.7 15.1 21.4

The unit of the measured value is ohm (OMEGA), and the resistivity is a value obtained by multiplying the resistance value by the electrode thickness.

Reproducible resistance values were measured even when the prepared transparent electrodes were made into a plurality of samples and the resistance was measured by repeating the respective samples.

When a conductive tape made of a copper film is used, time for curing is not necessary after adhesion to the transparent electrode, and immediate resistance measurement is possible after mounting the conductive tape.

Further, in measuring the resistance of the transparent electrode, the damage of the transparent electrode can be removed after the resistance measurement.

< Example 2 > 4 points Probe  resistance measurement

The resistance of the transparent electrode prepared in Example 1 was measured using a 4-point probe method.

A four-point probe was brought into contact with the transparent electrode and a current was applied. The current was applied to the two probes, and the resistance was measured using the voltage difference of the remaining two probes.

< Experimental Example  2> 4 points Probe  Resistance measurement result by

A 4-point probe was brought into contact with the transparent electrode prepared in Example 1 and a current was applied.

Table 2 is a table showing resistance measurement values by the 4-point probe method.

Where the unit is Ω / □ (ohm / square) and the resistivity is the measured value multiplied by the electrode thickness.

Measure
Number of times One 2 3 4 5 6 7 8 9 10 Sample 1 61.8 20.93 23.51 21.55 N / A N / A N / A N / A N / A N / A Sample 2 42.05 46.72 33.76 22.23 10.37 27.03 107.5 113.3 N / A N / A Sample 3 248.3 144.4 154.2 110.4 188 249.8 N / A N / A N / A N / A

Even in the case of the same sample, a different value is displayed for each measurement point at the time of measurement, and another value is measured or the measurement is not performed at the same place.

The resistance measurement by the 4-point probe method is generally used and can be used for the dense film, but it is judged that the resistance value can not be measured in the part where the network is not formed by the nanowire in the film.

In addition, the degree of damage of the transparent electrode manufactured by the contact of the repetitive probe was increased, and the resistance value could not be measured as the measurement was repeated due to damage of the transparent electrode.

< Example 3 > Silver paste  Containing conductive copper Tape

In order to compare the performance of the conductive tape, the conductive tape was prepared as a silver paste.

1 g of the curing agent was mixed with 1 g of the silver paste to prepare a mixture.

The mixture was deposited at both ends of the transparent electrode and cured at 120 DEG C for 36 hours.

A resistance value of the transparent electrode was measured by connecting a capacitor, a resistor and an RC circuit to the tip of the conductive tape made of the silver paste.

< Experimental Example  3> Silver paste  contain Conductive Tape  resistance measurement

In order to compare the performance of the conductive tape made of the copper film, the resistance value of the transparent electrode was measured by applying a current or voltage to the capacitor, resistor and RC circuit at the tip of the conductive tape containing the silver paste.

Number of measurements One 2 3 4 5 6 7 8 9 10 Sample 50.3 55.6 69.7 53.0 52.0 N / A N / A N / A N / A N / A

The manufactured transparent electrode was fabricated as a sample, and the resistance value was measured five times.

In this case, the reproducible resistance value was measured in the same manner as the resistance value measured using the conductive tape manufactured using the copper foil.

When the resistance is measured by the conductive tape containing the silver paste, the interface resistance is low. However, in order to cure the silver paste, the silver paste should be dried at a temperature of 120 to 180 ° C for 24 to 48 hours. And the cost is increased.

Therefore, it is judged that it is not suitable for the production of the conductive tape for measuring the resistance of the transparent electrode.

As described above, according to the present invention, it is possible to measure the resistance of a transparent electrode in which a network is formed by using nanowires in the production of transparent electrodes. In particular, a transparent electrode resistance measuring device can be constructed by adhering a conductive tape to a transparent electrode, and the resistance value of the electrode can be easily obtained even when the resistance can not be measured by the conventional 4-point probe method.

Since there is no direct contact with the transparent electrode, the resistance of the transparent electrode can be measured without repetition of the transparent electrode.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

100: transparent substrate 200: copper film conductive tape
300: silver paste conductive tape 400: probe point
500: Resistance measuring circuit

Claims (5)

Fabricating a transparent electrode having a network formed using nanowires;
Forming an electrode on the transparent electrode using a conductive tape; And
And measuring a resistance of the electrode. The method according to claim 1,
The nanowire may be a nanowire,
Wherein the electrode is any one selected from the group consisting of metal nanowires, metal nano-rods, electrically conductive fibers, and carbon nanotubes. The method according to claim 1 or 2,
The transparent electrode
Wherein the nanowire is formed in a network using a sputtering method or an electric vapor deposition method. The method according to claim 1,
In the conductive tape,
Copper, silver, and aluminum. 2. The method according to claim 1, The method according to claim 1,
In the conductive tape,
Wherein an adhesive layer is formed on one surface of the transparent electrode, and the transparent electrode is electrically connected to the transparent electrode.

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