DE102008001578A1 - Producing transparent conductive layer, by applying dispersion from transparent conductive oxide nanoparticles on substrate e.g. glass, and partially removing solvent/dispersant from obtained layer and then irradiating with laser energy - Google Patents

Abstract

The method comprises applying a dispersion from transparent conductive oxide (TCO) nanoparticles on a substrate such as glass or plastic, partially removing solvent or dispersant from the obtained layer by drying at 20-180[deg] C for a time period of 1 second to 60 minutes, and subsequently irradiating the obtained layer with a laser energy uniquely by scanning in a continuous or pulsed manner and then subjecting to a plasma treatment. The dispersion contains indium-tin oxide nanoparticles and is applied on the substrate by inkjet-printings, flexographic printings and pad-printings. The method comprises applying a dispersion from transparent conductive oxide (TCO) nanoparticles on a substrate such as glass or plastic, partially removing solvent or dispersant from the obtained layer by drying at 20-180[deg] C for a time period of 1 second to 60 minutes, and subsequently irradiating the obtained layer with a laser energy uniquely by scanning in a continuous or pulsed manner and then subjecting to a plasma treatment. The dispersion contains indium-tin oxide nanoparticles and is applied on the substrate by inkjet-printings, flexographic printings, pad-printings, spin coating, spraying, dipping, knife-coating, offset printings, screen printings, thermo-transfer printings, gravure printings, flooding, aerosol jet deposition process or pouring. The laser energy has a wavelength of 157-10600 nm with an average output of 5 W to 5 kW, and affects the material of the layer in the sectioned volumes of the focused laser beam with the layer during a duration of 5 ps to 1000 mu s. During scanning, an intersection plane of the focused laser beam is moved with the plane of the layer on the intersection plane with a speed of 50-150000 mm/s. An independent claim is included for a transparent conductive layer.

Description

The The present invention relates to a process for producing transparent conductive layers based on transparent, conductive oxide (TCO) nanoparticles, in particular indium tin oxide (ITO) nanoparticles by laser irradiation as well as the layers obtained by this method.

• – Widerstandsfähigkeit gegen Beanspruchung durch kratzende, scharfkantige Gegenstände oder Materialien, charakterisiert z. B. durch die Stifthärte nach Wolff-Wilborn oder durch die Bleistifthärte nach DIN EN 13523-4: 2001 ;
• – Haftung auf dem Substrat, ermittelt z. B. durch den Kreuzschnitt- oder Tape-Test nach DIN EN ISO 2409 .

A mechanically stable layer is understood in the following to mean a layer which has the following properties:

• - Resistance to stress from scratching, sharp-edged objects or materials, characterized z. B. by the pencil hardness to Wolff-Wilborn or by the pencil hardness after DIN EN 13523-4: 2001 ;
• - adhesion to the substrate, determined z. B. by the cross-cut or tape test after DIN EN ISO 2409 ,

Under Sheet resistance is hereafter the ohmic resistance understood that on a coating with a uniform Layer thickness is obtained when a square area of any Contacted size on two opposite edges and the current as a function of the (DC) voltage is measured. The sheet resistance is measured in Ω and marked with Ω / sq. The determination of sheet resistance can even after other methods, such. B. the four-point measurement.

Under resistivity is hereinafter the ohmic resistance understood by multiplying the sheet resistance with the layer thickness [in cm] is obtained and a measure of the ohmic properties of the conductive material itself represents. The resistivity is in Ω · cm specified.

Under Transmission is hereafter the permeability of a transparent body for light of wavelength 550 nm understood. The transmission of a coated substrate is in proportion to the transmission of the same uncoated substrate in percentages.

transparent Layers with high ohmic conductivity have surface resistances of at most 10,000 Ω / sq and a transmission of at least 40% and are used in all modern displays, eg. As in LCD, plasma displays, OLEDs, and z. B. also in organic Solar cells needed by the photovoltaic Effect of using low-energy stimulated electrical currents to be able to.

in the The state of the art becomes conductive layers, for example produced by flame spraying or in a vacuum by sputtering techniques. A Structuring is not possible or only very expensive. It is generally made by applying various etching techniques receive.

conductive Layers are also produced on the basis of nanoparticles, wherein These must be thermally treated, according to the state the technology, for example, in a furnace process to the desired To achieve conductivity. The thermal aftertreatment of coatings of metallic nanoparticles, for example from silver particles, can also be done by laser irradiation. thermal After treatment by laser irradiation at the same time more transparent and conductive coatings of non-metallic nanoparticles However, the prior art does not know.

all The common feature of these methods is that the nanoparticles interact with each other and / or sintered with other ingredients or the substrate or merged. So there in the nano-layer heat energy is generated so far, always make sure that the heat transfer in the substrate does not become so large that in the substrate Conversions of chemical (eg decomposition) or physical nature (eg melting). Especially with sensitive Substrates like most plastic films are the temperature, in which such unwanted processes occur in the substrate, in the general so low that not enough heat energy can be generated in the nanoparticulate layer that sinter or fuse the nanoparticles to an optimal extent. It is so far technical teaching that the resistivity is more conductive The lower the layers, the lower the nanoparticles become sinter and / or merge.

task The present invention was therefore to provide a method which reduces the thermal load of the substrate and thus overcomes the disadvantages of the prior art. It was also a task, a layer with improved mechanical To provide stability.

These Task is solved by a process for producing transparent conductive Layers with the characterizing features of claim 1 solved.

• (1) Bereitstellung einer Dispersion aus TCO Nanopartikeln, anschließend
• (2) Aufbringen der nach Schritt (1) erhaltenen Dispersion auf ein Substrat, und zumindest teilweises Entfernen des Lösungsmittels oder Dispersionsmittels, anschließend
• (3) Bestrahlen der nach Schritt (2) erhaltenen Beschichtung mit Laserenergie

umfasst.The subject matter of the present invention is therefore a process for producing transparent conductive layers, which comprises the steps

• (1) providing a dispersion of TCO nanoparticles, subsequently
• (2) applying the dispersion obtained after step (1) to a substrate, and at least partially removing the solvent or dispersant, subsequently
• (3) Irradiating the laser energy obtained after step (2)

includes.

The inventive method has the advantage that short interaction times are achieved and thus the thermal Loading of the substrate compared to methods in the state of Technology is greatly reduced. The invention Procedure is also inline-capable, synonymous So that this in a continuous production process for substrates with transparent conductive layers can be used, for example in a roll-to-roll process.

Therefore is also the subject of the present invention, a transparent conductive layer associated with the invention Procedure is obtained.

As well the subject of the present invention is an electronic component, having the layer according to the invention, as well as the use of the electronic according to the invention Component in an OLED (Organic Light Emitting Diodes), electroluminescent module, Display, photovoltaic element, touch-sensitive Screen, so-called touch panel, resistance heating element, infrared protection film, antistatic housing, chemical sensor, electromagnetic Sensor, FKD (liquid crystal display), so-called LCD, electrophoretic display.

The Invention will be explained in more detail below.

It may be advantageous to use in step (1) of the process according to the invention a dispersion which contains indium tin oxide nanoparticles. The preparation of such a dispersion is for example in the patent applications DE 10 2006 005 019.3 . DE 10 2006 005 025.8 , and DE 10 2006 005 026.6 , the publication DE 198 40 527 A1 , as well as the European patent application EP 06018493.4 disclosed.

Prefers can in step (2) of the method according to the invention dispersion by inkjet printing, flexo printing, pad printing, spin coating, spraying, dipping, knife coating, offset printing, screen printing, Thermal transfer printing, gravure printing, flood, Aerosil Jet Deposition Process of the company optomec, (optomec inc., Albuquerque, New Mexico) or pouring onto the substrate.

Thereby is a structuring, at least partially structuring up the substrate possible. Preferably, the dispersion applied once or several times and / or continuously or batchwise become. The environmental conditions are from the requirements of Dependent on and depending on how the dispersion is applied may be different.

Advantageously, in step (2) of the method according to the invention a substrate can be used which contains or is glass or plastic. Preference is given to using transparent materials, particularly preferably quartz glass, borosilicate display glass, alkali-free borosilicate display glass, white glass, window glass, float glass, polyester, polyamide, polyimide, polyacrylate, polycarbonate (PC), polyethersulfone (PES), polyetheretherketone (PEEK), polyvinyl chloride (PVC ), Polyethylene (PE), polypropylene (PP), polyacetal (POM), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polyhydroxybutyrate (PHB), polyamide 6, polyamide 6.6, polyamide 11, polyamide 12, Kapton ^® polymethyl methacrylate (PMMA) or a combination of these materials. Most preferably, these materials or a combination of these materials can be used in the form of films and / or laminates.

It may also be advantageous, prior to step (3) of the process according to the invention, the solvent or dispersant from the coating obtained according to step (2) at a temperature of 20 ° C to 180 ° C, preferably from 50 ° C to 130 ° C, especially preferably from 60 ° C to 120 ° C for a period of 1 s to 60 min to remove by drying. Most preferably, the solvent or dispersant may be removed from the dispersion or solution for a period of 10 minutes at a temperature of 120 ° C. The solvent or dispersant may be removed by, for example, introducing electromagnetic energy or by contacting the substrate with a hot plate in a roll-to-roll process, preferably by contact with at least one heated roll or calender. Further preferably, the solvent or dispersant can be removed by irradiation with IR, VIS, or UV light, for example by halogen or IR emitting laser, in a drying oven, or by purging with heated air or inert gas. Most preferably, the solvent or dispersant can be removed by at least one process that can be integrated in a roll-to-roll process. Particularly preferred may be non-contact methods, most preferably IR emitters. Up to 99% of the solvent or dispersant may preferably be removed from the coating obtained after step (2). The proportion of solvent or dispersant removed by drying can be determined by measuring methods known to the person skilled in the art, for example by gravimetric methods. After this Drying, a layer thickness of 0.05 to 100 .mu.m, preferably from 0.1 to 75 .mu.m, more preferably from 0.5 to 50 .mu.m, more preferably from 1 to 30 microns are obtained.

In It can be advantageous for the process according to the invention when in step (3) the laser energy coating with a wavelength of 157 nm to 10600 nm with a middle Power from 5 W to 5 kW, continuous or pulsed, at least once is irradiated by scanning, with the laser energy on the material the coating in the cutting volume of the focused laser beam with the coating for a duration of 5 ps to 1000 μs acts. Methods for measuring the average power are the Specialist known.

Of the Advantage is that by the short duration of exposure the laser energy no or much less heat energy is transferred to the substrate, as in the method according to Stand of the technique. Another advantage of the method according to the invention but also consists in that in step (3) a laser wavelength can be used, for which the substrate is transparent or nearly transparent, and thus in comparison with methods of the prior art no or little heat energy the substrate is transferred.

In step (3) comprises a CO ₂ laser used, most of the laser energy is absorbed or reflected by the ITO nanoparticles, is thus reduced for this reason also, the energy input into the substrate and, therefore, sensitive and / or more cost-effective, low heat-resistant Substrates can be used.

Preferably can in the process according to the invention, the coating With laser energy from 1 to 5000 times repeatedly irradiated by scanning become.

The in step (3) laser energy input can be advantageously reduced when in step (2) during drying An IR emitter is used because of the dried coating Has residual heat. Thus, in step (3) the heat transfer further reduced into the substrate by irradiation with laser energy become.

If in step (3), the coating obtained in step (2) is pulsed Laser energy is irradiated, can have a pulse duration of 5 ps to 1000 ns advantageous in the process according to the invention be. Pulse durations of 10 ps to 1000 ns, and more, may be preferred preferably from 5 ns to 900 ns, more preferably from 10 ns to 750 ns, more preferably from 20 ns to 500 ns, especially preferably from 30 ns to 400 ns are used.

at continuously operated beam sources can take time, during the laser energy to those obtained in step (2) Coating is registered, from 0.1 to 1000 μs advantageous be. Particularly preferably, these periods can be operated continuously Beam sources of 10 to 900 μs, further particularly preferred from 50 to 750 μs, more preferably from 100 up to 500 μs, very particularly preferably from 250 to 400 μs be.

in the Step (3) of the method according to the invention can Advantageously, lasers are used for their wavelengths the substrate is transparent or nearly transparent. Farther It may be advantageous to use lasers, pulsed or continuous Operation that at wavelengths in the UV range, eg. B. at 198, 248, 308 nm emit, preferably used excimer laser become. Furthermore, particularly preferred in step (3) frequency-converted solid-state lasers are used, which emit at 266 nm and 355 nm, respectively. Equally advantageous in the Step (3) also with Nd: YAG or Nd: YVO4 laser light with one wavelength of 1064 nm are irradiated. Furthermore, fiber laser radiation can also be used at 1070 nm.

Especially preferred may in the process according to the invention in step (3), an erbium fiber laser having a wavelength of 1550 nm, more preferably a thulium fiber laser with 1950-2050 nm, most preferably diode laser radiation be used with wavelengths of 1470 nm or 1980 nm. In addition, if ITO nanoparticles are used in step (1), this choice has the advantage that the absorption is more nanoparticulate ITO coatings is particularly high.

In It can be advantageous for the process according to the invention be when scanning the cut surface of the focused Laser beam with the plane of the coating obtained after step (2) at this level at a speed of 50 to 150,000 mm / s is moved. Preferably, this speed can be from 1000 to 35000 mm / s, more preferably from 5000 to 25000 mm / s, especially preferably from 7500 to 15000 mm / s.

It may also be advantageous to use a track spacing between the 0.05 to 2 mm next to the lines described by the scanning in step (3), depending on the laser beam diameter on the workpiece or dimension of the beam in the direction perpendicular to the scan direction. Preferably, a track spacing of 0.1 to 1.5 mm, more preferably from 0.5 to 1.25 mm, most preferably from 0.75 to 1 mm are used. The sectional area may be circular or elliptical, preferably elliptical, with the major axis of the ellipse oriented perpendicular to the direction of advance of the laser beam. Also one rectangular, preferably square, cut surface is advantageous.

To the Scanning can be a beam deflection system, such. A galvoscanner, a polygon scanner, and / or on the laser F-theta optics used.

In The process according to the invention can be carried out in step (3) are advantageously scanned meandering. Further preferred may be manually or through a small process control system scanned, which was particularly preferably implemented by a PC Software can be controlled. Furthermore preferred several lasers are used which are simultaneously or temporally staggered different or the same lines on the coating obtained in step (2) depart. If several lasers are used, track spacing, Speeds, and / or cut surfaces equal or different, preferably in each case the same.

In the method according to the invention, it may furthermore be advantageous to subject the layer obtained after step (3) to a plasma treatment in a further step (4). This possibility has the advantage that the layer obtained after the plasma treatment can have improved aging resistance and / or improved mechanical stability. It can be a hydrogen, oxygen, inert gas plasma, or a plasma of a mixture of these gases are used with a microwave power of 1 to 5 kW, preferably from 2 to 3 kW at a pressure of 50 to 1100 hPa. As an inert gas, nitrogen, argon, helium, neon, or a mixture of these inert gases can be used. Forming gases (with H ₂ ) are also advantageous, as well as fractions of O ₂ , and / or their mixture with inert gases.

The Steps (1), (2), (3), (4) of the invention Processes can be repeated as often as desired, preferably once become.

object The present invention is also a transparent conductive Layer using the method according to the invention is obtained.

The Layer according to the invention can have a sheet resistance from 10 to 10,000 Ω / sq, preferably from 10 to 100 Ω / sq, furthermore preferably from 50 to 250 Ω / sq, preferably from 250 to 1500 Ω / sq and from 1500 to 10000 Ω / sq exhibit.

The According to the invention, as already stated, have different layer thicknesses, which after drying in the step (2), preferably from 0.05 to 50 μm. Therefore can the sheet resistance depending on the use of the invention electronic component, the inventive Layer, advantageously selected.

Becomes the electronic component according to the invention, the the layer according to the invention, in one OLED or FKD may use this sheet resistance from 10 to 100 Ω / sq when used in an electroluminescent module from 50 to 250 Ω / sq, when used in a touch panel from 250 to 1500 Ω / sq, or in a sensor from 1500 to 10000 Ω / sq.

Furthermore the layer according to the invention may have a transmission of at least 40%, preferably of at least 80%, more preferably of at least 90%. Most preferably, the inventive Layer have a transmission of at least 95%.

The layer according to the invention can according to a tape test according to DIN EN ISO 2409 measured adhesion preferably from 0% to 65%, preferably from 0% to 35%, particularly preferably from 0% to 20%.

The layer according to the invention may preferably be made by means of a Scratch Hardness Tester from Erichsen, Model 291, according to test methods DIN 13523-4 measured pencil hardness of 8 B to 6 H, preferably from 7 B to 4 B, more preferably from 8 B to 7 B.

following The invention will be explained by way of example.

• – 20 Gew.-% ITO Nanopartikel mit Primärpartikel mit einer Größe unter 20 nm, und
• – 80 Gew.-% Ethanol als Lösungs- oder Dispersionsmittel,

wurde auf ein Glassubstrat durch Rakeln aufgebracht. 1 shows a layer according to the invention, which was obtained by the method according to the invention. A dispersion containing

• 20% by weight of ITO nanoparticles with primary particles smaller than 20 nm, and
• 80% by weight of ethanol as solvent or dispersion medium,

was applied to a glass substrate by knife coating.

Subsequently the coating was dried at 20 ° C in air, and afterwards with continuous laser light of the wavelength 1550 nm, a power of 75 W scanning at a scan speed of 2500 mm / s, a track offset of 0.1 mm and a beam diameter once irradiated on the workpiece of 0.7 mm.

The layer thus obtained had a sheet resistance 30 Ω / sq, a transmission of 95%, one with a Scratch Hardness Tester from Erichsen, Model 291, according to test methods DIN 13523-4 measured pencil hardness of 7 B, and one by tape test according to DIN EN ISO 2409 precisely measured ne liability of 0%.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 102006005019 [0017]
• - DE 102006005025 [0017]
• - DE 102006005026 [0017]
• - DE 19840527 A1 [0017]
• EP 06018493 [0017]

Cited non-patent literature

• - DIN EN 13523-4: 2001 [0002]
• - DIN EN ISO 2409 [0002]
• - DIN EN ISO 2409 [0042]
• - DIN 13523-4 [0043]
• - DIN 13523-4 [0047]
• - DIN EN ISO 2409 [0047]

Claims (15)

Process for producing transparent conductive Layers comprising the steps (1) Provision of a Dispersion of TCO nanoparticles, subsequently (2) Applying the dispersion obtained after step (1) to a substrate, and at least partially removing the solvent or Dispersant, then (3) irradiate the after step (2) obtained with laser energy coating. Method according to claim 1, characterized in that that in step (1) a dispersion is used, the indium tin oxide Contains nanoparticles. Method according to claim 1, characterized in that that in step (2) the dispersion by inkjet printing, flexographic printing, Pad printing, spin coating, spraying, dipping, knife coating, offset printing, screen printing, thermal transfer printing, gravure printing, Flooding, Aerosil jet deposition process, or pouring on the substrate is applied. Method according to claim 1, characterized in that that in step (2) the substrate is selected, the glass or plastic contains or is. Method according to claim 1, characterized in that in that before step (3) the solvent or dispersant from the coating obtained after step (2) at a temperature from 20 ° C to 180 ° C for a period of time from 1 second to 60 minutes by drying. Method according to claim 1, characterized in that in step (3), the laser energy coating with a Wavelength of 157 nm to 10600 nm with a medium Power from 5 W to 5 kW, continuous or pulsed, at least is irradiated once by scanning, with the laser energy on the material of the coating in the cutting volume of the focused Laser beam with the coating for a period of 5 ps to 1000 μs acts. Method according to one of claims 1 or 6, characterized in that when scanning the cut surface of the focused laser beam with the plane of step (2) obtained coating at this level at a speed from 50 to 150000 mm / s is moved. Method according to at least one of the claims 1-7, characterized in that after step (3) layer obtained in a further step (4) of a plasma treatment is subjected. Transparent conductive layer with a method according to any one of claims 1-8 becomes. Layer according to claim 9 having a sheet resistance from 10 to 10,000 Ω / sq. Layer according to claim 9 or 10 with a transmission of at least 40%. Layer according to at least one of the claims 9-11 with a tape test according to DIN EN ISO 2409 measured adhesion from 0% to 65%. Layer according to at least one of the claims 9-12 with one according to test method DIN 13523-4 measured pencil hardness from 8 B to 6 H. Electronic component, one layer after at least one of claims 9-13. Use of the electronic component according to claim 14 in an OLED, electroluminescent module, photovoltaic element, touch-sensitive screen, resistance heating element, Infrared protection film, antistatic housing, chemical Sensor, electromagnetic sensor, FKD, LCD, electrophoretic Display.