[co.sub.2]-laser treatment of indium tin oxide nanoparticle coatings on flexible polyethyleneterephthalate substrates.
by：Taian Lamination Film2020-09-25
Abstract A [CO. sub. 2]- Increasing the conductivity of oxidized indium tin coating by laser treatment (ITO) Nanoparticles on flexible polyethylene ester (PET)substrates. Conductivity and transparency [CO. sub. 2]-laser- In terms of application as a transparent electrode, the treated ITO nanoparticles coating was characterized. In addition, the stability of conductivity under oscillation bending was studied. Ratio resistance 0. 12 [OMEGA] Cm obtained [CO. sub. 2]- Laser treatment is performed without damaging the PET film. The increase in conductivity can be explained by the formation of a lightweight sintering neck. For a film with a thickness of 3 urn, the thickness is 400 [[OMEGA]/[? ? ]] The transmission within 80% visible range is realized. Stability of conductivity [CO. sub. 2]-laser- The ITO nanoparticles coating treated under bending was studied using a specially constructed device for the application of various oscillating bending loads. For plates with a bending radius of 10mm, the plate resistance does not exceed 1000 [[OMEGA]/[? ? ]] After 300 bending Compared with the commercial ITO coating ,[CO. sub. 2]-laser- The treated ITO nanoparticles coating exhibits significant stability under oscillating bending. Key words: tin oxide (ITO) Transparent electrodes are critical for display applications such as touch screens, flashlights, and organic light-LEDs (OLED). Tin oxide as a coating (ITO) Due to its excellent combination of low resistors, it is almost exclusively used (1-3 x [10. sup. -4][OMEGA]cm) High transparency ( Film thickness at 90% nm> 100) Within the visible range. (1) For flexible display applications and reelsto- Reel processing, which is getting more and more attention, must use polymer film as substrate material. The latest technology for depositing ITO on a polymer substrate is physical deposition technology such as sputtering (2) Or evaporation. (3) However, these technologies are very expensive due to the vacuum process, the extra structure and the associated waste of expensive ITO. Wet deposition techniques such as sol-gel method(4-6) Or a coating dispersed by nanoparticles ,(6-8) The cost of providing the asimpler process Reduce the potential by avoiding vacuum conditions and making it possible to directly map through printing. However, in order to improve the conductivity of ITO nanoparticles coating, it is necessary to annealing at high temperature. For polymer substrates, its low thermal stability limits the annealing temperature. New treatment methods must be applied to improve the conductivity of the nanoparticles coating without thermal damage to the substrate. The coating of ITO nanoparticles on a flexible polymer substrate is rarely described in the literature, focusing mainly on UV-curing binders. Al-Dahoudi et al. (9) The coating of ITO nanoparticles was studied. 3- Glycidoxypropyltrimethoxysilane (GPTS)and3- Methacryloxypropyltrimethodological silane (MPTS) Added as UV-curingbinders. Poly nail fat (PMMA) And pc (PC) The base layer is coated by rotating, dipping and spraying processes. Ratio resistance of 0. 25 [OMEGA] Cm corresponding to the stable chip resistance of 5000 [[OMEGA]/[? ? ]] For layers with a thickness of 570 nm, UV irradiation is used and then low is used Temperature heat treatment in air and reduction atmosphere. Puetz et al. (10)described alow- Temperature curing technology for coating ITO nanoparticles on plexiglass, PC and PET substrates using UV irradiation. MPTS and UV light starters were added to the dispersion system. Ratio resistance of 0. 1 [OMEGA] Cm was obtained after heat treatment in the introduced atmosphere. In further studies, Puetz et al. (11) Research on direct concave printing for transparent manufacturing Conductive nanoparticles coating based on the above-mentioned modified ITO nanoparticles dispersion. In this study ,[CO. sub. 2]- The conductive properties of ITO nanoparticles coating on PET substrate were improved by laser treatment. Aim generates ITO nanoparticles coating on a flexible PET substrate to meet the performance required for transparent flexible electrodes in Photoelectric Applications. Square resistance below 1000 [[OMEGA]/[? ? ]] The goal is to transmit within a visible range of at least 80%. In addition, regarding the application as a flexible electrode, the stability of the conductivity [CO. sub. 2]-laser- The ITO nanoparticles coating treated under oscillating bending was studied and compared with the commercial sputtering ITO coating using a special device described by Koniger et al. (12) As the experimental material of the base material, the Mylar film Hostaphan GN 4600 of Mitsubishi polyester film with thickness 96 [micro]m was chosen. PET film provides the high dimensional stability required for printable electronic applications. In addition, the surface is very smooth and supports the generation of a uniform coating. (13) As a coating solution, the ethanol dispersion of ITO nanoparticles with a solid content of 35. The use of the company\'s monthly % (weight. Arithmetic mean of volume particles- Measured by dynamic light scattering, the size distribution is about 100nm. First, the film was prepared and the PET film was treated by plasma to improve its wet performance. Plasma chamber plasma 4 from ilmvacmbh was used. The plasma is produced by an AC voltage of 50 kHz at a temperature of 1 mbar. Plasma treatment was carried out under the air condition of 30 s. Subsequently, the polymer substrate was coated through a doctor\'s blade using the Erichsen Coatmaster 509 MC device. Coil blade with thickness of 50 [micro] M is used to achieve the dry thickness of 3 [micro]m. Fix the PET film on a heated glass plate with tape. The speed of the coil blade is set to 10 mm/s and the plate is heated to 60 [degrees] Fast evaporation of ethanol. Under this condition, a uniform coating was obtained. Coating of ITO nanoparticles at 200 [annealing]degrees] C is placed in the air for 20 minutes to enhance the adhesion to the PET film. Laser treatment for laser treatment, Synrad series 48 [CO. sub. 2]- Laser module with wavelength of 10. 6 [micro]m was used. The laser beam is extended by a 1:2 telescope, guided by the galvo scanner SK1020 from the scanning laboratory, and focused by the coated ZnSe F-theta lens. The F- The Theta lens corrects the visual deviation with its special design. The diameter of the laser spot is 0. 65 mm. When the scanning speed is between 50mm/S-4, the laser point laments. 5 m/s. At the bottom layer, the structure is processed by filling the selected part of the processing plane with parallel laser lines. The distance of the line, also known as the Hatch distance, is the smallest at 0. 01 mm. The energy provided by the laser can be calculated as the permanent area of the energy input [E. sub. a]= [[P. sub. L]/[[v. sub. S]* [h. sub. S]]] The laser parameters are laser power ,[P. sub. L] Scanning Speed ,[v. sub. S] Distance from the hatch ,[h. sub. S]. Film representation the morphology of ITO nanoparticles film by scanning electron microscopy FE- SEM s4 800 from Hitachi. Determination of layer thickness of the coating ofwhite light focusing (WL-CF)microscopy. The WL-CF microscope\"[mu] \"Surfing\" from Nanofocus was used \". The square resistance of the coating is four- The point method setting of jishili SMU 236. The ratio resistance is calculated by multiplying the resistance by the determined layer thickness. Infrared transmission was measured using infrared spectroscopy- Nikko SpectrometerMagna infrared 750 th. To characterize the transmission within the visible range, the UV/VIS spectrometer Lambda 19 of Perkin Elmer was used. Conductivity under oscillation bending using a device described in detail by Koniger et al studied the conductivity stability of ITOnanoparticle coating under bending. (12) The device is able to measure the resistance of the conductive coating under oscillation bending. In this study, the application of tensile stress in the coating was used to study the conductivity of the ITO/PVP coating under oscillation bending (Fig. 1). [ Figure 1 slightly] The polymer film is supported by four reels and is flexible to fix the atits position through two springs on both sides. The middle of the film sample is bent by a core rod that can move up and down. The core rod is mounted on the rod driven by the extender. The sample is bent up and down, so the bending radius is defined by its geometry. The bending amplitude associated with the bending strength can be troubled by the displacement of the extender. The number of revolutions of the extender controls the frequency of the oscillating bending load. The electrical contact between the conductive coating and the electric measuring device is achieved by the conductive adhesive, which welds the wires from the electric measuring device together. For all measurements in this study, the frequency is 0. Select 1Hz and the bending amplitude is set to 20mm to ensure full bending around the core rod. Transport results and discussions of ITO nanoparticles and PET Films at 10 °c. 6[micro] M first, the transmission of ITO nanoparticles and PETfilm at the laser wavelength (10. 6 [micro]m) Investigated (Fig. 2). [ Figure 2: ITO nanoparticles ( ITO nanoparticles in \"potassium bromide granules) The transmission of 1% is shown at a wavelength of 10. 6 [micro] M of the laser used (Fig. 2a). ITO nanoparticles absorb most of the laser energy, thus reducing the risk of thermal damage in PET Films. The PET film was shown at 10: 25%. 6 [micro]m (Fig. 2b) This is close to maximum and helps reduce the energy input of PETfilm. Especially the high transmission of PET Films near the wavelength of 10. 6 [micro] N shows that ,[CO. sub. 2]- Laser is a suitable tool for ITO heat treatment on PET film. [CO. sub. 2]- Laser treatment of ITO nanoparticles on PET Films first study shows that after [the ITO nanoparticles] are stripped from the PET filmCO. sub. 2]- Laser therapy with all thelaser parameters is applied. The reason for this effect is that due to the short heating of the substrate by laser irradiation, the PET film is difficult to soften, which is a prerequisite for good adhesion of ITO nanoparticles coating to the pet substrate. Therefore, in 200 [annealingdegrees] C 20 minutes before [CO. sub. 2]- Laser treatment improves the adhesion of ITO nanoparticles coating to flexible PET Films. Using different energy inputs to laser treat the annealing ITO nanoparticles coating, the aim is to achieve the lowest possible square resistance without thermal damage to the PET film. Studies have shown that the best results are achieved when the maximum scan speed is 4. 5 m/s, Hatch distance 0. 05 mm. Fast scanning speed avoids thermal damage of PET film due to long time, focused energy input. A small hatch distance is the result of a uniform energy input. In Fig. 3. draw the square resistance of ITO nanoparticles coating on aPET film as a function of energy input per unit area. [ Figure 3 slightly] More than 30 energy inputs [kJ/[m. sup. 2]] Board resistance below 1000[OMEGA]/[? ? ]] It will not cause thermal damage to PET film. Withan energy investment increased to 40 [kJ/[m. sup. 2]] The resistance of Heet dropped to 400 [[OMEGA]/[? ? ]] It is observed that this is about 30 times lower than the square resistance of the only thermallyanneed ITO nanoparticles coating. This corresponds to the specific resistance of 0. 12 [OMEGA] 3 cm of film thicknessmicro]m. [Reasons for improving the conductivity of ITO nanoparticles coatingCO. sub. 2]- In terms of [the form], laser treatment becomes apparentCO. sub. 2]-laser- Treated ITO nanoparticles. In Fig. 4, [CO. sub. 2]-laser- Compared to the ITO nanoparticles coating that was annealing at 200 [treated ITO nanoparticles coatingdegrees]C. [ Figure 4 slightly] Compared to ITO nanoparticles coatings that are only annealing in at200 [degrees] C. slight sintering neck formation was observed [CO. sub. 2]-laser-treated (30-50 [kJ/[m. sup. 2]]) ITO nano-materials. In addition, it was found that the particle size increased slightly and the particles were round. The formation of the sintering neck can be explained by the surface and grain boundary diffusion caused by energy input, reducing the grain boundary scattering of electrons, thus proving the fluidity and conductivity of the charge carrier, respectively. About 45 [energy]kJ/[m. sup. 2]] , A slight increase in the resistance of the film is measured, which can be explained by the formation of cracks. This becomes more obvious for higher energy inputs (Fig. 5). [ Figure 5 Slightly] Due to the mismatch between the high energy input and the thermal expansion coefficient of the PET film and the ITO nanoparticles coating, the internal tension caused by the temperature rise may result in the observed stent formation. Energy> 60 [kJ/[m. sup. 2]] Thermal degradation of PET film was observed (Fig. 6). The resulting surface changes explain a significant increase in the resistance of the film. [ Figure 6 slightly] For  layers below thickness [micro] M, energy investment below 40kJ/[m. sup. 2]] Due to the less laser irradiation absorbed by ITO coating, the thermal damage of PET film has been caused. Therefore, there are at least 3 layers of thickness [micro] In order to avoid thermal damage of PET film, m must be selected. However, the survey shows that for 30-40 [kJ/[m. sup. 2]]a [CO. sub. 2]- The laser treatment of ITOnanoparticle coating on PET film significantly improves the conductivity without heat damage to PET film. The thickness of the layer is 3 [micro] M, square resistance of 400 [[OMEGA]/[? ? ]] Implemented, corresponding to a specific resistance of 0. 12 [OMEGA]cm. However, the application as a transparent electrode needs to be studied to determine [CO. sub. 2]- In the visible range, laser processing affects transmission. Effects of optical properties on [CO. sub. 2]- Laser treatment of the transmission of the annealing ITO nanoparticles coating in the visible range is shown in Fig. 7. [ Figure 7 Slightly] The uncoated PET film shows transmission in a visible range of about 85%. An annealed 3-[micro] The M-thick ITO nano-granular layer reduces the transmission to between 80% and 83%. The [CO. sub. 2]- Laser processing results in a further reduction in transmission, which is more pronounced at higher energy inputs. Energy input of 35 [kJ/[m. sup. 2]] Energy input 46 with maximum transmission of 81% [kJ/[m. sup. 2]] Maximum transmission was observed at 75%. As the energy input increases, the reduction in transmission can be explained with different effects. Crack formation for more than 40 [energy inputs] as described abovekJ/[m. sup. 2]] It will cause the light to spread. In addition, the scattering caused by the smaller particle size and the tightness of the film may also lead to a slight reduction. In addition, more than 45 [energy inputs]kJ/[m. sup. 2]] , Yellow due to slight thermal degradation of PET film caused by laser irradiation. However, the energy investment is 30-35 [kJ/[m. sup. 2]] , ITO nanoparticles coating on PET film can be produced, which shows less than 1000 [[OMEGA]/[? ? ]] And is transmitted within a visible range of at least 80%, so if used as a transparent electrode, the performance required for film resistance and transparency is met. Application of conductivity under oscillation bending with respect to flexible transparent electrode [stability of conductivity]CO. sub. 2]-laser- The treatment of nanoparticles coating under oscillation bending was studied. The purpose is to determine the bending radius, which does not exceed the required value of 1000 [[OMEGA]/[? ? ]]. InFig. 8. square resistance of a to 3 [micro]m [CO. sub. 2]-laser- The TreatedITO nanoparticles coating is plotted as a function of the bending period under different bending radius. The tension pattern described in \"Conductivity under oscillation bending\" under the experimental section was applied. The curve marked with the symbol indicates the resistance of the plate under bending. The dotted line gives the initial single resistance. [ Figure 8: With the decrease of the bending radius, the resistance of the plate under bending increases significantly. The bending radius is 3mm. Increase the square resistance from 700 to 4000 [[OMEGA]/[? ? ]] After 300 bending cycles. The film resistance is still lower than 10mm when the bending radius is 1000 [[OMEGA]/[? ? ]] After 300 bending cycles. A smaller bending radius causes a higher tensile stress in the coating, resulting in a more visible crack (12)(Figs. 9a and 9b) This leads to a greater increase in resistance. [ Figure 9 omittedIn addition, [CO. sub. 2]-laser- The treated ITO nanoparticles coating was compared with the commercial sputtering ITO coating, and the stability of the conductivity under oscillation bending was discussed. InFig. 10, the square resistance is displayed as a function of the bending period of the commercial sputtering ITO coating (125-[micro]m PET film; ~60 [[OMEGA]/[? ? ]]; Cadillac plastic)and the [CO. sub. 2]-laser- Treatment of 3-nanoparticles coating[micro]m thickness. A bending radius of 10mm was used for the study. [ Figure 10 slightly] Compared with the commercial ITO coating,CO. sub. 2]-laser- The treated ITO nanoparticles coating shows a higher conductivity stability under oscillating bending. For the sputtering ITO coating, a significant increase in resistance was observed immediately after several bending cycles. Plate resistance under tension increased from 60 [[OMEGA]/[? ? ]]to 15[[OMEGA]/[? ? ]] After 50 cycles In contrast, the square resistance of the laser after annealing The treated ITO nanoparticles coating increased from 700 to 900 [[OMEGA]/[? ? ]] After 50 cycles The different mechanical stability of the conductivity under oscillating bending can be interpreted as the morphology of the coating. Contrast with porous [CO. sub. 2]-laser- Treated ITOnanoparticle coating (Fig. 11a) , Because of its dense structure, the ITO coating is very brittle (Fig. 11b) This is conducive to cracking. [ Figure 11 omitted] Koniger et al compared in detail the formation of cracks in the sputtering ITOcoatings and ITO nanoparticles coatings. (13) The study on the stability of conductivity under bending shows that ,[CO. sub. 2]-laser- The treated ITOnanoparticle coating exhibits higher conductivity stability under oscillating bending, which is beneficial from the point of view that they are used as flexible electrodes in Photoelectric Applications. The conclusion of this study is that,CO. sub. 2]- Laser treatment is a new method to improve the conductivity of ITO nano-materials on flexible PET substrates. A post- The ITOnanoparticle coating on the PET film was treated with [previous thermal annealing]CO. sub. 2]- The laser significantly improves the conductivity without damaging the PET substrate. Square resistance of 400 [[OMEGA]/[? ? ]] Thickness of Layer 3 [micro]m ( Ratio resistance 0. 12 [OMEGA]cm) Achieved, less than 30 times compared to the annealing-only ITO nanoparticles coating. The increase in conductivity can be explained by a slight formation of the sintering neck, which reduces the scattering of grain boundaries and thus increases the conductivity. For the thickness of 3 layers [micro] Up to 35 [m and energy inputs]kJ/[m. sup. 2]] Transparency [CO. sub. 2]-laser- The treated ITOnanoparticle coating on PET film is about 80%. Thus, ITO- Nanoparticles on PET films can be produced with a film resistance of less than 1000 [[OMEGA]/[? ? ]] In ~ Transmission within visible range of 80%. In addition, the stability of the conductivity [CO. sub. 2]-laser- ITO nanoparticles coating treated under oscillating bending was studied and compared with commercial sputteredITO coating. ITO nanoparticles coating shows that due to the formation of acrack, the resistance of the sheet under bending increases with the increase of the number of cycles. The bending radius is 10mm, no more than the single resistance of 1000 [[OMEGA]/[? ? ]] 300 required after bending cycle. Compared with the commercial ITO coating ,[CO. sub. 2]-laser- The treated ITO nanoparticles coating shows higher conductivity stability under oscillating bending, which can be interpreted as low brittle due to its finer structure. All in all ,[CO. sub. 2]- Laser treatment of ITO nanoparticles provides great potential for improving the conductivity of ITOnanoparticle coating on a flexible PET substrate. This method brings a flexible transparent electrode based on the printable ITOnanoparticle coating achieved by close Technology. It has been shown that flexible conductive films can be made, which meets the conductivity and transparency requirements of simple photoelectric applications such as light-emitting lamps and touch screens. The authors thank the German Research Foundation for its financial support, and Evonik Degussa GmbH provides ITOnanoparticle dispersion, which is supplied by Mitsubishi polyester film. References (1. ) Paine, DC, Yeom, H- \"Transparent Oxide Materials and Technologies \". In: Crawford, general practitioner (ed. ) Flexible Flat Panel Display, pp. 79-98. Wiley series of display technology in New York (2005)(2. ) Properties of tin-doped oxidized indium films prepared by Ray, S, Banerjee, R, Basu, N, Batabyal, AK, Barua, AK, \"by RF sputtering\" J. Appl. Phys. , 54 3497-3501 (1983). doi:10. 1063/1. 332415 (3. ) Hamberg, I, granqvisa, CG, \"evaporated Sn-doped[In. sub. 2][O. sub. 3] Film: Basic optical properties and applications in energy Efficient window. \" J. Appl. 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Schmitt bayeresh Laser Center Co. , Ltd, Konrad-Zuse-Str. 2-6, D-