Wet chemical deposition of crystalline, redispersable ATO and ITO nanoparticles

A new wet chemical concept to produce coatings by dip, spin or spray processes is presented. It is based on the preparation of solutions made of crystalline nanoparticles fully redispersable in a solvent. It is exemplified for the preparation of SnO2 : Sb (ATO) and In2O3 : Sn (ITO) transparent conducting coatings. The process combines the advantages of using particles having already a low resistivity and the possibility to sinter the coatings at low temperature. The particles are prepared using an in-situ monitoring of the surface energy to control the growth of the particles and to avoid their agglomeration. The dried powders can be fully redispersed in alcohol (ITO) or water (ATO). Single layers with thickness up to 200 nm (ATO) and 400 nm (ITO) have been fabricated. The sheet resistance of the coatings decreases with the sintering temperature. Typical values are 430 Ω(open square) for ATO (550°C) and 380 Ω(open square) for ITO (550°C). Sols made by redispersing the powders in organosilanes allow to produce coatings at low temperature with antistatic (R(open square) > 100 kΩ(open square)) and anti-glare properties (R(open square) > 100 kΩ(open square), 60 to 80 gloss units)

Wet chemical deposition of crystalline, redispersable ATO and ITO nanoparticles

A new wet chemical concept to produce coatings by dip, spin or spray processes is presented. It is based on the preparation of solutions made of crystalline nanoparticles fully redispersable in a solvent. It is exemplified for the preparation of SnO2 : Sb (ATO) and In2O3 : Sn (ITO) transparent conducting coatings. The process combines the advantages of using particles having already a low resistivity and the possibility to sinter the coatings at low temperature. The particles are prepared using an in-situ monitoring of the surface energy to control the growth of the particles and to avoid their agglomeration. The dried powders can be fully redispersed in alcohol (ITO) or water (ATO). Single layers with thickness up to 200 nm (ATO) and 400 nm (ITO) have been fabricated. The sheet resistance of the coatings decreases with the sintering temperature. Typical values are 430 Ω(open square) for ATO (550°C) and 380 Ω(open square) for ITO (550°C). Sols made by redispersing the powders in organosilanes allow to produce coatings at low temperature with antistatic (R(open square) > 100 kΩ(open square)) and anti-glare properties (R(open square) > 100 kΩ(open square), 60 to 80 gloss units)

Comparison of spray pyrolyzed FTO, ATO and ITO coatings for flat and bent glass substrates

Transparent conductive FTO, ATO and ITO films were synthesized by spray pyrolysis technique on flat 12x12 cm borosilicate glass substrates at 500-550°C and investigated with respect to their electrical and optical properties. The resistivity of sprayed ITO films decreases with the thickness down to 3.0x10-4 Ω cm (300 nm). The optical transmission in the visible range is 80% and the near IR reflection up to 96% for thicknesses larger than 300 nm. A reducing treatment at 400°C in forming gas still decreases the resistivity by a factor of two. Bending of the coated glasses in air at 650°C for 1.5 h increases the resistivity of the coatings on the tensile side of the substrate by a factor of 3-4 and by a factor 2 on the compressed side. A subsequent reducing treatment in forming gas at 400°C leads to a drastic decrease of resistivity in both cases by a factor of 5-7 with resulting value Ρ=2-3¡x10-4 Ω cm. ATO layers have lower visible transmission (70-75%) due to stronger absorption and a higher resistivity (Ρ=1x10-3 Ω cm). Spray pyrolyzed FTO coatings have a resistivity Ρ=5x10-3 Ω cm for film thicknesses >350 nm

Comparison of spray pyrolyzed FTO, ATO and ITO coatings for flat and bent glass substrates

Transparent conductive FTO, ATO and ITO films were synthesized by spray pyrolysis technique on flat 12x12 cm borosilicate glass substrates at 500-550°C and investigated with respect to their electrical and optical properties. The resistivity of sprayed ITO films decreases with the thickness down to 3.0x10-4 Ω cm (300 nm). The optical transmission in the visible range is 80% and the near IR reflection up to 96% for thicknesses larger than 300 nm. A reducing treatment at 400°C in forming gas still decreases the resistivity by a factor of two. Bending of the coated glasses in air at 650°C for 1.5 h increases the resistivity of the coatings on the tensile side of the substrate by a factor of 3-4 and by a factor 2 on the compressed side. A subsequent reducing treatment in forming gas at 400°C leads to a drastic decrease of resistivity in both cases by a factor of 5-7 with resulting value Ρ=2-3¡x10-4 Ω cm. ATO layers have lower visible transmission (70-75%) due to stronger absorption and a higher resistivity (Ρ=1x10-3 Ω cm). Spray pyrolyzed FTO coatings have a resistivity Ρ=5x10-3 Ω cm for film thicknesses >350 nm

Comparison of spray pyrolyzed FTO, ATO and ITO coatings for flat and bent glass substrates

Transparent conductive FTO, ATO and ITO films were synthesized by spray pyrolysis technique on flat 12x12 cm borosilicate glass substrates at 500-550°C and investigated with respect to their electrical and optical properties. The resistivity of sprayed ITO films decreases with the thickness down to 3.0x10-4 Ω cm (300 nm). The optical transmission in the visible range is 80% and the near IR reflection up to 96% for thicknesses larger than 300 nm. A reducing treatment at 400°C in forming gas still decreases the resistivity by a factor of two. Bending of the coated glasses in air at 650°C for 1.5 h increases the resistivity of the coatings on the tensile side of the substrate by a factor of 3-4 and by a factor 2 on the compressed side. A subsequent reducing treatment in forming gas at 400°C leads to a drastic decrease of resistivity in both cases by a factor of 5-7 with resulting value Ρ=2-3¡x10-4 Ω cm. ATO layers have lower visible transmission (70-75%) due to stronger absorption and a higher resistivity (Ρ=1x10-3 Ω cm). Spray pyrolyzed FTO coatings have a resistivity Ρ=5x10-3 Ω cm for film thicknesses >350 nm

Transparent conducting, anti-static and anti-static-anti-glare coatings on plastic substrates

In2O3:Sn (ITO) sols made of crystalline nanoparticles, fully redispersable in an ethanol solution containing hydrolyzed organosilanes, have been developed to deposit conducting transparent and anti-glare coatings on plastic (PMMA, polycarbonate) and glass substrates by spin, dip and spray coating processes. The coatings are cured by UV irradiation and/or by a low temperature heat treatment (T=130°C) in air or reducing atmosphere. The electrical, optical, textural and mechanical properties of the coatings are reported. A stable sheet resistance as low as 5 kΩ(open square), was obtained with a single 500-nm thick transparent layer. Anti-glare—anti-static coatings exhibiting a 40-kΩ(open square) sheet resistance, a gloss of 60—70 GU, a clarity of 75—90% and an optical resolution >8 lines/mm were obtained by a room temperature spraying process. The abrasion resistance of both coatings is in agreement with DIN 58196-H25-class 1

Transparent conducting coatings made from redispersable crystalline nanoscaled powders

A new wet chemical concept is presented for the preparation of electrically conducting SnO2:Sb (ATO) and In2O3:Sn (ITO) coatings. It is based on the deposition by spin, dip or spray techniques of a solution containing crystalline nanoscaled particles fully redispersable in a solvent. The particle synthesis is carried out in a solution at temperatures < 200 °C by a controlled growth reaction using SnCI4 and InCl3 as precursors and SbCl3 and SnCl4 as dopant, respectively. The aggregation of the particles is avoided by in-situ surface modification with bifunctional organic molecules. After drying the nanocrystalline particles can be fully redispersed in ethanol at pH < 6 (for ITO) or water at pH > 8 (for ATO) with solid contents up to 8.8 vol. %. Single layers with thickness up to 200 nm (ATO) and 400 nm (ITO) have been fabricated. Their sheet resistance decrease with the sintering temperature. Typical lowest values are 430 &Omega; (550 °C) for ATO and 90 &Omega; (900 °C) for reduced ITO. The resistivity of as fired ATO and ITO coatings is stable but it slightly increases with time for ITO in the reduced state. All coatings have a transmission in the visible range of about 90 %. Anti-glare conducting coatings on glass with 70 GU as well as antistatic coatings on polycarbonate substrates have been obtained with chemically modified ITO suspensions