WO2014033753A2 - "a process for the preparation of transparent conductive oxides". - Google Patents

"a process for the preparation of transparent conductive oxides". Download PDF

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WO2014033753A2
WO2014033753A2 PCT/IN2013/000503 IN2013000503W WO2014033753A2 WO 2014033753 A2 WO2014033753 A2 WO 2014033753A2 IN 2013000503 W IN2013000503 W IN 2013000503W WO 2014033753 A2 WO2014033753 A2 WO 2014033753A2
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tin
oxide
reaction mass
doped
transparent conductive
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PCT/IN2013/000503
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French (fr)
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WO2014033753A3 (en
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Jashmin Pravinbhai PATEL
Sanjaykumar Hasmukhbhai PATEL
Jay Parsottambhai NIRMAL
Promise Abhaykumar DOSI
Mehulsinh Ranjitsinh CHHASATIA
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Sigma Energy
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Publication of WO2014033753A3 publication Critical patent/WO2014033753A3/en

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    • CCHEMISTRY; METALLURGY
    • C23COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23CCOATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/02Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition
    • C23C18/12Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material
    • C23C18/1204Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material inorganic material, e.g. non-oxide and non-metallic such as sulfides, nitrides based compounds
    • C23C18/1208Oxides, e.g. ceramics
    • C23C18/1216Metal oxides
    • CCHEMISTRY; METALLURGY
    • C23COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23CCOATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/02Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition
    • C23C18/12Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material
    • C23C18/125Process of deposition of the inorganic material

Definitions

  • the present invention relates to a process for the preparation of transparent conductive oxides. More particularly, the present invention relates to a process for the preparation of transparent conductive oxides using a chemical process wherein Aluminium doped Zinc oxide (AZO), Fluorine doped zinc oxide (FZO), Gallium doped Zinc Oxide (GZO), Fluorine Doped Tin Oxide (FTO), Antimony doped Tin Oxide (ATO), and Tin doped Indium Oxide (ITO) and the other similar transparent conductive oxides have been prepared by the process as disclosed herein below.
  • Aluminium doped Zinc oxide AZO
  • Fluorine doped zinc oxide FZO
  • Gallium doped Zinc Oxide GZO
  • Fluorine Doped Tin Oxide FTO
  • ATO Antimony doped Tin Oxide
  • ITO Tin doped Indium Oxide
  • TCO optically transparent and electrically conducting oxides
  • Their resistivity could be as low as 10 4 ⁇ . ⁇
  • their extinction coefficient k in the optical visible range (VIS) could be lower than 0.0001, owing to their wide optical band gap (Eg) that could be greater than 3 eV.
  • TCO thin films include: (1) transparent electrodes for flat panel displays (2) transparent electrodes for photovoltaic cells, (3) low emissivity windows, (4) window defrosters, (5) transparent thin films transistors, (6) light emitting diodes, and (7) semiconductor lasers.
  • TCO thin films As the usefulness of TCO thin films depends on both their optical and electrical properties, both parameters should be considered together with physical, chemical & thermal durability, etchability, conductivity, deposition temperature, uniformity, environmental stability, abrasion resistance, electron work function, and compatibility with substrate and other components of a given device, as appropriate for the application.
  • the availability of the raw materials and the economics of the deposition method are also significant factors in choosing the most appropriate TCO material.
  • the selection decision is generally made by maximizing the functioning of the TCO thin film by considering all relevant parameters, and minimizing the expenses. TCO material selection only based on maximizing the conductivity and the transparency can be faulty.
  • Patents /Patent Applications US4370310, US20060247354 and IN223109 have suggested a process for the preparation of Zinc Aluminate powder.
  • IN223109 has disclosed a process for the preparation of Zinc Aluminate wherein the process comprises preparing mixed salt solution by mixing soluble salts of zinc and aluminium in 1: 1 molar proportion with water in such amount that the concentration of mixed salt solution obtained lies in the range of 0.05 to 0.15 molar, ' maintaining the pH of the mixed salt solution in the range of 7.5 to 8.0 by adding a basic media into the mix solution under stirring till the gelation is completed with the formation of gel, ageing the gel for a period in the range of 24-30 hours, filtering the aged gel to obtain a solid mass, washing the solid mass with water, drying the washed solid mass at a temperature in the range of 80°- 110°C to obtain a dried solid mass, calcining the said dried solid mass at a temperature in the range of 500°-800°C, pulverizing the calcined mass by conventional methods to obtain zinc aluminate powder.
  • Zinc Aluminate as obtained by the above process is in the form of spinals and spinals are non-conductive or less conductive.
  • US4370310 has disclosed a process for the preparation of Zinc Aluminate.
  • a strong zinc aluminate is prepared by first wetting a particulate alumina hydrate with a dilute acid to form a paste. Particulate zinc oxide is then added to the resulting paste. The mixture of alumina hydrate and zinc oxide is then dried and calcined to form zinc aluminate.
  • a new method of manufacturing nanoscale single- and multi-component metal oxide particles is described.
  • a first solution that includes one or more metal salts, an acid, and a solvent is formed;
  • a second solution that includes * an organic polymer, a base, and water is formed;
  • the first solution is combined with the second solution to form a combined solution, and a precipitation reaction occurs such that metal hydroxide particles precipitate out of the combined solution;
  • the metal hydroxide particles are collected, rinsed, and dried; and finally, in a fifth step, the metal hydroxide particles are heated, thereby forming nanoscale metal oxide particles of less than about 100 nm in size.
  • Exemplary nanoscale particles that may be produced using this method include Aluminium doped Zinc Oxide, Tin doped Indium Oxide (ITO) and Antimony doped Tin Oxide (ATO).
  • US4246143 has disclosed a process of preparing a conductive tin dioxide powder doped with 0.001-2.0 mole % of antimony oxide by heating a mixture of stannous oxalate and an antimony compound, preferably a halide, to form tin dioxide through thermal decomposition of stannous oxalate and accomplish firing of the formed tin dioxide without causing sintering.
  • the mixture is prepared by using a solution of an antimony halide, followed by evaporation of the solvent.
  • fluorine-doped tin oxide powder is prepared by combining a solution of a stannic salt in a water- miscible alcohol with an aqueous solution of a fluoride and separating the resulting precipitate of tin hydroxide from the liquid. This precipitate is then dried at a temperature not exceeding about room temperature and then calcined by heating it for some time to a temperature of at least 500°C. Duririg calcination, it is heated at least until the fluorine content of the powder is at most 10% by weight and is preferably between 1 and 5% by weight.
  • KR2012021837 has disclosed a process for the preparation of Fluorine doped tin oxide wherein the method comprises (1) mixing tin chloride pentahydrate and ethanol to prepg. 0.66-0.69 M soln., (2) prepg. 0.950-0.954 M aq. ammonium fluoride soln., (3) mixing the tin chloride soln. and ammonium fluoride soln., (4) adding ethylene glycol to the soln. mixt. to prep. 0.14-0.18 M coating soln., (5) heating a substrate at 450-500°, (6) spraying the coating soln. with a spray nozzle to form micro liq. drops, and (7) heating the micro liq. drops at 450-500°C followed by, vaporizing the solvent to give the desire product.
  • a process for the preparation of antimony doped tin oxide comprises: (1) dissolving tin salt in water to have a concn. of 0.3-0.8 mol/L, and adding 2-6 wt% (calcd. to tin salt) complexing agent; (2) dissolving Sb salt in ale. to have a concn. of 0.1-0.5 mol/L; (3) simultaneously dropping Sb soln. and ammonia water in tin soln. in 16-60 min under stirring, allowing reaction at pH 2-4, and ageing at 50-70°C for 2-5 h; (4) filtering, washing with water to obtain precursor; (5) dispersing the precursor in org.
  • the tin salt is chloride, nitrate, and/ or citrate.
  • the Sb salt is chloride, nitrate, and/ or citrate.
  • the complexing agent is tartaric acid, citric acid and/or polyacrylic acid.
  • the ale. is methanol, ethanol, and/ or propanol.
  • the org. solvent is toluene, xylene and/or n-butanol. According to CN 101327948, the method comprises prepg. SnCU/ethanol soln.
  • SbC /ethanol soln. resp., mixing at a SbC /SnCU molar ratio of 0.02-0.4, adding de-ionized water to 0.005-3 mol/L SnC , regulating pH value with ammonia water to 8.5-9.5, evenly dispersing, hydrothermally reacting in a reactor at 100-200°C for 1-2 h, centrifuging, washing, drying, grinding, and thermally- treating at 400-700°C for 0.5-1 h to obtain the final product.
  • transparent conductive oxides that includes but not limited to conductive zinc oxides, conductive tin oxides and conductive indium oxide.
  • the present invention provides environment and plant friendly process which reduces process operation stages and thereby saving the manufacturing cost, manpower, time cycles and can avoid generation of unwanted excessive effluent.
  • the main object of the present invention is to obviate the problems of the prior art processes.
  • the other object of the present invention is to provide an environment friendly, safe, commercially viable, easy to operate and cost effective process for the preparation of transparent conductive oxides.
  • AZO aluminium doped zinc oxide
  • GZO gallium doped zinc oxide
  • FZO fluorine doped zinc oxide
  • ATO antimony doped tin oxide
  • the other object of the present invention to provide a process for the preparation of fluorine doped tin oxide (FTO).
  • FTO fluorine doped tin oxide
  • a process for the preparation of transparent conductive oxides wherein, in a reactor, reaction mass containing a solution of metal salt used as doping element, preferred metal salt and a solvent in an appropriate quantity is added and stirred it to get the clear solution of the reaction mass.
  • Base is added to obtain the desire pH of the reaction mass.
  • the said reaction mass is stirred under gaseous pressure of 5kg/cm 2 to 80kg/cm 2 in an autoclave at a temperature below 250°C, preferably at a temperature between 100°C to 175°C for 1 to 10 hrs.
  • the reaction mass is cooled to below 50°C, preferably to room temperature, centrifuge it and wash it with water to remove the inorganic salt formed during the reaction followed by solvent washing thereby removing water from the product, dried the product in oven at a temperature below 100°C for 5 to 10 hrs to give the desired transparent conductive oxide.
  • the transparent conductive oxides produced with this process contain particle size between lnm to lOOnm.
  • Doping element is selected from the salts of metal selected from fluorine, tin, antimony, aluminium, indium and gallium. In the present invention, doping is carried out between 0.5wt% to 15wt%.
  • Solvent used in the reaction is selected from water, N-methyl Pyrollidone (NMP), acetonitrile or (Ci - C 4 ) alcohol, dimethyl formamide, DMSO, glycol, cellosolve or mixtures thereof.
  • Base used in the reaction is selected from organic or inorganic bases.
  • organic base is selected from triethanol amine, triethylamine, diethyl amine, oleylamine, ethanol amine, diethanol amine, n-alkylamine amine (Ci-Ce), diamine, (d-Ce), hexamine, di- isopropylethylamine
  • inorganic base is selected from aqueous ammonium hydroxide, sodium hydroxide (NaOH), potassium hydroxide (KOH) or ammonium acid carbonate.
  • FIG. 1 is an X-ray diffraction pattern for the powder produced in accordance with Example- 1 of Set- 1.
  • FIG. 2 is a transmission electron micrograph (TEM) for the powder produced in accordance with Example- 1 of Set- 1.
  • FIG. 3 is an energy dispersive graph (EDS) for the powder produced in accordance with Example- 1 of Set- 1.
  • EDS energy dispersive graph
  • FIG. 4 is an X-ray diffraction pattern for the powder produced in accordance with Example-2 of Set- 1.
  • FIG. 5 is a transmission electron micrograph (TEM) for the powder produced in accordance with Example-2 of Set- 1.
  • FIG. 6 is an energy dispersive graph (EDS) for the powder produced in accordance with Example-2 of Set- 1.
  • EDS energy dispersive graph
  • FIG. 7 is an X-ray diffraction pattern for the powder produced in accordance with Example- 1 of Set-2.
  • FIG. 8 is a transmission electron micrograph (TEM) for the powder produced in accordance with Example- 1 of Set-2.
  • FIG. 9 is an energy dispersive graph (EDS) for the powder produced in accordance with Example- 1 of Set-2.
  • FIG. 10 is an X-ray diffraction pattern for the powder produced in accordance with Example-2 of Set-2.
  • FIG. 11 is a transmission electron micrograph (TEM) for the powder produced in accordance with Example-2of Set-2.
  • TEM transmission electron micrograph
  • FIG. 12 is an energy dispersive graph (EDS) for the powder produced in accordance with Example-2 of Set-2.
  • EDS energy dispersive graph
  • FIG. 13 is an X-ray diffraction pattern for the powder produced in accordance with Example- 1 of Set-3.
  • FIG. 14 is a transmission electron micrograph (TEM) for the powder produced in accordance with Example- 1 of Set-3.
  • FIG. 15 is an energy dispersive graph (EDS) for the powder produced in accordance with Example- 1 of Set-3.
  • EDS energy dispersive graph
  • FIG. 16 is an X-ray diffraction pattern for the powder produced in accordance with Example-2 of Set-3.
  • FIG. 17 is a transmission electron micrograph (TEM) for the powder produced in accordance with Example-2of Set-3.
  • FIG. 18 is an energy dispersive graph (EDS) for the powder produced in accordance with Example-2 of Set-3.
  • FIG. 19 is an X-ray diffraction pattern for the powder produced in accordance with Example- 1 of Set-4.
  • FIG. 20 is a transmission electron micrograph (TEM) for the powder produced in accordance with Example- 1 of Set-4.
  • FIG. 21 is an energy dispersive graph (EDS) for the powder produced in accordance with Example- 1 of Set-4.
  • EDS energy dispersive graph
  • FIG. 22 is an X-ray diffraction pattern for the powder produced in accordance with Example-2 of Set-4.
  • FIG. 23 is a transmission electron micrograph (TEM) for the powder produced in accordance with Example-2 of Set-4.
  • FIG. 24 is an energy dispersive graph (EDS) for the powder produced in accordance with Example-2 of Set-4.
  • EDS energy dispersive graph
  • the process may overcome the limitations and disadvantages of conventional processes and enable the environmentally-friendly preparation of transparent conductive oxides in higher volumes and at lower manufacturing costs.
  • Transparent conductive oxides are selected from but not limited to conductive zinc oxides, conductive tin oxides and conductive indium oxides.
  • Conductive zinc oxides are prepared using the doping element wherein the doping element is selected from but not limited to aluminium, gallium or fluorine.
  • Conductive tin oxides are prepared using - the doping element wherein doping element is selected from but not limited to antimony or fluorine.
  • Antimony doped tin oxide Antimony(III) Tin (IV) chloride, tin (IV) (ATO) chloride, Sb(OAc)3, bromide, tin (IV)
  • Tin doped indium oxide Tin(IV) chloride Tin doped indium oxide Tin(IV) chloride, tin Indium (III) chloride, (ITO) (IV) bromide, tin(IV) indium (III) acetate, isopropoxide indium (III) nitrate
  • a process for the preparation of transparent conductive oxides having particle size between lnm to 100 nm comprising:
  • reaction mass by mixing salt of metal doping element, preferred metal salt and solvent;
  • reaction mass containing a solution of metal salt used as doping element, preferred metal salt and a solvent in an appropriate quantity is added and stirred it to get " the clear solution of the reaction mass.
  • Base is added to obtain the desire pH of the reaction mass.
  • the said reaction mass is stirred under gaseous pressure of 5kg/ cm 2 to 80kg/cm 2 in an autoclave at a temperature below 250°C, preferably at a temperature between 100°C to 175°C for 1 to 10 hrs.
  • the reaction mass is cooled to below 50°C, preferably to room temperature, centrifuge it and wash it with water to remove the inorganic salt formed during the reaction followed by solvent washing thereby removing water from the product, dried the product in oven at a temperature below 100°C for 5 to 10 hrs to give the desired transparent conductive oxide.
  • Reaction is carried out in a stainless steel gas pressure reactor or in an autoclave lined with teflon or quartz as they are safe to conduct the reaction at higher temperature and they are also resistant to corrosion.
  • Solvent used in the reaction is selected from water, N-methyl Pyrollidone (NMP), acetonitrile or (C 1 -C 4 ) alcohol, dimethyl formamide, DMSO, glycol, cellosolve or mixtures thereof.
  • Preferred quantity of solvent is 1 volume to 25 volumes compared to the weight of salt of zinc or aluminium or indium, more preferably 3volumes to 25volumes compared to the said salt.
  • base is added as per the requirement of the pH adjustment of the reaction mass and in some cases aqueous solution of a base is also may be used in adjusting pH of the reaction mass.
  • Base used in the reaction is selected from organic or inorganic bases.
  • Organic base is selected from triethanol amine, triethylamine, diethyl amine, oleylamine, ethanol amine, diethanol amine, n-alkylamine amine (d-C6), diamine, (Ci-C6), hexamine, di-isopropylethylamine while inorganic base is selected from aqueous ammonium hydroxide (NH4OH), sodium hydroxide (NaOH), potassium hydroxide (KOH) or ammonium acid carbonate. Quantity of base is dependent on the pH of the reaction mass to be adjusted between 6.5 to 9, preferably 6.5 to 7.5.
  • reaction under gaseous pressure in which the gaseous pressure is maintained between 5 kg/cm 2 to 80kg/cm 2 , more preferably 5kg/cm 2 to 20kg/cm 2 wherein pressure is applied using air, oxygen or inert gas like nitrogen or argon.
  • gaseous pressure helps in avoiding agglomeration of the formed transparent conductive oxide with maintaining the particle size of the transparent conductive oxide between lnm to lOOnm.
  • Reaction is stirred for 1 to 10 hrs, preferably 2-5 hrs below 250°C, preferably between the temperature ranges of 100°C to 175°C.
  • the reaction mass is cooled below 50°C, preferably to room temperature, centrifuge it and wash it with water to remove the inorganic salt formed during the reaction followed by solvent washing thereby removing water irom 3 ⁇ 4ie product, dried the product at a temperature below 100°C, preferably between 50°C to 100°C in any of the conventional dryer, for 5 to 10 hrs to give the desired transparent conductive oxide.
  • a favorable aspect of the present invention is that the drying can be accomplished successfully at significant lower temperature than in the conventional methods and stage of calcination of the obtained transparent conductive oxide at a temperature more than 400°C is not required.
  • the transparent conductive oxides produced with this process are having the particle size between 1 nm to 100 nm. It is observed that the reaction parameters like applying gaseous pressure to the reaction mass, adjusting pH between 6.5 to 9, preferably at pH between 6.5 to 7.5 and stirring the reaction mass during the reaction hours enables the production of uniform particles of transparent conductive oxides at relatively high yields avoiding the nonagglomeration of the particles of the transparent conductive oxide during the reaction.
  • the transparent conductive oxides of the present invention are characterized by particle size, XRD, conductivity confirmation, energy dispersive spectroscopy (EDS).
  • the transparent conductive oxides can be used to form sputtering targets, which serve as raw materials for the deposition of transparent conductive and other types of films, or they may be formulated into liquid dispersions and coated directly onto substrates of interest, thereby forming transparent conductive and other types of films.
  • TCO transparent conductive oxides
  • EDS Energy dispersive spectrometer
  • Samples were analyzed for bulk resistance (in ohm) using the said instrument which is a 4 probe system and gives results directly when applies on the tablet made from the transparent conductive oxide (TCO) Powder at 20 ton pressure in tungsten carbide die.
  • TCO transparent conductive oxide
  • Example-1 (Batch no.: AZO/SE01/2012/06/ 13):
  • Example-2 (Batch no.: AZO/SE01/2012/2017 15):
  • Example-1 (Batch No.: GZO/SE01/2012/1905):
  • Example-2 (Batch No.: GZO/SEOl/2012/1507):
  • ATO Antimony doped tin oxide
  • Example-1 (Batch No.: ATO/SE01/2012/04/ 16):
  • Example-2 (Batch No.: ATO/SE01/2012/07/07):
  • Example-1 (Batch No.: FTO/SEOl /2012/04/ 11):
  • Example-2 (Batch No.: FTO/SEOl /2012/04/ 12):
  • Example-3 (Batch No.: FTO/SE01/2012/01/08):
  • Example-1 (Batch No.: ITO/SE01/2012/07/09):
  • the other transparent conductive oxides are also prepared and analyzed.

Abstract

The present invention relates to a process for the preparation of transparent conductive oxides. More particularly, the present invention relates to a process for the preparation of transparent conductive oxides using a chemical process wherein Aluminium doped Zinc oxide (AZO), Fluorine doped zinc oxide (FZO), Gallium doped Zinc Oxide (GZO), Fluorine Doped Tin Oxide (FTO), Antimony doped Tin Oxide (ATO), and Tin doped Indium Oxide (ITO) and the other similar transparent conductive oxides have been prepared by the process as disclosed herein below.

Description

FIELD OF THE INVENTION
The present invention relates to a process for the preparation of transparent conductive oxides. More particularly, the present invention relates to a process for the preparation of transparent conductive oxides using a chemical process wherein Aluminium doped Zinc oxide (AZO), Fluorine doped zinc oxide (FZO), Gallium doped Zinc Oxide (GZO), Fluorine Doped Tin Oxide (FTO), Antimony doped Tin Oxide (ATO), and Tin doped Indium Oxide (ITO) and the other similar transparent conductive oxides have been prepared by the process as disclosed herein below.
BACKGROUND OF THE INVENTION
Most of the optically transparent and electrically conducting oxides (TCO) are binary or ternary compounds, containing one or two metallic elements. Their resistivity could be as low as 10 4 Ω.αη, and their extinction coefficient k in the optical visible range (VIS) could be lower than 0.0001, owing to their wide optical band gap (Eg) that could be greater than 3 eV.
This remarkable combination of conductivity and transparency is usually impossible in intrinsic stoichiometric oxides; however, it is achieved by producing them with a non- stoichiometric composition or by introducing appropriate dopants.
Badeker (1907) discovered that thin CdO films possess such characteristics. Later, it was recognized that thin films of ZnO, Sn02, Ι _θ3 and their alloys were also TCOs. Doping these oxides resulted in improved electrical conductivity without degrading their optical transmission. Al doped ZnO (AZO), tin doped Ιη2θ3, (ITO) and antimony or fluorine doped Sn02 (ATO and FTO), are among the most utilized TCO thin films in modern technology. In particular, ITO is used extensively. The actual and potential applications of TCO thin films include: (1) transparent electrodes for flat panel displays (2) transparent electrodes for photovoltaic cells, (3) low emissivity windows, (4) window defrosters, (5) transparent thin films transistors, (6) light emitting diodes, and (7) semiconductor lasers.
As the usefulness of TCO thin films depends on both their optical and electrical properties, both parameters should be considered together with physical, chemical & thermal durability, etchability, conductivity, deposition temperature, uniformity, environmental stability, abrasion resistance, electron work function, and compatibility with substrate and other components of a given device, as appropriate for the application. The availability of the raw materials and the economics of the deposition method are also significant factors in choosing the most appropriate TCO material.
The selection decision is generally made by maximizing the functioning of the TCO thin film by considering all relevant parameters, and minimizing the expenses. TCO material selection only based on maximizing the conductivity and the transparency can be faulty.
Recently, the scarcity and high price of Indium needed for ITO, the most popular TCO, as spurred R&D aimed at finding a substitute. Its electrical resistivity (p) should be ~10"4 Q.cm or less, with an absorption coefficient (a) smaller than 104 cm-1 in the near-UV and VIS range, and with an optical band gap>3eV. A 100 nm thick film TCO film with these values for and will have optical transmission (T) 90% and a sheet resistance (Rs) 10 Ω/Ώ. At present, AZO and ZnO:Ga (GZO) semiconductors are promising alternatives to ITO for thin-film transparent electrode applications. The best candidates is AZO, which can have a low resistivity, e.g. on the order of 10~4 Ω. cm3 and its source materials are inexpensive and non-toxic. However, the development of large area, high rate deposition techniques is needed.
Patents /Patent Applications US4370310, US20060247354 and IN223109 have suggested a process for the preparation of Zinc Aluminate powder.
IN223109 has disclosed a process for the preparation of Zinc Aluminate wherein the process comprises preparing mixed salt solution by mixing soluble salts of zinc and aluminium in 1: 1 molar proportion with water in such amount that the concentration of mixed salt solution obtained lies in the range of 0.05 to 0.15 molar,' maintaining the pH of the mixed salt solution in the range of 7.5 to 8.0 by adding a basic media into the mix solution under stirring till the gelation is completed with the formation of gel, ageing the gel for a period in the range of 24-30 hours, filtering the aged gel to obtain a solid mass, washing the solid mass with water, drying the washed solid mass at a temperature in the range of 80°- 110°C to obtain a dried solid mass, calcining the said dried solid mass at a temperature in the range of 500°-800°C, pulverizing the calcined mass by conventional methods to obtain zinc aluminate powder.
Zinc Aluminate as obtained by the above process is in the form of spinals and spinals are non-conductive or less conductive.
US4370310 has disclosed a process for the preparation of Zinc Aluminate. According to the process, a strong zinc aluminate is prepared by first wetting a particulate alumina hydrate with a dilute acid to form a paste. Particulate zinc oxide is then added to the resulting paste. The mixture of alumina hydrate and zinc oxide is then dried and calcined to form zinc aluminate.
According to the US20060247354, a new method of manufacturing nanoscale single- and multi-component metal oxide particles is described. In a first step of the method, a first solution that includes one or more metal salts, an acid, and a solvent is formed; in a second step, a second solution that includes* an organic polymer, a base, and water is formed; in a third step, the first solution is combined with the second solution to form a combined solution, and a precipitation reaction occurs such that metal hydroxide particles precipitate out of the combined solution; in a fourth step, the metal hydroxide particles are collected, rinsed, and dried; and finally, in a fifth step, the metal hydroxide particles are heated, thereby forming nanoscale metal oxide particles of less than about 100 nm in size. Exemplary nanoscale particles that may be produced using this method include Aluminium doped Zinc Oxide, Tin doped Indium Oxide (ITO) and Antimony doped Tin Oxide (ATO).
The other Patents/ Patent Applications US4246143, KR2012021837, CN 101428849, US5202211 and US5238674 have suggested a process for the preparation of Conductive Tin Oxides such as Fluorine doped tin oxide (FTO), Tin doped Indium Oxide (ITO), Antimony doped Tin Oxide (ATO).
US4246143 has disclosed a process of preparing a conductive tin dioxide powder doped with 0.001-2.0 mole % of antimony oxide by heating a mixture of stannous oxalate and an antimony compound, preferably a halide, to form tin dioxide through thermal decomposition of stannous oxalate and accomplish firing of the formed tin dioxide without causing sintering. Preferably the mixture is prepared by using a solution of an antimony halide, followed by evaporation of the solvent.
According to the process disclosed in US 5202211 & US5238674, fluorine-doped tin oxide powder is prepared by combining a solution of a stannic salt in a water- miscible alcohol with an aqueous solution of a fluoride and separating the resulting precipitate of tin hydroxide from the liquid. This precipitate is then dried at a temperature not exceeding about room temperature and then calcined by heating it for some time to a temperature of at least 500°C. Duririg calcination, it is heated at least until the fluorine content of the powder is at most 10% by weight and is preferably between 1 and 5% by weight.
KR2012021837 has disclosed a process for the preparation of Fluorine doped tin oxide wherein the method comprises (1) mixing tin chloride pentahydrate and ethanol to prepg. 0.66-0.69 M soln., (2) prepg. 0.950-0.954 M aq. ammonium fluoride soln., (3) mixing the tin chloride soln. and ammonium fluoride soln., (4) adding ethylene glycol to the soln. mixt. to prep. 0.14-0.18 M coating soln., (5) heating a substrate at 450-500°, (6) spraying the coating soln. with a spray nozzle to form micro liq. drops, and (7) heating the micro liq. drops at 450-500°C followed by, vaporizing the solvent to give the desire product.
According to the process of CN101428849, a process for the preparation of antimony doped tin oxide comprises: (1) dissolving tin salt in water to have a concn. of 0.3-0.8 mol/L, and adding 2-6 wt% (calcd. to tin salt) complexing agent; (2) dissolving Sb salt in ale. to have a concn. of 0.1-0.5 mol/L; (3) simultaneously dropping Sb soln. and ammonia water in tin soln. in 16-60 min under stirring, allowing reaction at pH 2-4, and ageing at 50-70°C for 2-5 h; (4) filtering, washing with water to obtain precursor; (5) dispersing the precursor in org. solvent, and drying; and (6) calcining in air at 600-900°C for 0.5-3h to give the title product. The tin salt is chloride, nitrate, and/ or citrate. The Sb salt is chloride, nitrate, and/ or citrate. The complexing agent is tartaric acid, citric acid and/or polyacrylic acid. The ale. is methanol, ethanol, and/ or propanol. The org. solvent is toluene, xylene and/or n-butanol. According to CN 101327948, the method comprises prepg. SnCU/ethanol soln. and SbC /ethanol soln., resp., mixing at a SbC /SnCU molar ratio of 0.02-0.4, adding de-ionized water to 0.005-3 mol/L SnC , regulating pH value with ammonia water to 8.5-9.5, evenly dispersing, hydrothermally reacting in a reactor at 100-200°C for 1-2 h, centrifuging, washing, drying, grinding, and thermally- treating at 400-700°C for 0.5-1 h to obtain the final product.
The other reference i.e. J. Sol-gel Sci Technol: (2010), V-55, pages- 171-174 discloses a process for the preparation of nanometric particles of Aluminium doped zinc oxide (AZO) using hydrothermal method. Aluminum nitrate hydrate, aluminum sec-butoxide and zinc nitrate hydrate were used as the starting materials, and n- propanol and 2-butanol were used as solvents. Ratio of AI2O3 in ZnO was kept at 10 wt%. Reaction was conducted in a Teflon autoclave at 175-225°C for 5 h. Aluminium nitrate hydrate is a strong oxidizing agent further both the chemicals i.e. Aluminium nitrate hydrate and aluminium sec butoxide are hazardous chemicals and provoking fire if contacted with other related chemicals.
It is to be noted that in the said prior art, no common approach is adopted for the preparation of transparent conductive oxides. Further, sol-gel method, CVD method, hydrothermal method have been described for the preparation of transparent conductive oxides and all the said methods, due to their high temperature range (about more than 400°C) at the calcination stage, safety and environment issues cannot be avoided and thus the above processes are not feasible and commercially not viable.
As the transparent conductive oxides extensively and widely used in the industry, it is now a need of an hour to provide an environment friendly, safe, commercially viable, easy to operate and cost effective process for the preparation of transparent conductive oxides.
Further, there is also a need to provide a process for the preparation of transparent conductive oxides that includes but not limited to conductive zinc oxides, conductive tin oxides and conductive indium oxide.
The present invention provides environment and plant friendly process which reduces process operation stages and thereby saving the manufacturing cost, manpower, time cycles and can avoid generation of unwanted excessive effluent.
OBJECTS OF THE INVENTION /
The main object of the present invention is to obviate the problems of the prior art processes.
The other object of the present invention is to provide an environment friendly, safe, commercially viable, easy to operate and cost effective process for the preparation of transparent conductive oxides.
There is also an object to provide a process for the preparation of transparent conductive oxides that includes but not limited to conductive zinc oxides, conductive tin oxides and conductive indium oxide.
It is an object of the present invention to provide a process for the preparation of aluminium doped zinc oxide (AZO).
It is yet an object of the present invention to provide a process for the preparation of gallium doped zinc oxide (GZO).
It is also an object of the present invention to provide a process for the preparation of fluorine doped zinc oxide (FZO). It is an object of the present invention to provide a process for the preparation of antimony doped tin oxide (ATO).
The other object of the present invention to provide a process for the preparation of fluorine doped tin oxide (FTO).
It is an object of the present invention to provide a process for the preparation of tin doped indium oxide (ITO).
SUMMARY OF THE INVENTION
According to the present invention, a process for the preparation of transparent conductive oxides is disclosed wherein, in a reactor, reaction mass containing a solution of metal salt used as doping element, preferred metal salt and a solvent in an appropriate quantity is added and stirred it to get the clear solution of the reaction mass. Base is added to obtain the desire pH of the reaction mass. The said reaction mass is stirred under gaseous pressure of 5kg/cm2 to 80kg/cm2 in an autoclave at a temperature below 250°C, preferably at a temperature between 100°C to 175°C for 1 to 10 hrs. After completion of the reaction, the reaction mass is cooled to below 50°C, preferably to room temperature, centrifuge it and wash it with water to remove the inorganic salt formed during the reaction followed by solvent washing thereby removing water from the product, dried the product in oven at a temperature below 100°C for 5 to 10 hrs to give the desired transparent conductive oxide. The transparent conductive oxides produced with this process contain particle size between lnm to lOOnm.
Doping element is selected from the salts of metal selected from fluorine, tin, antimony, aluminium, indium and gallium. In the present invention, doping is carried out between 0.5wt% to 15wt%. Solvent used in the reaction is selected from water, N-methyl Pyrollidone (NMP), acetonitrile or (Ci - C4) alcohol, dimethyl formamide, DMSO, glycol, cellosolve or mixtures thereof.
Base used in the reaction is selected from organic or inorganic bases. Wherein organic base is selected from triethanol amine, triethylamine, diethyl amine, oleylamine, ethanol amine, diethanol amine, n-alkylamine amine (Ci-Ce), diamine, (d-Ce), hexamine, di- isopropylethylamine while inorganic base is selected from aqueous ammonium hydroxide, sodium hydroxide (NaOH), potassium hydroxide (KOH) or ammonium acid carbonate.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is an X-ray diffraction pattern for the powder produced in accordance with Example- 1 of Set- 1.
FIG. 2 is a transmission electron micrograph (TEM) for the powder produced in accordance with Example- 1 of Set- 1.
FIG. 3 is an energy dispersive graph (EDS) for the powder produced in accordance with Example- 1 of Set- 1.
FIG. 4 is an X-ray diffraction pattern for the powder produced in accordance with Example-2 of Set- 1.
FIG. 5 is a transmission electron micrograph (TEM) for the powder produced in accordance with Example-2 of Set- 1.
FIG. 6 is an energy dispersive graph (EDS) for the powder produced in accordance with Example-2 of Set- 1.
FIG. 7 is an X-ray diffraction pattern for the powder produced in accordance with Example- 1 of Set-2.
FIG. 8 is a transmission electron micrograph (TEM) for the powder produced in accordance with Example- 1 of Set-2.
FIG. 9 is an energy dispersive graph (EDS) for the powder produced in accordance with Example- 1 of Set-2.
FIG. 10 is an X-ray diffraction pattern for the powder produced in accordance with Example-2 of Set-2. FIG. 11 is a transmission electron micrograph (TEM) for the powder produced in accordance with Example-2of Set-2.
FIG. 12 is an energy dispersive graph (EDS) for the powder produced in accordance with Example-2 of Set-2.
FIG. 13 is an X-ray diffraction pattern for the powder produced in accordance with Example- 1 of Set-3.
FIG. 14 is a transmission electron micrograph (TEM) for the powder produced in accordance with Example- 1 of Set-3.
FIG. 15 is an energy dispersive graph (EDS) for the powder produced in accordance with Example- 1 of Set-3.
FIG. 16 is an X-ray diffraction pattern for the powder produced in accordance with Example-2 of Set-3.
FIG. 17 is a transmission electron micrograph (TEM) for the powder produced in accordance with Example-2of Set-3.
FIG. 18 is an energy dispersive graph (EDS) for the powder produced in accordance with Example-2 of Set-3.
FIG. 19 is an X-ray diffraction pattern for the powder produced in accordance with Example- 1 of Set-4.
FIG. 20 is a transmission electron micrograph (TEM) for the powder produced in accordance with Example- 1 of Set-4.
FIG. 21 is an energy dispersive graph (EDS) for the powder produced in accordance with Example- 1 of Set-4.
FIG. 22 is an X-ray diffraction pattern for the powder produced in accordance with Example-2 of Set-4.
FIG. 23 is a transmission electron micrograph (TEM) for the powder produced in accordance with Example-2 of Set-4.
FIG. 24 is an energy dispersive graph (EDS) for the powder produced in accordance with Example-2 of Set-4.
Table-2 is a tabulated form of batch-wise results for the examples shown in the said specification. DESCRIPTION OF THE INVENTION
According to the present invention, there is a process provided for the preparation of transparent conductive oxides. The process may overcome the limitations and disadvantages of conventional processes and enable the environmentally-friendly preparation of transparent conductive oxides in higher volumes and at lower manufacturing costs.
Transparent conductive oxides are selected from but not limited to conductive zinc oxides, conductive tin oxides and conductive indium oxides.
Conductive zinc oxides are prepared using the doping element wherein the doping element is selected from but not limited to aluminium, gallium or fluorine.
Conductive tin oxides are prepared using - the doping element wherein doping element is selected from but not limited to antimony or fluorine.
In a similar manner tin doped indium oxides are also prepared.
Selection of different types of salts for the preparation of transparent conductive oxide is shown in table- 1 as follows:
Table- 1: Preparation of transparent conductive oxides:
Figure imgf000012_0001
(AZO) aluminium chloride, chloride, Zinc bromide, aluminium bromide, Zinc sulfate, Zinc Acetate aluminium sulfate,
aluminium
isopropoxide
Antimony doped tin oxide Antimony(III) Tin (IV) chloride, tin (IV) (ATO) chloride, Sb(OAc)3, bromide, tin (IV)
Sb2(S04)3 isopropoxide
Fluorine doped tin oxide Ammonium Tin (IV) chloride, tin (IV) (FTO) fluoride(NH4F), bromide, tin (IV)
potassium fluoride isopropoxide
(KF)
Tin doped indium oxide Tin(IV) chloride, tin Indium (III) chloride, (ITO) (IV) bromide, tin(IV) indium (III) acetate, isopropoxide indium (III) nitrate
According to the present invention, a process for the preparation of transparent conductive oxides having particle size between lnm to 100 nm comprising:
forming a reaction mass by mixing salt of metal doping element, preferred metal salt and solvent;
adjusting pH of the reaction mass using base;
applying gaseous pressure to the reaction mass;
heating the reaction mass;
collecting, rinsing, and drying the reaction mass to obtain the transparent conductive oxides.
Accordingly, a process for the preparation of transparent conductive oxides is disclosed. In a reactor, reaction mass containing a solution of metal salt used as doping element, preferred metal salt and a solvent in an appropriate quantity is added and stirred it to get "the clear solution of the reaction mass. Base is added to obtain the desire pH of the reaction mass. The said reaction mass is stirred under gaseous pressure of 5kg/ cm2 to 80kg/cm2 in an autoclave at a temperature below 250°C, preferably at a temperature between 100°C to 175°C for 1 to 10 hrs. After completion of the reaction, the reaction mass is cooled to below 50°C, preferably to room temperature, centrifuge it and wash it with water to remove the inorganic salt formed during the reaction followed by solvent washing thereby removing water from the product, dried the product in oven at a temperature below 100°C for 5 to 10 hrs to give the desired transparent conductive oxide.
Normally, before charging the reaction mass in an autoclave, just to simplify the process, it is also possible to prepare a first solution of metal salt used as doping element in a solvent and adding the same into the second solution of preferred metal salt in a solvent.
Reaction is carried out in a stainless steel gas pressure reactor or in an autoclave lined with teflon or quartz as they are safe to conduct the reaction at higher temperature and they are also resistant to corrosion.
Solvent used in the reaction is selected from water, N-methyl Pyrollidone (NMP), acetonitrile or (C1-C4) alcohol, dimethyl formamide, DMSO, glycol, cellosolve or mixtures thereof.
Preferred quantity of solvent is 1 volume to 25 volumes compared to the weight of salt of zinc or aluminium or indium, more preferably 3volumes to 25volumes compared to the said salt.
In the present invention, base is added as per the requirement of the pH adjustment of the reaction mass and in some cases aqueous solution of a base is also may be used in adjusting pH of the reaction mass. Base used in the reaction is selected from organic or inorganic bases. Organic base is selected from triethanol amine, triethylamine, diethyl amine, oleylamine, ethanol amine, diethanol amine, n-alkylamine amine (d-C6), diamine, (Ci-C6), hexamine, di-isopropylethylamine while inorganic base is selected from aqueous ammonium hydroxide (NH4OH), sodium hydroxide (NaOH), potassium hydroxide (KOH) or ammonium acid carbonate. Quantity of base is dependent on the pH of the reaction mass to be adjusted between 6.5 to 9, preferably 6.5 to 7.5.
The reaction is carried out under gaseous pressure in which the gaseous pressure is maintained between 5 kg/cm2 to 80kg/cm2, more preferably 5kg/cm2 to 20kg/cm2 wherein pressure is applied using air, oxygen or inert gas like nitrogen or argon. Surprisingly, it is observed that reaction under gaseous pressure helps in avoiding agglomeration of the formed transparent conductive oxide with maintaining the particle size of the transparent conductive oxide between lnm to lOOnm.
Reaction is stirred for 1 to 10 hrs, preferably 2-5 hrs below 250°C, preferably between the temperature ranges of 100°C to 175°C.
After completion of the reaction, the reaction mass is cooled below 50°C, preferably to room temperature, centrifuge it and wash it with water to remove the inorganic salt formed during the reaction followed by solvent washing thereby removing water irom ¾ie product, dried the product at a temperature below 100°C, preferably between 50°C to 100°C in any of the conventional dryer, for 5 to 10 hrs to give the desired transparent conductive oxide.
A favorable aspect of the present invention is that the drying can be accomplished successfully at significant lower temperature than in the conventional methods and stage of calcination of the obtained transparent conductive oxide at a temperature more than 400°C is not required.
The transparent conductive oxides produced with this process are having the particle size between 1 nm to 100 nm. It is observed that the reaction parameters like applying gaseous pressure to the reaction mass, adjusting pH between 6.5 to 9, preferably at pH between 6.5 to 7.5 and stirring the reaction mass during the reaction hours enables the production of uniform particles of transparent conductive oxides at relatively high yields avoiding the nonagglomeration of the particles of the transparent conductive oxide during the reaction.
The following examples illustrate the present invention, a process for preparing transparent conductive oxides having particle size between lnm to 100 nm. These examples are provided for the purpose of clarifying the invention and terms used in describing same. The examples should not be viewed as limiting the invention as described hereinabove, particularly in view of the ability for a skilled artisan to use differing standard techniques known in the art, some of which are set forth or alluded to here to implement the present invention.
In summary, the examples set forth below demonstrate that the transparent conductive oxides of the present invention are characterized by particle size, XRD, conductivity confirmation, energy dispersive spectroscopy (EDS).
Furthermore, the transparent conductive oxides can be used to form sputtering targets, which serve as raw materials for the deposition of transparent conductive and other types of films, or they may be formulated into liquid dispersions and coated directly onto substrates of interest, thereby forming transparent conductive and other types of films. Different applications of the transparent conductive oxides (TCO) are shown in the references cited below:
(i) J. Sol-gel Sci Technol: (2010), V-55, pp.(171- 174)
(ii) US20060247354
(iii) Journal of Nanoscience and Nanotechnology, Volume 12, Number 2, February 2012 , pp.(1675- 1678) (iv) NSTI-Nanotech: (2010), Vol-1, pp. (340-343)
Samples from the below experiments were given for analysis like for (i) EDS at TCR Advanced Labs-Vadodara, Gujarat, India and (ii) TEM and (iii) XRD analysis at SICART, Vallabh Vidhyanagar, Dist: Anand, Gujarat, India and the results are provided as per the Table-2.
Instrument details:
(a) Energy dispersive spectrometer (EDS): Instrument can analyze the wt % of doping element present in transparent conductive oxides.
Make: Oxford instruments, UK
Model: X-Max 20
(b) Transmission electron microscope (TEM):
Make: Phillips, Holland
Model: Tecnai 20
(c) X-Ray Differactometer (XRD):
Make: Phillips Holland
Model: Xpert MPD
(d) Band gap determination (energy in ev):
Make: Ocean Optics
Model: USB HR400 ί
Reference for band gap determination: While determining the band gap (energy in ev) using the above instrument, applicant has adopted a method as described in the non-patent literature Optical Materials: (1999), V-12, pp. (115- 1 19)".
(e) Bulk resistance (ohm):
Make: National instruments
Model: NI 4065 (61/2 digit digital multimeter)
Samples were analyzed for bulk resistance (in ohm) using the said instrument which is a 4 probe system and gives results directly when applies on the tablet made from the transparent conductive oxide (TCO) Powder at 20 ton pressure in tungsten carbide die.
EXAMPLES
[Set-1]
A process for the preparation of Aluminium doped Zinc Oxide (AZO):
Example-1: (Batch no.: AZO/SE01/2012/06/ 13):
In an autoclave, in a solution of zinc nitrate (320gm) in water (1000ml), aluminium nitrate (30.04gm) is added and stirred it for 30 minutes to get the clear solution of the reaction mass. Triethylamine (325ml) is added in the reaction mass to get the pH between 6.5 to 7.5. The autoclave is closed properly and nitrogen gas pressure is applied to get the pressure about 10kg/cm2. Reaction mass is cooled to room temperature and nitrogen pressure is released slowly from the autoclave. Centrifuge the reaction mass, washed with water (700 ml) and then with acetone (200ml) and dried it in oven at 90°C- 100°C to get aluminium doped zinc oxide (AZO).
Dry wt.: 86 gm
Example-2: (Batch no.: AZO/SE01/2012/05/ 15):
In an autoclave, combined solution of zinc nitrate (320gm) in water (1000ml) and aluminium nitrate (15.52gm) is added and stirred it for 30 minutes to get the clear solution of the reaction mass. Triethylamine (330ml) is added in the reaction mass to get the pH between 6.5 to 7.5. The autoclave is closed properly and nitrogen gas pressure is applied to get the pressure about 10kg/cm2. Reaction mass is heated to 140°C to 145°C and stirred at the same temperature under 10kg/ cm2 for 4 hrs. Reaction mass is cooled to room temperature and nitrogen pressure is released slowly from the autoclave. Centrifuge the reaction mass, washed with water (700 ml) and then with acetone (200ml) and dried it in oven at 90°C-100°C to get aluminium doped zinc oxide (AZO).
Dry wt.: 86. 35gm
[Set-21
A process for the preparation of Gallium doped Zinc Oxide GZO):
Example-1: (Batch No.: GZO/SE01/2012/09/05):
In an autoclave, combined solution of zinc nitrate (179gm) in water (500ml) and gallium chloride (1.87gm) is added and stirred it for 30 minutes to get the clear solution of the reaction mass. Triethylamine (175ml) is added in the reaction mass to get the pH between 6.5 to 7.5. The autoclave is closed properly and nitrogen gas pressure is applied to get the pressure about 10kg/cm2. Reaction mass is heated to 140°C to 145°C and stirred at the same temperature under 10kg/ cm2 for 4 hrs. Reaction mass is cooled to room temperature and nitrogen pressure is released slowly from the autoclave. Centrifuge the reaction mass, washed with water (600 ml) and then with acetone (100ml) and dried it in oven at 90°C-100°C to get gallium doped zinc oxide (GZO).
Dry wt: 43.14gm
Example-2: (Batch No.: GZO/SEOl/2012/09/07):
In an autoclave, combined solution of zinc nitrate (179gm) in water (500ml) and gallium chloride (3,75gm) is added and stirred it for 30 minutes to get the clear solution of the reaction mass. Triethylamine (175ml) is added in the reaction mass to get the pH between 6.5 to 7.5. The autoclave is closed properly and nitrogen gas pressure is applied to get the pressure about 10kg/ cm2. Reaction mass is heated to 140°C to 145°C and stirred at the same temperature under 10kg/cm2 for 4 hrs. Reaction mass is cooled to room temperature and nitrogen pressure is released slowly from the autoclave. Centrifuge the reaction mass, washed with water (600 ml) and then with acetone (100ml) and dried it in oven at 90°C-100°C to get gallium doped zinc oxide (GZO).
Dry wt: 45.15gm
[Set-3
A process for the preparation of Antimony doped tin oxide (ATO):
Example-1: (Batch No.: ATO/SE01/2012/04/ 16):
In an autoclave, combined solution of tin (IV) chloride (40gm) in water (500ml) and antimony (III) chloride (1.04gm) is added and stirred it for 30 minutes to get the clear solution of the reaction mass. A solution of ammonium hydroxide (37ml) is added in the reaction mass to get the pH between 6.5 to 7.5. The autoclave is closed properly and nitrogen gas pressure is applied to get the pressure about 10kg/ cm2. Reaction mass is heated to 140°C to 145°C and stirred at the same temperature under 10kg/ cm2 for 4 hrs. Reaction mass is cooled to room temperature and nitrogen pressure is released slowly from the autoclave. Centrifuge the reaction mass, washed with water (600 ml) and then with acetone (100ml) and dried it in oven at 90°C- 100°C to get antimony doped tin oxide (ATO). Dry wt: 45.15gm
Example-2: (Batch No.: ATO/SE01/2012/07/07):
In an autoclave, combined solution of tin (IV) chloride (lOOgm) in water (1000ml) and antimony (III) chloride (5.2gm) is added and stirred it for 30 minutes to get the clear solution of the reaction mass. A solution of ammonium hydroxide (108ml) is added in the reaction mass to get the pH between 6.5 to 7.5. The autoclave is closed properly and nitrogen gas pressure is applied to get the pressure about 10kg/cm2. Reaction mass is heated to 140°C to 145°C and stirred at the same temperature under 10kg/cm2 for 4 hrs. Reaction mass is cooled to room temperature and nitrogen pressure is released slowly from the autoclave. Centrifuge the reaction mass, washed with water (600 ml) and then with acetone (100ml) and dried it in oven at 90°C-100°C to get antimony doped tin oxide (ATO). Dry wt: 49.4gm
fSet-4]
A process for the preparation of Fluorine doped Tin Oxide (FTO):
Example-1: (Batch No.: FTO/SEOl /2012/04/ 11):
In an autoclave, combined solution of tin (IV) chloride (56gm) in isopropyl alcohol (920ml) and ammonium fluoride (8.28gm) in water (80ml) is added and stirred it for 30 minutes to get the clear solution of the reaction mass. Ammonium hydroxide (41ml) is added in the reaction mass to get the pH between 6.5 to 7.5. The autoclave is closed properly and nitrogen gas pressure is applied to get the pressure about 10kg/cm2. Reaction mass is heated to 140°C to 150°C and stirred at the same temperature under 10kg/ cm2 for 2-4 hrs. Reaction mass is cooled to room temperature and nitrogen pressure is released slowly from the autoclave. Centrifuge the reaction mass, washed with water (1500 ml) and then with acetone (100ml) and dried it in oven at 90°C- 100°C to get fluorine doped tin oxide (FTO). Dry wt: 21.44gm
Example-2: (Batch No.: FTO/SEOl /2012/04/ 12):
In an autoclave, combined solution of tin (IV) chloride (120gm) in water (1000ml) and ammonium fluoride (25.36gm) in water (80ml) is added and stirred it for 30 minutes to get the clear solution of the reaction mass. Ammonium hydroxide (115ml) is added in the reaction mass to get the pH between 6.5 to 7.5. The autoclave is closed properly and nitrogen gas pressure is applied to get the pressure about 10kg/cm2. Reaction mass is heated to 140°C to 150°C and stirred at the same temperature under 10kg/cm2 for 2- 4 hrs. Reaction mass is cooled to room temperature and nitrogen pressure is released slowly from the autoclave. Centrifuge the reaction mass, washed with water (1500 ml) and then with acetone (1000ml) and dried it in oven at 90°C- 100°C to get fluorine doped tin oxide (FTO). Dry wt: 52.34gm
Example-3: (Batch No.: FTO/SE01/2012/01/08):
In an autoclave, clear solution of tin (IV) chloride (lOgm) in water (250ml) and ammonium fluoride (0.73gm) is added and stirred it for 30 minutes to get the clear solution of the reaction mass. pH is adjusted between 6.5 to 7.5 with ammonium hydroxide (12ml). The autoclave is closed properly and nitrogen gas pressure is applied to get the pressure about 20kg/cm2. Reaction mass is heated to 160°C to 175°C and stirred at the same temperature under 20kg/ cm2 for 5 hrs. Reaction mass is cooled to below 45°C and nitrogen pressure is released slowly from the autoclave. Centrifuge the reaction mass, decanted it, washed with acetone (40ml) and dried it in oven at 50°C to get to get fluorine doped tin oxide (FTO).
[Set-5]
A process for the preparation of tin doped indium oxide (ITO): Example-1: (Batch No.: ITO/SE01/2012/07/09):
In an autoclave, clear solution of indium (III) chloride (lOgm) in water (250ml) and tin (IV) chloride (1.53gm) is added and stirred it for 30 minutes to get the clear solution of the reaction mass. pH is adjusted between 6.5 to 7.5 with ammonium hydroxide (15ml). The autoclave is closed properly and nitrogen gas pressure is applied to get the pressure about 20kg/cm2. Reaction mass is heated to 160°C to 175°C and stirred at the same temperature under 20kg/ cm2 for 5 hrs. Reaction mass is cooled to below 45°C and nitrogen pressure is released slowly from the autoclave. Centrifuge the reaction mass, decanted it, washed with acetone (40ml) and dried it in oven at 50°C to get to get tin doped indium oxide (ITO).
In a similar manner, the other transparent conductive oxides are also prepared and analyzed.

Claims

We claim:
1. A process for the preparation of transparent conductive oxide having particle size between 1 nm to 100 nm comprising:
forming a reaction mass by mixing salt of metal doping element, preferred metal salt and solvent;
adjusting pH of the reaction mass using base;
applying gaseous pressure to the reaction mass;
heating the reaction mass;
collecting, rinsing, and drying the reaction mass to obtain the transparent conductive oxide.
2. The process of claim 1, wherein the salt of metal doping element is selected from the group of Ammonium fluoride (NH4F), potassium fluoride (KF), Aluminium nitrate, aluminium chloride, aluminium bromide, aluminium sulfate, aluminium isopropoxide, Antimony(III) chloride, Sb(OAc)3, Sb2(S04)3, Ammonium fluoride(NH4F) , potassium fluoride (KF), Tin(rV) chloride, tin (IV)bromide, tin(IV) isopropoxide and gallium chloride.
3. The process of claim 1, wherein the preferred metal salt is selected from the group of Zinc nitrate, Zinc chloride, Zinc bromide, Zinc sulfate, Zinc Acetate, Tin (IV) chloride, tin (IV) bromide, tin (IV) isopropoxide, Indium (III) chloride, indium (III) acetate, indium (III) nitrate.
4. The process of claim 1, wherein transparent conductive oxides obtained with this process are from the group of Fluorine doped zinc oxide (FZO), Gallium doped zinc oxide (GZO), Aluminium doped zinc oxide (AZO), Antimony doped tin oxide (ATO), Fluorine doped tin oxide (FTO), Tin doped indium oxide (ITO).
5. The process of claim 1, wherein solvent is selected from water, N-methyl Pyrollidone (NMP), acetonitrile or (C1-C4) alcohol, dimethyl formamide, DMSO, glycol, cellosolve or mixtures thereof.
6. The process of claim 1 wherein pH is adjusted between 6.5 to 9.
7. The process of claim 1, wherein the base is selected from organic or inorganic bases.
8. The process of claim 1, wherein organic base is selected from triethanol amine, triethylamine, diethyl amine, oleylamine, ethanol amine, diethanol amine, n-alkylamine amine (d-C6), diamine, (Ci-C6), hexamine, di-isopropylethylamine.
9. The process of claim 1 wherein inorganic base is selected from ammonium hydroxide (NH4OH), sodium hydroxide (NaOH), potassium hydroxide (KOH) or ammonium acid carbonate.
10. The process of claim 1, wherein pressure is applied using gas selected from air, oxygen, nitrogen or argon.
11. The process of claim 1 & 10, wherein pressure is applied between 5 kg/cm2 to 80kg/cm2, preferably 5 kg/cm2 to 20kg/cm2.
12. The process of claim 1 wherein heating is applied at a temperature below 250°C, preferably between 100°C to 175°C.
13. The process of claim 1, wherein collecting the transparent conductive oxide comprises a filtration step.
14. Aluminium doped Zinc Oxide (AZO) obtained by the process of claim 1.
15. Aluminium doped Tin Oxide (ATO) obtained by the process of claim 1.
16. Gallium doped Zinc Oxide (GZO) obtained by the process of claim 1.
17. Fluorine doped Tin Oxide (FTO) obtained by the process of claim 1.
18. Indium doped Tin oxide (ITO) obtained by the process of claim 1.
PCT/IN2013/000503 2012-08-21 2013-08-16 "a process for the preparation of transparent conductive oxides". WO2014033753A2 (en)

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CN112939058A (en) * 2021-02-19 2021-06-11 安徽景成新材料有限公司 Hydrothermal synthesis method for preparing novel zinc oxide with special crystal morphology
CN113066900A (en) * 2021-03-24 2021-07-02 河北北方学院 Preparation method of low-cost ZnO transparent conductive film
CN115015305A (en) * 2022-08-09 2022-09-06 矿冶科技集团有限公司 Doped zinc oxide standard sample, preparation method thereof and method for measuring content of doping elements in unknown doped zinc oxide sample

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CN112939058A (en) * 2021-02-19 2021-06-11 安徽景成新材料有限公司 Hydrothermal synthesis method for preparing novel zinc oxide with special crystal morphology
CN113066900A (en) * 2021-03-24 2021-07-02 河北北方学院 Preparation method of low-cost ZnO transparent conductive film
CN113066900B (en) * 2021-03-24 2022-03-18 河北北方学院 Preparation method of low-cost ZnO transparent conductive film
CN115015305A (en) * 2022-08-09 2022-09-06 矿冶科技集团有限公司 Doped zinc oxide standard sample, preparation method thereof and method for measuring content of doping elements in unknown doped zinc oxide sample
CN115015305B (en) * 2022-08-09 2022-10-25 矿冶科技集团有限公司 Doped zinc oxide standard sample, preparation method thereof and method for measuring content of doping elements in unknown doped zinc oxide sample

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