I have prepared ZnO based thin films by sol gel dip coating method. First sol was prepared by following process. Zinc acetate dihydrate (Zn(COOCH3)2.2H2O) is used as precursor and aluminium nitrate nonahydrate (Al(NO3)3.9H2O) as a dopant source. 2-methoxyethanol (C3H8O2) and monoethanolamine (MEA, C2H7NO) are used as solvent and stabilizer respectively. ZnO sol was prepared first by dissolving Zinc acetate dihydrate in mixture of 2-methoxyethanol and MEA solution. The molar ratio of zinc acetate and MEA was kept 1:1 and concentration of zinc acetate was 0.4 M. For doping of aluminium, aluminium nitrate nonahydrate was added along zinc acetate. The mixture was stirred at 80°C on magnetic stirrer for 3 hours the solutions were allowed to age at room temperature by varying ageing time (24 and 48 hours) before the deposition process. Dip coating method was used to fabricate the films under ambient conditions. And after dipping it in sol glass substrate was heated at 250 degree celcius for 5 minutes and cycles were repeated. Now there is difference in properties in films prepared by sol aged at 24 hours and 48 hours. Now I know this difference in properties is due to ageing and science behind it is hidden in guiding reaction of my sol. please enlighten me if anyone can?
Dear Artur Braun,
Solvent has boiling point around 80 degree celcius. yes there was difference in rheological properties as solution became more viscous after ageing. Just want to know why these changes? And what can be guiding reaction? Something I know about it after reading the literature is that zinc acetate crystallizes into ZnO when I heat my films above 240 degree celcius which is 250 degree celcius in my case. So, what is happening during magnetic stirring which is done at 80 degree celcius for 3 hours? And what is happening during ageing? Why my solution becoming viscous? And how viscosity is affecting properties of thin films. Films prepared from solution aged for 48 hours are showing better transmittance and electrical conductivity than films prepared by 24 hours ageing.
1, It is no dout that during the annealing process (>240 C) the mixture precursor convert to metal oxide.
2, the aging process affected the precursor ( component? reaction? homogeneous?)
3, note that the melting point of AlN3O9#9H2O
4, there must be a relevance among processing condition, film structure ( component, morphology) and film properties. therefore, a further study on the film structure is necessary.
Zinc Acetate powder will convert 100% to ZnO at around 309oC, If you doped with other element using other precursor than acetate, the conversion temperature will be a little bit higher.
i suggest, to have the same properties, without influenced by aging, anneal at temperature higher than 309 oC. But if you annealed with different temeprature, you will also get different properties such as optical properties,..etc.
http://www.sciencedirect.com/science/article/pii/S0169433210002205
hope this paper helps
Hi, Sushil Kumar,
The paper recommended by Sunil Uprety may be helpful to you.
I recommend a paper about SnO2 thin films obtained from sol-gel with different aging time, that affects the electrical conductivity by the reduced grain sizes present in thin films obtained from aged solution.
Hope this helps you.
Article Effects of Solution History on Sol-Gel Processed Tin-Oxide T...
Have you been done post annealing after final deposition process ?
Thanks,
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