Actually I quoted many times Graphene Oxide, ZnO, P3HT on FTO but i couldnt get the uniform layer. The layer on FTO substrate looks very dilute. How can I solve this problem. Any expert suggestion ?
GO is prepared in DI water, while P3HT and ZnO were prepared in methanol.
In case of spin coating the parameters which mainly control the growth is rotation speed and time. The film thikness as well as uniformity depends on it. Make sure after every complete rotation keep a hot plate on to heat the fim by some temperature(85~100 0 c). And basicaly there is no such rule or fixed mathod to get an uniform film. You have to go through trial error method to optimize the film.
Dear Rai
I think you must Knew the structure of FTO substrate and your materials which you want deposited on this substrate (calculating mismatch between them), because this is very important parameter. you can use glass or ITO substrates and compare between them. With best regards
Dear Rai,
For the spin coating of any material, The following conditions should be consider while coating,
1. Viscosity of the gel, if the gel is highly viscous means there be a problem of spreading throughout the substrate.
2. Instead of using DI water u can try the Methanol, Ethanol, Ethylene Glycol for the solvents
3. Generally Binder for gel is mostly used DEA, MEA
4. Film coating rpm u should optimize for better coating, in the case of thin film I suggest 3000-4000 rpm for 30seconds
Dear @ R. Murugan
Actually ZnO and P3HT are in absolute methanol while GO is in DI water. AS per your recomendation i will change the solvent system of GO. My samples are not viscous. Some body suggest me to add Poly vinyl alcohol as a binder material. What do you suggest ?. How much binder we will add in the solution before coating? Does binder shows any chemical interaction with ZnO and P3HT? or it will be chemically inert?
Dear Rai,
Suppose for example, U make ZnO thin films with five repeated coating. After each coating the film was heated for 10 mint for solvent evaporation, the solvent evaporation temperature we fixed generally, above boiling point of solvent as well as binder, in the case of DEA used samples we fix 300C for solvent evaporation, and after five coating we further annealed at 500C, here there is no way to chemically react the binder into the main material. In ur case, boiling point of PVA also 228C, so u can fix the solvent evaporation temperature to 280 or 300C. at the time of heating binder was not present in ur sample.
Thank u.
@Rai Nauman Ali, please tell me how should I spin coat graphene powder over fto? What solvent should I use??
@Rai Nauman Ali @Priyanka Roy Prepare a dilute graphene oxide dispersion (about 0.1 mg/ml) in deionized water and then drop cast the dispersion on the FTO surface and let it dry at room temperature. Afterward, put it in the oven and heat it at 200-300 degrees celcius. In this way, a very thin layer of thermally reduced GO rigorously adheres to the surface on which you can properly spin coat other materials e.g. GO.
Best
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