I am trying to repeat the fabrication of BiVO4 (BVO) using the metal-organic deposition method. This is a well-reported way to make BVO thin film on FTO.
So basically, I just dissolve Bi(NO3)3 and Vanadium(III) acetylacetonate in acetylacetone and stir overnight to get a transparent precursor solution for spin coating.
However, the precursor solution has rather low viscosity, and during my coating process, most of the liquid was splashed on the surface of my spin coater. As a result, I can only get a very thin and non-uniform BVO film.
So, does anyone know how can I improve film quality? Thank you very much.
Dear Mengnan Zhu,
To make a film from such solutions, you had better to use different film-forming techniques such as spray-coating, bar-coating or slot-die coating to have uniform films with desirable thickness.
Spin-coating such solutions is very difficult to make variable thickness films and also consumes a large quantity of solutions.
You could buy a simple spray gun or drawdown bar-coating very economically to make your own film-coating tools.
Hope it helps.
In the spin coating method, a better coating can be performed when a solution having a low viscosity is used. It is also an optimal solution processing method for obtaining reproducible thin films on a laboratory scale.
However, the disadvantage of spin coating is that most of the solution is lost due to the centrifugal force from the center. If you spin-coated a 100 uL solution over an FTO substrate, the actual remaining amount would have been lost by almost 80% or more. However, the remaining solution determines the thickness and quality of the thin film you want.
First, you need to figure out the quality and properties of the film you want. I know that the BVO solution you use is a material used as a photocatalyst semiconductor.
If so, a certain thickness of the film is required, so the coating must be repeated to the desired thickness. I think that the use of the syringe filter of the solution is very important to remove the unknown cluster particles which making the low-quality films. In addition, after the coating, it is necessary to repeat the intermediate mild and light heat treatment or the high-temperature annealing process.
Although it takes a long time, it is inevitable if it is important to get a good quality film.
I hope it helps.
Won-June Lee Hello Won-June, thanks for your reply. The light heat treatment you mentioned is an interesting one. I'll try it and see how it goes.
Mengnan Zhu The light heat treatment called different words such as 'soft baking or soft annealing or mild heating, etc.' You can search many research articles of the sol-gel film deposition with those key words above.
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