I read some papers about sol-gel method to make the ZnO thin film or seed layers. But I don't know what's the difference between using sol solvent and gel solvent to make the film?
Dear Zhou Qian, this is just to differentiate between the solvent of the precursor and the solvent forming the medium for gel formation. Please take a look at the following documents. My Regards
https://doi.org/10.1016/j.mseb.2010.07.001
https://doi.org/10.1016/j.proche.2016.03.095
https://iopscience.iop.org/article/10.1149/2162-8777/abe095
https://aip.scitation.org/doi/abs/10.1063/5.0001593
https://iopscience.iop.org/article/10.1088/1742-6596/853/1/012041
DOI: 10.5772/67857
Dear Zhou Qian many thanks for asking this interesting technical question. There is normally no need to distinguish between the terms "sol solvent" and "gel solvent". In fact, I never heard about these terms, and normally the solvent or solvent mixture is the same for both steps. The basic principle of any sol-gel process is the hydrolysis of precursor molecules (e.g. metal alkoxides) under formation of reactive species which then condensate to form new materials. In between ther is no need to change the solvents. In this context please see e.g. the respective Wikipedia entry at
https://en.wikipedia.org/wiki/Sol–gel_process
As a typical example of a sol-gel synthesis of ZnO thin films please have a look at the following interesting reference:
Transparent semiconductor zinc oxide thin films depositedon glass substrates by sol–gel process
Article Transparent semiconductor zinc oxide thin films deposited on...
This article has been posted by the authors as public full text on RG, so that you can freely download a pdf file. As you can see, the process involves dissolving a Zn precursor (in this case zinc acetate dihydrate (Zn(CH3COO)2x2H2O) in a mixture of a protic solvent (2-methoxyethanol, ethanol or isopropyl alcohol) and monoethanolamine (MEA) as stabilizer. This forms a homogeneous sol first and then a gel which, after spin-coating and annealing, provides thin films of ZnO. During the entire process the solvent doesn't change, so that it makes no sense to talk about "sol solvent" and "gel solvent".
I hope this helps. Good luck with your research and best wishes, Frank Edelmann
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