When an organic small molecule is thermally deposited, the film is very powdery and it peels off from the substrate easily. Any suggestion Why?
Substrate used: ITO glass
Dissolving the small organic molecules into a solution of polymer, after thermal deposition
The molecular weight is small. Two suggestions: improving the molecular weight by incorporating alkyl chain or polar groups which could interact with each other by physical bonds. Another: dissolving the small organic molecules into a solution of polymer, after thermal deposition, the polymer film can act as a matrix and your organic molecules dispersed into the matrix.
Dissolving the small organic molecules into a solution of polymer, after thermal deposition
ITO surfaces are oxide rich and will not interact well with nonpolar organic molecules, so you are probably seeing the opposite of "wetting" the surface with your compound. Of course, I have to guess because you haven't supplied much information. For ITO to interact with nonpolar organic molecules, ITO is usually modified, for example with alkyl silyl trichloride derivatives. In the same way, many other surfaces are modified, including silicon dioxide, which is converted from highly polar to highly nonpolar, e.g., in the generation of reverse phase HPLC stationary phases. The length of the alkyl chain affects how nonpolar a molecule can be bound to the surface (the longer the alkyl chain, the more nonpolar a substrate will bind). You might want to look at this review for more about the surface properties of ITO: Article Effect of ITO surface properties on SAM modification: A revi...
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