I want to prepare ATO transparent, conductive films using doctor blade method on transparent conductive substrates. For this porpose I use an aqueous ATO colloidal solution containing 15-30% (wt) nanoparticles in which I dezolved poly-ethylene-glycol (PEG) with MW in the range 12000-20000k g/mol to increase the viscosity. The resulted film I treated at 450° for 1 hour. The coresponding films are transparent but develops cracks when the PEG polymer is burned off.
What may preduce cracking of the film and how can be avoid? Thank you to all of those that would like to contribute on this topic.
Hi Marius, I suggest making a terpineol-paste (optionally adding ethyl-cellulose for further viscosity and film-stability during annealing) instead. I have done this with ITO, ZnO and ATO nanoparticles successfully for crack-free films up to 10um thickness. I documented the procedure in detail on my open hardware platform: http://docubricks.com/viewer.jsp?id=22282785798926336. I hope this helps!
Hi Tobias, Thanks for your answer. I tried the method you propose and the film was crack-free but not fully transparent. What is the source of your ATO nanoparticles?
I am pretty sure I used the nano-powder from sigma http://www.sigmaaldrich.com/catalog/product/aldrich/549541?lang=en®ion=GB. As I am sure you are already aware, ATO is a lot more absorbing than other metal oxides and the additional amount of scattering depend on the particle size. Those (and the lack of knowledge on biocompatibility) were the reasons why I stopped working with it. I never characterised the ATO films optically, to see how much light is transmitted.
I used so far aqueous ATO coloidal solutions containing 15%(wt) nanoparticles. Therefore I was limited to work with PEG-based aqueous paste.
I tried also to use a comercially nanopowder (http://www.hwnanomaterial.com/Antimony-Tin-Oxide-ATO-Nanopowder-Nanoparticles_p670.html) but I didnt find a way to dispers it in any solvent. Do you may have experience in how to despers properly the nanopowders?
Hi Marius, the powder seemed to easily disperse in IPA and Ethanol when vortexing and sonicating in an ultrasound bath. After adding the Terpineol, these voluntarily solvents evaporated in the rotary evaporator. As far as I know, some groups use a very powerful sonication "horn" to create good dispersions, but I have not tried that. I mainly work with ITO nanoparticles that already come suspended in IPA.
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