As in DSSCs porous structure of photo-anode is one of the major factor for performance. How much is the porosity of TiO2 photo-anode? and What will happen to porosity if we make CeO2 photo-anode?
Dear Suhail and friends, porosity of your TiO2 and other film can be evaluated by measuring index refraction in region of their spectral transparancy under comparing to solid mather film of the same material. Addres of my paper with similar measurement of porous glasses I have provided here:https://www.researchgate.net/publication/275039018_Refractive_index_of_nanoscale_thickness_films_measured_by_Brewster_refractometry. defenitely instead Brewster refractometry Yiy can retern to ellypsometry and other method if it will fit for your films. Hope it will be usefull for You.
Article Refractive index of nanoscale thickness films measured by Br...
Thank you Eugene sir for adding very much helpful information.
Dear Suhail,
Professor Eugene gave a material parameter which is indicative for the degree of the porosity of a material including titanium oxide for photo anode in DSSCs.
It is so that TiO2 works as a scaffold for the photosensitive die which is very thin organic donor acceptor blend. If the titanium oxide is compact without pores the quantity of the absorbed light will be small. Making bores in the TiO2 would increase the effective thickness of the light absorbing die in the path of the light. In principle one would lie only to stack the die such that its thicness is sufficient to absorb the incident light in the absorption range of the die. On the other side increasing the the the contact area would increase also area of the interface leading to increased recombination of the photogenerated electron hole pairs and thereby a reduction in the photcurrent and increase in the dark current. Consequently there is optimum pore pattern to achieve the highest possible conversion efficiency. The other factor affecting the pore size is the deposition of the die inside the pores. This process can take relatively long time when the pores are too small. So, relatively large pores with sufficient interface area between die an the TIO2 are preferred. The pores are characterized microscopically by their pore size statistical distributions and macroscopically by their volume percentage to the total volume of the material.
The last comment is the TiO2 serves as a scaffold for the Die and at the same time as an electron transport layer while it is blocking for the holes.
For more information please refer to the link:http://link.springer.com/article/10.1007/s10008-014-2401-7
wish you success
Thank you very much Respected Professor Abdelhalim Zekry sir for adding very much useful answer regarding porosity of TiO2. The answer gives key points for increasing the efficiency of DSSCs.
Thank you sir
with warm regards
Suhail
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