Your question might make more sense if you culd provide more information regarding

* What do you men by optimal results ?

* What system are you using with PDMS ?

* What you want to analyze ?

Nevertheless, for any study conducted with PDMS chips, the chips were pre-calibrated and tested for performance and optimized for a particular system. Since, there is of course differences in different research and PDMS usage, the thickness could differ.

sorry for the improper description. let me explain once more.

I have prepared plain and textured PDMS films by soft lithography. my aim is to measure its reflectance( by UV/Vis spectrometer) and notice the change in reflectance after texturing. This textured PDMS films further can be use for Solar cell application. Here the question is how much thick PDMS films should i need to prepare? because by changing the thickness i examined a change in reflectance.

Dear Arti,

I hope, i understood your question correctly.

Based on your description, I would suggest, that layer thickness is also one parameter in your parameter space, besides the structuring. In other words, it seems that one should investigate the dependence of structure AND thickness. While the investigation of both structure and thickness may be a much bigger effort, why don't you just fix the layer thickness to a value which is reasonable for your application and keep that constant throughout all your structuring experiments. Based on your application on photovoltaic cells, I would think, that you want the reflectance to be as low as possible?

Best regards and good luck for your research.

Dear Lukas piral ,

Yes i want reflectance as low as possible and

Thankyou so much for your answer. The samething I am also thinking to do. Hopefully it will work .

-Just a further idea- Maybe you could also choose the thickness in a way, that its influence on the overall result concerning reflectivity is as low as possible (limited by stability?). Then the influence of your structures could be judged with better statistical significance as there is less "background" from the thickness effect.

Dear Lukas Pirl,

Thankyou so much , definately you give me valuable suggetion and a confidance to start in this way . Will surely try .

Arti Gupta & Lukas Pirl

I not in this field, but as a general understanding, I would say first different thickness of PDMS must be tested to find an optimal value which suits your application. If I know a bit of physics, I would say the thickness of any layer over photocells is inversly proportional to the intensity photons is colliding to the cell surface. Increasing thickness might reduce the efficiency of cells. On the other hand, reduction in reflective index will increase the photoelectic effect. Thus, the model for such research should be plotting the hyperbolic curves of both variables and find a threshold or Maxwell point.

Correct me if I am wrong.

Dear Arti Gupta,

Thickness vary with the type of cell you are using. for example for thick crystalline silicon cell, thickness will be different than thin film cells or tandem solar cells. But this could be an interesting parameter in your experimentation. Try to find optimum thickness related to your solar cell.