Dependence of P3HT powder (morphology, manufacturer) on performance of inverted solar cell.
I mean the same P3HT powder is well suitable for normal geometry solar cell, however inverted solar cell fails to show any performance. Another P3HT powder works well for inverted solar cell. We don't discuss SC fabricating mistakes etc.
Does anyone has similar experience? Phenomena.
What do you think about it?
Hi,
can you please specify what you mean with "powder"? Are there any differences in molecular weight, regioregularity, purity etc.? Are the processing conditions exactly the same, espacially the solvent and the annealing conditions?
Dear Amir
In my opinion the problems you are facing with the reverse structures are not due to P3HT. If you use a P3HT with high regioregularity and dissolve it in an appropriate solvent (such as chlorobenzene or chloroform) then it should work fine irrespective of the device architecture. Are you sure that the substrate in the reverse structure is ok (are you using ZnO, TiO2 or what? with sol-gel derived ZnO for instance is very difficult to find the process for best device operation) I think you are facing problems with your interfaces (the other layers in your devices) and not with your P3HT.
Dear Dr. Vasilopoulou!
Thank you for your answer.
I used various P3HT powders. It was found that only fine P3HT powder showed good result. That means there is no influence of fabrication method.
I have no information about its regioregularity. Also I used organic and inorganic HTL and ETL.
IV curve has normal shape. However Isc and Voc are low for inverted geometry.
Dear Amir
The problem is with your P3HT then. You need to use a regioregular not a regiorandom material. Check the following link for the commercially available P3HT we use
https://www.sigmaaldrich.com/catalog/product/aldrich/445703?lang=en®ion=GR
Regards
Maria
Another possibility could be that your different types of P3HT provide different vertical composition gradients in the mixture with PCBM. For example, it has been shown that, under certain conditions, the P3HT:PCBM bulk heterojunction layers can exhibit a nearly pure PCBM phase on top, which would be beneficial for the standard devices but a clear drawback in the inverted configuration with the hole-collecting top electrode.
Dear Sebastian!
Thanks for your interesting answer. I also have similar idea
How do you think it depends to P3HT type? Is there any experience?
Dear Amir,
we have also compared different P3HT types from different commercial suppliers in our labs and found that the optical and electrical behavior of the resulting P3HT:PCBM devices are clearly dependent on the P3HT properties. Concerning the vertical composition profiles, we performed no direct investigations on that, but I guess that the solvent and the kind of annealing procedure play a crucial role. Those gradients within the bulk heterokjunction films can develop due to differences in the solubility between the P3HT and PCBM component, as well as diffusive processes of one of the material phases during the anneling procedure. Both of them should be affected by the P3HT properties, such as the molecular weight.
Vertical composition gradiends within P3HT:PCBM films have intensively been studied by van Bavel et al.:
http://onlinelibrary.wiley.com/doi/10.1002/adfm.200902247/abstract
http://pubs.acs.org/doi/abs/10.1021/ma900817t
http://pubs.acs.org/doi/abs/10.1021/nl8014022
Dear Seabstian!
Thanks for information. Let's check it. I will let you know the results.
Best regards
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