Possible options are additions of CDCA-coadsorbate, and co-sensitization. I have tried both options, CDCA do not help a lot by increasing to 100x compared to amount of dye. Co-sensitization improved the device from 5 to 7.5% efficient, however according to current dynamics study i still see aggregation related losses. Any suggestions related to that will be greatly appreciated...
when you work with concentrated dye solutions, they may be hard to desolve, I usually use an ultrasound bath for a minute or two to disrupt pi-pi-interactions between the conjugated systems of the dyes, maybe that will already do the trick
Christoph, it works very well what you are sharing in solution, however i am talking about kind of aggregation while anchored to TiO2 which generally result in charge transfer losses causing inefficient solar cells.
I am not sure what solvents you are using, but MeOH or EtOH/toluene are good ones. Another way is to treat dye-coated films in CDCA solution for sometime. It worked for some our porphyrin dyes.
Prof. He, thanks for the feedback. I am using EtOH:THF (80:20) kind of classic for organic dyes. Just downloaded your porphyrin work, it seems very interesting.
Some results have been published.
Bis(9,9-dihexyl-9H-fluorene-7-yl)amine (BDFA) as a new donor for porphyrin-sensitized solar cells
Article in Organic Electronics 15(10):2448–2460 · September 2014
Impact Factor: 3.83 · DOI: 10.1016/j.orgel.2014.07.006.
The PDF file is available under my ResearchGate profile. We found THF was actually no good for porphyrin-sensitized solar cell at all,but I am not sure if it is also true for other organic dyes.
I did not see you when I visited the UM last time.
Thanks for sharing the resource i will look up.
When did you last time visited UM? I joined Dr. Jared Delcamp group in January 2016. Now we have fully equipped lab and routinely making high efficiency devices, with the capability to do Transient photovoltage, charge extraction and election lifetime along with IPCE and IV measurements.
One of efficient way to reduce the dye aggregation is the use of nano/meso porous substrates. We demonstrated this effect with Rhodamiine family dye and nanoporous alumina ( APL , 2002). I don't know how porous your TiO2, but if you find the method to increase its porosity it could help
Igor what you mentioned, can be very useful. We are testing it now. Let you know once i have new data....
Prof. He, you mentioned about treating dye adsorbed films with CDCA in your earlier comments. However, in the referee you shared, only the addition of CDCA to dye solution was mentioned? is that what you meant? or there is different dye adsorbed film post treatment procedure for CDCA?
This is the paper I was talking about. Check it out.
Li, W.; Liu, Z.; Xu, X.; Cheng, Y.-B.; Zhao, Z.; He, H., Near-Infrared Absorbing Porphyrin Dyes with Perpendicularly Extended [Small Pi]-Conjugation for Dye-Sensitized Solar Cells. RSC Advances 2014, 4, 50897-50905.
http://pubs.rsc.org/en/Content/ArticleLanding/2014/RA/c4ra08338e#!divAbstract
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