Comments on: How Do Organic Solar Cells Function? – Part Two

By: deibel

deibel — Fri, 30 Dec 2011 09:58:03 +0000

Hi Richard, you need to make the product of I and V at the same voltage (or did I misunderstand you? Your example was -Vmpp for the voltage and at 0V (sc) for the current). Thus, if you have an I(V) vs V curve and plot P=I(V)xV vs V, you get only one maximum (actually minimum, a power you can “extract”): at the maximum power point, which is always in the fourth quadrant. Best, Carsten

By: Richard

Richard — Fri, 30 Dec 2011 09:43:43 +0000

Hi Carsten
I’m not sure if this is a stupid question. The maximum power output of a solar cell is always given as the point where the product P=I_mpp V_mpp is maximum in the fouth quadrant. But of course there are also positions in the third quadrant when this product is greater (e.g. at V=-V_mpp,I=-I_sc). What are therefore the secondary (aside from maximizing P) considerations that go into choosing the operating bias for solar cells.
Thanks!
Richard

By: deibel

deibel — Thu, 24 Nov 2011 12:50:25 +0000

You are welcome to use them, Linda. Cheers, Carsten

By: Linda

Linda — Thu, 24 Nov 2011 11:23:06 +0000

Carsten,i beneift a lot form your bolg,thank you very much!I like those pictures in this topic,i want to know if i can use them in my presentation?of course i’ll indicate the copyright. Linda

By: deibel

deibel — Sat, 03 Jul 2010 03:01:40 +0000

Quite so, but less for proving the efficiency as for seeing how a bilayer behaves. The results or Alex are really striking, and–including the supporting information with SEM cross sections–pretty convincing. Still, I discussed with him quite a bit, because I have not stopped wondering why it works so well!

By: ineverwantedtobeascientistiwantedtobealumberjack

ineverwantedtobeascientistiwantedtobealumberjack — Tue, 22 Jun 2010 10:31:44 +0000

I read the Ayzner 2009 paper and thought it was really good. Would have liked to have seen some EQE spectra though

By: deibel

deibel — Fri, 11 Jun 2010 13:44:59 +0000

My pleasure! Don’t hesitate to come back for discussion, Nigel. Best wishes, in particular for your research on exciton diffusion, Carsten

By: solarstudent

solarstudent — Fri, 11 Jun 2010 13:36:29 +0000

Hi,
Thanks for the references! – from a first look I think they will be very useful. I did a quick literature search on the topic already and surprisingly I did not find some of these papers, thanks for sending me in the right direction.

Your curiosity was very close, although I am not in the Bittner Group, I am an Irish graduate student based in Houston doing some work on organic solar cells.

Thanks again,

Nigel

By: deibel

deibel — Thu, 10 Jun 2010 22:50:21 +0000

Hi! Not much time now, so only references: more maybe another time;-) [Kurrle 2008] Determination of exciton diffusion length on an organic crystal. Better even is to combine this method with an optical model (transfer matrix algorithm or so) [Ineverwantedtobeasciencistiwantedtobealumberjack 2010] 27nm for P3HT, wow, probably only possible for the optimised synthesis routes, because earlier measurements gave much lower values, such as 8nm in [Shaw 2008]. If not for a long exciton diffusion length, however, Alex would not have had success with his solution processed bilayer [Ayzner 2009]. Regards, C P.S. from Bittner group? only temporarily? Forgive my (potential) indiscretion, just curiosity;)

By: solarstudent

solarstudent — Thu, 10 Jun 2010 18:02:26 +0000

Hi Carsten, I have read much of your blog and find it very interesting – you do a great job at explaining some of the more complex processes in OSCs. I have a quick question for you which may help me an others understand some more about how they work and the important processes involved:

How do you measure the exciton diffusion length and what is theoretical basis for such a measurement?