I covered the photocurrent already before, for instance here. I pointed out that from the light intensity dependence of the short circuit current, it is impossible for many typical conditions to unambiguously determine the dominant loss mechanism or even the recombination order (1st (often called monomolecular, but not my favourite term;-) or 2nd order of decay).
If, however, you know (or guess) that the recombination order is two, you can use the above mentioned vs. data to determine which fraction of charges is lost to bimolecular recombination, . This was shown recently by [Koster 2011]. For , they found . Although I was not able to follow the exact derivation ([Update 5.4.2011] it can be derived by solving a simple differential equation, ), it seems to work. Easy method, although make sure not to have too much space charge in your device – even at the contacts, induced by low (ohmic) injection barriers (we compared it to our device simulation, and then you get significant deviations)! In my opinion, the latter point is not stressed enough in the paper, despite the nice approach. Continue reading “Photocurrent again”
Kid is growing, lack of sleep makes euphoric, but less time is less time;-)
The 2010 impact factors were just released by Thomson Reuters, as most of you will know due to the mails sent by almost all publishers to tell about recent boosts of impact for their journals. A sober post was written by Jörg Heber, editor of Nature materials. A brief quote
So what use is the impact factor number? Well, being cynical one could say it is a quick measure for those that don’t read the journals but still want to know how good they are on average. The danger is of course that this is then used as a kind of metric to assess the quality of research or to decide on the career of researchers.
Continue reading “This and that”
Children change the life, how very true. Not that I am less interested in Science in general, I do enjoy it! Nevertheless, somehow work seems less important these days – which maybe I should not admit openly ;-)
I received this statement,
Blue suits the lecturer better than pink
as one of the results of the lecture evaluation (Atom Physics for “Teachers to be”). Yes, I also received some other comments, most positive, some negative, all useful (including that one?;-)
Just to say that I am still amongst the living, here some bits and pieces I found during the last weeks, when time allowed. Continue reading “Blue suits him better than pink”
On the 1st of March, our daughter Chiara Marie was born: we are so happy and overjoyed:-) As you can imagine, there is little time (and there is lack of sleep;-). So please bear with me if there are no posts and replies to questions forthcoming in the next few weeks. All the best, Carsten
I just changed the comment settings: up to now, a WordPress account was needed in order to be able to comment on my posts. Believe me or not, I did not even know about this setting till today. Now, you only have to give your (or some;-) name and an email address (yours? I do not know). Maybe this lowers the barrier for some of you to ask questions or provide further insights and critical views.
Tomorrow is abstract deadline for the SPIE Optics and Photonics 2011, including the session Organic Photovoltaics XII. See you there:-)
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EU proposal submitted today, acceptance rate last year was 7%… so something for relaxing is required;-) As everybody relaxes differently, you have the choice of looking at the photograph or watching the video Bad project (disclaimer: a parody – thanks to Thiemo for the link).
For unrelated reading, but following up some other notes on publishing and peer review (see overview of posts here), an insightful post by Cameron Neylon: What is it with researchers and peer review? or; Why misquoting Churchill does not an argument make. If you are researcher, peer review is (and will remain) important. Therefore, staying up to date is not only interesting (e.g., you get to see the real Churchill quote;) but also useful to see its pros and cons more clearly. Interesting may be this Nature Materials editorial on Transparency in peer review (free with registration). Out of curiosity I just checked: I reviewed 21 papers in 2010, so a couple more than I (or a coauthor) actually submitted, but a lot less than I was asked to review…
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A happy and successful new year to you! It is almost three years since I started this blog, this being the 69th post. A lot happened in this time, also for me: both personally (as some of the long term readers now;-) and professionally (despite still being in Würzburg;-). So, let me thank you, valued reader – and comments contributor, an active participation which I highly appreciate!
Many things I want to write about I have not had time to handle in the recent months. For now, let me start with just briefly revisiting what I have written. Hints of what I will add in the coming weeks and months are to come soon (soon meaning: worst case mid February, as one proposal is submitted by then, lecture is finished and project meeting / seminar talk marathon “finished”;-).
Find the overview below. Continue reading “2011”
A few weeks ago, Heliatek managed to take the lead for organic solar cell efficiencies, achieving 8.3% confirmed power conversion efficiency on 1.1cm2 active area with vacuum deposited small molecules. The device was a tandem. Thomas Körner, VP of Sales, marketing and Business Development at Heliatek, added
The first products should be coming onto the market at the start of 2012.
Second, you may remember my post on photocurrent in organic solar cells back in July. It was inspired by a comment I wrote on a paper by Street et al, who proposed monomolecular recombination to dominate the loss of free charges in organic bulk heterojunction solar cells. My comment and Bob Street’s reply to it are now online at Phys Rev B. I’ll not comment this interesting exchange any further (unless requested by you;-), so read and think for yourself!
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Today, I saw the article Publish like a pro by Kendall Powell in Nature. Some tips on how to write:
- You are only as good as your last paper – previous success does not guarantee future acceptance.
- You’ve got to hook the editor with the abstract.
- Don’t delete those files. Keep every version. You never know what aspect you can use for some other piece of writing.
- Writing is an amazingly long learning curve. many authors say that they’re still getting better as a writer after several decades.
- The most significant work is improved by subtraction. Keeping the clutter away allows a central message to be communicated with a broader impact.
- Write every day if possible.
- once you’ve written what you wanted to convey, end it there.
These go hand in hand with this earlier post, although Kendall’s article does not stop there. Therefore, read it!
Personally, what I need for writing is a quiet, non-distracting environment with the internet switched off.
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Via Scott Berkun, a nice 2007 article by Louis Menand in the New Yorker:
Sherlock Holmes never said “Elementary, my dear Watson.” Neither Ingrid Bergman nor anyone else in “Casablanca” says “Play it again, Sam”; Leo Durocher did not say “Nice guys finish last”; Vince Lombardi did say “Winning isn’t everything, it’s the only thing” quite often, but he got the line from someone else. Patrick Henry almost certainly did not say “Give me liberty, or give me death!”; William Tecumseh Sherman never wrote the words “War is hell”; and there is no evidence that Horace Greeley said “Go west, young man.” Marie Antoinette did not say “Let them eat cake”; Hermann Göring did not say “When I hear the word ‘culture,’ I reach for my gun”; and Muhammad Ali did not say “No Vietcong ever called me nigger.”
In order to have one that was said – Daniel Patrick Moynihan:
Everyone is entitled to his own opinion, but not his own facts.
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