Author: deibel

2011

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;-). Golden Pavilion (Kinkaku-ji) 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”

Two notes

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. Madeira Rainbow in AutumnThe 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.

Good!

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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Publish like a pro

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.Walking to Schloss Burg
  • 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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“Notable Quotables”

Via Scott Berkun, a nice 2007 article by Louis Menand in the New Yorker:

Sherlock Holmes never said “Elementary, my dear Watson.” Sea LionNeither 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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Hot CT complexes and Geminate Recombination

Lately, the notion that geminate recombination in organic solar cells is a major loss mechanism is more and more under fire. Foothill MountainsStreet et al present an “experimental test” for geminate recombination [Street 2010a]. They investigate P3HT:PC60BM nor PCDTBT:PC70BM bulkheterojunction solar cells with a transient current technique at 200K and 300K between -1 and 1V external voltage bias. The authors conclude that neither exhibit significant geminate recombination, while pointing out that

Since the relative importance of geminate or nongeminate recombination depends on the specific materials comprising the cell and possibly on the method of preparation, other cells may or may not have a larger geminate recombination contribution.

Continue reading “Hot CT complexes and Geminate Recombination”

Metrics – yet another one

Hungry butterflyJust came across a posting on Academic Productivity: the Reader Meter can create an analogue to the h-index (or Hirsch index). Instead of measuring how many papers of a certain researcher are cited how often, it determines – based on data of the academic reference management software Mendeley – how many papers have been bookmarked by Mendeley users. Certainly, the software is an alpha version, and the original h-index is a more important measure as citations carry more impact than bookmarks. Nevertheless, the additional information is quite interesting, either general or on a per-paper basis concerning readership and nationality (the journal entry for my review is not correct, however, but the DOI is;-) Find “my” Reader Meter entry here;-)

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Efficiencies and other notes

I mentioned the record bulkheterojunction solar cell from Solarmer recently:On top of the others 8.13%, although on a small area of 0.1cm2. The evporated small molecule solar cells had almost 6% on a ~10 times larger area. On the SPIE Optics&Photonics conference in August in San Diego I heard inofficially that Heliatek achieved more than 6%, but now on foil. Even better: more than 7% (active area efficiency; about one percent-point less for the complete area) on a module with more than 70cm2! This one is not flexible, I believe. Amazing if you consider that the evaporation is by point sources. If these modules are encapsulated, they are said to have an extrapolated lifetime exceeding 10 years.

Continue reading “Efficiencies and other notes”

Brief Ad: Organic Solar Cell Review Online [Update]

Sunset in UmbriaIf interested, find it here (Reports on Progress in Physics 73, 096401 (2010)). Included: how do bulk heterojunctions and bilayers work, how to improve the performance, how to mass print, and a brief section on the cost. I am happy it is finally “on air”:) Free from IOP for the first 30 days, if you register. Otherwise, choose the arXiv version or drop me a line. As I am on vacation, expect some delay…

[Update 30.8.2010 ] Back from vacation for already a week: was very relaxing:) In order to avoid another “ad post”, I just extend this one a bit: the progress report on charge transfer complexes (submitted to Advanced Materials already in February) is now published online. You will not find this one on arXiv, so if you cannot access it, ask me to send you the preprint. As always, I am interested in your opinion and/or criticism!

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Several people speaking

Adding to my selection of sayings (previously here, here and here;-) Not always very deep, but mostly quite nice.

Stanford University
Jack London:

You can’t wait for inspiration. You have to go after it with a club.

William Gibson:

The future is here. It’s just not evenly distributed.

Niels Bohr:

I try never to write more clearly than I am able to think.

John von Neumann:

There is no sense in being precise when you don’t even know what you are talking about.

Henry Ford:

If I’d listened to customers, I’d have given them a faster horse.

Peter Drucker:

What everybody knows is frequently wrong.

Do not believe that it is very much of an advance to do the unnecessary three times as fast.

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New Record for Organic Solar Cells and other stuff

Solarmer did it again: 8.13% power conversion efficiency, certified by NREL, were anounced at the currently running SPIE Optics and Photonics conference in San Diego.

I am also here, my talk will be on wednesday afternoon – but do not expect any breakthroughs in terms of performance from me:-) Maybe there will be more news here in the days to come.

Foothill Mountains - Russian RidgeIn June and July, I was visiting scientist in the group of Mike McGehee at Stanford University for five very interesting weeks. Thanks again for hosting me, and for the interesting discussions we had! I also had a brief visit to PARC, the Palo Alto Research Center, for an interesting discussion with Robert Street about the photocurrent in organic solar cells. We finally agreed to disagree on some issues, but from my point of view, that’s absolutely fine.

During my Stanford visit, there was fortunately time enough for hiking in the Foothill Mountains as well! Highly recommended. Thanks to Andreas and Verena as well as Matthias for getting me started.

Continue reading “New Record for Organic Solar Cells and other stuff”