mandag 13. desember 2010
Scrap metal solar cell
A quest for new materials that can be suitable for solar cells has been going on over the last 50 years. Some good candidates have been found and even successfully commercialized, but the rarity of elements that are essential for these technologies is eventually expected to be their Achilles heel. In order to make a serious contribution to the transition from fossil fuels to renewables, a solar cell technology has to be based on abundant elements. IFE is now investigating a new class of materials, which could result in a highly efficient solar cells made of scrap metal!
Limitations for thin film photovoltaics
Expensive 3rd generation cells
Metal + hydrogen = metal hydride
onsdag 4. august 2010
Papers and journals
Being a scientist is revolving around these papers, and a scientist is generally evaluated on the basis on the papers she has written. Applying for a future job, she needs to refer to good papers in good journals with a lot of citations. In some countries you will get bonuses and raises as a scientist based on the papers you have written. Good papers and citations will also make it easier for you to establish new research projects and apply for official funding.
As a PhD candidate, the main objective is actually to write these papers. I need to write about 4-6 of them for my PhD degree to be approved. A paper can be anything from three to twenty pages. It sounds easy, but it's a real pain. For writing a paper of three pages I have to spend half a year in the laboratory pulling out my hair and another half in the office reading the thousands of pages other scientists have written before me about similar subjects.
Scientific journals are really not journals any more. I have not seen a journal since I started working on my PhD about a year ago. Well, many people have heard about Science and Nature, that are scientific journals that you might actually find on the shelf in the library. However, most researchers just use the on-line versions, which are databases of papers. If you know the author, the journal and the year a paper was published, you can find it.
But these journals are actually not so easy to get to. People outside universities that try to find a scientific paper, might find it, but would normally have to pay 50 dollars or so for downloading the document. If you are in a university you can download it for free, but the universities pay extremely large amounts of money to have this access. Who gets the money? Certainly not the actual scientists. I will not get any money publishing a paper, and I would actually have to pay for publishing it if I send a paper with color photographs.
And there is also the choice about the journal which you want to publish in. The journals are rated, they have what is called impact factor, which says something about how many people read the papers in this journal. Here is a list of impact factors for journals that are relevant for me:
- Nature: 34.5
- Science: 29.7
- Physical Review Letters: 7.8
- Solar Energy Materials and Solar Cells: 3.9
- Applied Physics Letters: 3.6
- Physical Review B: 3.2
- Europhysics Letters: 2.9
- Journal of Alloys and Compounds: 2.1
- Journal of Applied Physics: 2.1
onsdag 28. april 2010
Life in a cleanroom
tirsdag 30. mars 2010
Financial crisis in photovolatics
tirsdag 9. mars 2010
Spinning electrons
Anyway, what's a synchrotron? Well, it's a big ring where electrons run around at a speed close to the speed of light. They are kept going around in the circle by magnetic fields that are guiding them around. When these electrons are pulled around by the magnetic field, they start emitting very high energetic radiation in the same direction as they are propagating. This radiation is mainly consisting of x-rays, which can be pretty useful for many things. The main thing about x-rays, as you probably know already, is that they go through things that normal light does not go through. They are also smaller (have shorter wavelength) than light, so they can see smaller things. And last but not least, if they propagate through a crystal, the atoms in the crystal can spread the x-rays into a special pattern that gives a lot of information about the crystallic structure. That's what's important to me, and many other researchers. A lot of things are crystalline, and certainly most semiconducturs, which is what we are making solar cells of. But you can discover crystalline structures even in chocolate, as some of the participants in the course have been able to see in their practicals.
Neutrons techniques is the other subject of the course. The neutrons can do similar things as the x-rays. Although neutrons constitute about half of the matter on earth, they are not so easy to get out from the atoms. You actually need a huge thing to kick the neutrons out, as for example a nuclear reactor. The fission of uranium gives neutrons flying out in every direction, which in energy reactors could be considered a problem. However, the neutrons has the property that they penetrate through things that not even x-rays would consider possible, so they can be quite
useful for structural analysis.
Here's a photo of the synchrotron ring and the reactor here in Grenoble, from a photo I took on my mountain hike this Saturday:
fredag 12. februar 2010
Metal hydride switchable windows and mirrors
mandag 18. januar 2010
Bad results make nice photos
onsdag 13. januar 2010
Review: Sony Ebook Reader for research (and little things)
So, when I was in the
The justification I presented for myself, was that this was something I needed for my research. As a researcher, I have hundreds of journal papers to read, and they are all in my computer in PDF format. The ebook reader would make me able to take advantage of the time I spend on the bus going to and from work, and it would make me able to carry an incredible heap of documents where ever I go. Perfect!
And what do I think? The ebook reader has been accompanying me now for almost two months, and I am really very happy about it. It reads the PDF documents very nicely, and the e-paper in combination with the opportunity to take notes directly on the touch-screen make it very much similar the real paper experience.
Getting away from the computer can also be a great pleasure at times. I can have real trouble in concentrating when trying to read something complicated in the computer screen, as I have gotten so used to the restless zapping between documents and endless information search on the internet. Printing the important documents was always necessary when it was something important, but this is no longer the case. I save paper, and my desk does no longer look like a big mess.
But real paper is still there. I still read real books when on the bus, and I still print some documents. The reader is a small device, which can of course be convenient for carrying it around, but for reading comfortably it would have been better having a display of at least twice the size of this one. The contrast of the screen is not extremely good, so it requires quite good light to read well. Another thing that should be commented is that it does react a little slow, especially when reading scanned PDF files and taking notes in them. For scrolling through large documents this is definitely not the solution.
But after all, it because of all the little things I have really started to love my ebook. Just slipping the SD-card into my computer makes it so simple to put documents onto it, and it can be used to carry anything from cooking receipts to bus timetables. The opportunity to take notes is also really handy because I carry it almost anywhere, and I do not have to worry about where I left that damn piece of paper where I put down the reservation number of whatever, you know?
I recommend utilizing an ebook for research and all the other little things. But if you are in doubt, you could always wait one more year for the larger versions to get on the market.