Towards more efficient solar cells A layer of silicon nanocrystals and erbium ions may help solar cells to extract more energy from the ultraviolet (UV, high-energy) part of the solar spectrum. Experimental physicists from the FOM Foundation, the STW Technology Foundation and the University of Amsterdam published this news in Nature Communications on 13th August 2014. When conventional silicon-based solar cells absorb UV light, much of its energy is lost in the form of heat. The researchers showed that this excess energy can be used to excite multiple erbium ions. This causes the ions to emit light, which can then be converted into electricity. Conventional solar cells can only convert a small part of the solar spectrum into electricity efficiently. Low-energy light particles (photons) are not absorbed, as they do not have enough energy to bridge the band gap of the material from which solar cells are made. By contrast, high-energy photons can be absorbed, but in just a few picoseconds (10-12 seconds) much of their energy is transformed into heat. This limits maximum efficiency to just 30 percent.
Posted on: Wed, 13 Aug 2014 20:23:36 +0000
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