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Avalanche Effect Demonstrated In Solar Cells 234

esocid writes "Researchers at TU Delft (Netherlands) and the FOM (Foundation for Fundamental Research on Matter) have found irrefutable proof that the so-called avalanche effect by electrons occurs in specific semiconducting crystals of nanometer dimensions. This physical effect could pave the way for cheap, high-output solar cells. Solar cells currently have relatively low output, typically 15%, and high manufacturing costs. One possible improvement could derive from a new type of solar cell made of semiconducting nanocrystals and could theoretically lead to a maximum output of 44%, with the added benefit of reducing manufacturing costs. In conventional solar cells, one photon can release precisely one electron. However, in some semiconducting nanocrystals, one photon can release two or three electrons, hence the term 'avalanche effect.' This effect was first measured by researchers at the Los Alamos National Laboratories in 2004, and since then the scientific world had raised doubts about the value of these measurements. This current research does in fact demonstrate that the avalanche effect can occur."

Scientists Build New Type of Photon Gun 90

KentuckyFC writes "Single photons are surprisingly difficult to generate. But since they are crucial for quantum communication, a number of research groups are working on photon guns that fire single photons on demand. The problem they have come up against is that making the photons identical is proving harder than expected. Now a group in Cambridge, UK, has cracked the problem using a quantum dot on a transistor to emit single photons that are essentially identical. In the process, the group has developed an entirely new technique to trigger photon emission (abstract on the physics arxiv)."

"The most important thing in a man is not what he knows, but what he is." -- Narciso Yepes