科学家证实太阳能电池存在“雪崩”效应

根据Physorg报道,来自荷兰的多位科学家日前找到了确凿证据,明用于太阳能制造的半导体晶体中存在“雪崩效应”,将有望为打造高效廉价的太阳能电池带来更多希望。 传统太阳能电池中,每光子只能释放一个电子,这些电子保证电池可以正常工作。释放的电子越多,太阳能电池的效率也越高。然而,在2004年美国Los Alamos国家实验室的研究人员在一些半导体纳米晶体材料中发现,一个光子可以释放出2到3个电子,也即“雪崩效应”。 在这种情况下,太阳能电池理论最大效率可以达到44%。不过之后许多研究人员一直对当时测量的准确度持怀疑态度。 在最新的研究中,荷兰Delft理工大学Laurens Siebbeles教授和同事利用超快激光进行了细致认真的测量,证实在硒化铅纳米晶体中尽管不如之前测量结果那么大但是确实存在雪崩效应,Siebbeles教授相信,进一步的研究将会揭示其中的奥秘。 http://www.physorg.com/news131027836.html 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, very small semiconducting crystals. This physical effect could pave the way for cheap, high-output solar cells. The findings are to be published in scientific journal Nano Letters this week. Solar cells provide great opportunities for future large-scale electricity generation. However, there are currently significant limitations, such as the relatively low output of most solar cells (typically fifteen percent) and high manufacturing costs. One possible improvement could derive from a new type of solar cell made of semiconducting nanocrystals (crystals with dimensions in the nanometre size range). In conventional solar cells, one photon (light particle) can release precisely one electron. The creation of these free electrons ensures that the solar cell works and can provide power. The more electrons released, the higher the output of the solar cell. In some semiconducting nanocrystals, however, one photon can release two or three electrons, hence the term avalanche effect. This could theoretically lead to a maximum output of 44 percent in a solar cell comprising the correct semiconducting nanocrystals. Moreover, these solar cells can be manufactured relatively cheaply. The avalanche effect was first measured by researchers at the Los Alamos National Laboratories in 2004. Since then, the scientific world has raised doubts about the value of these measurements. Does the avalanche effect really exist or not? Within the Joint Solar Programme TU Delft’s Prof. Laurens Siebbeles has now demonstrated that the avalanche effect does indeed occur in lead selenide (PbSe) nanocrystals. It has been established, however, that the effect in this material is smaller than previously assumed. Siebbeles’ results are more reliable than those of other scientists thanks to more careful and more detailed measurement using ultra-fast laser methods. Siebbeles believes that this research paves the way for further unravelling the secrets of the avalanche effect. The paper can be found here (requires subscription). Source: TU Delft