Laser technology can greatly improve solar cell conversion efficiency

Researchers at the University of California, Davis, have confirmed through computer simulations that the use of a special 'silicon BC8' structure can generate multiple electron-hole pairs based on a single photon, greatly improving the conversion efficiency of solar cells. The research report was published in the latest issue of Physical Review Letters. Solar cells are based on the photoelectric effect. When a photon or particle of light hits a single silicon crystal, it generates a negatively charged electron and a positively charged hole. Collecting these electron-hole pairs can generate current. As co-author of the paper, Julia Gary, of the school's chemistry department, said that conventional solar cells generate an electron-hole pair based on each photon, so their theoretical maximum conversion efficiency is about 33 percent. The new approach is able to generate multiple electron-hole pairs based on a single photon, thereby actually increasing the efficiency of solar cells. Using a supercomputer at Lawrence Berkeley National Laboratory, the researchers simulated the behavior of silicon BC8, a silicon structure that is formed under high pressure but is stable under normal pressure. The simulations showed that the silicon BC8 nanoparticle did indeed generate multiple electron-hole pairs based on a single photon, even when it was exposed to visible light. The study's lead author, postdoctoral researcher Stephen Weberman, said that this approach can increase the maximum conversion efficiency of solar cells to 42%, surpassing any existing solar cells, which is of great significance. 'In fact, if parabolic mirrors are used to concentrate sunlight for a new type of solar cell, we have reason to believe that the conversion efficiency could be as high as 70%,' he added. It is a pity that, by combining with traditional silicon nanoparticles, the current solar cell model can only work under the irradiation of ultraviolet light, and can not work normally under the irradiation of visible light. Scientists from Harvard University and MIT have previously published papers pointing out that when ordinary silicon solar cells are irradiated with laser light, the energy emitted by the laser may create a local high voltage to form silicon BC8 nanocrystals. Therefore, it is possible to convert existing solar cells into high-efficiency new solar cells by applying laser light or chemical pressure. Solar cells are perhaps the cleanest and most convenient source of energy. But there is one thing that the current solar panels are not completely satisfactory: the photoelectric conversion efficiency. In recent years, many new materials have been developed internationally, which can improve the efficiency of solar cells, and the highest can reach 20%. This time, the new microstructure invented by American scientists has doubled the upper limit of the efficiency of semiconductors. Of course, this is the result of computer simulation, and it is too early for large-scale application. From experience, the difficulty of producing new photovoltaic cells with low energy consumption cannot be underestimated.