Metal-Plasmas Enhance Light Absorption In Si-Film Solar Cell

Traditional solar cells are faced with two problems, one is to reduce the cost andthe other is how to improve the photoelectric conversion efficiency of solar cells.Currently the material of commercialized solar cells are silicon, and the market share ofsilicon solar cell is about80%, they have been widely used in our daily life. In order toreduce the cost of solar cells, many research works have been done in Si-film solar cells.The thickness of traditional silicon solar cells is about180-300um, but Si-film solarcells are only about several micrometers, so a lot of Si materials are saved which canreduce the cost of solar cells. But reducing the thickness of Si will decrease thephotoelectric conversion efficiency of solar cells. In order to improve photoelectricconversion efficiency of solar cells. Researches show that it can effectively improve thelight absorption in Si-film solar cells by using localized plasma resonance and lightscattering of nano metal particles. In this article, the research contents and results can besummarized as follows:1. In order to study the effect of mental nano particles enhance Si-film solar cells, inthe article the extinction characteristics of three shapes of Ag nano particles areresearched with finite-difference time-domain method at first, the results show that thesize and shapes of nano particles have important influences on Si substrate lightabsorption. And we can see a red-shift absorption spectrum of Si by increasing theparticles size and this can increase the absorption of infrared light.2. Refer to the results of Ag nano particles influence the absorption spectrum of Sisubstrate, then a structure of Si-film solar cells with Ag nano particles on both Si filmtop and bottom surfaces is designed. The calculated results show that both sphere radiusand the length of square can influence the absorption of Si-film solar cells, by optimizingthe structural parameters of the solar cells, we can get80%light absorption enhancementcompared with single Si film.3. By using the antireflection and diffraction characteristics of two dimension nanograting, a second structure of Si-film solar cells with grating on the top and Ag squareparticles on the bottom is designed. Theoretical analysis show that the two-dimensionalsurface grooves cycle structure can effectively reduce the reflection coefficient on thesurface of the light, especially through adjusting the radius of the semicircular grooves,it can change the surface reflection coefficient, and the angle of incident light polarization light absorption is also discussed, by adjusting the parameters of the thinfilm solar cells, we can get a total integrated absorption of solar spectrum wavelengthrang from300nm to1000nm is on the order of123%greater than single silicon thin film,especially in long wavelength from700to900nm, we can see evidently light absorptionenhance.