Published in Proceedings of the SPIE : San Diego, CA, Volume 8111, Issue 811111, August 21, 2011.
Copyright © 2011 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited. This paper is also available at http://dx.doi.org/10.1117/12.892807.
We study solar-cell designs using nano-grating on both top (transmission) and bottom (reflection) of the solar cell. First, we perform simulations based on rigorous coupled wave analysis (RCWA) to evaluate the diffraction top gratins. In RCWA method, we calculate up to 20 harmonics, and sweep the launch angle of incident light from 0 to 90 degree. The incident light varies from100nm to 1200nm wavelength. Triangular grating can achieve higher light absorption compared to the rectangular grating. The best top grating is around 200nm grating period, 100nm grating height, and 50% filling factor, which responses to 37% improvement for triangular grating and 23% for rectangular grating compared to non-grating case. Then, we use Finite-Difference Time-Domain (FDTD) to simulate transmission/reflection double grating cases. We simulated triangular-triangular (top-bottom) grating cases and triangular-rectangular (top-bottom) grating case. We realize solar cell efficiency improvement about 42.4%. For the triangular-rectangular (top-bottom) grating case, the 20% efficiency improvement is achieved. Finally, we present weighted-light simulation for the double grating for the first time and show the best grating can achieve 104% light improvement, which is quite different from traditional non-weighted calculation.
Electrical and Computer Engineering