Optimization-based design of surface textures for thin-film Si solar cells
Author(s)Sheng, Xing; Johnson, Steven G.; Michel, Jurgen; Kimerling, Lionel C.
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We numerically investigate the light-absorption behavior of thin-film silicon for normal-incident light, using surface textures to enhance absorption. We consider a variety of texture designs, such as simple periodic gratings and commercial random textures, and examine arbitrary irregular periodic textures designed by multi-parameter optimization. Deep and high-index-contrast textures exhibit strong anisotropic scattering that is outside the regime of validity of the Lambertian models commonly used to describe texture-induced absorption enhancement for normal incidence. Over a 900–1100 nm wavelength range, our optimized surface texture in two dimensions (2D) enhances absorption by a factor of 2.7πn, considerably larger than the original πn Lambertian result and exceeding by almost 50% a recent generalization of Lambertian model for periodic structures in finite spectral range. However, the πn Lambertian limit still applies for isotropic incident light, and our structure obeys this limit when averaged over all the angles. Therefore, our design can be thought of optimizing the angle/enhancement tradeoff for periodic textures.
DepartmentMassachusetts Institute of Technology. Materials Processing Center; Massachusetts Institute of Technology. Department of Materials Science and Engineering; Massachusetts Institute of Technology. Department of Mathematics; Massachusetts Institute of Technology. Microphotonics Center
Optical Society of America
Sheng, Xing, Steven G. Johnson, Jurgen Michel, and Lionel C. Kimerling, "Optimization-based design of surface textures for thin-film Si solar cells," Optics Express 19.S4, A841-A850 (2011) © 2011 OSA.
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