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Energy Express

Energy Express

  • Editor: Bernard Kippelen
  • Vol. 20, Iss. S1 — Jan. 2, 2012
  • pp: A20–A27

Light trapping by backside diffraction gratings in silicon solar cells revisited

Markus Wellenzohn and Rainer Hainberger  »View Author Affiliations

Optics Express, Vol. 20, Issue S1, pp. A20-A27 (2012)

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This numerical study investigates the influence of rectangular backside diffraction gratings on the efficiency of silicon solar cells. Backside gratings are used to diffract incident light to large propagation angles beyond the angle of total internal reflection, which can significantly increase the interaction length of long wavelength photons inside the silicon layer and thus enhance the efficiency. We investigate the influence of the silicon thickness on the optimum grating period and modulation depth by a simulation method which combines a 2D ray tracing algorithm with rigorous coupled wave analysis (RCWA) for calculating the grating diffraction efficiencies. The optimization was performed for gratings with period lengths ranging from 0.25 µm to 1.5 µm and modulation depths ranging from 25 nm to 400 nm under the assumption of normal light incidence. This study shows that the achievable efficiency improvement of silicon solar cells by means of backside diffraction gratings strongly depends on the proper choice of the grating parameters for a given silicon thickness. The relationship between the optimized grating parameters resulting in maximum photocurrent densities and the silicon thickness is determined. Moreover, the thicknesses of silicon solar cells with and without optimized backside diffraction gratings providing the same photocurrent densities are compared.

© 2011 OSA

OCIS Codes
(050.1950) Diffraction and gratings : Diffraction gratings
(350.6050) Other areas of optics : Solar energy

ToC Category:

Original Manuscript: September 6, 2011
Revised Manuscript: November 2, 2011
Manuscript Accepted: November 4, 2011
Published: November 15, 2011

Markus Wellenzohn and Rainer Hainberger, "Light trapping by backside diffraction gratings in silicon solar cells revisited," Opt. Express 20, A20-A27 (2012)

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