Employing dielectric diffractive structures in solar cells – a numerical study

Abstract

We study numerically in detail optical effects occurring during the interaction of light with dielectric gratings and explain how they can be exploited to enhance light absorption in thin‐film solar cells. We analyze in depth two scenarios with practical relevance where dielectric gratings are incorporated. The first is an one‐dimensional, binary grating, which can be manufactured lithographically. The second is a two‐dimensional grating of dielectric spheres that can be fabricated employing self organization processes on pre‐textured substrates. From a universally valid point of view, we finally outline strategies to optimize the geometry of textured surfaces permitting for a maximization of absorption in a solar cell. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

A numerical study of Bi-periodic binary diffraction gratings for solar cell applications

“…This can be achieved by light trapping, one means of which is application of a diffraction grating to either face of the solar cell [1][2][3][4][5]. The diffraction grating allows incident light to be coupled to internal orders whose wavevector lateral component is greater than those of the set of incident wavevectors.…”

Optical Absorption Enhancement in Solar Cells via 3d Photonic Crystal Structures

“…Wave optics approaches can be aimed at enhancing absorption for a certain range of wavelengths, which can be more advantageous for efficiency [3,4]. Several light trapping approaches of wave optics were studied such as plasmonics based designs [5], grating couplers [6], fluorescent concentrator systems [7], and photonic crystals (PhCs) [8][9][10]. A variety of means to refract, diffract, and reflect light are with the aim of increasing the absorption path length of light in the materials.…”

Dielectric gratings for wide-angle, broadband absorption by thin film photovoltaic cells

“…For example, it has recently been discussed how dielectric particles can outperform metallic ones. 11 Hence, dielectric gratings and photonic crystals [12][13][14][15][16] that can excite resonant modes without introducing significant additional absorption are a promising alternative. Further, solar concentration allows larger achievable efficiencies and can lower costs.…”

“…For proposed hot-carrier solar cells, [17][18][19] the large energy density in the thin active layer should help reducing thermalization speed and increasing the cell efficiency above the limit for a standard one-junction cell. The behavior of the structure changes as the incidence angle is varied, 12,15,20 which will affect systems working under light concentration. 21 In this paper, we demonstrate significantly increased absorption in a thin active layer for PV systems working under solar concentration.…”

“…12,31 An unambiguous separation of both effects is difficult and not even necessarily possible. It seems nonetheless clear that the antireflection mechanism cannot account alone for the obtained results, since the absorption in the thin GaSb layer is more efficient for the thick grating structure than for the ideal antireflection coating.…”