Optimization of the absorption efficiency of an amorphous-silicon thin-film tandem solar cell backed by a metallic surface-relief grating

Abstract

The rigorous coupled-wave approach was used to compute the plane-wave absorptance of a thin-film tandem solar cell with a metallic surface-relief grating as its back reflector. The absorptance is a function of the angle of incidence and the polarization state of incident light; the free-space wavelength; and the period, duty cycle, the corrugation height, and the shape of the unit cell of the surface-relief grating. The solar cell was assumed to be made of hydrogenated amorphous-silicon alloys and the back reflector of bulk aluminum. The incidence and the grating planes were taken to be identical. The AM1.5 solar irradiance spectrum was used for computations in the 400-1100 nm wavelength range. Inspection of parametric plots of the solar-spectrum-integrated (SSI) absorption efficiency and numerical optimization using the differential evolution algorithm were employed to determine the optimal surface-relief grating. For direct insolation, the SSI absorption efficiency is maximizable by appropriate choices of the period, the duty cycle, and the corrugation height, regardless of the shape of the corrugation in each unit cell of the grating. A similar conclusion also holds for diffuse insolation, but the maximum efficiency for diffuse insolation is about 20% smaller than for direct insolation. Although a tin-doped indium-oxide layer at the front and an aluminum-doped zinc-oxide layer between the semiconductor material and the backing metallic layer change the optimal depth of the periodic corrugations, the optimal period of the corrugations does not significantly change.

Enhanced efficiency of Schottky-barrier solar cell with periodically nonhomogeneous indium gallium nitride layer

“…1 These strategies include texturing the front surface of the solar cell, 2,3 incorporating a periodically corrugated metallic back reflector, [4][5][6] coating the front surface with an "antireflection" (AR) layer, 7,8 embedding nanoparticles inside the light-absorbing layer (s), [9][10][11] and using light concentrators.…”

“…the periodic corrugation of the metallic back reflector [4][5][6]17 facilitating the excitation of surface-plasmon-polariton waves [18][19][20] and waveguide modes 21 to intensify the electric field inside the semiconductor region, leading to an increase in the electron-hole pair (EHP) generation rate; ii. the periodic nonhomogeneity of the i-layer that may facilitate the excitation of multiple surface-plasmon-polariton waves 22 and waveguide modes, 17 thereby further boosting the EHP generation rate; and iii.…”

Adequacy of the rigorous coupled-wave approach for thin-film silicon solar cells with periodically corrugated metallic backreflectors: spectral analysis

“…The metallic layer serves as an electrode as well as an optical backreflector. To enhance optical absorption and, therefore, the generation of electron-hole pairs, the metallic backreflector is often periodically corrugated [2][3][4][5][6][7][8]; i.e., a metallic grating is used instead of planar metal. The enhancement occurs due to the excitation of surface-plasmon-polariton waves by taking advantage of the periodicity of the metallic grating [2,3].…”

Periodically multilayered planar optical concentrator for photovoltaic solar cells

“…In the second step, the optimized concentrator was used with the solar cell and the indium-tin-oxide layer, and the average current density in the solar cell was calculated using the finite element method (FEM). 12 The differential evolution algorithm 13,14 is suitable for optimization when the cost function is non-differentiable, multidimensional, and/or several local maximums. Hence, this algorithm is attractive for optimizing the stand-alone concentrator.…”