Light harvesting by planar photonic crystals in solar cells: the case of amorphous silicon

Abstract

Abstract. In this paper, we discuss on light management in silicon thin film solar cells, using photonic crystals (PhC) structures. We particularly focus on photovoltaic devices including amorphous silicon absorbers patterned as 2D PhCs. Physical principles and design rules leading to the optimized configuration of the patterned cell are discussed by means of optical simulations performed on realistic thin film solar cell stacks. Theoretically, a maximum 40% rel increase of integrated absorption in the a-Si:H layer of the patterned cell is expected compared to the unpatterned case. Moreover, both simulation and optical characterization of the fabricated cells demonstrate the robustness of their optical properties with regards to the angle of incidence of the light and to the fabrication induced defects in the PhCs. Finally, the impact of the surface recombination due to the generation of new free surfaces with higher defect densities is addressed. We demonstrate that patterning still induces a substantial increase of the conversion efficiency, with a reasonable surface recombination velocity.

Performance optimization of flexible a-Si:H solar cells with nanotextured plasmonic substrate by tuning the thickness of oxide spacer layer

“…Besides the limit of materials diffusion [24], the AZO spacer, with a lower refractive index, also acts the function to inhibit the losses in reflected light due to the excitation of surface plasmon resonance. The role of the spacer is to shift the plasmon resonance frequencies toward higher energies, that is already absorbed in the front part of the cell [25,26].…”

Photonic light trapping and electrical transport in thin-film silicon solar cells

“…In this regard, an electro-optical modeling allows one to design solar cells that simultaneously meet these criteria [36][37][38][39][40][41].…”

Modal approach for tailoring the absorption in a photonic crystal membrane

“…We highlight the role played by the coupling anisotropy and demonstrate that two degenerate modes can lead to an absorption as large as 100% for a given wavelength. In the third section, we illustrate this concept using a 2D PhC membrane, a structure known to enhance absorption [13] and that can be easily fabricated by various methods including holographic [14], e-beam [15] or nano-imprint [16] lithography. Finite Difference Time Domain (FDTD) simulations are performed on this patterned membrane so as to understand the influence of its main parameters on the modal properties as shown on section IV.…”