Multi-resonant absorption in ultra-thin silicon solar cells with metallic nanowires

Inès Massiot,Clément Colin,Philippe Lalanne,Stéphane Collin,Christophe Sauvan,Pere Roca I Cabarrocas,Jean-Luc Pelouard

doi:10.1364/oe.21.00a372

Abstract

We propose a design to confine light absorption in flat and ultra-thin amorphous silicon solar cells with a one-dimensional silver grating embedded in the front window of the cell. We show numerically that multi-resonant light trapping is achieved in both TE and TM polarizations. Each resonance is analyzed in detail and modeled by Fabry-Perot resonances or guided modes via grating coupling. This approach is generalized to a complete amorphous silicon solar cell, with the additional degrees of freedom provided by the buffer layers. These results could guide the design of resonant structures for optimized ultra-thin solar cells.

Highlights

Thin film solar cells are a promising solution to reduce the overall cost of photovoltaic cells and increase production rates
We propose a design to confine light absorption in flat and ultra-thin amorphous silicon solar cells with a one-dimensional silver grating embedded in the front window of the cell
Each resonance is analyzed in detail and modeled by Fabry-Perot resonances or guided modes via grating coupling. This approach is generalized to a complete amorphous silicon solar cell, with the additional degrees of freedom provided by the buffer layers

Summary

Introduction

Thin film solar cells are a promising solution to reduce the overall cost of photovoltaic cells and increase production rates. Remarkable progress has been made in amorphous silicon (a-Si:H) solar cells technology leading to stable energy conversion efficiencies of 10% with 250 nm thick a-Si:H [1]. Reducing further the absorber layer thickness towards ultra-thin (≤ 100 nm) a-Si:H solar cells should improve the collection of current in the cell [2] as well as the stability against light-induced degradation [3, 4]. Random texturing of the interfaces [5, 6] is used to enhance the optical path length but is incompatible with ultra-thin absorber layers. Metallic nanostructures have been integrated at the front surface of the cell to scatter light in crystalline [14,15,16] or amorphous [17] silicon solar cells, or to realize partially transparent electrodes [18]

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