Paper
27 February 2019 Light absorption enhancement in ultra-thin layers for hot-carrier solar cells: first developments towards the experimental demonstration of an enhanced hot-carrier effect with light trapping
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Abstract
Hot-carrier solar cells (HCSC) can potentially overcome the Shockley-Queisser limit, by having carriers at a higher temperature than the lattice. To this end, the carriers need to thermalize slower than power is generated by absorbing photons. In thin films, a hot-carrier distribution can only be achieved with very high incident power, by saturating the thermalization channels. Ultra-thin absorbers have a smaller thermalization rate, due to fewer channels. However, they typically absorb only a limited amount of light, which prevents them from reaching high efficiencies. Light trapping is an excellent way to increase significantly the amount of light absorbed in an ultra-thin material. Yet, studies on the coupling between light trapping and hot carriers are still lacking, due to the complexity of the whole system. We analyze numerically and experimentally how light trapping can enable high-efficiency HCSC. This manuscript presents the progress towards the experimental demonstration of the enhancement of the hot-carrier effect with light trapping. 280 nm-thick devices have successfully been reported on a gold mirror using epitaxial lift-off (ELO) and gold-gold bonding. These devices have been characterized by photoluminescence spectroscopy. Hot carriers with a temperature 37 K above lattice temperature were measured, in accordance with theoretical predictions. We are now working towards the ELO of absorbers 10 times thinner, on which we will implement light trapping to increase the carrier temperature.
© (2019) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Maxime Giteau, Kentaroh Watanabe, Naoya Miyashita, Hassanet Sodabanlu, Julie Goffard, Amaury Delamarre, Daniel Suchet, Ryo Tamaki, Zacharie Jehl, Laurent Lombez, Masakazu Sugiyama, Andrea Cattoni, Stéphane Collin, Jean-François Guillemoles, and Yoshitaka Okada "Light absorption enhancement in ultra-thin layers for hot-carrier solar cells: first developments towards the experimental demonstration of an enhanced hot-carrier effect with light trapping", Proc. SPIE 10913, Physics, Simulation, and Photonic Engineering of Photovoltaic Devices VIII, 109130D (27 February 2019); https://doi.org/10.1117/12.2505908
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KEYWORDS
Gallium arsenide

Epitaxial lateral overgrowth

Solar cells

Absorption

Etching

Luminescence

Mirrors

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