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arXiv · 1912.07889

Upper limit to the photovoltaic efficiency of imperfect crystals

Sunghyun Kim·José A. Márquez·Thomas Unold·Aron Walsh
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Abstract

The Shockley-Queisser (SQ) limit provides a convenient metric for predicting light-to-electricity conversion efficiency of a solar cell based on the band gap of the light-absorbing layer. In reality, few materials approach this radiative limit. We develop a formalism and a computational method to predict the maximum photovoltaic efficiency of imperfect crystals from first principles. Our scheme includes equilibrium populations of native defects, their carrier-capture coefficients, and the associated recombination rates. When applied to kesterite solar cells, we reveal an intrinsic limit of 20% for $\mathrm{Cu_2ZnSnSe_4}$, which falls far below the SQ limit of 32%. The effects of atomic substitution and extrinsic doping are studied, leading to pathways for enhanced efficiency of 31%. This approach can be applied to support targeted-materials selection for future solar-energy technologies.

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Sunghyun Kim, José A. Márquez, Thomas Unold, Aron Walsh. 2019-12-17. Upper limit to the photovoltaic efficiency of imperfect crystals. https://doi.org/10.1039/d0ee00291g

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