Issue 10, 2021

Hidden spontaneous polarisation in the chalcohalide photovoltaic absorber Sn2SbS2I3

Abstract

Perovskite-inspired materials aim to replicate the optoelectronic performance of lead-halide perovskites, while eliminating issues with stability and toxicity. Chalcohalides of group IV/V elements have attracted attention due to enhanced stability provided by stronger metal-chalcogen bonds, alongside compositional flexibility and ns2 lone pair cations – a performance-defining feature of halide perovskites. Following the experimental report of solution-grown tin-antimony sulfoiodide (Sn2SbS2I3) solar cells, with power conversion efficiencies above 4%, we assess the structural and electronic properties of this emerging photovoltaic material. We find that the reported centrosymmetric Cmcm crystal structure represents an average over multiple polar Cmc21 configurations. The instability is confirmed through a combination of lattice dynamics and molecular dynamics simulations. We predict a large spontaneous polarisation of 37 μC cm−2 that could be active for electron–hole separation in operating solar cells. We further assess the radiative efficiency limit of this material, calculating ηmax > 30% for film thicknesses t > 0.5 μm.

Graphical abstract: Hidden spontaneous polarisation in the chalcohalide photovoltaic absorber Sn2SbS2I3

Supplementary files

Article information

Article type
Communication
Submitted
12 May 2021
Accepted
01 Jul 2021
First published
05 Jul 2021
This article is Open Access
Creative Commons BY license

Mater. Horiz., 2021,8, 2709-2716

Hidden spontaneous polarisation in the chalcohalide photovoltaic absorber Sn2SbS2I3

S. R. Kavanagh, C. N. Savory, D. O. Scanlon and A. Walsh, Mater. Horiz., 2021, 8, 2709 DOI: 10.1039/D1MH00764E

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