Cu2SiSe3 as a promising solar absorber: harnessing cation dissimilarity to avoid killer antisites

Adair Nicolson, Seán R. Kavanagh, Christopher N. Savory, Graeme W. Watson, David O. Scanlon*

*Corresponding author for this work

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Abstract

Copper-chalcogenides are promising candidates for thin film photovoltaics due to their ideal electronic structure and potential for defect tolerance. To this end, we have theoretically investigated the optoelectronic properties of Cu2SiSe3, due to its simple ternary composition, and the favourable difference in charge and size between the cation species, limiting antisite defects and cation disorder. We find it to have an ideal, direct bandgap of 1.52 eV and a maximum efficiency of 30% for a 1.5 μm-thick film at the radiative limit. Using hybrid density functional theory, the formation energies of all intrinsic defects are calculated, revealing the p-type copper vacancy as the dominant defect species, which forms a perturbed host state. Overall, defect concentrations are predicted to be low and have limited impact on non-radiative recombination, as a consequence of the p–d coupling and antibonding character at the valence band maxima. Therefore, we propose that Cu2SiSe3 should be investigated further as a potential defect-tolerant photovoltaic absorber.
Original languageEnglish
Pages (from-to)14833-14839
Number of pages7
JournalJournal of Materials Chemistry A
Volume11
Issue number27
Early online date19 Jun 2023
DOIs
Publication statusPublished - 21 Jul 2023

Bibliographical note

Acknowledgements:
We acknowledge Bodoo Batnaran for sharing data which was useful for comparisons in the early stages of this project. A. N and S. R. K acknowledge the EPSRC and SFI Centre for Doctoral Training in Advanced Characterisation of Materials (EP/S023259/1) for funding a PhD studentship. C. N. S. is grateful to the Department of Chemistry at UCL and the Ramsay Memorial Fellowship Trust for the funding of a Ramsay Fellowship. The authors acknowledge the use of the UCL Kathleen and Thomas High Performance Computing Facility. Via membership of the UK's HEC Materials Chemistry Consortium, which is funded by the EPSRC (EP/L000202, EP/R029431, EP/T022213), this work used the ARCHER2 UK National Supercomputing Service (http://www.archer2.ac.uk/) and the UK Materials and Molecular Modelling (MMM) Hub (Thomas – EP/P020194 & Young – EP/T022213).

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