Understanding the role of selenium in defect passivation for highly efficient selenium-alloyed cadmium telluride solar cells

Fiducia, Thomas A.M.; Mendis, Budhika G.; Li, Kexue; Grovenor, Chris R.M.; Munshi, Amit H.; Barth, Kurt; Sampath, Walajabad S.; Wright, Lewis D.; Abbas, Ali; Bowers, Jake W.; Walls, John M.

doi:10.1038/s41560-019-0389-z

Understanding the role of selenium in defect passivation for highly efficient selenium-alloyed cadmium telluride solar cells

Fiducia, Thomas A.M.; Mendis, Budhika G.; Li, Kexue; Grovenor, Chris R.M.; Munshi, Amit H.; Barth, Kurt; Sampath, Walajabad S.; Wright, Lewis D.; Abbas, Ali; Bowers, Jake W.; Walls, John M.

Authors

Thomas A.M. Fiducia

Dr Buddhika Mendis b.g.mendis@durham.ac.uk
Associate Professor

Kexue Li

Chris R.M. Grovenor

Amit H. Munshi

Kurt Barth

Walajabad S. Sampath

Lewis D. Wright

Ali Abbas

Jake W. Bowers

John M. Walls

Abstract

Electricity produced by cadmium telluride (CdTe) photovoltaic modules is the lowest-cost electricity in the solar industry, and now undercuts fossil fuel-based sources in many regions of the world. This is due to recent efficiency gains brought about by alloying selenium into the CdTe absorber, which has taken cell efficiency from 19.5% to its current record of 22.1%. Although the addition of selenium is known to reduce the bandgap of the absorber material, and hence increase the cell short-circuit current, this effect alone does not explain the performance improvement. Here, by means of cathodoluminescence and secondary ion mass spectrometry, we show that selenium enables higher luminescence efficiency and longer diffusion lengths in the alloyed material, indicating that selenium passivates critical defects in the bulk of the absorber layer. This passivation effect explains the record-breaking performance of selenium-alloyed CdTe devices, and provides a route for further efficiency improvement that can result in even lower costs for solar-generated electricity.

Citation

Fiducia, T. A., Mendis, B. G., Li, K., Grovenor, C. R., Munshi, A. H., Barth, K., …Walls, J. M. (2019). Understanding the role of selenium in defect passivation for highly efficient selenium-alloyed cadmium telluride solar cells. Nature Energy, 4, 504-511. https://doi.org/10.1038/s41560-019-0389-z

Journal Article Type	Article
Acceptance Date	Apr 5, 2019
Online Publication Date	May 13, 2019
Publication Date	May 13, 2019
Deposit Date	May 19, 2019
Publicly Available Date	Nov 13, 2019
Journal	Nature energy.
Print ISSN	2058-7546
Publisher	Nature Research
Peer Reviewed	Peer Reviewed
Volume	4
Pages	504-511
DOI	https://doi.org/10.1038/s41560-019-0389-z