Grain-Boundary Structural Relaxation in Sb2Se3 Thin-Film Photovoltaics

Lomas-Zapata, R.A.; McKenna, K.P.; Ramasse, Q.M.; Williams, R.E.; Phillips, L.J.; Durose, K.; Major, J.D.; Mendis, B.G.

Abstract

Grain boundaries play an important role in the efficiency of thin-film photovoltaics, where the absorber layer is invariably polycrystalline. Density-functional-theory simulations have previously identified a “self-healing” mechanism in Sb2Se3 that passivates the grain boundaries. During “self-healing,” extensive structural relaxation at the grain boundary removes the band-gap electronic defect states that give rise to high carrier recombination rates. In this work, lattice imaging in a transmission electron microscope is used to uncover evidence for the theoretically proposed structural relaxation in Sb2Se3. The strain measured along the [010] crystal direction is found to be dependent on the nature of the grain-boundary plane. For a (010) grain boundary, the strain and structural relaxation is minimal, since no covalent bonds are broken by termination of the grain. On the other hand, strains of up to approximately 4% extending approximately 2 nm into the grain interior are observed for a (041) grain boundary, where grain termination results in significant structural relaxation due to the ideal atomic coordination being disrupted. These results are consistent with theory and suggest that Sb2Se3 may have a high level of grain-boundary-defect tolerance. Published by the American Physical Society 2024

Citation

Lomas-Zapata, R., McKenna, K., Ramasse, Q., Williams, R., Phillips, L., Durose, K., Major, J., & Mendis, B. (2024). Grain-Boundary Structural Relaxation in Sb2Se3 Thin-Film Photovoltaics. PRX Energy, 3(1), Article 013006. https://doi.org/10.1103/prxenergy.3.013006

• Journal Article Type: Article
• Acceptance Date: Jan 12, 2024
• Online Publication Date: Feb 8, 2024
• Publication Date: Feb 8, 2024
• Deposit Date: Mar 4, 2024
• Publicly Available Date: Mar 6, 2024
• Journal: PRX Energy
• Print ISSN: 2768-5608
• Electronic ISSN: 2768-5608
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 3
• Issue: 1
• Article Number: 013006
• DOI: https://doi.org/10.1103/prxenergy.3.013006
• Public URL: https://durham-repository.worktribe.com/output/2308731