Phase Instability in van der Waals In2Se3 Determined by Surface Coordination. Issue 17 (20th March 2023)

• Record Type: Journal Article
• Authors: Yan, Shanru; Xu, Chao; Zhong, Cenchen; Chen, Yancong; Che, Xiangli; Luo, Xin; Zhu, Ye
• Is Part Of: Angewandte Chemie international edition. Volume 62:Issue 17(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-03-20
• Subjects: Chalcogenides -- Ferroelectric Materials -- 2D Materials -- Phase Stability -- Surface Oxidation; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.202300302
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: van der Waals In2 Se3 has attracted significant attention for its room‐temperature 2D ferroelectricity/antiferroelectricity down to monolayer thickness. However, instability and potential degradation pathway in 2D In2 Se3 have not yet been adequately addressed. Using a combination of experimental and theoretical approaches, we here unravel the phase instability in both α‐ and β′‐In2 Se3 originating from the relatively unstable octahedral coordination. Together with the broken bonds at the edge steps, it leads to moisture‐facilitated oxidation of In2 Se3 in air to form amorphous In2 Se3−3 x O3 x layers and Se hemisphere particles. Both O2 and H2 O are required for such surface oxidation, which can be further promoted by light illumination. In addition, the self‐passivation effect from the In2 Se3−3 x O3 x layer can effectively limit such oxidation to only a few nanometer thickness. The achieved insight paves way for better understanding and optimizing 2D In2 Se3 performance for device applications. Abstract : A mixture of experimental and theoretical approaches reveals that the ambient stability of 2D In2 Se3 strongly depends on the surface coordination. Tetrahedral‐coordinated surfaces were found to be more stable and suitable for device applications.