Abstract
PdSe2, an emerging 2D material with a novel anisotropic puckered pentagonal structure, has attracted growing interest due to its layer-dependent electronic bandgap, high carrier mobility, and good air stability. Herein, a detailed Raman spectroscopic study of few-layer PdSe2 (two to five layers) under the in-plane uniaxial tensile strain up to 3.33% is performed. Two of the prominent PdSe2 Raman peaks are influenced differently depending on the direction of strain application. The (Formula presented.) mode redshifts more than the (Formula presented.) mode when the strain is applied along the a-axis of the crystal, while the (Formula presented.) mode redshifts more than the (Formula presented.) mode when the strain is applied along the b-axis. Such an anisotropic phonon response to strain indicates directionally dependent mechanical and thermal properties of PdSe2 and also allows the identification of the crystal axes. The results are further supported using first-principles density-functional theory. Interestingly, the near-zero Poisson’s ratios for few-layer PdSe2 are found, suggesting that the uniaxial tensile strain can easily be applied to few-layer PdSe2 without significantly altering their dimensions at the perpendicular directions, which is a major contributing factor to the observed distinct phonon behavior. The findings pave the way for further development of 2D PdSe2-based flexible electronics.
Original language | English |
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Article number | 2003215 |
Journal | Advanced Functional Materials |
Volume | 30 |
Issue number | 35 |
DOIs | |
State | Published - Aug 1 2020 |
Funding
This work was supported by the National Science Foundation (NSF) under Grant No. 1945364. X.L. acknowledges the membership of the Photonics Center at Boston University. W.L. acknowledges the high‐performance computing resources of the Boston University Shared Computing Cluster (SCC). L.L., A.D.O., Y.G., A.P., and K.X. acknowledge work conducted at the Center for Nanophase Materials Sciences, which is a US Department of Energy Office of Science User Facility. A.D.O acknowledges support from the Bredesen Center, University of Tennessee, Knoxville. This work was supported by the National Science Foundation (NSF) under Grant No. 1945364. X.L. acknowledges the membership of the Photonics Center at Boston University. W.L. acknowledges the high-performance computing resources of the Boston University Shared Computing Cluster (SCC). L.L., A.D.O., Y.G., A.P., and K.X. acknowledge work conducted at the Center for Nanophase Materials Sciences, which is a US Department of Energy Office of Science User Facility. A.D.O acknowledges support from the Bredesen Center, University of Tennessee, Knoxville.
Keywords
- PdSe
- Raman spectroscopy
- strain engineering
- stretchable
- transition metal dichalcogenides