“School of Nano-Sciences”
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| Paper IPM / Nano-Sciences / 15801 |
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On the basis of first principle calculation, we discussed a new class of two dimensional materials, CuXSe2 (X = Cl, Br) nanocomposite monolayers and bilayers, whose their bulk parent were experimentally reported in 1969. We show that the monolayers are dynamically, mechanically, and thermodynamically stable, and have very small cleavage energies of 0.26 J/m2, suggesting their feasible experimental exfoliation. The monolayers are indirect-gap semiconductors with practically the same moderate band gaps of 1.74 eV, possessing extremely anisotropic and very high carrier mobilities (e.g., their electron mobilities are 21263.45 and 10274.83 cm2V-1s-1 along the Y direction for CuClSe2 and CuBrSe2, respectively, while hole mobilities reach 2054.21 and 892.61 cm2V-1s-1 along X direction). CuXSe2 bilayers are also indirect band gap semiconductors with slightly smaller band gaps of 1.54 and 1.59 eV, suggesting weak interlayer quantum confinement effects. On the other hand, the monolayers show pronounced absorption coefficients (>10^5 cm-1) in a wide range of visible region. The moderate band gaps, very high unidirectional electron and hole mobilities, and pronounced absorption coefficients make the proposed CuXSe2 (X = Cl, Br) nanocomposite monolayers promising for application in optoelectronic devices.
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