Abstract
In bilayers of two-dimensional semiconductors with stacking arrangements which lack inversion symmetry charge transfer between the layers due to layer-asymmetric interband hybridisation can generate a potential difference between the layers. We analyse bilayers of transition metal dichalcogenides (TMDs)—in particular, hbox {WSe}_2—for which we find a substantial stacking-dependent charge transfer, and InSe, for which the charge transfer is found to be negligibly small. The information obtained about TMDs is then used to map potentials generated by the interlayer charge transfer across the moiré superlattice in twistronic bilayers.
Highlights
Many two-dimensional (2D) materials[1] lack inversion symmetry in their stoichiometric monolayers
The potential variation across a layer-asymmetric 2D material system in which charge transfer has occurred is a natural subject for first principles density functional theory (DFT) calculations
For comparison with the PBE generalised gradient approximation (GGA) results presented above, calculations were carried out using the local density approximation (LDA), via the exchange correlation functional of Ceperley and Alder[13] as parametrized by Perdew and Zunger[14], and in Fig. 2 we show the differences between bilayer and monolayer plane-averaged local electrostatic potentials using LDA alongside the PBE results
Summary
Many two-dimensional (2D) materials[1] lack inversion symmetry in their stoichiometric monolayers. The potential variation across a layer-asymmetric 2D material system in which charge transfer has occurred is a natural subject for first principles density functional theory (DFT) calculations.
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