English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Janus MoSSe monolayers were recently synthesised by replacing S by Se on oneside of MoS$_2$ (or vice versa for MoSe$_2$). Due to the differentelectronegativity of S and Se these structures carry a finite out-of-planedipole moment. As we show here by means of density functional theory (DFT)calculations, this intrinsic dipole leads to the formation of built-in electricfields when the monolayers are stacked to form $N$-layer structures. Forsufficiently thin structures ($N<4$) the dipoles add up and shift the vacuumlevel on the two sides of the film by $\sim N \cdot 0.7$ eV. However, forthicker films charge transfer occurs between the outermost layers formingatomically thin n- and p-doped electron gasses at the two surfaces. The dopingconcentration can be tuned between about $5\cdot 10^{12}$ e/cm$^{2}$ and$2\cdot 10^{13}$ e/cm$^{2}$ by varying the film thickness. The surface chargescounteract the static dipoles leading to saturation of the vacuum level shiftat around 2.2 eV for $N>4$. Based on band structure calculations and theMott-Wannier exciton model, we compute the energies of intra- and interlayerexcitons as a function of film thickness suggesting that the Janus multilayerfilms are ideally suited for achieving ultrafast charge separation over atomiclength scales without chemical doping or applied electric fields. Finally, weexplore a number of other potentially synthesisable 2D Janus structures withdifferent band gaps and internal dipole moments. Our results open newopportunities for ultrathin opto-electronic components such as tunnel diodes,photo-detectors, or solar cells.

Efficient Charge Separation in 2D Janus van der Waals Structures with Build-in Electric Fields and Intrinsic p-n Doping