Dipole moment and pressure dependent interlayer excitons in MoSSe/WSSe heterostructures

Active strong coupling of exciton and nanocavity based on GSST-WSe2 hybrid nanostructures

The strong coupling between optical resonance microcavity and matter excitations provides a practical path for controlling light-matter interactions. However, conventional microcavity, whose functions are fixed at the fabrication stage, dramatically limits the modulation of light-matter interactions. Here, we investigate the active strong coupling of resonance mode and exciton in GSST-WSe2 hybrid nanostructures. It is demonstrated that significant spectral splitting is observed in single nanostructures, tetramers, and metasurfaces. We further confirm the strong coupling by calculating the enhanced fluorescence spectra. The coupling effect between the excited resonance and exciton is dramatically modulated during the change of GSST from amorphous to crystalline, thus realizing the strong coupling switching. This switching property has been fully demonstrated in several systems mentioned earlier. Our work is significant in guiding the study of actively tunable strong light-matter interactions at the nanoscale.

Electronic Properties of CrB/Co2CO2 Superlattices by Multiple Descriptor-Based Machine Learning Combined with First-Principles

In recent times, newly unveiled 2D materials exhibiting exceptional characteristics, such as MBenes and MXenes, have gained widespread application across diverse domains, encompassing electronic devices, catalysis, energy storage, sensors, and various others. Nonetheless, numerous technical bottlenecks persist in the development of high-performance, structurally flexible, and adjustable electronic device materials. Research investigations have demonstrated that 2D van der Waals superlattices (vdW SLs) structures comprising materials exhibit exceptional electrical, mechanical, and optical properties. In this work, the advantages of both materials are combined and compose the vdW SLs structure of MBenes and MXenes, thus obtaining materials with excellent electronic properties. Furthermore, it integrates machine learning (ML) with first-principles methods to forecast the electrical properties of MBene/MXene superlattice materials. Initially, various configurations of MBene/MXene superlattice materials are explored, revealing that distinct stacking methods exert significant influence on the electronic structure of MBene/MXene materials. Specifically, the BABA-type stacking of CrB (layer A) and Co2CO2 MXene (layer B) is most stable configureation. Subsequently, multiple descriptors of the structure are constructed to predict the density of states  of vdW SLs through the employment of ML techniques. The best model achieves a mean absolute error (MAE) as low as 0.147 eV.

Enhanced photoelectric performance of MoSSe/MoS2 van der Waals heterostructures with tunable multiple band alignment

Janus MoSSe with mirror asymmetry has recently emerged as a new two-dimensional (2D) material with a sizeable out-of-plane dipole moment. Here, based on first-principles calculations, we theoretically investigate the electronic properties of two patterns of 2D MoSSe/MoS₂ van der Waals heterostructures (vdWHs). The electronic properties of MoSSe can be tuned by the intrinsic out-of-plane dipole field. When the Se side of the Janus layer faces the MoS₂ layer, the dipole field points from the MoSSe layer towards the MoS₂ layer, and the vdWH possesses a type-I band alignment which is desirable for light emission applications. With a reversal of the Janus layer, the intrinsic field inverts accordingly, and the band alignment becomes a typical type-II band alignment, which benefits carrier separation. Moreover, it possesses superior optical absorption (∼10⁵ cm^-1), and the calculated photocurrent density under visible-light radiation is up to 0.9 mA cm^-2 in the MoSSe/MoS₂ vdWH. Meanwhile, an external electric field and vertical strain can remarkably modulate the band alignment to switch it between type-I and type-II. Thus, MoSSe/MoS₂ vdWHs have promising applications in next-generation photovoltaic devices.

Out-of-plane dipole-modulated photogenerated carrier separation and recombination at Janus-MoSSe/MoS2 van der Waals heterostructure interfaces: Ab initio time-domain study

Out-of-plane mirror symmetry-breaking provides a powerful tool for engineering the electronic property and the exciton behavior of two-dimensional materials. Here, combined the time-domain density functional theory with nonadiabatic dynamics, we...