One-Dimensional Flat Bands and Anisotropic Moire′ Excitons in Twisted Tin Sulfide Bilayers

Group IV monochalcogenides have attracted significant recent attention due to their similarities to black phosphorus and their potential applications in twistronics, inspired by the synthesis of nanowires and nanocrystals with continuous interlayer Eshelby twists. They are also proposed as an ideal platform to study strongly correlated physics with dimensional crossover. However, little is known on moire ' superlattices formed by twisted monochalcogenide bilayers. In particular, the optoelectronic properties of the twisted monochalcogenide bilayers are largely unexplored and it is not clear whether moire ' excitons can be hosted in such bilayers. In this work, we reveal the structural, optoelectronic, and excitonic properties of twisted SnS bilayers from first-principles. The key aspects of the moire ' superlattices, including lattice reconstructions, moire ' potentials, formation of flat bands, one-dimensional and anisotropic moire ' excitons, and tuning of moire ' excitons by twist angle and interlayer distance, are examined.

Automated summary

The IV monochalcogenides, resembling black phosphorus, have attracted significant attention for their potential applications in twistronics. This study reveals the structural, optoelectronic, and excitonic properties of twisted SnS bilayers, showing the existence of one-dimensional and anisotropic moire ' excitons that can be tuned by twist angle and interlayer distance.