Strain induced tunable optoelectronic properties of Janus HfSSe bilayer

Janus materials show remarkable and promising applications in the optoelectronic field. Herein, we systematically explored the optical, electronic and structural properties of the Janus bilayer HfSSe through first-principles-based density functional theory calculations. The dynamic stability of Janus bilayer HfSSe is corroborated through phonon dispersion calculations. Bilayer HfSSe exhibited a bandgap of 1.09 eV and showed a high absorption coefficient of 10.8 x 1 0 5 c m − 1 in the visible region. Further, we have also investigated the strain-modulated optical and electronic properties of bilayer HfSSe. Our findings clearly indicate tunable electronic properties of Janus bilayer HfSSe due to direct-to-indirect bandgap transformation upon application of strain and correspondingly, the absorption spectrum shows redshifts under the influence of compressive strain and blueshifts under tensile strain. The absorption coefficient peak value can be tuned in a broad visible light spectrum range from green ( 515 nm ) to violet ( 380 nm ) upon applying in-plane strain. The optical absorption coefficient remained high of the order of 1 0 6 c m − 1 within the visible spectrum. Our findings suggest that the studied bilayer Janus material could be considered for realizing next-generation flexible optoelectronic devices.