We investigate the shift current in two-dimensional (2D) Janus transition-metal dichalcogenides (TMDs). The shift current is evaluated using a real-time approach, where the coupling with an external field is described in terms of a dynamical Berry phase. This methodology incorporates electron-hole interactions and quasiparticle band structure renormalization through an effective Hamiltonian derived from many-body perturbation theory. We find that the shift current is strongly enhanced in correspondence with C excitons. An analysis in terms of the electron-hole pairs reveals that electron and hole are localized on different atoms, and thus, following an optical excitation, the center of the electron charge is displaced, giving rise to a significant photocurrent. Janus TMDs, with their intrinsic out-of-plane asymmetry and tunable electronic properties, are particularly appealing for next-generation optoelectronic and energy-harvesting technologies. These results highlight the role of excitons in the shift-current response of Janus TMDs and demonstrate their potential as promising building blocks for future photovoltaic devices.
@article{arxiv.2506.16067,
title = {Shift current in 2D Janus Transition-Metal Dichalcogenides: the role of excitons},
author = {Yuncheng Mao and Ju Zhou and Myrta Grüning and Claudio Attaccalite},
journal= {arXiv preprint arXiv:2506.16067},
year = {2025}
}