The shift current effect, in materials lacking inversion symmetry, may potentially allow the performance of photovoltaics to surpass the Shockley-Queisser limit for traditional p-n junction-based photovoltaics. Although the shift-current effect has been studied from first-principles via second-order perturbation theory, an understanding of the dynamics of hot carriers is still lacking. We investigate the dynamics of the shift current in monolayer WS2 via real-time propagation time-dependent density functional theory (rt-TDDFT). We find that the shift current can be generated within 10 - 20 fs after turning on the lights and dissipates within approximately a few tens of femtoseconds after turning off the lights. This property can be used for ultrafast photon detection. This work provides an important step toward understanding the dynamics of shift-current effects, which is crucial for device applications.
@article{arxiv.2207.03772,
title = {Ultrafast shift current dynamics in WS$_{2}$ monolayer},
author = {Fuxiang He and Xinguo Ren and Sheng Meng and Lixin He},
journal= {arXiv preprint arXiv:2207.03772},
year = {2022}
}