Quantum coherence enhanced carrier lifetime of WS2 nanotubes: A time-domain ab initio study

Abstract

Transition-metal dichalcogenide (TMD) nanotubes with small band gap exhibit higher photocurrent than their layered counterparts [J. H. Smet and Y. Iwasa, Nature (London) 570, 349 (2019); X. Zhou et al., Small 15, 1902528 (2019)], but the mechanism remains unclear. Herein, using ${\mathrm{WS}}_{2}$ as an example, we revealed that the higher photovoltaic effect of the nanotubes originates from the quantum coherence between the band edges in the perspective of photogenerated carrier recombination. By using first-principles calculations and nonadiabatic molecular dynamics simulations, we revealed that small nonadiabatic coupling and short pure-dephasing time improve the photogenerated carrier lifetime and increase the photocurrent of ${\mathrm{WS}}_{2}$ nanotubes. Moreover, an extremum of carrier lifetime in ${\mathrm{WS}}_{2}$ nanotubes is found at a certain diameter, where the nanotube exhibits the longest carrier lifetime. The insights into the high photocurrent of TMD nanotubes may provide ideas for the design of advanced optoelectronic devices.