How the Stacking Pattern Influences the Charge Transfer Dynamics of van der Waals Heterostructures: An Answer from a Time-Domain Ab Initio Study.

Abstract

Here, we perform a time domain density functional study in conjunction with a non-adiabatic molecular dynamics (NAMD) simulation to investigate the charge carrier dynamics in a series of van der Waals heterostructures made of two-dimensional (2D) SnX2 (X = S or Se)-supported ZrS2, ZrSe2, and ZrSSe monolayers. Results from NAMD simulation reveal delayed electron-hole recombination (in the range of 0.53-2.13 ns) and ultrafast electron/hole transfer processes (electron transfer within 108.3-321.5 fs and hole transfer between 107.6 and 258.8 fs). The most interesting finding of our study is that switching from AB to AA stacking in the heterostructures extends the carrier lifespan by a significant amount. The delayed electron-hole recombination because of the switching stacking pattern can be rationalized by weak electron-phonon coupling, lower non-adiabatic coupling (NAC), and fast decoherence time. Thus, these insightful NAMD studies of excited charge carriers reveal that the stacking pattern variation is an effective tool to develop efficient photovoltaic devices based on 2D van der Waals heterostructures.