Charge Separation and Recombination in Two-Dimensional MoS2/WS2: Time-Domain ab Initio Modeling

Abstract

With applications in high performance electronics, photovoltaics and catalysis, two-dimensional transition metal dichalcogenides (TMDs) attract strong attention. Isolated TMDs, which are already remarkably complex, can stack in sequence to make even more complex heterostructures. Surprisingly, charge separation is ultrafast in layered TMD heterostructures, even though the interlayer interaction is weak. Also surprisingly, the charge separated state is long-lived, despite the close proximity of electron and hole. Using real-time time-dependent density functional theory combined with nonadiabatic (NA) molecular dynamics, we model hole and electron transfer, and electron–hole recombination at a MoS2/WS2 heterojunction. Hole transfer is ultrafast, in excellent agreement with the experiment, due to significant delocalization of the photoexcited state between the donor and acceptor materials. Electron transfer is 1 order of magnitude longer, due to weaker donor–acceptor and NA couplings, lower density of accept...