Unveiling ultrafast carrier dynamics in photocatalytic 2-D heterostructures: insights from first-principles and nonadiabatic molecular dynamics

Abstract

The ultrafast carrier dynamics in 2-D heterostructures is crucial for photocatalytic performance during clean energy production while designing it rationally is a challenge. Herein, we combine first-principles calculations with nonadiabatic molecular dynamics (NAMD) methods to unravel ultrafast carrier dynamics in two novel 2-D heterostructures, GaN/SnS₂ and GaN/HfS₂, to explore the rational design methods of ultrafast carrier dynamics. Despite the similar electronic ground-state properties of the two heterostructures, NAMD simulations reveal significant differences in their ultrafast carrier dynamics. The GaN/SnS₂ heterostructure exhibits faster interlayer carrier recombination and slower interlayer electron transfer rate compared to the GaN/HfS₂ heterostructure. The in-depth study reveals that carrier dynamics is related to nonadiabatic coupling elements (NACs). Charges distributed at the interface of the heterostructure and highly delocalized wavefunctions facilitate strong NACs, thereby accelerating interlayer carrier recombination. Conversely, weak NACs, resulting from large energy level differences, delay the transfer of photogenerated electrons. This work reveals the influencing factors of ultrafast carrier dynamics in 2-D heterostructures and provides theoretical guidance for the rational design of high-performance 2-D photocatalytic heterostructures for renewable energy applications.