Understanding Twist-Angle-Dependent Carrier Lifetimes in MoSSe Bilayer

Two-dimensional (2D) materials with tunable interlayer interactions hold immense potential for optoelectronic and photocatalytic applications. Understanding the dependence of carrier dynamics on twist angle in Janus bilayers is essential, as it directly impacts device efficiency. This study employs time-dependent density functional theory (TD-DFT) and nonadiabatic molecular dynamics (NAMD) to investigate twist-angle-dependent carrier dynamics in Janus MoSSe bilayers with type-II band alignment. Simulations reveal ultrafast charge transfer times of approximately 70 and 500 fs, largely independent of the twist angle due to multiple intermediate states. In contrast, the electron-hole recombination times depend strongly on twist angles, extending up to 133 ns for twisted configurations (21.8° and 38.2°) compared to 57 ns in high-symmetry bilayers (0.0° and 60.0°). Structural randomness in twisted bilayers weakens interlayer interactions, reducing nonadiabatic coupling and coherence time, which collectively prolong carrier lifetimes. These findings offer valuable guidance for designing 2D materials for high-efficiency photovoltaics and long-durable photocatalysts.