Theoretical review of photogenerated carrier dynamics in two-dimensional semiconductors

Two-dimensional (2D) semiconductors, with atomically thin structures, large surface areas, and tunable band structure, have attracted significant attention in optoelectronics, photovoltaics and photocatalysis. The photogenerated carrier dynamics of 2D materials play a pivotal role in determining photovoltaic and photocatalytic efficiencies. However, owing to the complexity of experimental conditions and the diversity of influencing factors, the underlying physical mechanisms governing photogenerated carrier dynamics in 2D semiconductors remain poorly understood. Recent advances in excited-state simulations have opened new avenues for analyzing carrier dynamics at the atomic scale. This review summarizes theoretical progress in understanding the excited-state carrier dynamics of 2D semiconductors, including graphene, black phosphorus, carbonitrides, transition metal dichalcogenides, III-VI compounds, the MoSi₂N₄and CrI₃families. By combining first-principles calculations with time-dependent ab initio density functional theory, we discuss strategies to modulate photogenerated carrier transfer, separation, and recombination through component regulation, environmental effects, molecular functionalization, and defect or interface engineering. Moreover, we outline design principles for high-performance 2D optoelectronic and photocatalytic systems. Finally, we highlight current challenges in exploring photogenerated carrier dynamics of 2D semiconductors, for promoting the design of high-performance optoelectronics, photovoltaic devices and photocatalysts.