Atomically thin transition-metal dichalcogenides (TMDs) exhibit strong light–matter interaction and pronounced excitonic behavior. Understanding the nonequilibrium dynamical processes of photoexcited carriers in such materials is a key step in view of their technological applications. Here, we review the ultrafast photophysics of 2D TMDs and related heterostructures (HSs) measured by femtosecond optical spectroscopy. First, we provide a general introduction on the physics of the materials and a brief explanation of the ultrafast optical techniques. Then we discuss the physical processes governing their nonequilibrium optical response, with a particular emphasis on the intervalley scattering dynamics, and the charge-transfer processes in 2D HSs. We conclude by discussing open issues and perspectives for future experiments.

原子上较薄的过渡金属二硫键（TMD）表现出很强的光-物质相互作用和明显的激子行为。鉴于此类材料的技术应用，了解此类材料中光激发载体的非平衡动力学过程是关键的一步。在这里，我们回顾了飞秒光谱学测量的二维TMD和相关异质结构（HSs）的超快光物理。首先，我们对材料的物理特性进行了一般性介绍，并对超快光学技术作了简要说明。然后，我们讨论了控制其非平衡光学响应的​​物理过程，特别着重于间隔间隔散射动力学以及二维HS中的电荷转移过程。最后，我们讨论了开放的问题和未来实验的观点。