Ultrafast Photocurrent Detection in Low-Dimensional Materials

Photocurrent generation from photon absorption to electron collection involves various physical processes and reflects the whole life of excited charge carriers. The investigation of photocurrent enables the revelation of fundamental material properties and improvement of electronic device performance. Recently, with the development of ultrafast optics, the time-resolved photocurrent (TRPC) technique is innovated as a photocurrent detection method with a time resolution down to subpicosecond, which allows exploring the ultrafast carrier dynamics and the photodetector intrinsic response highly efficiently. Herein, the advancement of TRPC studies in low-dimensional materials is focused on. First, the TRPC technique is first introduced, including the setup composition and its measurement mechanism, and compared with the conventional transport-based method to demonstrate its uniqueness. Then, the TRPC studies in various low-dimensional materials including 2D graphene, transition metal dichalcogenides and black phosphorus, 1D nanowires, and 0D nanocrystals are discussed, where the originations of their ultrafast photocurrent are analyzed. Finally, an outlook is given on the research prospects of this powerful technique. The TRPC measurement is highlighted as a significant tool to analyze the ultrafast carrier dynamics in the generation of photocurrent and to instruct the structure design of a new generation of ultrafast photodetectors.