Harnessing Hot Carriers in Two-Dimensional Materials

Hot carriers in semiconductors play a key role in the performance of optoelectronic devices. To successfully design an optimal device with efficiency beyond the Shockley-Queisser limit, a deep understanding of the underlying physics and, more importantly, efficient methods for utilizing photoexcited hot carriers are required. Two-dimensional (2D) materials, such as graphene and transition metal dichalcogenides (TMDs), offer a promising platform for exploring hot carrier generation and utilization due to their unique excitonic properties, high density of states, and ultrafast charge transfer at the 2D interface. This Perspective aims to critically summarize recent advancements of transient spectra on hot carrier harnessing in 2D materials, including hot electron extraction and utilization in graphene and TMD heterostructures as well as multiple exciton generation and transfer in TMDs and black phosphorus (BP). These studies underscore the potential of 2D materials as an excellent platform for harnessing hot carriers and highlight the role of transient spectra in exploring these physical pictures. Additionally, we discuss the challenges and opportunities associated with the efficient and practical use of hot carriers.