Ultrafast hot carrier extraction and diffusion at the MoS2/Au van der Waals electrode interface | Science Advances

Metal electrode deposition is universally adopted in the community for optoelectronic device fabrication, inducing hybridization at electrode interfaces, and allows efficient extraction or injection of photocarriers. However, hybridization-induced midgap states increase photocarrier recombination pathways, creating a paradoxical trade-off. Here, we discovered that efficient photocarrier extraction and a long photocarrier lifetime can be achieved simultaneously in MoS ₂ /van der Waals Au contact, minimizing photocarrier loss at the interface. Using transient reflection spectroscopy, we quantified an ultrafast hole extraction time of 310 femtoseconds and a photocarrier lifetime of 259 picoseconds. Suppressed exciton formation in diffusion measurement validated ultrafast hole extraction. We further revealed a short photocarrier lifetime of ~8.7 picoseconds in deposited contact and negligible hole extraction in unintimate contact with space gap at the interface. We unraveled the hot electron transfer process from Au to MoS ₂ in different contact interfaces. Our results on different metal contact interfaces provide valuable insights into electrode engineering for future optoelectronic devices.