Enhanced Plasmonic Hot-Carrier Transfer in Au/WS2 Heterojunctions under Nonequilibrium Condition

The plasmonic hot-carrier is of great importance in applications of photonharvesting, photocatalysis, and photodetectors. However, the plasmonic hot-carrierharvesting efficiency is limited by their ultrafast thermalization in plasmonic nanostructures.Here, we revealed that the hot-carrier of the gold nanostructure could be captured bymonolayer-WS2before thermalization to enhance the harvesting efficiency. We found thatthe thermalization time of electrons within intraband transition was as long as 600 fs underpumpfluence of 21 mu J/cm2, which was much longer than the charge transfer time of 160 fs,and thus nonthermal electrons could be transferred prior to thermalization. We furtherdemonstrated that the contribution of nonthermal electrons increased with decreasing pumpfluence or increasing lattice temperature. Finally, the decay process of plasmonic hot-carriertransferred into WS2was strikingly different from that of intrinsic carriers in WS2via directphotoexcitation, which is attributed to their different recombination channels. Our resultsprovide insights for microscopic understanding of the nonequilibrium carrier-transfer physicsand will facilitate performance optimization of plasmonic hot-carrier-based optoelectronic devices