TY - JOUR A1 - Policht, Veronica R. A1 - Mittenzwey, Henry A1 - Dogadov, Oleg A1 - Katzer, Manuel A1 - Villa, Andrea A1 - Li, Qiuyang A1 - Kaiser, Benjamin A1 - Ross, Aaron M. A1 - Scotognella, Francesco A1 - Zhu, Xiaoyang A1 - Knorr, Andreas A1 - Selig, Malte A1 - Cerullo, Giulio A1 - Dal Conte, Stefano T1 - Time-domain observation of interlayer exciton formation and thermalization in a MoSe2/WSe2 heterostructure JF - Nature Communications N2 - Vertical heterostructures of transition metal dichalcogenides (TMDs) host interlayer excitons with electrons and holes residing in different layers. With respect to their intralayer counterparts, interlayer excitons feature longer lifetimes and diffusion lengths, paving the way for room temperature excitonic optoelectronic devices. The interlayer exciton formation process and its underlying physical mechanisms are largely unexplored. Here we use ultrafast transient absorption spectroscopy with a broadband white-light probe to simultaneously resolve interlayer charge transfer and interlayer exciton formation dynamics in a MoSe2/WSe2 heterostructure. We observe an interlayer exciton formation timescale nearly an order of magnitude (~1 ps) longer than the interlayer charge transfer time (~100 fs). Microscopic calculations attribute this relative delay to an interplay of a phonon-assisted interlayer exciton cascade and thermalization, and excitonic wave-function overlap. Our results may explain the efficient photocurrent generation observed in optoelectronic devices based on TMD heterostructures, as the interlayer excitons are able to dissociate during thermalization. Y1 - 2023 U6 - https://doi.org/10.1038/s41467-023-42915-x VL - 14 SP - 1 EP - 9 PB - Springer Nature ER -