Efficient and ultrafast formation of long-lived charge-transfer exciton state in atomically thin cadmium selenide/cadmium telluride type-II heteronanosheets.

摘要: Colloidal cadmium chalcogenide nanosheets with atomically precise thickness of a few atomic layers and size 10-100 nm are two-dimensional (2D) quantum well materials strong confinement in the direction. Despite their many advantageous properties, excitons these other 2D metal short-lived due to large radiative nonradiative recombination rates, hindering applications as light harvesting charge separation/transport for solar energy conversion. We showed that problems could be overcome type-II CdSe/CdTe core/crown heteronanosheets (with CdTe crown laterally extending on CdSe nanosheet core). Photoluminesence excitation measurement revealed nearly all generated domains localized interface form long-lived transfer electrons domain hole domain). By ultrafast transient absorption spectroscopy, we efficient exciton localization efficiency attributed (0.64 ± 0.07 ps), which was facilitated by in-plane mobility competed effectively exiton trapping at or domains. The spatial separation holes across heterojunction suppressed processes, leading state half-life ∼ 41.7 2.5 ns, 30 times longer than core-only nanosheets.