Science | 2019
Atomic packing controls exciton lifetime
Abstract
Nanomaterials\nLike semiconductors, small metallic clusters can absorb light and create excitons (electron-hole pairs). In ligand-capped gold clusters of 30 to 40 atoms (Au30 to Au40) that adopt the usual face-centered cubic packing, the lifetime of these excitons is ∼100 nanoseconds. Zhou et al. found that atomic packing and molecular orbital overlap can greatly affect carrier lifetimes. Despite having similar bandgaps to those of face-centered cubic clusters, a hexagonal close-packed Au30 cluster had a much shorter lifetime (∼1 nanosecond), and a body-centered cubic Au38 cluster had a lifetime of ∼5 microseconds, which is comparable to bulk silicon.\n\nScience , this issue p. [279][1]\n\n [1]: /lookup/doi/10.1126/science.aaw8007