Doping-mediated excited state dynamics of diphosphine-protected M@Au12 (M = Au, Ir) superatom nanoclusters

Abstract

Doping heterometal atoms into ligand-protected gold superatom nanoclusters (Au_n NCs) is proposed to further diversify their geometrical and electronic structures and enhance their photoluminescence properties, which is attributed to the mixing and effects between atoms. However, the fundamental principles that govern the optoelectronic properties of the doped Au_n NCs remain elusive. Herein, we systematically explored two prototypical 8-electron Au_n (n = 11 and 13) NCs with and without Ir dopant atoms using comprehensive ab initio calculations and real-time nonadiabatic molecular dynamics simulations. These doped Au_n NCs maintain their parent geometrical structures and 8-electron superatomic configuration (1S²1P⁶). Strong core–shell (Ir–Au_n) electronic coupling significantly expands the energy gap, resulting in a weak nonadiabatic coupling matrix element, which in turn increases the carrier lifetime. This increase is mainly governed by the low-frequency vibration mode. We uncovered the relationship between electronic structures, electron–vibration, and carrier dynamics for these doped Au_n NCs. These calculated results provide crucial insights for the atomically precise design of metal NCs with superior optoelectronic properties.