Electron relaxation dynamics to get information on decay time constants of excited state populations are very useful to determine whether the nanoclusters are suitable candidates as sensitizers of solar cells. In this work, Au25(SeCH3)18-, which is thought to be more stable than its thiolate-stabilized counterpart, and [Au13(P2H4C2H4)5Cl2]3+, which has not received much attention from researchers despite being easy to synthesize on a large scale, have been studied theoretically. Time dependent density functional theory (TDDFT) calculations are performed on these systems to study the core and higher excited states up energies of 2.5 eV and 3.5 eV in the selenolate and diphosphine-stabilized systems, respectively. The dynamics of the systems are studied using a surface hopping approach. Six states with excitations ranging from HOMO-2 to LUMO+1 based in the core of the selenolate-stabilized cluster contribute while 25 states from HOMO-4 to LUMO+4 contribute to the core of diphosphine-stabilized system. Electron relaxation among excited states occurs in the range of 2.7 ps to 10.5 ps in the selenolate-stabilized system while the time to repopulate the ground state ranges from 52.8 ps to 117.1 ps. Similarly, decay time constants for the diphosphine-stabilized system lie in the range of 0.5 ps to 20.3 ps and ground state growth times range from 81.6 ps to 375.5 ps.

Theoretical study of nonadiabatic relaxation dynamics in [Au25(SeCH3)18]- and [Au13(P2H4C2H4)5Cl2]3+

2019 Spring National Meeting

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