Decay time dynamics of red and blue luminescence of surface-functionalized silicon quantum dots

Highlights: • Fabricating the silicon quantum dots (Si QDs) based on chemical methods using HSiCl₃ and SiCl₄. • By using surface functionalization with alkyl and amine groups, the red and the blue emissions are represented from Si QDs. • Observing the significant difference of the luminescence properties between alkyl and amine-functionalized Si QDs. • Time resolved photoluminescence measurement and electronic structure calculation were performed for the study. Controlling the emission wavelength by the quantum confinement or the size effect of silicon quantum dots (Si QDs) has a limitation in that it can be only approximately 600 nm or above. To overcome this limitation, in the recent decade, numerous studies have been conducted for reproducing the entire visible range from blue to red from Si QDs by their surface functionalization. In this study, we fabricated alkyl- and amine-passivated Si QDs and investigated their emission mechanism following surface functionalization. We interpreted the emission mechanism of the surface-functionalized Si QDs by combined experimental analysis of the decay time dynamics and density functional theory-based model calculation of the highest occupied molecular orbital-lowest unoccupied molecular orbital electronic structures. Our comprehensive studies could provide insight into the debated problems of the luminescence mechanism of surface-functionalized Si QDs.