title: Abrupt Size Partitioning of Multimodal Photoluminescence Relaxation in Monodisperse Silicon Nanocrystals.
abstract: Intrinsic constraints on efficient photoluminescence (PL) from smaller alkene-capped silicon nanocrystals (SiNCs) put limits on potential applications, but the root cause of such effects remains elusive. Here, plasma-synthesized colloidal SiNCs separated into monodisperse fractions reveal an abrupt size-dependent partitioning of multilevel PL relaxation, which we study as a function of temperature. Guided by theory and simulation, we explore the potential role of resonant phonon interactions with "minigaps" that emerge in the electronic density of states (DOS) under strong quantum confinement. Such higher-order structures can be very sensitive to SiNC surface chemistry, which we suggest might explain the common implication of surface effects in both the emergence of multimodal PL relaxation and the loss of quantum yield with decreasing nanocrystal size. Our results have potentially profound implications for optimizing the radiative recombination kinetics and quantum yield of smaller ligand-passivated SiNCs.
authors.affiliation: North Dakota State University , Fargo, North Dakota 58108, United States.
authors.forename: Samuel L
authors.initials: SL
authors.lastname: Brown
authors.affiliation: North Dakota State University , Fargo, North Dakota 58108, United States.
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Miller
authors.affiliation: University of Minnesota , Minneapolis, Minnesota 55455, United States.
authors.forename: Rebecca J
authors.identifier: 0000-0003-3391-4442
authors.initials: RJ
authors.lastname: Anthony
authors.affiliation: University of Minnesota , Minneapolis, Minnesota 55455, United States.
authors.forename: Uwe R
authors.initials: UR
authors.lastname: Kortshagen
authors.affiliation: North Dakota State University , Fargo, North Dakota 58108, United States.
authors.forename: Andrei
authors.initials: A
authors.lastname: Kryjevski
authors.affiliation: North Dakota State University , Fargo, North Dakota 58108, United States.
authors.forename: Erik K
authors.identifier: 0000-0001-6158-8977
authors.initials: EK
authors.lastname: Hobbie
keywords: photoluminescence; quantum confinement; silicon nanocrystals; surface effects