The CuInSe2 quantum dots (QDs) are “green” infrared optoelectronic materials with fruitful optically active point defects, but their roles in photodynamics remain unclear. We observe different types of stoichiometry-sensitive emission bands spanning red-near-infrared region in strongly quantum confined CuInSe2 QDs. The saturation of photoluminescence intensity versus excitation power follows law I ∝ P k with 0.54 < k <0.94 that is characteristic of defect dominated photon emission. The radiative quantum transitions have lifetimes of 15.2–32.0 μs that are far longer than usual interband transition lifetimes by three orders of magnitude. Multiple defects-involved electron transition processes are revealed.

People know little about the characteristics of the photonic crystals (PhCs) made of nanoscale building blocks, which can be quite distinct from the usual PhCs made of microscale or even larger units, because the unit size strongly affects the photonic structure. The PhCs made of fluorescent CuInSe2 quantum dots (QDs) having an ultrasmall average size of 2.2–5.3 nm are studied. The experiments and hybrid density‐functional theory calculation reveal that these QDs have defect‐related fluorescence, and the light absorption exhibits an unexpected indirect‐gap feature because of the discrete and small density of states at the direct‐gap maximum. The frequency‐domain electromagnetic calculations reveal that the PhCs made of the CuInSe2 QDs have a remarkable out‐of‐plane bandgap in the extreme‐UV (EUV) region. The frequency modes below and above the forbidden gap are separately air band and dielectric band modes. These multifunctional fluorescent semiconductor QD PhCs have application potential in nanoscale photonic devices and EUV photolithography.

No abstract

Italian cocklebur (Xanthium italicum Moretti) invades liquorice farmlands, but specific consequences of the invasion remain unclear. Therefore, in this study, we simulated soil fertility levels of liquorice farmlands and performed replacement experiments to compare the relative competition intensity between X. italicum and Chinese liquorice (Glycyrrhiza uralensis), and investigated the differences in the effects of planting patterns (monoculture and mixture) on the growth and reproduction of the two species. Under monoculture treatment, the growth of X. italicum was more than that of G. uralensis. Vegetative and reproductive growth of X. italicum was significantly increased under mixture culture treatment compared to that under monoculture treatment; however, growth and clonal reproduction ability of G. uralensis were significantly suppressed. The biomass and contents of secondary metabolites of G. uralensis were significantly decreased under mixed culture treatment, and rhizome development was completely inhibited after mixed planting with X. italicum. The differences in vegetative growth between the two plants became larger under mixed culture treatment. Therefore, X. italicum exhibited significantly higher competitiveness than G. uralensis when coexisting within a community, and the X. italicum exerted significantly negative effects on the growth, reproduction, nodule development, yield of medicinal materials and contents of medicinal secondary metabolites of G. uralensis.