Browsing by Subject "quantum dots"

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    Light Management Strategies for Luminescent Solar Concentrators
    (2018-09) Pinnell, Christian
    This thesis explores three light management strategies for luminescent solar concentrators (LSCs). LSCs are concentrating photovoltaic systems in which luminophores are embedded within a polymer slab. Incident sunlight is absorbed by the luminophores, which then fluoresce. Fluorescent light is trapped within the polymer slab via total internal reflection and propagates to the edge of the slab where it is collected by solar cells. The first light management strategy uses wavelength-selective mirrors placed above the top surface of the concentrator to trap fluorescent light while transmitting sunlight in to be absorbed. Two mirrors are designed, and their performance is simulated when placed above a variety of LSCs. LSC parameters such as lateral size, quantum yield, and luminophore concentration were varied to study the effects of LSC design on top mirror design. The second strategy involves the use of multiple LSC layers for spectrum splitting. High energy light is absorbed by the top layer with minimal thermalization, while lower energy light is transmitted into the bottom layer, where it is absorbed. A multijunction LSC is modeled and its performance is simulated. Coupling effects between top and bottom layer performance are evaluated. Finally, the thin film architecture is considered, where a thin luminophore-quantum dot layer is deposited onto a glass substrate. A wave optics model is used to determine the effects of this architecture on luminophore emission and reabsorption. The performance of these LSCs are found to be superior to bulk polymer LSCs. Thin film LSCs are realized experimentally by synthesizing quantum dots and depositing a quantum dot-polymer layer onto a glass substrate. The optical properties of the quantum dots in solution and in the LSC are characterized and the light guiding properties of the thin film LSC are measured.
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    Supporting data for "Direct tracking of pollen with quantum dots reveals surprising uniformity in dispersal distance across eleven populations of an annual plant"
    (2023-06-01) Kern, Brooke R; Carley, Lauren N; Moeller, David A; kern0193@umn.edu; Kern, Brooke R
    Pollen movement is a crucial component of dispersal in seed plants. We used quantum dot pollen labeling, a new technique that overcomes past limitations, to evaluate the spatial scale of pollen dispersal and its relationship with conspecific density within eleven populations of Clarkia xantiana ssp. xantiana, a bee pollinated, annual plant. We used experimental arrays in two years to track pollen movement across distances of 5 – 35 m within nine populations and across distances of 10 – 70 m within two additional populations. We tested for distance decay of pollen dispersal and whether conspecific density modulated dispersal distance. We also asked whether dispersal kernels varied among populations across an environmentally complex landscape. We did not observe a decline in labeled pollen receipt with distance over 35 m within eight of nine populations or over 70 m within either of two populations. Pollen receipt increased with conspecific density. Overall, dispersal kernels were consistent across populations.