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Title: | 高效面之上轉換效率:結合上轉換奈米粒子與具有雙曲色散曲線之奈米顆粒之內核-外殼超穎材料 Integration of Uponconversion Nanoparticles and Core-Shell Meta-Structure: An Efficient Platform towards High Uponconversion Efficiency |
Authors: | Ting-Jia Chang 張庭嘉 |
Advisor: | 陳永芳(Yang-Fang Chen) |
Keyword: | 上轉換奈米粒子 超穎材料 奈米光子學, Upconversion nanoparticles,Hyperbolic meta-structure,Nanophotonics, |
Publication Year : | 2020 |
Degree: | 碩士 |
Abstract: | 上轉換奈米粒子可吸收近紅外光而發出可見光,且相對於其他多光子吸收之非線性光學具有更高的能量轉換效率及更低之激發能量。近年來,上轉換奈米粒子被廣泛應用於多種研究應用方面,例如:太陽能電池及生物影像等。然而,其所需的激發能量還是遠高於一般螢光所需。 在此論文中,藉由使用新穎之具有雙曲色散曲線之奈米顆粒之內核-外殼超穎材料,我們發現上轉換粒子的所需激發能量大幅下降,並有顯著提升的發光量。此奈米顆粒之內核-外殼超穎材料由多層球殼結構所組成,其核心材料為金與二氧化矽。此結構具有高度的上轉換效率是因為其背後機制讓持續的耦合效應產生在多層球殼結構之中,並生成顯著的能量進而可提高上轉換粒子的發光。這獨特的性質讓上轉換粒子只需要相當低的能量去激發出短波長的光。 我們對於雙曲色散曲線之超穎材料的研究讓在提高上轉換效率有了一個優異的選擇並在各種上轉換的應用上有了更深的了解。 Upconversion nanoparticles (UCNPs) absorb two and more photons to emit the light covering the whole visible wavelength light under the excitation of near infrared radiation, which is much more effective than other nonlinear optical materials, so that it has been used in a wide range of applications spanning from bio-imaging to solar battery. However, upconversion of photon still requires a relatively high pumping power density (MW/cm²). To circumvent this challenge in this work, by using a newly designed hyperbolic meta structure, namely the core-shell hyperbolic meta-structure decorated UCNPs, we demonstrate that the pumping power density can be drastically reduced and the emission arising from UCNPs can be greatly enhanced. The core-shell hyperbolic meta-structure is composed of the multi-shells with the alternative layers of Au/ SiO2. The underlying mechanism of the observed giant upconversion efficiency arises from the strong coupling effect in between the multi-shells that can generate a pronounced energy to subsequently couple out. Then, the emission of UCNPs is enhanced. This unique characteristic makes the emission of UCNPs only require an ultra-low power density of light illumination with an extremely enlarged emission intensity. Our study therefore provides an excellent alternative for the design of hyperbolic meta-structure with spherical shape and offers a new platform for the enhancement of light emitters, which is very useful for the development of high-performance optoelectronic devices with practical applications covering from solid state lighting to infrared images. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/58727 |
DOI: | 10.6342/NTU202001430 |
Fulltext Rights: | 有償授權 |
Appears in Collections: | 物理學系 |
Files in This Item:
File | Size | Format | |
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U0001-1007202012560600.pdf Restricted Access | 2.11 MB | Adobe PDF |
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