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Title: | 表面電漿與激子耦合系統分析及應用 Analysis and Application of Plasmon-Exciton Coupling System |
Authors: | Fu-Cheng Tsai 蔡富程 |
Advisor: | 張培仁(Pei-Zen Chang) |
Co-Advisor: | 施文彬(Wen-Pin Shih),陳育霖(Yu Lim Chen) |
Keyword: | 表面電漿,激子,富勒烯,奈米結構, Plasmon,Exciton,Fullerene,Nanostructure, |
Publication Year : | 2018 |
Degree: | 博士 |
Abstract: | 表面電漿子(plasmon)和激子(exciton)的交互作用會激發出例如:可調變光致發光(tunable photoluminescence)、混合模態共振(hybridized-mode resonance)、高能熱載子(high energetic hot carrier)等不同於材料本身的特性。本論文發展一金奈米結構與富勒烯(fullerene, C60)薄膜構成的複合層結構,探討其產生表面電漿與激子耦合的特殊光學及光電特性。首先我們提出由金奈米結構、富勒烯薄膜、金薄膜而成的三明治共振腔結構,透過光譜儀及橢偏儀等光學儀器量測其電漿子與激子耦合之效應,富勒烯將原本應被局域在金奈米結構表面的電漿子延伸出近場(optical near-field)範圍,並與底下金薄膜的漸逝場(evanescent field)結合形成一長距離的共振現象。此長距離的共振系統可以具有連續及離散的混合振動模態,造成其反射光譜成一非對稱且快速變化的曲線,此非對稱的光譜導致薄膜呈現出飽和的色彩。除此之外,其色彩近似全向,無明顯視角上的色差,在光譜的表現上,±60度內的偏轉在光譜的量測上變化很小。這些優點促使此三明治共振結構應用在反射器、彩色濾光片、感測器以及大面積的顯示器。
而另一部分的研究為探討富勒烯激子對於表面電漿致電效應(plasmoeletric effect)的增強,在10 mW/cm2的紫外光(400 nm)的照射下,其開路電壓可達277毫伏,其轉換效率為單純金奈米顆粒所產生出的數百倍,此一高效率的轉換歸功於富勒烯激子所帶來的效應,透過激子與電漿子的耦合,將表面電漿所形成的熱點(hot spot)帶入富勒烯薄膜裡,由於富勒烯具有超低熱輻射率,在相同強度的光照射下,可以將等校的溫度提升至幾千度,以致輸出電壓大幅提升,這一實驗結果與熱力學理論所預測的結果相當吻合。富勒烯激子將表面電漿效應所產生的電壓提升至可以實際利用的大小,未來可望應用於光催化、光伏元件甚至太陽能電池。 The interaction of surface plasmon and exciton brings the materials performing several non-intrinsic properties, such as tunable photoluminescence, hybridized-mode resonance, and ultrahigh energetic hot-carrier generation. This dissertation focuses on the optical and optoelectronic phenomena of the metallic nanoparticle, fullerene, and their interaction. At the first part, we propose a new structure, a plasmon fullerene cavity, to investigate the plasmon-exciton coupling effect. Fullerene in the plasmon fullerene cavity is utilized to transport plasmon energy in order to break the confinement of the plasmonic coupling effect, which relies on the influential near-field optical region. It acts as a plasmonic inductor for coupling gold nano-islands to the gold film; the separation distances of the upper and lower layers are longer than conventional plasmonic cavities. This coupling effect causes the discrete and continuum states to cooperate together in a cavity and produces asymmetric curve lines in the spectra, producing a hybridized resonance. The effect brings about a bright and saturated displaying film with abundant visible colors. In addition, the reflection spectrum is nearly omnidirectional, shifting by only 5% even when the incident angle changes beyond ±60°. These advantages allow plasmon fullerene cavities to be applied in reflectors, color filters, visible chromatic sensors, and large-area display. For the second part, we report upon the significant plasmoelectric effect obtained through the interaction between fullerene excitons and gold plasmons. Under a UV (400 nm) illumination intensity of 10 mW/cm2, the open-circuit voltage was 277 mV, hundreds of times that produced by single-layer gold nanoparticles. This high-efficiency plasmoelectric effect is attributed to the transport of hot spots into the fullerene film via the coupling between the excitons and plasmons. The effective temperature of these hot spots may reach thousands of kelvins because of the very low emissivity of the fullerene. The measured plasmoelectric potential agrees well with the thermodynamic prediction at thermal equilibrium. This high plasmoelectric potential increases the optoelectronic efficiency of these fullerene films, thus enabling their application to solar cells, photocatalysis, and photovoltaic devices. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/69643 |
DOI: | 10.6342/NTU201801015 |
Fulltext Rights: | 有償授權 |
Appears in Collections: | 應用力學研究所 |
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