Design of Metallic Nanostructures for Wavelength and Angle Selective Light Management.

nano-optics;plasmonics;photovoltaics;light management;anodized aluminum oxide;Electrical Engineering;Engineering;Electrical Engineering

Roberts, Brian JamesZhong, Zhaohui ;

University of Michigan

关键词: nano-optics;    plasmonics;    photovoltaics;    light management;    anodized aluminum oxide;    Electrical Engineering;    Engineering;    Electrical Engineering;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/113523/brobrts_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Sub-wavelength metal nanoparticles demonstrate a resonant coupling to incident optical fields known as the localized surface plasmon resonance, enabling enhanced absorption, scattering, and nano-focusing of light.In this work, plasmonic properties of metal nanoparticles and nanorods are studied and engineered to realize selective management of incident light as a function of wavelength, angle, and polarization, for application to photovoltaics and selectively transmissive / absorptive systems.For photovoltaics (PV) applications, metal nanoparticle scattering is exploited to realize a wavelength selective backscattering layer.Placed behind a thin film PV absorbing layer, an array of silver nanoparticles backscatters light on resonance while off-resonance light is transmitted, allowing engineering of selective transparency vs. absorption and modulation of photocurrent.Further tuning the array by considering anisotropic particle shape (increasing the aspect ratio),the plasmonic resonance becomes a function of both wavelength and incident angle.We propose employing such a nanorod array to realize an angle selective photovoltaic window for building integration: light normal to the window is off resonance, retaining high transmission and window quality visibility, while angled light, including direct sunlight, is resonantly scattered and harvested for conversion to photocurrent.Optical analysis indicates 20 - 30% improvement in direct sunlight absorption and photocurrent is possible without sacrificing window transparency in the viewing direction.Beyond photovoltaics, we consider integrating angle selective metal nanorods with actuating micro-origami structures to control their orientation with respect to incident light.By tuning the plasmonic and angular properties of the system, we propose a novel method to realize balanced 0 - 90+% transmission modulation of the full visible spectrum for application to adjustable smart glass window coatings, potentially significantly improving on current implementations.Large area patterning of deeply sub-wavelength (10;;s of nm) metal nanorods remains a challenge for traditional nanofabrication techniques.We investigate and describe ways to realize the structures of interest based on the electrochemical synthesis of high aspect ratio self-assembled nanoporous anodized aluminum oxide (AAO) films, including both bottom-up (electroplating) and top-down (reactive ion etching) approaches.Finally, the anisotropic and angle dependent scattering properties of high aspect ratio AAO itself are considered for similar light management applications.