Near-unity broadband absorption designs for semiconducting nanowire arrays via localized radial mode excitation

Fountaine, Katherine T.; Kendall, Christian G.; Atwater, Harry A.

doi:10.1364/oe.22.00a930

Cited by 96 publications

(94 citation statements)

References 50 publications

(68 reference statements)

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“…These modes are well-defined and well understood. For nanowire arrays, mode identification is less straight forward, due to the introduction of periodicity; absorption enhancements in nanowire arrays have been attributed to both leaky waveguide modes of individual nanowires [19][20][21][22] and photonic crystal Bloch modes. 12,[23][24][25][26] Previous reports have examined a wide variety of array dimensions, nanowire geometries, and illumination angles, which also exhibit varying dominant mode resonances.…”

Section: Introductionmentioning

confidence: 99%

Resonant absorption in semiconductor nanowires and nanowire arrays: Relating leaky waveguide modes to Bloch photonic crystal modes

Fountaine

Whitney

Atwater

2014

Journal of Applied Physics

Self Cite

105

107

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We present a unified framework for resonant absorption in periodic arrays of high index semiconductor nanowires that combines a leaky waveguide theory perspective and that of photonic crystals supporting Bloch modes, as array density transitions from sparse to dense. Full dispersion relations are calculated for each mode at varying illumination angles using the eigenvalue equation for leaky waveguide modes of an infinite dielectric cylinder. The dispersion relations along with symmetry arguments explain the selectivity of mode excitation and spectral red-shifting of absorption for illumination parallel to the nanowire axis in comparison to perpendicular illumination. Analysis of photonic crystal band dispersion for varying array density illustrates that the modes responsible for resonant nanowire absorption emerge from the leaky waveguide modes.

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Section: Introductionmentioning

confidence: 99%

Resonant absorption in semiconductor nanowires and nanowire arrays: Relating leaky waveguide modes to Bloch photonic crystal modes

Fountaine

Whitney

Atwater

2014

Journal of Applied Physics

Self Cite

105

107

View full text Add to dashboard Cite

show abstract

“…View Article Online allows for a simple approximation of the charge generation term, but is unable to accurately quantify the absorbed radiation in non-planar, heterogeneous, and anisotropic absorbers. 24,25 The radiation absorption analysis has to be adapted to account for scattering effects of bubbles and absorption in the electrolyte if the photoabsorber is covered by electrolyte. 26 Once charge carriers are generated, they need to be transported to the interface of the semiconductor so as to participate in the electrochemical reactions.…”

Section: Processes In the Semiconductormentioning

confidence: 99%

Mass transport aspects of electrochemical solar-hydrogen generation

Modestino

Hashemi

Haussener

2016

Energy Environ. Sci.

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The conception of practical solar-hydrogen generators requires the implementation of engineering design principles that allow photo-electrochemical material systems to operate efficiently, continuously and stably over their lifetime. At the heart of these engineering aspects lie the mass transport of reactants, intermediates and products throughout the device. This review comprehensively covers these aspects and ties together all of the processes required for the efficient production of pure streams of solar-hydrogen. In order to do so, the article describes the fundamental physical processes that occur at different locations of a generalized device topology and presents the state-of-the-art advances in materials and engineering approaches to mitigate masstransport challenges. Processes that take place in the light absorber and electrocatalyst components are only briefly described, while the main focus is given to mass transport processes in the boundary-layer and bulk liquid or solid electrolytes. Lastly, a perspective on how engineering approaches can enable more efficient solar-fuel generators is presented. Broader contextSolar-hydrogen generators have the potential to trigger the incorporation of a much larger share of solar energy sources in our current energy landscape. These technologies can directly capture and store energy from the sun in the form of hydrogen molecules. As hydrogen can be transported, and stored for long periods of time, solar-hydrogen devices allow for the spacio-temporal decoupling of the energy generation and consumption processes, and in this way provide a larger flexibility to the electrical grid. While significant focus has been given to the development of photoelectrochemical materials for solar water-splitting, equally important are engineering aspects related to the materials' integration into devices that can operate stably, and produce pure hydrogen streams continuously over long lifetimes. This review provides a broad view on these engineering challenges and approaches to conceive practical solar-hydrogen generators.

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“…These thermal management schemes can be effectively harnessed in catalytically separated and protected photoabsorber devices, where the excess heat from the light-absorption process can be used to enhance the rate of the catalytic processes (29,117). Lastly, radiation management techniques can potentially be used to enhance the radiation absorption in the semiconductor material and increase the STH efficiency (118)(119)(120)(121)(122). These techniques can reduce the use of materials by concentrating the light into the photoactive units of devices, which could result in cost savings for device fabrication.…”

Section: Figurementioning

confidence: 99%

An Integrated Device View on Photo-Electrochemical Solar-Hydrogen Generation

Modestino

Haussener

2015

Annu. Rev. Chem. Biomol. Eng.

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Devices that directly capture and store solar energy have the potential to significantly increase the share of energy from intermittent renewable sources. Photo-electrochemical solar-hydrogen generators could become an important contributor, as these devices can convert solar energy into fuels that can be used throughout all sectors of energy. Rather than focusing on scientific achievement on the component level, this article reviews aspects of overall component integration in photo-electrochemical water-splitting devices that ultimately can lead to deployable devices. Throughout the article, three generalized categories of devices are considered with different levels of integration and spanning the range of complete integration by one-material photo-electrochemical approaches to complete decoupling by photovoltaics and electrolyzer devices. By using this generalized framework, we describe the physical aspects, device requirements, and practical implications involved with developing practical photo-electrochemical water-splitting devices. Aspects reviewed include macroscopic coupled multiphysics device models, physical device demonstrations, and economic and life cycle assessments, providing the grounds to draw conclusions on the overall technological outlook.

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Near-unity broadband absorption designs for semiconducting nanowire arrays via localized radial mode excitation

Cited by 96 publications

References 50 publications

Resonant absorption in semiconductor nanowires and nanowire arrays: Relating leaky waveguide modes to Bloch photonic crystal modes

Resonant absorption in semiconductor nanowires and nanowire arrays: Relating leaky waveguide modes to Bloch photonic crystal modes

Mass transport aspects of electrochemical solar-hydrogen generation

An Integrated Device View on Photo-Electrochemical Solar-Hydrogen Generation

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