Specular side reflectors for high efficiency thermal-to-optical energy conversion

Leroy, Arny; Bhatia, Bikram; Zhao, Lin; Wang, Evelyn N.

doi:10.1364/oe.26.00a462

Cited by 9 publications

(5 citation statements)

References 31 publications

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“…In addition, thanks to the narrowband emission, our HAE‐based STPV can earn 10% efficiency increment compared to the counterpart of broadband emitters (Part III, Supporting Information). Note that in a real system, the unavoidable conduction loss through the absorber/emitter's holder and the nonideal view factor of emitter would introduce extra heat loss, leading to the currently low system efficiency of no more than 10% . Our HAE‐based cage‐type STPV system can provide a feasible route to essentially increase this efficiency limit.…”

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confidence: 99%

Hybrid Solar Absorber–Emitter by Coherence‐Enhanced Absorption for Improved Solar Thermophotovoltaic Conversion

Wang

Lin

Zhang

et al. 2018

Advanced Optical Materials

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etc. In order to maximize the utilization of solar energy, STPV requires the cooperative spectral manipulation of a broadband solar absorber and a narrowband infrared emitter. An ideal STPV absorber must simultaneously absorb input power and suppress radiation loss, while an STPV emitter should possess high emissivity only at the target infrared wavelength matching well with the base PV cell. [9] Extensive efforts have been devoted to design and fabricate such absorbers and emitters, including intrinsically spectrally selective materials, [10][11][12] multilayer structures, [13][14][15][16][17] cermets, [18] plasmonic metamaterials, [19][20][21][22][23][24][25][26] and photonic crystals. [27][28][29][30][31] Up to now, most of the reported absorbers and emitters are demonstrated by two isolated structures, [1,2] such as the compound metallic structures patterned on both sides of a substrate in a recently developed STPV system. [30] Such an optical design is intuitive and straightforward. However, the double-side lithography process severely increases the fabrication and systematic complexity. A hybrid absorber-emitter (HAE) with the two functions built on the same surface of the structure is beneficial for STPV. Great efforts have been made to integrate these two functionalities of broadband-absorption and narrowband-emission into one metasurface or plasmonic structure. [32][33][34] However, these structures are rather complicated and the well-defined morphologies are unstable at high temperature that the STPV system requires. An integrated HAE with ideal spectral selectivity, high temperature tolerance as well as scalable fabrication process is highly pursued but still elusive.Most specifically, in this work, we present a much simpler HAE design of a layered structure on a metallic surface based on multiple coherence-enhanced absorption, especially the coherent perfect absorption (CPA) effect. Such a structure is lithography-free, scalable, and possesses excellent thermal stability. In addition, the full spectrum responses demonstrate weak angular-dependence and polarization sensitivity, all of which make it beneficial for the STPV applications.The CPA phenomenon was first proposed for the case that two coherent counter-propagating light beams can be totally absorbed in a dielectric Fabry-Pérot cavity, [35][36][37] which was Spectrum selective absorbers and emitters, with advantages of high temperature tolerance, wide angle insensitivity, and scalable fabrication processes, are crucial components for solar thermophotovoltaics (STPV). A bifunctional hybrid absorber-emitter (HAE) for efficient STPV by sequentially depositing HfO 2 /Mo/HfO 2 films on a metallic surface is demonstrated here. Simultaneous broadband solar absorption and narrowband infrared emission are enabled by the same surface of the structure. By fine steering coherent perfect absorption of the ultrathin Mo film and destructive interference of interfacial reflections across the top HfO 2 layer, the HAE exhibits a measured emissivity of 0.97 at 1.8...

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confidence: 99%

Hybrid Solar Absorber–Emitter by Coherence‐Enhanced Absorption for Improved Solar Thermophotovoltaic Conversion

Wang

Lin

Zhang

et al. 2018

Advanced Optical Materials

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“…However, the design of optical cavities for STPV systems has rarely been studied, despite the fact that optical cavities can be used to increase the system efficiency, photon recycling (also known as photon recuperation or regenerative TPV [35]), and emitter-to-cell effective view factor [37], [38]. Optical cavities can be made using durable and relatively inexpensive mirror-polished metallic surfaces that direct the radiation from the emitter toward the TPV cell [39]. Sansoni et al [40] evaluated a combustion-based TPV system in a tubular optical cavity with an elliptical cross-section.…”

Section: Ellipsoidal Optical Cavities For Enhanced Thermophotovoltaicsmentioning

confidence: 99%

Ellipsoidal Optical Cavities for Enhanced Thermophotovoltaics

Talebzadeh

Pirvaram

O’Brien

2022

IEEE J. Photovoltaics

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Herein we present an optical cavity in the form of a prolate ellipsoid that can greatly enhance the performance of solar thermophotovoltaic (STPV) systems. The geometrical parameters of the cavity can be designed to control the degree of photon recycling, the temperature of the emitter within the STPV system, gap distance and effective view factor between the PV cell and the emitter, and to minimize the emission losses. Numerical analysis shows the ellipsoidal optical cavity can be designed to achieve an effective view factor of 88.7% between the emitter and PV cell within a STPV system. Results show an efficiency of 5.62% in a STPV system with a GaSb PV cell and a black-body emitter under solar radiation at a concentration factor of 350X. Further, assuming the surface of the ellipsoidal optical cavity is capable of reflecting 99% of the radiation incident onto its surface, efficiencies of 15.54% can be attained when the solar concentration factor is 1400X. These results are attained for STPV systems without using selective absorbers, emitters or filters. The ellipsoidal optical cavity can be integrated into the design of advanced TPV systems and bring them closer to the high theoretical efficiencies TPV systems are capable of.

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“…[47][48][49][50] Optical cavities can be fabricated using robust and relatively low-cost mirror-polished metallic surfaces that reflect emitted radiation toward the PV cell. [51][52][53] In the previous work, we performed numerical analysis to show the potential of using a prolate spheroid optical cavity in STPV systems. 54 Results showed a solar-to-electric power conversion efficiency of 15.5% could be achieved in an STPV system comprising an optical cavity under concentrated sunlight (1400X).…”

Section: Introductionmentioning

confidence: 99%

“…However, optical cavities for STPV systems have rarely been investigated, regardless of the fact that they can increase photon recycling and the emitter-to-cell effective view factor 47 – 50 Optical cavities can be fabricated using robust and relatively low-cost mirror-polished metallic surfaces that reflect emitted radiation toward the PV cell 51 – 53 In the previous work, we performed numerical analysis to show the potential of using a prolate spheroid optical cavity in STPV systems 54 .…”

Section: Introductionmentioning

confidence: 99%

Spheroid-based optical cavities for tunable photon recycling and emitter temperature control in robust solar thermophotovoltaic systems

Talebzadeh

O’Brien

2023

J. Photon. Energy

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.The theoretical efficiency of solar thermophotovoltaic (STPV) systems is much greater than their efficiencies achieved in practice. Optical cavities can improve the performance of STPV systems by increasing the emitter-to-PV cell view factor and by facilitating photon recycling, whereby photons are reflected back to the emitter. Photon recycling reduces losses and increases the temperature of the emitter, thereby increasing efficiency. Our study presents STPV systems comprising optical cavities in the form of oblate and prolate spheroids. The geometry of the optical cavity can be tuned to control the degree of photon recycling, emitter temperature, emission losses, and the emitter-to-PV cell effective view factor and separation distance without using complex nano- or microstructured materials or optical filters. Numerical analysis shows an optical cavity in the form of a prolate spheroid, prolate spheroid with a middle annular aperture specular reflector, and integrated oblate- and prolate-spheroid can be used to achieve efficiencies of 17.7%, 18.9%, and 22%, respectively, under solar irradiation at a concentration factor of 1500X. These robust spheroid-based optical cavities can be used to design improved STPV systems with increased durability and higher performance.

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Specular side reflectors for high efficiency thermal-to-optical energy conversion

Cited by 9 publications

References 31 publications

Hybrid Solar Absorber–Emitter by Coherence‐Enhanced Absorption for Improved Solar Thermophotovoltaic Conversion

Hybrid Solar Absorber–Emitter by Coherence‐Enhanced Absorption for Improved Solar Thermophotovoltaic Conversion

Ellipsoidal Optical Cavities for Enhanced Thermophotovoltaics

Spheroid-based optical cavities for tunable photon recycling and emitter temperature control in robust solar thermophotovoltaic systems

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