Andrej Lenert
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View article: High albedo daytime radiative cooling for enhanced bifacial PV performance
High albedo daytime radiative cooling for enhanced bifacial PV performance Open
We present a radiative cooling material capable of enhancing albedo while reducing ground surface temperatures beneath fielded bifacial solar panels. Electrospinning a layer of polyacrylonitrile nanofibers, or nanoPAN, onto a polymer-coate…
View article: Opportunities for mesoporous silica aerogels in parabolic trough collectors
Opportunities for mesoporous silica aerogels in parabolic trough collectors Open
There has recently been a renewed interest in mesoporous silica as an insulation material for use in linear concentrated solar receivers, but there has not yet been an evaluation of their performance in next-generation receiver designs. He…
View article: Internally-heated thermal and externally-cool photovoltaic cascade solar energy system for full solar spectrum utilization
Internally-heated thermal and externally-cool photovoltaic cascade solar energy system for full solar spectrum utilization Open
A single-stack, solar power receiver comprising both a thermal absorber layer and a photovoltaic cell layer. The stack includes an aerogel layer, that is optically transparent and thermally insulating ("OTTI"); a spectrally selective high …
View article: Spectrally-engineered solar thermal photovoltaic devices
Spectrally-engineered solar thermal photovoltaic devices Open
A solar thermal photovoltaic device, and method of forming same, includes a solar absorber and a spectrally selective emitter formed on either side of a thermally conductive substrate. The solar absorber is configured to absorb incident so…
View article: Semitransparent thermophotovoltaics for efficient utilization of moderate temperature thermal radiation
Semitransparent thermophotovoltaics for efficient utilization of moderate temperature thermal radiation Open
Recent advances in thermophotovoltaic (TPV) power generation have produced notable gains in efficiency, particularly at very high emitter temperatures. However, there remains substantial room for improving TPV conversion of waste, solar, a…
View article: Geometric defects induced by strain relaxation in thin film oxide superlattices
Geometric defects induced by strain relaxation in thin film oxide superlattices Open
Functional thin film superlattices with stability in extreme environments can lead to transformative performance in optical and thermal applications such as thermophotovoltaics. In this work, key issues associated with defects that prevent…
View article: High-Temperature Linear Receiver Enabled by Multicomponent Aerogels
High-Temperature Linear Receiver Enabled by Multicomponent Aerogels Open
Concentrating solar thermal (CST) technology has significant potential mainly due to its dispatchability and low cost of storage. However, to compete with other sources, including utility-scale solar PV, its final cost (cents/kWh) still ne…
View article: Transparent Refractory Aerogels for Efficient Spectral Control in High‐Temperature Solar Power Generation
Transparent Refractory Aerogels for Efficient Spectral Control in High‐Temperature Solar Power Generation Open
Although spectrally selective materials play a key role in existing and emerging solar thermal technologies, temperature‐related degradation currently limits their use to below 700 °C in vacuum and even lower temperatures in air. Here a so…
View article: Stabilizing Highly Dispersed Halo Sites in Thermally Restructured Palladium Core@shell Nanoparticles for Improved Catalyst Activity and Durability
Stabilizing Highly Dispersed Halo Sites in Thermally Restructured Palladium Core@shell Nanoparticles for Improved Catalyst Activity and Durability Open
Stabilizing high dispersions of catalytically active metals is integral to improving the lifetime, activity, and material utilization of catalysts that are periodically exposed to high temperatures during operation or maintenance. We have …
View article: Stabilizing Highly Dispersed Halo Sites in Thermally Restructured Palladium Core@shell Nanoparticles for Improved Catalyst Activity and Durability
Stabilizing Highly Dispersed Halo Sites in Thermally Restructured Palladium Core@shell Nanoparticles for Improved Catalyst Activity and Durability Open
Stabilizing high dispersions of catalytically active metals is integral to improving the lifetime, activity, and material utilization of catalysts that are periodically exposed to high temperatures during operation or maintenance. We have …
View article: Sustaining Efficiency at Elevated Power Densities with InGaAs Air Bridge Cells
Sustaining Efficiency at Elevated Power Densities with InGaAs Air Bridge Cells Open
Here we investigate the use of single-junction InGaAs airbridge cells (ABCs) at elevated power densities. Such conditions are relevant to many thermophotovoltaic (TPV) applications, ranging from space to on-demand renewable electricity, an…
View article: Enabling Highly Efficient Solar Thermal Generation with 800{\deg}C-Stable Transparent Refractory Aerogels
Enabling Highly Efficient Solar Thermal Generation with 800{\deg}C-Stable Transparent Refractory Aerogels Open
Although spectrally selective materials play a key role in existing and emerging solar thermal technologies, temperature-related degradation currently limits their use to below 700C in vacuum, and even lower temperatures in air. Here we de…
View article: Enabling Highly Efficient Solar Thermal Generation with 800°C-Stable Transparent Refractory Aerogels
Enabling Highly Efficient Solar Thermal Generation with 800°C-Stable Transparent Refractory Aerogels Open
Although spectrally selective materials play a key role in existing and emerging solar thermal technologies, temperature-related degradation currently limits their use to below 700C in vacuum, and even lower temperatures in air. Here we de…
View article: Tunable Atomic Layer Deposition into Ultra-High-Aspect-Ratio (>60000:1) Aerogel Monoliths Enabled by Transport Modeling
Tunable Atomic Layer Deposition into Ultra-High-Aspect-Ratio (>60000:1) Aerogel Monoliths Enabled by Transport Modeling Open
Atomic layer deposition (ALD) modification of ultra-high-aspect-ratio structures (>10,000:1) is a powerful platform with applications in catalysis, filtration, and energy conversion. However, the deposition of conformal and tunable ALD coa…
View article: Robust and Spectrally Selective Aerogels for Solar Receivers
Robust and Spectrally Selective Aerogels for Solar Receivers Open
The development of next generation concentrated solar thermal (CST) plants requires solar receivers to reach high temperatures (> 600°C) while minimizing costs. Efficiently generating such high temperatures using a line-focusing collector …
View article: Robust and Spectrally Selective Aerogels for Solar Receivers (Final Technical Report)
Robust and Spectrally Selective Aerogels for Solar Receivers (Final Technical Report) Open
The development of next generation concentrated solar thermal (CST) plants requires solar receivers to reach high temperatures (> 600°C) while minimizing costs. Efficiently generating such high temperatures using a line-focusing collector …
View article: Plasmon-Enhanced Greenhouse Selectivity for High-Temperature Solar Thermal Energy Conversion
Plasmon-Enhanced Greenhouse Selectivity for High-Temperature Solar Thermal Energy Conversion Open
The greenhouse effect arises when thermal radiation is forced to undergo absorption and re-emission many times before escaping, while sunlight transmits largely unimpeded. Although this effect is responsible for global warming, it is gener…
View article: Extending the Thermal Near Field Through Compensation in Hyperbolic Waveguides
Extending the Thermal Near Field Through Compensation in Hyperbolic Waveguides Open
A promising method to leverage near-field power densities without the use of\nnanoscale vacuum gaps is through hyperbolic metamaterial (HMM) waveguides. When\nplaced between a hot and cold reservoir, an ideal HMM can transmit surface\nwave…
View article: Design of thermophotovoltaics for tolerance of parasitic absorption
Design of thermophotovoltaics for tolerance of parasitic absorption Open
With advances in thermophotovoltaic (TPV) cells enabling recycling of sub-bandgap photons, a key barrier to reaching high prototype efficiencies has become radiative losses to parasitic high-emissivity regions, such as heavily doped contac…
View article: Special Section Guest Editorial: Thermal Photonics in Energy
Special Section Guest Editorial: Thermal Photonics in Energy Open
The Journal of Photonics for Energy (JPE) covers fundamental and applied research areas focused on the applications of photonics for renewable energy harvesting, conversion, storage, distribution, monitoring, consumption, and efficient usa…
View article: Radiative Thermal Runaway Due to Negative-Differential Thermal Emission Across a Solid-Solid Phase Transition
Radiative Thermal Runaway Due to Negative-Differential Thermal Emission Across a Solid-Solid Phase Transition Open
Thermal runaway occurs when a rise in system temperature results in heat-generation rates exceeding dissipation rates. In this work, we demonstrate that thermal runaway occurs in radiative (photon) systems given a sufficient level of negat…
View article: Radiative Thermal Runaway Due to Negative-Differential Thermal Emission Across a Solid-Solid Phase Transition
Radiative Thermal Runaway Due to Negative-Differential Thermal Emission Across a Solid-Solid Phase Transition Open
Thermal runaway occurs when a rise in system temperature results in heat-generation rates exceeding dissipation rates. Here, we demonstrate that thermal runaway occurs in radiative (photon) systems given a sufficient level of negative-diff…
View article: Spectral splitting optimization for high-efficiency solar photovoltaic and thermal power generation
Spectral splitting optimization for high-efficiency solar photovoltaic and thermal power generation Open
Utilizing the full solar spectrum is desirable to enhance the conversion efficiency of a solar power generator. In practice, this can be achieved through spectral splitting between multiple converters in parallel. However, it is unclear wh…
View article: Temperature dependence of thermopower in molecular junctions
Temperature dependence of thermopower in molecular junctions Open
The thermoelectric properties of molecular junctions are of considerable interest due to their promise for efficient energy conversion. While the dependence of thermoelectric properties of junctions on molecular structure has been recently…
View article: Nanoengineered Surfaces for Thermal Energy Conversion
Nanoengineered Surfaces for Thermal Energy Conversion Open
We provide an overview of the impact of using nanostructured surfaces to improve the performance of solar thermophotovoltaic (STPV) energy conversion and condensation systems. We demonstrated STPV system efficiencies of up to 3.2%, compare…
View article: Nanoengineered Surfaces for Thermal Energy Conversion
Nanoengineered Surfaces for Thermal Energy Conversion Open
We provide an overview of the impact of using nanostructured surfaces to improve the performance of solar thermophotovoltaic (STPV) energy conversion and condensation systems. We demonstrated STPV system efficiencies of up to 3.2%, compare…
View article: Ultrathin planar hematite film for solar photoelectrochemical water splitting
Ultrathin planar hematite film for solar photoelectrochemical water splitting Open
Hematite holds promise for photoelectrochemical (PEC) water splitting due to its stability, low-cost, abundance and appropriate bandgap. However, it suffers from a mismatch between the hole diffusion length and light penetration length. We…