Papers

2025

Large area transparent refractory aerogels with high solar thermal performance ZJ Berquist, AJ Gayle, AM Mañón, V Vogt, KK Yao, V Ramasawmy, … Solar Energy Demonstrates the scalability and durability of high-performing refractory aerogels for solar heat trapping at 600-700 ºC.

2024

Gas-Phase Photocatalytic CO2 Methanation over Ru/TiO2: Effects of Pressure, Temperature, and Illumination AM Ortiz-Ortiz, CS Yim, DO Delgado Cornejo, AJ Gayle, AJ Hill, VA Vogt, … Journal of Chemistry C Photoexcitation of charge carriers in the semiconductor influences the surface coverage of intermediates to drive enhanced methane formation at lower temperatures and pressures.
High-efficiency air-bridge thermophotovoltaic cells B Roy-Layinde, J Lim, C Arneson, SR Forrest, A Lenert, Joule Improves thermophotovoltaic (TPV) efficiency up to 44% at heat source temperatures relevant to energy storage and modular nuclear reactors.
Integrated Air-Bridge Tandem Thermophotovoltaics with High Efficiency over a Broad Heat Source Temperature Range B Roy-Layinde, J Lim, A Lenert, SR Forrest, ACS Energy Letters Describes the fabrication of a dual air-bridge architecture which eliminates the need for tunnel junctions used in conventional tandems.
Molecular design of defect passivators for thermally stable metal-halide perovskite films H Kim, CAF Morales, S Seong, Z Hu, N Muyanja, S Penukula, T Zheng, Z Pizzo, CS Yim, A Lenert, N Rolston, X Gong, Matter Improves thermal stability of perovskite thin films using small molecule additives.

2023

High albedo daytime radiative cooling for enhanced bifacial PV performance H Kim, Y Gao, E Moran, A Howle, S McSherry, S Cira, A Lenert, Nanophotonics Demonstrates a ground reflector with near-unity albedo that can improve thermal management and light harvesting in fielded bifacial PV installations.
Enhanced Photon Utilization in Single Cavity Mode Air-Bridge Thermophotovoltaic Cells J Lim, B Roy-Layinde, B Liu, A Lenert, SR Forrest, ACS Energy Letters Implements an epitaxial buffer layer to mechanically support the suspended semiconductor membrane and enable a single optical cavity mode.
Air-Bridge Cells for Higher Emission Temperatures B Roy-Layinde, A Rahman, J Lim, S Paul, SR Forrest, A Lenert, IEEE 50th Photovoltaic Specialists Conference (PVSC) Theoretical study of air-bridge cells implemented in a range of semiconductor bandgaps for applications in energy storage using thermal batteries.
Transparent Aerogel Materials in Solar Thermal Devices Z Berquist, A Davoodabadi, AM Manon, A Lenert, Annual Review of Heat Transfer Reviews progress in solar transparent aerogel materials and discusses strategies to develop aerogels with a combination of solar transmittance, thermal resistance, and environmental stability for next-generation solar thermal applications.

2022

Semitransparent thermophotovoltaics for efficient utilization of moderate temperature thermal radiation Tobias Burger, Bosun Roy-Layinde, Rebecca Lentz, Zachary J. Berquist, Stephen R. Forrest, and Andrej Lenert, PNAS Demonstrates a semitransparent TPV cell architecture that transmits ~99% of uncollected light, thereby enabling high efficiency.
Geometric defects induced by strain relaxation in thin film oxide superlattices Matthew Webb, Tao Ma, Allen H Hunter, Sean McSherry, Jonathan Kaufman, Zihao Deng, William B Carter, Emmanouil Kioupakis, Keivan Esfarjani, Andrej Lenert, John T Heron, Journal of Applied Physics *Editor’s Pick* Investigates the structure of defects that prevent layer-by-layer growth in epitaxial, low-miscibility oxide superlattices.
Design of a gradient epsilon-near-zero refractory metamaterial with temperature-insensitive broadband directional emission Sean McSherry and Andrej Lenert, Applied Physics Letters *Editor’s Pick* A thermal emitter made from low-miscibility refractory oxides is designed to control the direction of emission over a wide spectral range.
Intermediate temperature exposure regenerates performance and active site dispersion in sintered Pd–CeO2 catalysts AJ Hill, GB Fisher, A Lenert, JW Schwank, Journal of Catalysis Explores how Pd-ceria catalysts evolve during temperature and environmental cycling
Nanophotonic control of thermal emission under extreme temperatures air Sean McSherry, Matthew Webb, Jonathan Kaufman, Zihao Deng, Ali Davoodabadi, Tao Ma, Emmanouil Kioupakis, Keivan Esfarjani, John T Heron, Andrej Lenert, Nature Nanotechnology Press: Optics & Photonics News, Michigan News Research Briefing by Andrej Lenert and John Heron Behind the Paper by Sean McSherry
Air-Bridge Si Thermophotovoltaic Cell with High Photon Utilization Byungjun Lee, Rebecca Lentz, Tobias Burger, Bosun Roy-Layinde, Jihun Lim, R. Matthew Zhu, Dejiu Fan, Andrej Lenert, and Stephen R. Forrest, ACS Energy Letters Implements a scalable air-bridge approach in Si and demonstrates 98% reflectance of below-bandgap photons.
Nexus of solar and thermal photovoltaic technology could help solve the energy storage problem Andrej Lenert, Stephen R. Forrest, Joule Provides context for recent work by MIT and NREL demonstrating >40% TPV efficiency using a tandem cell.
Sustaining efficiency at elevated power densities in InGaAs airbridge thermophotovoltaic cells Bosun Roy-Layinde, Tobias Burger, Dejiu Fan, Byungjun Lee, Sean McSherry, Stephen R. Forrest, Andrej Lenert, Solar Energy Materials and Solar Cells Develops a predictive device model and uses it to design an airbridge cell with improved carrier and thermal management.

2021

Transparent Refractory Aerogels for Efficient Spectral Control in High‐Temperature Solar Power Generation Zachary J. Berquist, Andrew J. Gayle, Neil P. Dasgupta, Andrej Lenert, Advanced Functional Materials, 2021 Demonstrates record-high thermal stability and solar-thermal conversion efficiency among solar selective materials.
Stabilizing Highly Dispersed Halo Sites in Thermally Restructured Palladium Core@Shell Nanoparticles for Improved Catalyst Activity and Durability Alexander J. Hill, Adarsh Bhat, Zachary J. Berquist, Galen B. Fisher, Andrej Lenert, Johannes W. Schwank, ACS Applied Nano Materials, 2021 Identifies the criteria needed to form and stabilize highly dispersed catalytic sites, known as halo sites, in core@shell structures.
Tunable Atomic Layer Deposition into Ultra-High-Aspect-Ratio (>60000:1) Aerogel Monoliths Enabled by Transport Modeling Andrew J. Gayle, Zachary J. Berquist, Yuxin Chen, Alexander J. Hill, Jacob Y. Hoffman, Ashley R. Bielinski, Andrej Lenert, Neil P. Dasgupta, Chemistry of Materials, 2021 Demonstrates tunable control of the ALD infiltration depth into an aerogel monolith and provides a predictive model that enables process design and optimization.

2020

Near-Perfect Photon Utilization in an Air-Bridge Thermophotovoltaic Cell Dejiu Fan, Tobias Burger, Sean McSherry, Byungjun Lee, Andrej Lenert, Stephen R. Forrest, Nature, 2020 Demonstrates incorporation of an air cavity into a thin-film InGaAs cell enabling ~99% reflectance and record-high TPV power conversion efficiency (32%). Press: Chemical & Engineering News, PV magazine
Plasmon-Enhanced Greenhouse Selectivity for High-Temperature Solar Thermal Energy Conversion Zachary J. Berquist, Kevin K. Turaczy, Andrej Lenert, ACS Nano, 2020 Demonstrates plasmonic suppression of reradiation losses in a solar-transparent insulator for use in next-generation solar thermal receivers.
Selectively Enhancing Solar Scattering for Direct Radiative Cooling through Control of Polymer Nanofiber Morphology Hannah Kim, Sean McSherry, Brendon Brown, Andrej Lenert, ACS Applied Materials & Interfaces, 2020 Investigates the scattering and transmission properties of electrospun polyacrylonitrile (PAN) nanofibers with varying morphologies for passive radiative cooling.
Present Efficiencies and Future Opportunities in Thermophotovoltaics Tobias Burger, Caroline Sempere, Bosun Roy Layinde, Andrej Lenert, Joule, 2020 Analyzes the features and limitations of leading TPV approaches. See our Project TPV page for more details.
Extending the thermal near field through compensation in hyperbolic waveguides Sean McSherry, Andrej Lenert, Physical Review Applied, 2020 Investigates the use of a solid-state waveguide that is interposed between a hot and cold object to extend the separation distance at which near-field electromagnetic channels enhance heat transfer.
Thermophotovoltaic Energy Conversion: Materials and Device Engineering Tobias Burger, Caroline Sempere, Andrej Lenert, Nanoscale Energy Transport, 2020. Reviews the development of thermophotovoltaic energy conversion and advancements in materials and fabrication of thermophotovoltaic devices.
Thermally Induced Restructuring of Pd@CeO2 and Pd@SiO2 Nanoparticles as a Strategy for Enhancing Low-Temperature Catalytic Activity Alexander J Hill, Chang Yup Seo, Xiaoyin Chen, Adarsh Bhat, Galen B Fisher, Andrej Lenert, Johannes W Schwank, ACS Catalysis, 2020. Investigates the formation and chemistry of active halo sites within the shell of a core@shell catalyst.

2019

Design of thermophotovoltaics for tolerance of parasitic absorption V. K. Raman, T. Burger, A. Lenert, Optics Express, 2019 Provides guidelines for minimizing the gap between lab and prototype efficiencies of TPV systems by making them more tolerant of parasitic absorption.
Thermal photonics in energy A. Lenert, Y. Zheng, S. Shen, Journal of Photonics for Energy, 2019 Introduces the special issue and highlights recent developments in the field.
Effects of narrowband transport on near-field and far-field thermophotonic conversion S. McSherry, T. Burger, A. Lenert, Journal of Photonics for Energy, 2019 Looks at how near-field electroluminescence enhances the energy flux in solid-state heat engines and which heat engines benefit from near-monochromatic emission.

2018

Thin-film architectures with high spectral selectivity for thermophotovoltaic cells T. Burger, D. Fan, K. Lee, S.R. Forrest, A. Lenert, ACS Photonics, 2018 Proposes strategies for enhancing the spectral selectivity of thin-film III-V thermophotovoltaic cells and evaluates their impact on efficiency.
Optical and thermal filtering nanoporous materials for sub-ambient radiative cooling H. Kim, A. Lenert, Journal of Optics, 2018 Proposes a new approach for radiative cooling to low temperatures using infrared-transparent nanoporous materials, and develops a model for evaluating various structures and material compositions. *Special issue on new materials for nanophotonics
Optically transparent thermally insulating silica aerogels for solar thermal insulation A.A. Gunay, H. Kim, N. Nagarajan, M. Lopez, R. Kantharaj, A. Alsaati, A. Marconnet, A. Lenert, N. Miljkovic, ACS Applied Materials and Interfaces, 2018 Looks at the effects of hydrophobicity of transparent aerogels on solar thermal energy conversion.
Radiative Thermal Runaway Due to Negative-Differential Thermal Emission Across a Solid-Solid Phase Transition David M Bierman, Andrej Lenert, Mikhail A Kats, You Zhou, Shuyan Zhang, Matthew De La Ossa, Shriram Ramanathan, Federico Capasso, Evelyn N Wang, Physical Review Applied, 2018 Shows how a small increase in heat generation (eg, 10 nW/mm2) results in a large change in surface temperature (eg,∼ 35 K), as the thermal emitter switches from high emittance to low emittance.

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