Article
Thermodynamics
Jihong Zhang, Bo Wang, Congying Li, Xiyuan Li
Summary: In this study, a theoretical enhancement of near-field thermal radiation between stacked arrangement of graphene sheet and Bi2Se3 slab is reported, due to the coupling of hyperbolic phonon polaritons and surface plasmon polaritons. It is found that tuning the chemical potential of graphene and the thickness of Bi2Se3 film can efficiently modulate the near-field thermal radiation, which may be helpful for microscale and nanoscale energy saving and radiative cooling applications.
CASE STUDIES IN THERMAL ENGINEERING
(2021)
Article
Materials Science, Multidisciplinary
Fuwei Yang, Bai Song
Summary: Twisted bilayer graphene (TBLG) is a versatile platform for studying various transport phenomena. In this study, it is found that thermal flow is suppressed near the magic angle, with greater suppression at lower temperatures and larger gaps. When the chemical potential lies in the energy gap, over 100-fold heat-flow variation can be achieved within a small twist angle. By reducing the electron scattering rate, the radiation spectrum near the magic angle dramatically narrows, leading to over 10,000-fold suppression.
MATERIALS TODAY PHYSICS
(2022)
Article
Multidisciplinary Sciences
Ruiyi Liu, Lixin Ge, Biyuan Wu, Zheng Cui, Xiaohu Wu
Summary: This study demonstrates the excellent near-field radiative heat transfer of monolayer topological insulator (Bi2Se3) and discovers the non-monotonic dependence of the Fermi energy of Bi2Se3 on heat transfer. It indicates that great thermal adjustability can be achieved by controlling the Fermi energy of the system. The research also explores the effect of substrate on the near-field radiative heat transfer.
Article
Thermodynamics
Ziqi Yu, Xiaopeng Li, Taehwa Lee, Hideo Iizuka
Summary: The study demonstrates that significant enhancement of heat transfer can be achieved by introducing multilayer Weyl semimetals and simultaneously modulating rotation and material loss. By tuning the rotation angle and off-diagonal components of the permittivity tensor in the multilayer system, optimal heat transfer enhancement can be realized.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Chemistry, Physical
Jihong Zhang, Haotuo Liu, Bing Yang, Yang Hu, Yasong Sun, Xiaohu Wu
Summary: Epsilon-near-zero (ENZ) materials exhibit exotic optical characteristics and have attracted significant research interest recently. This study investigates the ENZ characteristics in near-field radiative heat transfer (NFRHT) and finds that NFRHT is greatly enhanced near specific frequencies.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Nanoscience & Nanotechnology
Saman Zare, Ramin Pouria, Philippe K. Chow, Tom Tiwald, Carl P. Tripp, Sheila Edalatpour
Summary: In this study, we experimentally demonstrate the thermal emission of transverse and longitudinal modes from 6H-SiC nanopillars in near-field distance. We show that the spectral locations of these modes can be greatly influenced by the near-field coupling between neighboring nanopillars and the intercoupling of the nanopillars and the substrate. Moreover, we find that the spectrum of near-field thermal radiation from the nanopillar arrays can be tuned by varying the dimensions of the nanopillars, enabling the design of emitters with tailored near-field thermal radiation.
Article
Nanoscience & Nanotechnology
Saman Zare, Ramin Pouria, Philippe K. Chow, Tom Tiwald, Carl P. Tripp, Sheila Edalatpour
Summary: This study experimentally explores the thermal emission mechanism of polaritonic materials' localized surface phonons (LSPhs) in nanostructures, revealing that the dimensions of the nanostructure can tune the spectral position of the narrow-band peaks in near-field spectra, offering an opportunity for designing emitters with tailored near-field thermal radiation.
Article
Nanoscience & Nanotechnology
Roberto Merlin
Summary: The tutorial discusses the differences between the near and far regions of the electromagnetic field, highlighting the source-dependent behavior of the former and the universal nature of the latter. It also delves into the field patterns of near-field plates used for sub-wavelength applications, providing examples of exponential and algebraic decays. Additionally, it demonstrates how a properly designed system of two parallel near-field plates can generate fields with pseudo minima, which could be beneficial for certain applications.
Article
Chemistry, Multidisciplinary
Mathieu Giroux, Michel Stephan, Maxime Brazeau, Sean Molesky, Alejandro W. Rodriguez, Jacob J. Krich, Karin Hinzer, Raphael St-Gelais
Summary: In this study, we investigated near-field radiative heat transfer (NFRHT) using widely available silicon nitride (SiN) membrane nanomechanical resonators. We successfully measured heat transfer at a minimal distance of 180 nm between a glass radiator with a large radius of curvature (15.5 mm) and a SiN membrane resonator.
Article
Materials Science, Multidisciplinary
Saman Zare, Behrad Zeinali Tajani, Sheila Edalatpour
Summary: In this paper, the nonlocality of graphene electrical conductivity and its effect on near-field radiative conductance are analyzed using the Lindhard model combined with the Mermin relaxation time approximation. It is shown that the commonly used local Kubo and Drude formulas are not accurate in estimating the electrical conductivity and radiative conductance of graphene in certain conditions.
Article
Chemistry, Physical
Jihong Zhang, Yang Hu, Qing Han, Haotuo Liu, Yasong Sun, Xiaohu Wu
Summary: The orientation of the optical axis of calcite has been found to affect near-field radiative heat transfer, with a larger heat flux observed when the optical axis is along the z-axis. Additionally, the thickness also plays a significant role in heat transfer between calcite slabs.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Thermodynamics
Jimin Fang, Manzhuo Wang, Jianbo Yue, Zhaoyang Sun, Xiaoqiang Sun, Yuanda Wu, Daming Zhang
Summary: This study proposes a solution for achieving nonreciprocal thermal radiation for both TE and TM polarizations at small angles, and verifies its effectiveness through experimental data. The proposed scheme offers valuable guidance for the development of dual-polarization nonreciprocal radiation devices.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2023)
Article
Thermodynamics
J. Chen, B. X. Wang, C. Y. Zhao
Summary: A theoretical model is proposed to study the near-field radiative heat transfer between SiC/Au nanoparticles in a cavity comprised of two semi-infinite SiC plates. The cavity configuration is found to greatly enhance the heat transfer between the nanoparticles, with amplification exceeding seven orders of magnitude for SiC nanoparticles and two orders of magnitude for Au nanoparticles. Moreover, the electric contribution can surpass the magnetic contribution for Au nanoparticles. The strong coupling between the surface modes of the SiC plates is shown to play a major role in this significant amplification. Additionally, the cavity configuration enables super-diffusive radiative heat transport in one-dimensional SiC nanoparticle chains, allowing for ballistic heat transport. These findings have potential applications in nanoscale thermal management.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Chemistry, Multidisciplinary
Rohith Mittapally, Ju Won Lim, Lang Zhang, Owen D. Miller, Pramod Reddy, Edgar Meyhofer
Summary: Recent experiments have revealed that near-field radiative heat transfer (NFRHT) between objects separated by nanoscale gaps can significantly enhance heat transfer rates. Silicon dioxide (SiO2) surfaces, which support surface phonon polaritons (SPhP), demonstrate the most prominent enhancements. However, theoretical analysis suggests that SPhPs in SiO2 occur at frequencies much higher than optimal. In this study, we demonstrate theoretically that NFRHT mediated by SPhPs can be 5-fold larger for materials supporting SPhPs closer to the optimal frequency of 67 meV at room temperature. Furthermore, we experimentally show that MgF2 and Al2O3 closely approach this limit, with near-field thermal conductance between MgF2 plates separated by 50 nm reaching nearly 50% of the global SPhP bound. These findings lay the foundation for exploring the limits of radiative heat transfer rates at the nanoscale.
Article
Physics, Multidisciplinary
Gaomin Tang, Lei Zhang, Yong Zhang, Jun Chen, C. T. Chan
Summary: The near-field radiative energy transfer between two separated parallel plates can be controlled by electric current and an in-plane magnetic field, resulting in tunable thermoelectric current generation in graphene. This control is achieved through the interplay between nonreciprocal photon occupation number in graphene and nonreciprocal surface modes in the magneto-optic plate.
PHYSICAL REVIEW LETTERS
(2021)
Article
Thermodynamics
Siwon Yoon, Dongwoo Chae, Junyong Seo, Minwoo Choi, Hangyu Lim, Heon Lee, Bong Jae Lee
Summary: Daytime radiative cooling has gained much attention for its potential in next-generation cooling systems. Existing indicators cannot accurately estimate the energy saving caused by the radiative cooling effect. This study proposes a device that can directly measure the daily averaged radiative cooling power and cooling energy reduction, providing a starting point for more realistic and sophisticated evaluation of radiative cooling performance.
APPLIED THERMAL ENGINEERING
(2022)
Review
Energy & Fuels
Jaeman Song, Jihye Han, Minwoo Choi, Bong Jae Lee
Summary: This article provides an in-depth review of charge transport models utilized to analyze the performance of near-field thermophotovoltaic (NF-TPV) devices, and a comprehensive examination of NF-TPV experiments performed to date. The article categorizes the analysis models into four categories and compares the results of each model. It also discusses the different approaches used in NF-TPV experiments and the experimental results achieved. Additionally, it introduces advanced concepts for improving NF-TPV performance.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2022)
Article
Energy & Fuels
Jaeman Song, Minwoo Choi, Mikyung Lim, Jungchul Lee, Bong Jae Lee
Summary: By optimizing the configuration of the near-field tandem TPV converter, high-efficiency electrical power output was achieved. Two resonance modes were demonstrated to significantly contribute to the enhanced performance of the optimized system.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2022)
Article
Nanoscience & Nanotechnology
Jaeman Song, Junho Jang, Mikyung Lim, Minwoo Choi, Jungchul Lee, Bong Jae Lee
Summary: This study demonstrates the oscillatory nature of near-field thermophotovoltaic energy conversion in the transition between the far-field and near-field regimes. It is found that the same amount of photocurrent can be generated at different vacuum gaps, which is 10% larger than the far-field value.
Article
Thermodynamics
Dong-min Kim, Dong Ju Han, Tae Wook Heo, ShinYoung Kang, Brandon C. Wood, Jungchul Lee, Eun Seon Cho, Bong Jae Lee
Summary: Engineering thermophysical properties of metal hydrides nanocomposites is crucial for effective thermal management during hydrogen storage reactions. This study investigates the microstructural factors that determine the effective thermal conductivity of individual reduced graphene oxide-magnesium (rGO/Mg) nanocomposites and their packed bed using an integrated experiment-modeling approach. The results demonstrate that the anisotropy of the effective thermal conductivity of the individual nanocomposites plays a significant role in determining the overall thermal conductivity of the packed bed. The developed mesoscopic model also reveals the complex interplay between intrinsic properties and extrinsic structural features.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Physics, Applied
Jaeman Song, Minwoo Choi, Zhimin Yang, Jungchul Lee, Bong Jae Lee
Summary: In this study, a multi-junction-based near-field STPV system was designed to achieve high-efficiency energy conversion through photon tunneling and optimization of multi-junction PV cells. The use of a genetic algorithm and an artificial neural network provided a better design approach.
APPLIED PHYSICS LETTERS
(2022)
Article
Thermodynamics
Minwoo Choi, Junyong Seo, Siwon Yoon, Youngsuk Nam, Jungchul Lee, Bong Jae Lee
Summary: In this study, a novel structure for all-day radiative cooling is proposed. By optimizing the grating structure, the emissivity of the emitter surface is increased, leading to efficient cooling throughout the day. Additionally, the grating-patterned surface has a self-cleaning feature, making it suitable for long-term usage.
APPLIED THERMAL ENGINEERING
(2022)
Article
Engineering, Electrical & Electronic
Zhimin Yang, Jaeman Song, Bong Jae Lee
Summary: In this study, the performance of graphene-based Schottky junction thermophotovoltaic (TPV) devices in near-field conditions is investigated. It is found that the semiconductor layer dominates the generation of photocurrent, with a less than 40% internal quantum efficiency (IQE) for graphene. Under an emitter temperature of 1000 K and a vacuum gap of 100 nm, using an indium tin oxide (ITO)-covered tungsten (W) emitter can increase photocurrents by a factor of around 10 and 11 for the semiconductor and graphene, respectively. Furthermore, using a hyperbolic metamaterial (HMM) emitter can enhance photocurrents by around 4.7 and 5.2 times for the semiconductor and graphene, respectively, at the cost of higher heat flux from the HMM emitter. These findings provide valuable insights for the design and optimization of TPV devices to improve their photocurrent and efficiency.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Physics, Multidisciplinary
Dong-min Kim, Sinwoo Choi, Jungwan Cho, Mikyung Lim, Bong Jae Lee
Summary: We experimentally demonstrate boosted in-plane thermal conduction by surface plasmon polaritons (SPPs) propagating along a thin Ti film on a glass substrate. We show that SPPs can propagate over centimeter-scale distances even along a supported metal film, and quantitatively validate the resulting ballistic heat conduction. Moreover, we experimentally demonstrate a significant enhancement of in-plane thermal conductivity compared to bulk value (approximately 25%) for a 100-nm-thick Ti film on a glass substrate. This research provides a new avenue to employ SPPs for heat dissipation along a supported thin film and can potentially mitigate hot-spot issues in microelectronics.
PHYSICAL REVIEW LETTERS
(2023)
Article
Multidisciplinary Sciences
Gyeongsuk Park, Hyunmin Park, Junyong Seo, Jun Chang Yang, Min Kim, Bong Jae Lee, Steve Park
Summary: The authors developed a hydrogel that mimics thermal homeostasis, providing improved heat trapping and enhanced evaporative cooling. The hydrogel includes materials that reflect and absorb infrared waves for heat trapping at low temperatures, and has a porous structure for enhanced evaporative cooling at high temperatures. An optimized auxetic pattern acts as a heat valve to amplify heat release. This hydrogel provides effective bidirectional thermoregulation, making it useful for autonomic nervous system disorders and susceptible soft robotics.
NATURE COMMUNICATIONS
(2023)
Article
Physics, Applied
Jose Ordonez-Miranda, Yuriy A. Kosevich, Bong Jae Lee, Masahiro Nomura, Sebastian Volz
Summary: The thermal conductance and thermal conductivity of plasmons in metallic nanofilms deposited on a substrate were studied. The symmetric and antisymmetric spatial distribution modes of the magnetic field drive the plasmon energy transport along the film interfaces. The plasmon thermal conductance is higher for hotter and/or longer films, saturating for films thicker than 50 nm. The transition of plasmon modes maximizes the thermal conductivity for thinner films, and a 10 nm thick gold nanofilm at 300 K has a maximum thermal conductivity of 15 W m-1 K-1, about 25% of its electron counterpart. The plasmon thermal conductivity increases significantly with film length and temperature, potentially improving heat dissipation along metallic nanofilms.
PHYSICAL REVIEW APPLIED
(2023)
Article
Green & Sustainable Science & Technology
Junyong Seo, Minwoo Choi, Siwon Yoon, Bong Jae Lee
Summary: This paper presents a practical approach to estimate the performance of radiative cooling, using the model of accumulated cold energy production (ACEP), and applies it to optimize and select photonic structures under different climatic conditions.
Article
Nanoscience & Nanotechnology
Juhee Ko, Bong Jae Lee, Jungchul Lee
Summary: In this paper, we report the development of heated fluidic resonators for simultaneous and quantitative thermophysical measurements of ultrasmall liquid volumes. By reducing thermal loss, we were able to significantly improve the precision of these resonators in a vacuum. The increased measurement sensitivities for thermal conductivity and specific heat capacity make the differentiation between liquids with similar properties more accurate.
MICROSYSTEMS & NANOENGINEERING
(2023)
Article
Instruments & Instrumentation
Jeongmin Nam, Dong-min Kim, Minwoo Choi, Jinsung Rho, Jungchul Lee, Bong Jae Lee
Summary: This article introduces a micro-infrared thermometer that utilizes a bolometer-type infrared detector and a reflective objective lens, allowing for high-resolution temperature measurements of microscale heating devices. The experimental results are reasonably consistent with COMSOL simulations.
INFRARED PHYSICS & TECHNOLOGY
(2023)
Article
Nanoscience & Nanotechnology
Jaeman Song, Minwoo Choi, Bong Jae Lee
Summary: This study comprehensively investigates the effectiveness of multi-junction-based near-field thermophotovoltaic (NF-TPV) devices, considering additional losses. By proposing two approximative expressions and verifying against rigorously optimized results, a criterion for effective performance is established. Our method provides precise power output density estimations for different parameters and offers a roadmap for scalable design. The importance of multi-junction PV cells is emphasized, and vital insights for future high-performance TPV devices are provided.
