Article
Nanoscience & Nanotechnology
Teng-Fei Lu, Sraddha Agrawal, Marina Tokina, Weibin Chu, Daniel Hirt, Patrick E. Hopkins, Oleg Prezhdo
Summary: Phonon-mediated charge relaxation plays a vital role in controlling thermal transport across an interface for efficient functioning of two-dimensional (2D) nanostructured devices. Adhesion layers at the Au/WSe2 interface have a strong influence on nonequilibrium charge relaxation, providing benefits for photovoltaic and photocatalytic applications. Metallic Ti layers accelerate energy flow, meeting the efficient heat dissipation requirements of electronic devices.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Electrochemistry
Sudip Saha, Jie Yang, S. Shayan Mousavi Masouleh, G. A. Botton, Leyla Soleymani
Summary: Optically-excited gold nanoparticles generate hot charge carriers that improve the energy conversion efficiency of photochemical and photoelectrochemical reactions. In this study, interband excitation showed higher photocurrent generation efficiency than intraband excitation. The surface distribution of gold nanoparticles was found to strongly affect the efficiency of photocurrent generation.
ELECTROCHIMICA ACTA
(2022)
Article
Physics, Applied
Jianrong Zhang, Hongfei Xie, Xu Zhang, Ze Yan, Yongbo Zhai, Junhong Chi, Hengyi Xu, Yalu Zuo, Li Xi
Summary: This study reports an effective approach to demonstrate the strong orbital torques in the light metal Cr and achieve energy efficient magnetization switching and domain wall motion in vertically magnetized Cr/Au/Co/Ti multilayers. The findings confirm the existence of orbital Hall torques in Cr and provide an effective way to investigate the orbital Hall effect.
APPLIED PHYSICS LETTERS
(2022)
Article
Chemistry, Physical
Buyang Yu, Lan Chen, Zhengkang Qu, Chunfeng Zhang, Zhengyuan Qin, Xiaoyong Wang, Min Xiao
Summary: The study demonstrates the presence of a phonon bottleneck effect in CsPbI3 nanocrystals through broadband two-dimensional electronic spectroscopy, showing a size-dependent relaxation of hot carriers and doubling of their lifetime as the nanocrystal size decreases. This finding suggests the feasibility of controlling hot carrier dynamics in perovskite semiconductors for potential applications.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Chemistry, Physical
Wenyan Wang, Ning Sui, Xiaochun Chi, Zhihui Kang, Qiang Zhou, Li Li, Hanzhuang Zhang, Jianbo Gao, Yinghui Wang
Summary: The hot carrier cooling dynamics in monolayer MoS2 C-excitonic state is affected by the hot phonon bottleneck and Auger heating effects, and can be prolonged by increasing the excitation photon energy or absorbed photon flux. The combination of these effects weakens the hot phonon bottleneck and extends the hot carrier lifetime, which has implications for various applications in advanced energy conversion and quantum technology.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Jie-Jun Wang, Tao Wang, Chuan-Gui Wu, Wen-Bo Luo, Yao Shuai, Wang-Li Zhang
Summary: A multilayer resistive temperature sensor (Ti/Pt/Cr/Au) was proposed and investigated for precise temperature measurement in microfluidic devices. The sensor exhibited excellent stability and sensitivity during the annealing process, with through-thickness migration of chromium and partial depletion of the adhesive layer. The capability of the sensor to detect sudden temperature changes caused by bubble effects is significant for microfluidic devices.
Article
Pharmacology & Pharmacy
Petr Slepicka, Dominik Fajstavr, Marketa Krejcova, Silvie Rimpelova, Nikola Slepickova Kasalkova, Zdenka Kolska, Vaclav Svorcik
Summary: This study focuses on preparing and characterizing PLLA composites with antibacterial properties, using a combination of gold, titanium nanolayers, and heat treatment to create a unique wrinkled pattern. A simple technique for large-scale sample modification has been developed, allowing for tailored dimensions of wrinkles based on the sequence and thickness of deposited metals.
Article
Chemistry, Physical
Krishna Mishra, Debopam Acharjee, Ayendrila Das, Subhadip Ghosh
Summary: The carrier cooling time of colloidal graphene quantum dots (GQDs) is at least an order of magnitude slower compared to that in its bulk form, which is a coveted property that allows for easy harvesting of high energy species using a suitable molecular system. The efficient transfer of hot carriers in a GQD-molecular system composite suggests a potential dramatic enhancement of the efficiency of GQD-based optoelectronic devices.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Polymer Science
Elodie Strupiechonski, Marisa Moreno-Rios, Erika O. Avila-Davila, Ramon Roman-Doval, Evgeny Prokhorov, Yuriy Kovalenko, Diana G. Zarate-Trivino, Dora Medina, Gabriel Luna-Barcenas
Summary: Chitosan-gold nanoparticle thin films were synthesized through chemical reduction of HAuCl4. The behavior of these films was investigated in relation to moisture and HAuCl4 content, revealing two relaxation processes related to glass transition and local diffusion of ions. The HAuCl4 content affected the conductivity of the films, demonstrating a percolation effect.
Article
Chemistry, Physical
Kyoungjae Song, Hyunhwa Lee, Moonsang Lee, Jeong Young Park
Summary: Research indicates that the size of metallic nanostructures is crucial for the injection of plasmonic hot holes, with smaller Au nanoprisms showing higher quantum efficiencies and significant enhancement of photoelectrocatalytic reactions.
ACS ENERGY LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Tong Wang, Thomas R. Hopper, Navendu Mondal, Sihui Liu, Chengning Yao, Xijia Zheng, Felice Torrisi, Artem A. Bakulin
Summary: Transition metal dichalcogenides (TMDs) have excellent semiconductor properties, making them promising materials for next-generation optoelectronic and electronic devices. Recent studies have reported the ultrafast carrier cooling rate in TMDs and the slowing effect by hot-phonon bottleneck (HPB) at high excitation densities. However, quantitative descriptions of HPB in TMDs and the effects of carrier-carrier interactions on cooling are still lacking. In this study, using femtosecond pump-push-probe spectroscopy, the scattering of hot carriers with optical phonons, cold carriers, and defects in a benchmark TMD monolayer of polycrystalline WS2 is systematically characterized.
Article
Chemistry, Multidisciplinary
Tong Wang, Thomas R. Hopper, Navendu Mondal, Sihui Liu, Chengning Yao, Xijia Zheng, Felice Torrisi, Artem A. Bakulin
Summary: Transition metal dichalcogenides (TMDs) have potential applications in next-generation optoelectronic and electronic devices due to their outstanding semiconducting properties. However, there is still a lack of detailed understanding of the carrier cooling mechanisms in TMDs.
Article
Chemistry, Physical
Ki Chang Kwon, Tae Hyung Lee, Seokhoon Choi, Kyoung Soon Choi, Seung O. Gim, Sa-Rang Bae, Jong-Lam Lee, Ho Won Jang, Soo Young Kim
Summary: This study presents a simple method for synthesizing alloyed transition metal disulfides (TMD) thin films and their application as hole transport layers in OLEDs. The physical and chemical properties of the alloyed TMD layers can be controlled by varying precursor concentrations. The device performance of OLEDs based on alloyed TMD layers is comparable to conventional PEDOT:PSS, and device stability in air is significantly improved.
APPLIED SURFACE SCIENCE
(2021)
Article
Engineering, Mechanical
Fei Cai, Jiamin Zhang, Jianming Wang, Jun Zheng, Qimin Wang, Shihong Zhang
Summary: Cr/CrSiN multi-layer coatings with different structures were fabricated on titanium alloy by ion-plating technology. Among them, the Cr/CrSiN-10 multi-layer coating showed higher adhesive strength, lower friction coefficient, and wear rate, leading to improved wear resistance due to reduced coating peeling. Additionally, the Cr/CrSiN-10 multi-layer coating exhibited lower erosion wear rate compared to the Cr/CrSiN-1 coating, possibly due to the interception and capture of erosion cracks by the ductile Cr layers and the multi-layer structures.
TRIBOLOGY INTERNATIONAL
(2021)
Article
Materials Science, Multidisciplinary
Aswathi K. Sivan, Lorenzo Di Mario, Yunyan Zhang, Daniele Catone, Patrick O'Keeffe, Stefano Turchini, Valentina Mussi, Huiyun Liu, Faustino Martelli
Summary: Thinner semiconductor nanowires show easier buildup of hot-phonon bottleneck due to increased phonon scattering at the sidewalls, leading to higher carrier temperature compared to thicker nanowires. This indicates that phonon-mediated scattering processes play a major role in thin nanowires at the investigated carrier densities.
Article
Chemistry, Physical
Andrey A. Kistanov, Vladimir R. Nikitenko, Oleg Prezhdo
Summary: This study investigated seven kinds of point defects in a two-dimensional phosphorus carbide gamma allotrope, finding that these defects have a significant impact on the electronic structure of the material, with slightly higher formation energies compared to other materials.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Guoqing Zhou, Gang Lu, Oleg Prezhdo
Summary: Auger-type energy exchange is crucial in nanomaterials due to strong carrier-carrier interactions. A new ab initio technique was developed to accurately model Auger scattering with nonadiabatic molecular dynamics, describing charge-charge and charge-phonon scattering in a nonperturbative manner. This technique successfully reproduced experimental processes, providing detailed insights into carrier dynamics in nanomaterials with strong carrier-carrier interactions.
Article
Chemistry, Multidisciplinary
Yucheng Xiong, Guoqing Zhou, Nien-Chu Lai, Xiaomeng Wang, Yi-Chun Lu, Oleg Prezhdo, Dongyan Xu
Summary: This research demonstrates switchable n-type and p-type electrical conduction in Bi2Se3 nanoribbons through a facile chemical approach, opening up new possibilities for the development of thermoelectric devices and offering significant implications in the fields of spintronics and quantum computing.
Article
Physics, Applied
David H. Olson, Maria G. Sales, John A. Tomko, Teng-Fei Lu, Oleg V. Prezhdo, Stephen J. McDonnell, Patrick E. Hopkins
Summary: This study experimentally determined the electron-electron conductance at Au/TiOx interface regions and electron-phonon coupling of thin TiOx layers for x=0-2.62. The research found that electronic energy transport mechanisms at metal/metal oxide interfaces are enhanced through metallic defects and analyzed the processes using pump/probe technique and a two-temperature model. The results also showed that TiOx stoichiometries near TiO2 have ultrahigh electron-phonon coupling factors, and electron-phonon coupling is reduced for x=2.62 in TiOx.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Applied
Ramin Ghiyasi, Milena Milich, John Tomko, Girish C. Tewari, Mika Lastusaari, Patrick E. Hopkins, Maarit Karppinen
Summary: ZnO thin films fabricated via atomic layer deposition process can simultaneously manipulate the electrical and thermal transport characteristics by elongating the N-2 purge time. This leads to increased carrier density and enhanced electrical conductivity, but may hinder thermal transport. This is of fundamental importance in thermoelectrics and desired in optics and microelectronics.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
Kathleen Quiambao-Tomko, Richard R. White, John A. Tomko, Christina M. Rost, Lavina Backman, Elizabeth J. Opila, Patrick E. Hopkins
Summary: This work presents a laser-based heating and sensing metrology to study the failure mechanisms of materials under extreme heat fluxes near surfaces. By controlling the localization of heat fluxes through focusing the laser beam, the material damage can be evaluated using a secondary probe laser. The experiment focuses on the damage mechanisms of commercially pure titanium under high heat fluxes induced by absorbed laser energy. The study reveals correlations between microstructural evolution events and thermoreflectance trends as a function of absorbed power density.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Physics, Applied
Patrick E. Hopkins, John A. Tomko, Ashutosh Giri
Summary: In this study, a theoretical model for phonon thermal boundary conductance across solid interfaces in the high temperature classical limit is derived using quasi-harmonic thermodynamics. The model takes into account the effects of phonon anharmonicity on energy density changes and shows good agreement with experimental and simulation results. This model has the potential to be applied in various applications to increase thermal conductance and mitigate temperature.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Mallory E. DeCoster, Hasan Babaei, Sangeun S. Jung, Zeinab M. Hassan, John T. Gaskins, Ashutosh Giri, Emma M. Tiernan, John A. Tomko, Helmut Baumgart, Pamela M. Norris, Alan J. H. McGaughey, Christopher E. Wilmer, Engelbert Redel, Gaurav Giri, Patrick E. Hopkins
Summary: In this study, we experimentally and theoretically investigate the effects of guest molecules on the thermal conductivity and mechanical properties of porous crystals. The results show that the infiltration of guest molecules reduces the thermal conductivity and increases the density and heat capacity. Atomistic simulations reveal that the reduction in thermal conductivity is attributed to increased vibrational scattering and modifications to the intrinsic vibrational structure of the crystal induced by the guest molecules.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Nanoscience & Nanotechnology
Md Rafiqul Islam, M. A. Zubair, Roisul H. Galib, Md Shafkat Bin Hoque, John A. Tomko, Kiumars Aryana, Animesh K. Basak, Patrick E. Hopkins
Summary: This study reports the magnetic and thermal properties of holmium-substituted bismuth ferrite and their dependence on oxygen vacancies and structural modifications. The results show that the excess of oxygen vacancies shifts the magnetic transition temperature and the structural modification increases heat capacity. The research highlights the importance of understanding the correlation between the magnetic and thermal properties of multiferroics.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Multidisciplinary Sciences
Kiumars Aryana, John A. Tomko, Ran Gao, Eric R. Hoglund, Takanori Mimura, Sara Makarem, Alejandro Salanova, Md Shafkat Bin Hoque, Thomas W. Pfeifer, David H. Olson, Jeffrey L. Braun, Joyeeta Nag, John C. Read, James M. Howe, Elizabeth J. Opila, Lane W. Martin, Jon F. Ihlefeld, Patrick E. Hopkins
Summary: Materials with tunable thermal properties are crucial for the development of solid-state refrigeration, energy scavenging, and thermal circuits. This study demonstrates the bidirectional switching of thermal conductivity in antiferroelectric PbZrO3 by manipulating phonon scattering rates. PbZrO3 shows potential as a fast, repeatable, simple trigger, and reliable thermal switch.
NATURE COMMUNICATIONS
(2022)
Article
Multidisciplinary Sciences
John A. Tomko, Michael J. Johnson, David R. Boris, Tzvetelina B. Petrova, Scott G. Walton, Patrick E. Hopkins
Summary: This study demonstrates the ability of plasmas to both heat and transiently cool a material surface. Photon-stimulated desorption of adsorbates from the surface is identified as the main mechanism responsible for this plasma cooling effect.
NATURE COMMUNICATIONS
(2022)
Article
Physics, Applied
Thomas W. Pfeifer, John A. Tomko, Eric Hoglund, Ethan A. Scott, Khalid Hattar, Kenny Huynh, Michael Liao, Mark Goorsky, Patrick E. Hopkins
Summary: In this study, a new method for analyzing the thermal conductivity variations in a material with spatial distribution of defects is developed using time-domain thermoreflectance. The near-surface thermal conductivity of silicon wafers irradiated with Kr+ ions is measured using this method. The results are validated using transmission electron microscopy, which confirms the spatial variation of the sub-surface silicon structure. The drastic reduction in silicon thermal conductivity is primarily attributed to structural defects and boundary scattering between amorphous and crystalline regions.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Mackenzie J. Ridley, Kathleen Q. Tomko, John A. Tomko, Eric R. Hoglund, James M. Howe, Patrick E. Hopkins, Elizabeth J. Opila
Summary: Multi-component rare earth silicates offer a unique solution for simultaneously optimizing phase stability, thermo-chemical, and thermo-mechanical properties through variation of the rare earth elements implemented in the coating material.
Article
Physics, Applied
Kenny Huynh, Yekan Wang, Michael E. Liao, Thomas Pfeifer, John Tomko, Ethan Scott, Khalid Hattar, Patrick E. Hopkins, Mark S. Goorsky
Summary: The recovery of silicon thermal conductivity was achieved through recrystallization of partially amorphized silicon. Transmission electron microscopy revealed nanoscale amorphous regions within a structurally distorted crystalline material. After annealing, strain recovery and recrystallization occurred, resulting in a bulk-like thermal conductivity in silicon.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Teng-Fei Lu, Shriya Gumber, Marina V. Tokina, John A. Tomko, Patrick E. Hopkins, Oleg V. Prezhdo
Summary: Thermal transport at nanoscale metal-semiconductor interfaces via electron-phonon coupling plays a crucial role in modern microelectronic, electro-optic, and thermoelectric devices. This study demonstrates that incorporating a thin Ti adhesion layer at the Au/WSe2 interface can enhance the hot electron and hole relaxation rates due to enhanced electron-phonon coupling. The results provide insights for improving the design of materials at metal-semiconductor interfaces by optimizing heat dissipation.