Publications by authors named "Eungkyu Lee"

18 Publications

  • Page 1 of 1

Ballistic Brownian motion of supercavitating nanoparticles.

Phys Rev E 2021 Apr;103(4-1):042104

Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA.

We show that the Brownian motion of a nanoparticle (NP) can reach a ballistic limit when intensely heated to form supercavitation. As the NP temperature increases, its Brownian motion displays a sharp transition from normal to ballistic diffusion upon the formation of a vapor bubble to encapsulate the NP. Intense heating allows the NP to instantaneously extend the bubble boundary via evaporation, so the NP moves in a low-friction gaseous environment. We find the dynamics of the supercavitating NP is largely determined by the near field effect, i.e., highly localized vapor phase property in the vicinity of the NP.
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http://dx.doi.org/10.1103/PhysRevE.103.042104DOI Listing
April 2021

Optically Driven Gold Nanoparticles Seed Surface Bubble Nucleation in Plasmonic Suspension.

Nano Lett 2021 May 3. Epub 2021 May 3.

Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States.

Photothermal surface bubbles play important roles in applications like microfluidics and biosensing, but their formation on transparent substrates immersed in a plasmonic nanoparticle (NP) suspension has an unknown origin. Here, we reveal NPs deposited on the transparent substrate by optical forces are responsible for the nucleation of such photothermal surface bubbles. We show the surface bubble formation is always preceded by the optically driven NPs moving toward and deposited to the surface. Interestingly, such optically driven motion can happen both along and against the photon stream. The laser power density thresholds to form a surface bubble drastically differ depending on if the surface is forward- or backward-facing the light propagation direction. We attributed this to different optical power densities needed to enable optical pulling and pushing of NPs in the suspension, as optical pulling requires higher light intensity to excite supercavitation around NPs to enable proper optical configuration.
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http://dx.doi.org/10.1021/acs.nanolett.0c04913DOI Listing
May 2021

Bulk-like Intrinsic Phonon Thermal Conductivity of Micrometer-Thick AlN Films.

ACS Appl Mater Interfaces 2020 Jul 22;12(26):29443-29450. Epub 2020 Jun 22.

Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22904, United States.

Aluminum nitride (AlN) has garnered much attention due to its intrinsically high thermal conductivity. However, engineering thin films of AlN with these high thermal conductivities can be challenging due to vacancies and defects that can form during the synthesis. In this work, we report on the cross-plane thermal conductivity of ultra-high-purity single-crystal AlN films with different thicknesses (∼3-22 μm) via time-domain thermoreflectance (TDTR) and steady-state thermoreflectance (SSTR) from 80 to 500 K. At room temperature, we report a thermal conductivity of ∼320 ± 42 W m K, surpassing the values of prior measurements on AlN thin films and one of the highest cross-plane thermal conductivities of any material for films with equivalent thicknesses, surpassed only by diamond. By conducting first-principles calculations, we show that the thermal conductivity measurements on our thin films in the 250-500 K temperature range agree well with the predicted values for the bulk thermal conductivity of pure single-crystal AlN. Thus, our results demonstrate the viability of high-quality AlN films as promising candidates for the high-thermal-conductivity layers in high-power microelectronic devices. Our results also provide insight into the intrinsic thermal conductivity of thin films and the nature of phonon-boundary scattering in single-crystal epitaxially grown AlN thin films. The measured thermal conductivities in high-quality AlN thin films are found to be constant and similar to bulk AlN, regardless of the thermal penetration depth, film thickness, or laser spot size, even when these characteristic length scales are less than the mean free paths of a considerable portion of thermal phonons. Collectively, our data suggest that the intrinsic thermal conductivity of thin films with thicknesses less than the thermal phonon mean free paths is the same as bulk so long as the thermal conductivity of the film is sampled independent of the film/substrate interface.
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http://dx.doi.org/10.1021/acsami.0c03978DOI Listing
July 2020

Ballistic supercavitating nanoparticles driven by single Gaussian beam optical pushing and pulling forces.

Nat Commun 2020 May 15;11(1):2404. Epub 2020 May 15.

Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN, 46556, USA.

Directed high-speed motion of nanoscale objects in fluids can have a wide range of applications like molecular machinery, nano robotics, and material assembly. Here, we report ballistic plasmonic Au nanoparticle (NP) swimmers with unprecedented speeds (~336,000 μm s) realized by not only optical pushing but also pulling forces from a single Gaussian laser beam. Both the optical pulling and high speeds are made possible by a unique NP-laser interaction. The Au NP excited by the laser at the surface plasmon resonance peak can generate a nanoscale bubble, which can encapsulate the NP (i.e., supercavitation) to create a virtually frictionless environment for it to move, like the Leidenfrost effect. Certain NP-in-bubble configurations can lead to the optical pulling of NP against the photon stream. The demonstrated ultra-fast, light-driven NP movement may benefit a wide range of nano- and bio-applications and provide new insights to the field of optical pulling force.
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http://dx.doi.org/10.1038/s41467-020-16267-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7228977PMC
May 2020

Surface Bubble Growth in Plasmonic Nanoparticle Suspension.

ACS Appl Mater Interfaces 2020 Jun 27;12(23):26680-26687. Epub 2020 May 27.

Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States.

Understanding the growth dynamics of the microbubbles produced by plasmonic heating can benefit a wide range of applications like microfluidics, catalysis, micropatterning, and photothermal energy conversion. Usually, surface plasmonic bubbles are generated on plasmonic structures predeposited on the surface subject to laser heating. In this work, we investigate the growth dynamics of surface microbubbles generated in plasmonic nanoparticle (NP) suspension. We observe much faster bubble growth rates compared to those in pure water with surface plasmonic structures. Our analyses show that the volumetric heating effect around the surface bubble due to the existence of NPs in the suspension is the key to explaining this difference. Such volumetric heating increases the temperature around the surface bubble more efficiently compared to surface heating which enhances the expelling of dissolved gas. We also find that the bubble growth rates can be tuned in a very wide range by changing the concentration of NPs, besides laser power and dissolved gas concentration.
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http://dx.doi.org/10.1021/acsami.0c05448DOI Listing
June 2020

Light-Guided Surface Plasmonic Bubble Movement via Contact Line De-Pinning by In-Situ Deposited Plasmonic Nanoparticle Heating.

ACS Appl Mater Interfaces 2019 Dec 10;11(51):48525-48532. Epub 2019 Dec 10.

Department of Aerospace and Mechanical Engineering , University of Notre Dame , Notre Dame , Indiana 46556 , United States.

Precise spatiotemporal control of surface bubble movement can benefit a wide range of applications like high-throughput drug screening, combinatorial material development, microfluidic logic, colloidal and molecular assembly, and so forth. In this work, we demonstrate that surface bubbles on a solid surface are directed by a laser to move at high speeds (>1.8 mm/s), and we elucidate the mechanism to be the depinning of the three-phase contact line (TPCL) by rapid plasmonic heating of nanoparticles (NPs) deposited in situ during bubble movement. On the basis of our observations, we deduce a stick-slip mechanism based on asymmetric fore-aft plasmonic heating: local evaporation at the front TPCL due to plasmonic heating depins and extends the front TPCL, followed by the advancement of the trailing TPCL to resume a spherical bubble shape to minimize surface energy. The continuous TPCL drying during bubble movement also enables well-defined contact line deposition of NP clusters along the moving path. Our finding is beneficial to various microfluidics and pattern writing applications.
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http://dx.doi.org/10.1021/acsami.9b16067DOI Listing
December 2019

Tuning Water Slip Behavior in Nanochannels Using Self-Assembled Monolayers.

ACS Appl Mater Interfaces 2019 Sep 26;11(35):32481-32488. Epub 2019 Aug 26.

Moe Key Laboratory of Thermo-Fluid Science and Engineering, Energy and Power Engineering School , Xi'an Jiaotong University , Xi'an 710049 , China.

Water slip at solid surfaces is important for a wide range of micro-/nanofluidic applications. While it is known that water slip behavior depends on surface functionalization, how it impacts the molecular level dynamics and mass transport at the interface is still not thoroughly understood. In this paper, we use nonequilibrium molecular dynamics simulations to investigate the slip behavior of water confined between gold surfaces functionalized by self-assembled monolayer (SAM) molecules with different polar functional groups. We observe a positive-to-negative slip transition from hydrophobic to hydrophilic SAM functionalizations, which is found to be related to the stronger interfacial interaction between water molecules and more hydrophilic SAM molecules. The stronger interaction increases the surface friction and local viscosity, making water slip more difficult. More hydrophilic functionalization also slows down the interfacial water relaxation and leads to more pronounced water trapping inside the SAM layer, both of which impede water slip. The results from this work will provide useful insights into the understanding of the water slip at functionalized surfaces and design guidelines for various applications.
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http://dx.doi.org/10.1021/acsami.9b09509DOI Listing
September 2019

Effect of light atoms on thermal transport across solid-solid interfaces.

Phys Chem Chem Phys 2019 Aug 29;21(31):17029-17035. Epub 2019 Jul 29.

Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA. and Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA and Center for Sustainable Energy of Notre Dame (ND Energy), University of Notre Dame, Notre Dame, Indiana 46556, USA.

Thermal transport across solid interfaces is of great importance for applications like power electronics. In this work, we perform non-equilibrium molecular dynamics simulations to study the effect of light atoms on the thermal transport across SiC/GaN interfaces, where light atoms refer to substitutional or interstitial defect atoms lighter than those in the pristine lattice. Various light atom doping features, such as the light atom concentration, mass of the light atom, and skin depth of the doped region, have been investigated. It is found that substituting Ga atoms in the GaN lattice with lighter atoms (e.g. boron atoms) with 50% concentration near the interface can increase the thermal boundary conductance (TBC) by up to 50%. If light atoms are introduced interstitially, a similar increase in TBC is observed. Spectral analysis of interfacial heat transfer reveals that the enhanced TBC can be attributed to the stronger coupling of mid- and high-frequency phonons after introducing light atoms. We have also further included quantum correction, which reduces the amount of enhancement, but it still exists. These results may provide a route to improve TBC across solid interfaces as light atoms can be introduced during material growth.
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http://dx.doi.org/10.1039/c9cp03426aDOI Listing
August 2019

Exfoliated Graphene Leads to Exceptional Mechanical Properties of Polymer Composite Films.

ACS Nano 2019 Feb 11;13(2):1097-1106. Epub 2019 Jan 11.

Department of Aerospace and Mechanical Engineering , University of Notre Dame , Notre Dame , Indiana 46556 , United States.

Polymers with superior mechanical properties are desirable in many applications. In this work, polyethylene (PE) films reinforced with exfoliated thermally reduced graphene oxide (TrGO) fabricated using a roll-to-roll hot-drawing process are shown to have outstanding mechanical properties. The specific ultimate tensile strength and Young's modulus of PE/TrGO films increased monotonically with the drawing ratio and TrGO filler fraction, reaching up to 3.2 ± 0.5 and 109.3 ± 12.7 GPa, respectively, with a drawing ratio of 60× and a very low TrGO weight fraction of 1%. These values represent by far the highest reported to date for a polymer/graphene composite. Experimental characterizations indicate that as the polymer films are drawn, TrGO fillers are exfoliated, which is further confirmed by molecular dynamics (MD) simulations. Exfoliation increases the specific area of the TrGO fillers in contact with the PE matrix molecules. Molecular dynamics simulations show that the PE-TrGO interaction is stronger than the PE-PE intermolecular van der Waals interaction, which enhances load transfer from PE to TrGO and leverages the ultrahigh mechanical properties of TrGO.
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http://dx.doi.org/10.1021/acsnano.8b04734DOI Listing
February 2019

Low-Cost Nanostructures from Nanoparticle-Assisted Large-Scale Lithography Significantly Enhance Thermal Energy Transport across Solid Interfaces.

ACS Appl Mater Interfaces 2018 Oct 26;10(40):34690-34698. Epub 2018 Sep 26.

Enhancing thermal energy transport across solid interfaces is of critical importance to a wide variety of applications ranging from energy systems and lighting devices to electronics. Nanoscale surface roughness is usually considered detrimental to interfacial thermal transport because of its role in phonon scattering. In this study, however, we demonstrate significant thermal conductance enhancements across metal-semiconductor interfaces by as much as 90% higher than that of the planar interfaces using engineered nanostructures fabricated by Au nanoparticle (NP)-assisted lithography, where self-assembled Au NPs are used as an efficient etching mask to pattern solid substrates over large surface areas. The enlarged interfacial contact area due to the presence of nanostructures is the main reason for the significantly enhanced thermal transport. It is further demonstrated that the conductance can be systematically tuned over a wide range through the use of the Au NP self-assembly process that is regulated by a sacrificial Sb layer whose thickness determines the size and density of the nanostructures produced. This strategy is tested on two technologically important semiconductors, Si and GaN, and their interfacial thermal conductance with Al being measured using the time-domain thermoreflectance technique. Moreover, the nanostructured interfaces can maintain the enhanced conductance for a temperature range of 30-110 °C-the operating temperatures commonly experienced by energy, lighting, and electronic devices. Our results could provide a wafer-scale and low-cost strategy for improving the thermal management of these devices.
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http://dx.doi.org/10.1021/acsami.8b08180DOI Listing
October 2018

The role of optical phonons in intermediate layer-mediated thermal transport across solid interfaces.

Phys Chem Chem Phys 2017 Jul;19(28):18407-18415

Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556, USA.

Thermal transport across solid interfaces plays important roles in many applications, especially in the thermal management of modern power electronics. In this study, we use non-equilibrium MD (NEMD) simulations to systematically study a model SiC/GaN interface, which is an important interface in GaN-based power electronics, mated by different intermediate layers (ILs) with the focus on how the atomic masses of the ILs influence the overall thermal conductance. To isolate the mass effect, the Tersoff potential with the same parameters is used to approximate the interatomic interactions between all atoms, with the only differences between materials being their atomic masses. The NEMD results show that the thermal boundary conductance (TBC) of IL-mated interfaces depends not only on the total primitive cell mass of the IL but also on the relative masses of the atoms within the unit cell. By analyzing the vibrational power spectra (VPS) of SiC, IL, and GaN, it is found that the optical phonons play important roles in thermal transport across the solid/solid interfaces. There is an optimal mass ratio of the atoms in the unit cell of the IL that can maximize the overlap of IL optical phonon VPS with those of SiC and GaN. Furthermore, the atomic masses of a number of III-V semiconductor compounds are studied for the ILs. It is shown that when only considering the mass effect, in the classical limit, AlN will be the best IL to enhance thermal transport across SiC/GaN interfaces with an improvement of as much as 27% over that of a pristine SiC/GaN interface. Despite the known limitation of the model (e.g., absence of strain and quantum effects), the results from this work may still provide some useful information for the design of ILs to improve thermal transport across solid/solid interfaces.
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http://dx.doi.org/10.1039/c7cp02982aDOI Listing
July 2017

Nanostructures Significantly Enhance Thermal Transport across Solid Interfaces.

ACS Appl Mater Interfaces 2016 Dec 16;8(51):35505-35512. Epub 2016 Dec 16.

Department of Aerospace and Mechanical Engineering and ‡Center for Sustainable Energy at Notre Dame, University of Notre Dame , Notre Dame, Indiana 46556, United States.

The efficiency of thermal transport across solid interfaces presents large challenges for modern technologies such as thermal management of electronics. In this paper, we report the first demonstration of significant enhancement of thermal transport across solid interfaces by introducing interfacial nanostructures. Analogous to fins that have been used for macroscopic heat transfer enhancement in heat exchangers, the nanopillar arrays patterned at the interface help interfacial thermal transport by the enlarged effective contact area. Such a benefit depends on the geometry of nanopillar arrays (e.g., pillar height and spacing), and a thermal boundary conductance enhancement by as much as ∼88% has been measured using the time-domain thermoreflectance technique. Theoretical analysis combined with low-temperature experiments further indicates that phonons with low frequency are less influenced by the interfacial nanostructures due to their large transmissivity, but the benefit of the nanostructure is fully developed at room temperature where higher frequency phonons dominate interfacial thermal transport. The findings from this work can potentially be generalized to benefit real applications such as the thermal management of electronics.
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http://dx.doi.org/10.1021/acsami.6b12947DOI Listing
December 2016

Strong Influence of Humidity on Low-Temperature Thin-Film Fabrication via Metal Aqua Complex for High Performance Oxide Semiconductor Thin-Film Transistors.

ACS Appl Mater Interfaces 2017 01 20;9(1):548-557. Epub 2016 Dec 20.

Program in Nano Science and Technology, Graduate School of Convergence Science and Technology, Seoul National University , 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea.

Oxide semiconductors thin film transistors (OS TFTs) with good transparency and electrical performance have great potential for future display technology. In particular, solution-processed OS TFTs have been attracted much attention due to many advantages such as continuous, large scale, and low cost processability. Recently, OS TFTs fabricated with a metal aqua complex have been focused because they have low temperature processability for deposition on flexible substrate as well as high field-effect mobility for application of advanced display. However, despite some remarkable results, important factors to optimize their electrical performance with reproducibility and uniformity have not yet been achieved. Here, we newly introduce the strong effects of humidity to enhance the electrical performance of OS TFTs fabricated with the metal aqua complex. Through humidity control during the spin-coating process and annealing process, we successfully demonstrate solution-processed InO/SiO TFTs with a good electrical uniformity of ∼5% standard deviation, showing high average field-effect mobility of 2.76 cmVs and 15.28 cmVs fabricated at 200 and 250 °C, respectively. Also, on the basis of the systematic analyses, we demonstrate the mechanism for the change in electrical properties of InO TFTs depending on the humidity control. Finally, on the basis of the mechanism, we extended the humidity control to the fabrication of the AlO insulator. Subsequently, we successfully achieved humidity-controlled InO/AlO TFTs fabricated at 200 °C showing high average field-effect mobility of 9.5 cmVs.
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http://dx.doi.org/10.1021/acsami.6b11867DOI Listing
January 2017

Role of Hydrogen Bonds in Thermal Transport across Hard/Soft Material Interfaces.

ACS Appl Mater Interfaces 2016 Dec 22;8(48):33326-33334. Epub 2016 Nov 22.

Institute of Engineering Thermophysics, Chinese Academy of Sciences , Beijing 100190, China.

The nature of the bond is a dominant factor in determining the thermal transport across interfaces. In this paper, we study the role of the hydrogen bond in thermal transport across interfaces between hard and soft materials with different surface functionalizations around room temperature using molecular dynamics simulations. Gold (Au) is studied as the hard material, and four different types of organic liquids with different polarizations, including hexane (CHCH), hexanamine (CHNH), hexanol (CHOH), and hexanoic acid (CHCOOH), are used to represent the soft materials. To study the hydrogen bonds at the Au/organic liquid interface, three types of thiol-terminated self-assembled monolayer (SAM) molecules, including 1-hexanethiol [HS(CH)CH], 6-mercapto-1-hexanol [HS(CH)OH], and 6-mercaptohexanoic acid [HS(CH)COOH], are used to functionalize the Au surface. These SAM molecules form hydrogen bonds with the studied organic liquids with varying strengths, which are found to significantly improve efficient interfacial thermal transport. Detailed analyses on the molecular-level details reveal that such efficient thermal transport originates from the collaborative effects of the electrostatic and van der Waals portions in the hydrogen bonds. It is found that stronger hydrogen bonds will pull the organic molecules closer to the interface. This shorter intermolecular distance leads to increased interatomic forces across the interfaces, which result in larger interfacial heat flux and thus higher thermal conductance. These results can provide important insight into the design of hard/soft materials or structures for a wide range of applications.
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http://dx.doi.org/10.1021/acsami.6b12073DOI Listing
December 2016

Thermal boundary conductance enhancement using experimentally achievable nanostructured interfaces - analytical study combined with molecular dynamics simulation.

Phys Chem Chem Phys 2016 Jun;18(25):16794-801

Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556, USA and Center for Sustainable Energy at Notre Dame, University of Notre Dame, Notre Dame, IN 46556, USA.

Interfacial thermal resistance presents great challenges to the thermal management of modern electronics. In this work, we perform an analytical study to enhance the thermal boundary conductance (TBC) of nanostructured interfaces with square-shape pillar arrays, extendable to the characteristic lengths that can be fabricated in practice. As a representative system, we investigate a SiC substrate with the square-shape pillar array combined with epitaxial GaN as the nanostructured interface. By applying a first-order ray tracing method and molecular dynamics simulations to analyze phonon incidence and transmission at the nanostructured interface, we systematically study the impact of the characteristic dimensions of the pillar array on the TBC. Based on the multi-scale analysis we provide a general guideline to optimize the nanostructured interfaces to achieve higher TBC, demonstrating that the optimized TBC value of the nanostructured SiC/GaN interfaces can be 42% higher than that of the planar SiC/GaN interfaces without nanostructures. The model used and results obtained in this study will guide the further experimental realization of nanostructured interfaces for better thermal management in microelectronics.
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http://dx.doi.org/10.1039/c6cp01927gDOI Listing
June 2016

Direct electron injection into an oxide insulator using a cathode buffer layer.

Nat Commun 2015 Apr 13;6:6785. Epub 2015 Apr 13.

Program in Nano Science and Technology, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 151-742, Republic of Korea.

Injecting charge carriers into the mobile bands of an inorganic oxide insulator (for example, SiO2, HfO2) is a highly complicated task, or even impossible without external energy sources such as photons. This is because oxide insulators exhibit very low electron affinity and high ionization energy levels. Here we show that a ZnO layer acting as a cathode buffer layer permits direct electron injection into the conduction bands of various oxide insulators (for example, SiO2, Ta2O5, HfO2, Al2O3) from a metal cathode. Studies of current-voltage characteristics reveal that the current ohmically passes through the ZnO/oxide-insulator interface. Our findings suggests that the oxide insulators could be used for simply fabricated, transparent and highly stable electronic valves. With this strategy, we demonstrate an electrostatic discharging diode that uses 100-nm SiO2 as an active layer exhibiting an on/off ratio of ∼10(7), and protects the ZnO thin-film transistors from high electrical stresses.
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http://dx.doi.org/10.1038/ncomms7785DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4403381PMC
April 2015

High-power density piezoelectric energy harvesting using radially strained ultrathin trigonal tellurium nanowire assembly.

Adv Mater 2013 Jun 25;25(21):2920-5. Epub 2013 Apr 25.

Department of Materials Science and Engineering, Yonsei University, Seoul, Korea.

A high-yield solution-processed ultrathin (<10 nm) trigonal tellurium (t-Te) nanowire (NW) is introduced as a new class of piezoelectric nanomaterial with a six-fold higher piezoelectric constant compared to conventional ZnO NWs for a high-volume power-density nanogenerator (NG). While determining the energy-harvesting principle in a NG consisting of t-Te NW, it is theoretically and experimentally found that t-Te NW is piezoelectrically activated only by creating strain in its radial direction, along which it has an asymmetric crystal structure. Based upon this mechanism, a NG with a monolayer consisting of well-aligned t-Te NWs and a power density of 9 mW/cm(3) is fabricated.
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http://dx.doi.org/10.1002/adma.201300657DOI Listing
June 2013

Analysis and optimization of surface plasmon-enhanced organic solar cells with a metallic crossed grating electrode.

Opt Express 2012 Sep;20 Suppl 5:A740-53

Department of Nano Science and Technology, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, South Korea.

We perform a systematic analysis of enhanced short-circuit current density (J(sc) in organic solar cells (OSCs) where one metallic electrode is optically thick and the other consists of a two-dimensional metallic crossed grating. By examining a model device representative of such surface plasmon (SP)-enhanced OSCs by the Fourier modal and finite-element methods for electromagnetic and exciton diffusion calculations, respectively, we provide general guidelines to maximize J(sc) of the SP-enhanced OSCs. Based on this study, we optimize the performance of a small-molecule OSC employing a copper phthalocyanine-fullerene donor-acceptor pair, demonstrating that the optimized SP-enhanced device has J(sc) that is 75 % larger than that of the optimized device with an ITO-based conventional structure.
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http://dx.doi.org/10.1364/OE.20.00A740DOI Listing
September 2012