Symposium EP13: Thermoelectrics—Materials, Methods and Devices

Hyejeong Lee, Gwangju Institute of Science and Technology

Enhanced Thermoelectric Performance of PEDOT:PSS Nanotubes via AAO Template-Assisted Growth

Written by Bharati Neelamraju

Hyejeong Lee works with Ji Young Jo on using variations of PEDOT:PSS for thermoelectric applications. Lee addressed how conducting polymers are a good choice for wearable thermoelectric devices like thermoelectric generators (TEG). She said PEDOT:PSS is one of the highest conductivity polymers but that it still suffers from low thermoelectric efficiencies compared to their inorganic counterparts. The researchers fabricated PEDOT:PSS nanotubes in a template for enhanced thermoelectric efficiencies. They saw an increase in electrical conductivity due to the stretching of PEDOT chains as well as the decrease in thermal conductivity through phonon scattering in these nanotubes made in their laboratory. They achieved better efficiencies by adding post processing treatments and adding a solvent to these thin films. Lee concluded her talk by explaining to the audience why heading toward low-dimensional nanotubes is an interesting path forward for these materials.


Materials Needs for Energy Sustainability by 2050—Incentivizing a Zero-Waste Future

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Moderator: Elizabeth A. Kócs, University of Illinois at Chicago

Panelists:

  • Gabrielle Gaustad, Alfred University
  • Lucas Mariacher, Phoenix Public Works Department
  • Karsten Schischke, Fraunhofer Institute for Reliability and Microintegration

Written by Aashutosh Mistry

Population growth intrinsically strains resources supporting human life. The glocal (global and local) nature of today’s communities, combined with population growth, causes sustainability issues. Two separate paradigms have been advocated to assist sustainability goals: Materials for Sustainable Development (e.g., photovoltaics) and more recently Sustainable Development of Materials—a broader approach that promotes materials based on both application as well as sustainability. Despite the recognition of sustainability, waste management has been historically underappreciated, with most of the efforts contained in a linear system that either incinerates the final product or disposes it to landfills.

A panel discussion was organized around sustainability and waste management on Tuesday evening. It was argued that zero waste is a lofty goal, and the end effects may not be apparent immediately. Zero waste is difficult to achieve through waste management, and attention should be focused on waste prevention. Ensuring zero waste is a tricky balance due to a variety of often negatively correlated factors such as the interconnected nature of a zero waste economy, technological as well as policy challenges, the participation of producer and consumer, and different local standards to name a few. Additional ambiguity arises from the fact that zero waste is not consistently defined. For example, San Francisco, California enforces participation in recycling, in contrast to Phoenix, Arizona where it is voluntary. Circular economy, where materials are designed to be reutilized at the end of product life, creates problems as well, especially when a material is banned, and it needs to be phased out from all the phases of the circular economy.

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The panelists agreed to a need for lucrative incentives to pursue recycling. Many times, rearranging the process sequence itself can be an effective incentive, for example, a large fraction of recycling cost is attributed to processing—sorting out different waste types, and it is economically more feasible to incentivize consumers to categorize trash than handling it at a recycling plant. This cost of sorting waste often decides whether recycling can be pursued and, in the presence of unacceptable overheads, incinerators or landfills are preferred.

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A unique aspect of this panel discussion was the interactive participation of the audience in the form of audience polling. It was argued that good policies go a long way in realizing the zero waste future. Good policies are to be built upon scientific rationale and statistical data, both of which require active participation from scientists and engineers.

This event was supported in part by NSF, MRS Focus on Sustainability, MRS Energy & Sustainability journal, and Symposium ES13.


Symposium SM01: Materials for Biological and Medical Applications

Sebastian Kollenda, University of Duisburg-Essen and Centre for Nanointegration Duisburg-Essen (CeNIDE)

A Biosensor on the Nanoscale—About the Fate of Functionalized Inorganic Nanoparticles in Living Cells

Written by Gargi Joshi

Due to the natural occurrence of calcium phosphate in bones and teeth, nanoparticles based on calcium phosphate are being considered as a biocompatible option for drug delivery applications to carry cargo molecules like DNA, RNA, and proteins. In his talk, Sebastian Kollenda presented his recent results on therapeutic applications based on these nanoparticles in treatment of inflammation and derived carcinogenesis, vaccination against retroviral infections, as well as viral clearance. Moreover, the main goal was to monitor intracellular pathways and ejection from the body for such therapeutic nanoparticles. The particles have aspherical morphology, and were monodispersed with a typical diameter of 50–150 nm. Time-resolved CLSM demonstrated successful endocytosis of the particles loaded with protein into the cell which was found to be highly dependent on the localized pH values. Thus, a smart tool was designed by using a pH-responsive biosensor to efficiently visualize the intracellular pathways.


Symposium EP13: Thermoelectrics—Materials, Methods and Devices

Xavier Crispin, Linkoping University

Electronic and Ionic Thermoelectric Effects with Conducting Polymers

Written by Bharati Neelamraju

Organic thermoelectric materials are gaining traction for use as the power source for flexible wearable devices. Xavier Crispin talks about two kinds of thermoelectric charge carriers: hole and ion. His research group looks at both the electronic and ionic thermoelectric properties of these materials. Crispin showed how the time evolution of the thermo voltage between a pure hole transport, a pure ion transport, and then a mixed transport conductor is different with the mixed having the highest voltages. Ionic thermoelectric energy storage systems can be used such that it charges during the day due to a variation in temperature while it discharges in the night providing electricity. Polymer electrolytes that conduct ions have high Seebeck coefficients which makes them an ideal candidate for use in supercapacitors. However, these ionic polymer electrolytes are easily affected by humidity. Crispin’s group did a series of experiments to understand this humidity-dependence.


Symposium CP04: Interfacial Science and Engineering—Mechanics, Thermodynamics, Kinetics and Chemistry

Henri-Louis Girard, Massachusetts Institute of Technology

Waterbowls – Reducing Impacting Droplet Interactions by Momentum Reduction

Written by Aashutosh Mistry

Interactions of liquid drops and solid surfaces have been a classical problem in transport phenomena and extensively studied in various contexts such as heat, momentum, and mass exchanges. Depending on the application, one would want to either enhance the effective transport, for example, faster condensation on a colder solid (going from film-wise to drop-wise condensation) or attenuate the intrinsic characteristics of the solid–liquid pair, for example, icing of impacting drops on aircraft wings is detrimental and in turn reduced heat transfer is desired. The former problem of enhanced transport has received considerably more attention than the latter.

Henri-Louis Girard’s research focuses on the problem of attenuating the aforementioned transport modes. From a simplistic understanding, one could argue that liquid-repelling (e.g., hydrophobic for water-repelling) surfaces should provide reduced transport interactions. However, upon a closer look, Girard found that even if the hydrophobic surfaces do not let drops stick to the surface, the impact, oscillations, and rebound transients provide a thorough contact between the sold and flattened drop shape during the oscillation stage. In other words, both time of contact, as well as area of contact, contribute to effective transport. For a hydrophobic surface, the time of contact is smaller, but the contact area is fairly high which jointly leads to not so small interactions. Building upon this interpretation, the research group hypothesized that if the surface has circular ridges, the contact area can be reduced. Further experiments with varying circular ridge dimensions revealed three interaction regimes: (i) when the radius of the ring is smaller than that of the drop, upon drop impact it spreads over the ring and the ring cannot divert the momentum during spreading; (ii) when the radius of the ring is fairly higher than that of the drop (greater than three times), the effectiveness reduces as it does not divert the drop contact early on; and (iii) in between these two regimes, there is an interesting regime where the usefulness of the circular ridges deteriorates with an increase in their radii. At present, the researchers are analyzing the implications of an offset impact of the drop with such ridges in terms of momentum diversion and consequent attenuated transport interactions.


User Facilities for X-Ray and Neutron Absorption Spectroscopy - A survey of analyzing material properties when other syntheses don’t provide results!

At the Spring MRS 2019 conference, some of the U.S. Department of Energy’s laboratories held tutorials on their state-of-the-art nanoscale science research centers and user facilities. The Center of Nanophase Materials Sciences (CNMS) at Oak Ridge National Laboratory and the Center for Nanoscale Materials (CNM) at Argonne National Laboratory were prominently featured, with studies that included material local distortions, chemical short range bordering, nanostructuring, and crystallographic phase transitions.

The main tutorial, the ‘Mini X-Ray and Neutron School on In Situ Materials Research’, featured researcher Katharine L. Page (ORNL), where user facilities assessed data via constructing a pair distortion function (PDF), an atomic-level scattering technique, after detection. Chemical short range order via PDF can infer material substitution effects, chemical clustering, ion-specific local environments, and vacancy ordering. Nanomaterial structuring information based on a PDF can also be determined: finite size/shape effects, surface/interface structure, nanostructure polymorphs, and growth/transformation. Such a technique is also transferrable to amorphous structures, where an understanding of oxide liquids, for instance, is essential in nuclear meltdown scenarios, evolution of planetary bodies, glass formation, and crystal nucleation.

Researchers are encouraged to pursue PDF studies if they have already modeled many material parameters possible while in reciprocal space, and if they suspect local material structure may differ from the long-range structure. Evidence of a distinct local structure may be available if one finds signatures of disorder through complementary methods, or if an average structure model fails to explain observed material properties.

The user facilities for such nanoscale science research centers are as follows:

  • Center for Nanophase Materials Science at Oak Ridge National Laboratory (cnms.ornl.gov)
  • Center for Nanoscale Materials (CNM) at Argonne National Laboratory (anl.gov/cnm)
  • Center for Functional Nanomaterials (CFN) at Brookhaven National Laboratory (bnl.gov/cfn)
  • Center for Integrated Nanotechnologies (CINT) and Los Alamos and Sandia National Laboratories (cint.lanl.gov)
  • The Molecular Foundry (TMF) at Lawrence Berkeley National Laboratory (foundry.lbl.gov)

MRS Frontiers: Materials for Quantum, Biology, Sustainability, & Artificial Intelligence

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This 2019 MRS Spring Meeting featured a grandiose reception for attendees, concerning what would be the new topical areas of interest for future scientific meetings. While some seminal works in Quantum Information Technologies, Artificial Intelligence, Biomaterials (for example), and Materials for Sustainability have driven pop science intrigue, there is no doubt as to their research prominence, application, and concern for implementation based on where strategic materials advances could bring these fields into a more palatable reality.

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The networking reception itself was a very successful addition to the Meeting, collecting feedback and constructing working groups for where these topical areas are poised to inspire research presentations and publications, as well as secure collaborations for new research initiatives, grant applications, and establishing benchmarks for funding priorities.

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MRS, from grassroots initiatives of supporting higher level lobbying for initiatives pertinent to materials researchers, features political proceeds newsletters and the Materials Voice - a support feature for US constituents to e-mail their congressional representatives about specific policy concerns that are of vital importance to the materials research community. MRS, with the addition of other professional scientific organizations, features the National Photonics Initiative and National Quantum Initiative as a means for researchers to follow, at high level, the impending frontiers of research.

The MRS Frontiers Reception: Building Communities event was supported in part by ASU, ASM, LANL, ReACT, NSF, and Symposium ES13.


Material Structural Considerations for Energy Applications: How adapting a chemical synthesis at nanoscale drives improved performance

At the MRS Symposium for Energy Materials, materials for developing Concentrated Solar Power (CSP) technologies was for another year, a hot topic. CSP demands differ from those materials needed for driving photovoltaics - rather than certain semiconductor media or perovskites, this symposia examined materials that absorb the sun’s energy to transfer to a conventional Rankine- or Brayton-cycle thermodynamic process, using mechanical work to generate electricity as an intermediary.

Advances in this field have previously encouraged researchers to develop inorganic materials that exhibit spectral-selectivity, or a sensitivity to absorptance at specific solar wavelengths and reflectance at higher infrared wavelengths, to prohibit events of waste heat occurring based on re-radiative emissivity. However, with materials that can survive at higher working temperatures, this material feature isn’t as prudent as general absorptivity. Tailoring the structural properties of nano-materials can support improved light-trapping capabilities, where nanostructures trap light of very short wavelengths.

A research encouragement was in comparisons to the nanostructure of Surrey NanoSystems’ VantaBlack, that absorbs up to 99.96% of visible light based on a nano-needle structure. Researchers at the University of California, San Diego have shown a comparable nanomaterial structuring feasibility from a simplified chemical synthesis. As a cost-effective means of upscaling the process to large CSP power plants, such as the Crescent Dunes CSP Plant in Nevada, researchers are poised to explore how such a process can be further stabilized for longer survivability to ensure such a method can be commercially viable.


My MRS Experience

Blogging for 2019 MRS Spring Conference has been an educational experience for me. I had to learn how to balance taking notes for various talks, summarizing the developments succinctly without missing out on the important details, and trying to communicate scientific research without using too much jargon so that people outside of the field can understand it. Additionally, the beautiful city of Phoenix, Arizona has been punishing in its heat so going outside for a short walk in between sessions feels like running a marathon. Nevertheless, the place has been so welcoming, the Phoenix Convention Center was an excellent location to host so many people. 

The various talks, symposia and outreach activities really motivated me to go back to the laboratory and work hard on my research. My goal was to learn more about thermoelectric behavior, the basics of organic thermoelectrics and their applications in flexible devices. Talks by researchers like Prof. Gang Chen, Prof. Yi Cui, and Prof. Joseph Wang were very enlightening in terms of understanding where materials research is going and what future scientists like me should focus on. Moreover, talks by Prof. Graeve during the Women in MSE Breakfast and by Dr. Arenberg during the Symposium X session on The James Webb Space Telescope helped me understand the breadth of materials science, as well as my role in this community as a woman, an engineer, and a minority. 

Overall, this has been an excellent experience. I feel honored to have been able to write about it, and am thankful to Ms. Judy Meiksin for this opportunity. Moreover, I had a great experience presenting my own research on flexible electronics (the last presentation on the last day, so I like to pretend I got to close the MRS Conference) and look forward to attending this conference in the coming years.