MSE 520: Seminar Series

Every step from first synthesis of a new material to any later large-scale production and commercialization is necessarily dependent on analytical methods that give rapid feedback about the phases being fabricated and their physical properties. I’ll focus here on x-ray based materials diagnostics, where my group has been working to resolve a long-standing anomaly: the historically low access to advanced x-ray spectroscopies, and their consequent scientific underutilization.

Specifically, we are creating new benchtop analytical capability that will have high impact in materials science, chemistry, environmental science, and other fields. After giving background on x-ray absorption fine structure (XAFS) and very high resolution x-ray emission spectroscopy (XES), I’ll discuss how we have led the effort to develop XAFS and XES capability in the laboratory, thus giving a meaningful alternative to waiting for synchrotron beamtime. There are three reasons why this is not a mere issue of convenience: (1) synchrotron XAFS beamlines worldwide are typically more than 100% oversubscribed, slowing access even for experts; (2) synchrotron beamlines cannot support the type of routine, high-repetition, high-access analytical studies that are most powerful for materials discovery; and (3) synchrotron beamlines cannot support education about XAFS and XES on the scale needed for their much broader adoption and full scientific utilization. I’ll discuss examples of the use of our spectrometers at UW and elsewhere that illustrate new ways to accelerate research and development for a wide range of contemporary problems, including electrical energy storage, catalysis, light emitting diodes, several classes of nuclear materials including molten salts for next-generation reactors, and environmental regulatory testing for toxic metal content in consumer products.

This work has been supported by: Argonne National Laboratories, Pacific Northwest National Laboratories, Los Alamos National Laboratories, NIST, JCESR, UW’s MEM-C, the UW Clean Energy Institute, and the US Department of Energy.

Gerald Seidler has been a faculty member in the Physics department at the University of Washington since 1996. The Seidler group had two main research thrusts. First, we investigate the physics of environmentally- and industrially-relevant materials, with a strong emphasis on advanced x-ray techniques. This includes developing and applying new instruments and techniques for advanced x-ray spectroscopy in the laboratory setting and a wide range of major facilities. Our work and collaborations span electrical energy storage, inorganic and analytical chemistry, actinide chemistry in the context of environmental remediation and nuclear fuel processing, molten salt chemistry, and forensic science. Second, again using xray methods, we create and study high-energy density plasma systems, such as by illumination with x-ray free electron lasers. These experiments allow us to access experimental systems having electronic temperatures of millions of Kelvin but ion cores that still rest on a periodic lattice. Such systems are a rich testing ground for theoretical treatments of partially ionized plasmas, such is important for several astrophysical problems and also the early stages of inertial confinement fusions.

Halide perovskites are currently of intense interest for solar energy and optoelectronic applications. Remarkable gains in performance have been demonstrated in the past few years. However, most current devices are still limited by non-radiative recombination losses.

We focus on uncovering and eliminating these loss processes. Experiments suggest that electrical heterogeneities in both the perovskite active layer, as well as the perovskite/electrode interface affect carrier diffusion and non-radiative recombination processes. Both optical and scanning probe microscopy experiments show how grain boundaries slow lateral carrier transport and serve as recombination centers in these systems, and multimodal microscopy experiments also reveal the combined role of electrochemistry and ion motion on defect formation. We show that with controlled passivation of the perovskite surfaces we are able to obtain carrier lifetimes and photoluminescence intensities in solution-processed thin films that rival those in the best single crystals, achieving over 90% PL internal quantum efficiency and quasi-Fermi level splittings that exceed 96% of the Shockley-Queisser limit under illumination in passivated thin films. Finally, we characterize surface recombination velocities at many different perovskite/electrode interfaces and discuss what interface parameters will be needed to reach power conversion efficiencies over 28%.

David S. Ginger earned dual B.S. degrees in chemistry and physics at Indiana University in 1997 with departmental honors and highest distinction. He received a British Marshall Scholarship and an NSF Graduate Fellowship and completed his Ph.D. in physics at the University of Cambridge (UK) in 2001. After a joint NIH and DuPont Postdoctoral Fellowship at Northwestern University in Chad Mirkin’s lab, he joined the faculty at the University of Washington in Seattle where he is currently the Alvin L. and Verla R. Kwiram Endowed Professor in Chemistry, Washington Research Foundation Distinguished Scholar in Clean Energy, and Adjunct Professor of Physics, and serves as the Chief Scientist of the Washington state funded UW Clean Energy Institute. He holds a joint appointment as a Senior Scientist at Pacific Northwest National Lab (PNNL), and is the co-founding co-director of the Northwest Institute for Materials Physics, Chemistry, and Technology (NW IMPACT). His research centers on the physical chemistry of nanostructured materials with applications in optoelectronics, energy and sensing, and his group makes use of techniques ranging from scanning probe microscopy to optical spectroscopy.

Indium phosphide is the leading Cd-free quantum dot material for application in photoluminescence down-conversion display and lighting technologies. To date the performance of InP quantum dots has lagged behind cadmium selenide in terms of both luminescence line width and quantum yield. This talk will highlight extensive studies in our lab that have implicated kinetically persistent magic-sized cluster intermediates as a leading contributor to polydispersity in these samples, providing new opportunities for achieving high color purity.

Additionally, using a combination of X-ray emission and solid-state NMR spectroscopy we have studied evolution of InP surface structure during typical post-synthetic surface modifications. Correlations of this data with observed steady-state and time resolved absorption and luminescence will be used to reveal the role of interfacial oxidation and charge trapping mechanisms on the luminescence properties of InP QDs.

Brandi Cossairt obtained her B.S. in Chemistry from the California Institute of Technology in 2006. She went on to pursue graduate studies at the Massachusetts Institute of Technology under the guidance of Professor Christopher C. Cummins and was awarded her Ph.D. in 2010. She then continued her academic career as an NIH NRSA Postdoctoral Fellow at Columbia University between 2010 and 2012 working with Professor Jonathan Owen. Brandi joined the Department of Chemistry at the University of Washington as an Assistant Professor in 2012 and was promoted to Associate Professor with Tenure in 2018. She has received a number of awards for her research including a Sloan Research Fellowship, a Packard Fellowship, an NSF CAREER Award, a Dreyfus Teacher-Scholar Award, and the National Fresenius Award from the American Chemical Society. Outside of the lab Brandi is an Associate Editor at the ACS journal Inorganic Chemistry and is the co-founder of the Chemistry Women Mentorship Network (ChemWMN).

Electromechanical coupling is ubiquitous in nature that underpins functionalities of both synthetic materials and biology for information processing as well as energy conversion and storage. While dynamic strain based scanning probe microscopy (ds-SPM) has emerged as a powerful tool to investigate electromechanical coupling at the nanoscale, known as piezoresponse force microscopy (PFM) for ferroelectric materials and as electrochemical strain microscopy (ESM) for ionic systems, resolving intrinsic electromechanical mechanisms as well as quantitative response remains challenging for complex media.

In this talk, we introduce the basic concept of ds-SPM, highlight its various issues, and propose a number of techniques to overcome these difficulties. We show that first and second harmonic ds-responses can be used to distinguish piezoelectric and electrochemical strains, with which we reveal the co-existence of alternating polar and nonpolar domains in the emerging perovskite solar cells that correlate with photovoltaic conversion, and we shed new insight into the resistive switching in ultrathin ferroelectric heterostructures in the absence of polarization reversal. We also develop sequential excitation SPM, empowered by deep data, to determine intrinsic electromechanical coupling quantitatively at the nanoscale, wherein conventional methods fail. Finally, we present a vision for a big data SPM, wherein advanced data acquisition and analytics are coupled with machine learning and artificial intelligence to accelerate mechanistic understanding via scanning probe.

Jiangyu Li is a professor in the Department of Mechanical Engineering, University of Washington. He obtained his B.E. degree in 1994 from the Department of Materials Science and Engineering, Tsinghua University, and Ph.D. degree in 1998 from the Department of Mechanical Engineering, University of Colorado-Boulder. Li works in the general field of mechanics of materials, focusing on advanced scanning probe microscopy and its applications in functional materials. He has published over 200 journal articles, and has been recognized by Sia Nemat-Nasser Medal from ASEM, Young Investigator Award from ICCES, and Microscopy Today Innovation Award from Microscopy Society of America. He currently serves as Associate Editor for Journal of Applied Physics and Science Bulletin.

Given their intrinsic hierarchical micro-/nano-structures, unique chemical/physical properties and tailorable functionality, hydrogels and their derivatives have emerged as an important class of materials for many exciting applications beyond their traditional biomedical application. Bottom-up synthetic strategies to rationally design and modify their molecular architectures enable functional hydrogels to address critical challenges in renewable energy and environmental technologies.

In this talk, I will present our recent advances made in nanostructured functional hydrogels, particularly those based on conjugated polymers, as an emerging material platform for several significant applications in sustainable energy and environment, including high-energy-power lithium batteries and supercapacitors, electrocatalysts, and solar water desalination and atmospheric water harvesting. I will further illustrate ‘structure-derived multifunctionality’ of this special class of materials.

Guihua Yu is a tenured associate professor of Materials Science and Mechanical Engineering at University of Texas at Austin. He received his B.S. degree with the highest honor in chemistry from USTC, and earned Ph.D. from Harvard University, followed by postdoc at Stanford University. His research has focused on rational synthesis and self-assembly of functional organic and hybrid organic-inorganic nanomaterials, and fundamental understanding of their chemical/physical properties for advanced energy and environmental technologies.

Yu has published ~120 scientific papers in prominent journals such as Science, Nature, Nature Nanotech., Nature Commun., Chem. Soc. Rev., Acc. Chem. Res., PNAS, JACS, Adv. Mater., Angew. Chem. Energy Environ. Sci., Nano Lett., ACS Nano, Chem, Joule, which have received total citations ~20,000 times (Highly Cited Researcher 2018).

Yu has received a number of notable awards/honors, including DOE Early Career Award, ACS ENFL Emerging Researcher Award, Nano Letters Young Investigator Lectureship, Caltech’s Resnick Young Investigator, Fellow of Royal Society of Chemistry, Camille Dreyfus Teacher-Scholar Award, TMS Society Early Career Faculty Award, Sloan Research Fellowship, Chemical Society Reviews Emerging Investigator Lectureship, MIT Technology Review ‘35 Top Innovators Under 35’, IUPAC Prize for Young Chemists. Yu serves in Advisory/Editorial Board of Chem (Cell Press), ACS Central Science, Chemistry of Materials (ACS); Nature Scientific Reports, Energy Storage Materials (Elsevier), Science China Chemistry, Science China Materials, Batteries & Supercaps (Wiley), etc.

In this talk I will highlight our research in low-loss STEM-EELS in collaboration with Jon Camden (Notre Dame), Philip Rack and Gerd Duscher (UTK), Juan Carlos Idrobo (ORNL), and Peter Crozier (ASU). Emphasis will be placed on modeling the interaction of the fast electron probe with surface plasmon and photonic cavity modes in noble metal and dielectric oxide nanoparticles and their assemblies. Several topics ranging from plasmonic energy transfer, weak-to-strong coupling, Fano antiresonances, and magnetic plasmon hybridization will be discussed.

David J. Masiello is an Associate Professor of Chemistry and an Adjunct Associate Professor of Applied Mathematics at the University of Washington. He received his Ph.D. in theoretical chemical physics with Prof. Yngve Ohrn at the University of Florida’s Quantum Theory Project in 2004 and held postdoctoral positions at the University of Washington from 2004 to 2006 with Prof. William P. Reinhardt and Northwestern University from 2006 to 2009 with Prof. George C. Schatz. In 2010, he began his independent career at the University of Washington working in the fields of plasmonics and nanophotonics theory, and he is the recipient of an NSF CAREER Award and a Presidential Early Career Award for Scientists and Engineers (PECASE).