(4mb) Structure–Transport Engineering and the Interfacial Chemistry of Electronic Materials

Crystalline solids form the basis of devices found in modern energy conversion, energy storage, and energy-intensive computing technologies. The urgency to stem anthropogenic emissions has brought these technologies back into focus, placing a premium on energy efficiency and new renewable energy technologies.

Improving existing technologies—and developing new materials—rely on a deep understanding of the structure of functional materials, for instance in intercalation electrodes and semiconductors. The operational stability and transport mechanisms may differ in these disparate applications; however, both are linked to chemical bonding and electronic structure. Methods for average structure determination (both at the atomic- and micro-scale) in crystalline solids are well-established yet fail to capture the disorder and defects that influence the properties of the operative crystal. In the context of the prior examples, recent studies have elucidated similar modes of correlated disorder underlying ionic conductivity in battery electrodes and charge carrier mobility in semiconductors.My research group will develop novel applied crystallography and microstructure characterization methods: (i) to characterize structural disorder and dynamics in bulk crystals and functional device layers; (ii) to connect structure to operative transport properties across various length scales; (iii) probe buried interfaces and affect chemo-mechanical transformations. The results of these studies are expected to introduce a new paradigm of materials design and discovery by building towards a complete description of the true, operational structure of these materials.

In complementary efforts, my research group will establish comprehensive strategies to design and synthesize functionalized layered materials and heterostructures. The design features of interest here support components of existing technologies, for instance room-temperature ionic conductivity in solid electrolytes, and emerging devices, such as magnetic ions and coordination complexes as qubits in quantum information technologies. Heterostructures allow for unprecedented control over the electronic structure, driving forces for ion transport, surface and adsorption chemistry, and novel physical phenomena. Our work seeks to identify scalable synthetic methods for the assembly and functionalization of layered materials and heterostructures for next-generation devices. Translating bulk crystallization or painstaking layer-by-layer assembly methods to sustainable, high-throughput fabrication methods is a key target and could enable transformative breakthroughs in various renewable energy and optoelectronic technologies.

Research Experience

University of California, Berkeley (2023 – present) – College of Chemistry & National Center for Electron Microscopy (Lawrence Berkeley National Laboratory); Advised by Profs. Jeffrey R. Long & Andrew M. Minor.

Materials chemistry and electrical engineering. Synthesis and characterization of metal-organic magnets and hybrid layered materials for quantum information technologies; local-structure characterization using electron microscopy and diffraction.

Stanford University (2018 – 2023) – Departments of Chemistry & Chemical Engineering, SLAC National Accelerator Laboratory; Advised by Profs. Hemamala I. Karunadasa & Michael F. Toney.

Inorganic chemistry and semiconductor physics. Characterizing phase transitions and structural disorder in single-crystal and thin-film halide perovskites using X-ray scattering measurements; correlating defect chemistry with electronic doping in halide perovskites using ionic and electronic transport measurements.

University of Cambridge (2017 – 2018) – Department of Chemistry; Advised by Prof. Erwin Reisner.

Polymer synthesis and photoelectrochemistry. Synthesis of multi-functional coordination polymer electrocatalysts and fabrication of functional photoelectrode assemblies for solar-assisted CO₂ electroreduction.

Sandia National Laboratories (2012 – 2017) – Department of Materials, Devices & Energy Technologies; Advised by Dr. Timothy N. Lambert.

Materials chemistry and electrocatalysis. Development of non-precious metal electrocatalysts for oxygen electroreduction and water electrolysis; small-molecule coordination chemistry for liquid-phase separations; oxide materials as secondary alkaline battery electrodes.

Teaching Interests

Chemical engineers have—and will continue to advance—a unique and creative skillset among scientists and engineers. My pedagogical approach will emphasize problem-solving and design thinking in the application of principles to characteristically complex problems in chemical engineering practice and research. I am trained and motivated to teach the fundamentals of chemical engineering education with vision for the future workforce and evolving skillsets of chemical engineers. Modernizing the context of the chemical engineering “tool-box” is an important role of undergraduate education. I am interested in developing a course at the undergraduate level that emphasizes thermodynamics and transport in solids and the interfaces between solids and fluids. This course would extend classical topics in chemical engineering to modern topics in electronics, semiconductors, catalysts, and energy-storage materials. I am also intent on developing a new graduate-level course on the thermodynamics and kinetics of real solids and crystalline materials.

My formal training in chemical engineering and inorganic chemistry—combined with expertise in topics in materials science and applied physics—have prepared me to teach any course in the chemical engineering curriculum. At Stanford, I taught a redesigned undergraduate course alongside Prof. Matteo Cargnello, “Microkinetics – Molecular Principles of Chemical Kinetics,” for the first two years after its inception (2020, 2021). I played an active role in shaping the curriculum, student evaluation, and guest lecturing. In 2021, I received the Outstanding Teaching Assistant Award in recognition for these efforts. Here too I was able to observe effective pedagogical techniques from the lead instructor and seek feedback on my effectiveness as a lecturer, one-on-one tutor, and instructing in a group setting.

It is my priority to foster a respectful and inclusive atmosphere for learning. I will remain cognizant of students’ needs, eliminate potential biases, and advocate for marginalized or underrepresented groups in chemical engineering education (and, more broadly, STEMM).

Selected Awards

• Schmidt Science Fellow (2023 – present)
• National Science Foundation Graduate Research Fellowship (2018 – 2023)
• Stanford Graduate Fellowship in Science & Engineering (2018 – 2023)
• Stanford Energy Distinguished Student Lecturer, Precourt Institute for Energy (2021)
• Stanford Outstanding Teaching Assistant Award, Chemical Engineering (2021)
• Churchill Scholarship (2017 - 2018)
• ACS Division of Inorganic Chemistry Award for Undergraduate Research (2017)
• Barry M. Goldwater Scholarship (2016)

Selected Publications (6 of 24)

1. J. A. Vigil, N. R. Wolf, A. H. Slavney, R. Matheu, A. Saldivar Valdes, Y. S. Lee, and H. I. Karunadasa,* Halide Perovskites Breathe Too: The Iodide–Iodine Equilibrium and Self-Doping in Cs₂SnI₆. Accepted & In Press (ACS Cent. Sci. 2024). DOI: 10.1021/acscentsci.4c00056
2. J. A. Vigil, B. M. Wieliczka, B. W. Larson, M. Abdelsamie, N. S. Dutta, M. A. Haque, A. Hazarika, J. M. Luther,* and M. F. Toney,* Orientational Order in Spin-Cast Lead-Iodide Perovskite Nanocrystal Solids. Chem. Mater. 35, 9924-9934 (2023). DOI: 10.1021/acs.chemmater.3c01636
3. N. J. Weadock,^†* T. C. Sterling,^† J. A. Vigil, A. Gold-Parker, I. C. Smith, B. Ahammed, M. J. Krogstad, F. Ye, D. Voneshen, P. M. Gehring, H.-G. Steinrück, E. Ertekin, H. I. Karunadasa, D. Reznik,* and M. F. Toney,* The nature of local dynamic disorder in CH₃NH₃PbI₃ and CH₃NH₃PbBr₃. Joule 7, 1051-1066 (2023). DOI: 10.1016/j.joule.2023.03.017
4. R. Matheu,^† J. A. Vigil,^† E. J. Crace, and H. I. Karunadasa,* The halogen chemistry of halide perovskites. Trends Chem. 4, 3, 206-219 (2022). DOI: 10.1016/j.trechm.2021.12.002
5. J. A. Vigil, A. Hazarika, J. M. Luther,* and M. F. Toney,* FA_xCs_1–xPbI₃ nanocrystals: tuning crystal symmetry by A-site cation composition. ACS Energy Lett. 5, 8, 2475–2482 (2020). DOI: 10.1021/acsenergylett.0c01069
6. J. J. Leung,^† J. A. Vigil,^† J. Warnan,^† E. E. Moore, and E. Reisner,* Rational Design of Polymers for Selective CO₂ Reduction Catalysis. Angew. Chem. Int. Ed. 58, 7697–7701 (2019). DOI: 10.1002/anie.201902218

^† denotes equal contribution