Chemical Design of 2D Heterostructures for Next-Generation Computer Hardware

Abstract: Robust and escalating computing demand over the next several decades will necessitate the development of new materials, algorithms, and devices that address both performance and sustainability. We perform advanced materials synthesis, spectroscopy, and device integration focused on new classes of two-dimensional (2D) materials. These planar, few-atom thick 2D crystals and their assemblies exhibit intriguing phenomena that can be harnessed for optics, sensing, energy conversion, quantum control, and of course information technology. In this talk, I will summarize our research advances in 2D atomic crystals, 2D molecular lattices, and the first assembly of bespoke van der Waals heterostructures with these materials. First, I will share how careful control of precursor flux and substrate interactions can both shape and significantly reduce defects in 2D transition-metal dichalcogenide (TMD) crystals that show promise as building-blocks for future field effect transistors. Second, I will show how our unique capabilities in gas-phase synthesis and exfoliation of 2D metal-organic frameworks (MOFs), which harbor stimulus responsive properties and mixed-valency, enable the creation of unconventional sensors and catalytically-active substrates. Finally, I will discuss how seamless integration of 2D TMD monolayers with molecular thin films and 2D MOFs yields devices that exhibit efficient photon upconversion and unprecedented quantum emission phenomena. Collectively, these efforts help address some of the essential materials needs critical to future computer hardware.

Bio: Thomas J. Kempa is an Associate Professor of Chemistry and of Materials Science and Engineering (by courtesy) at Johns Hopkins University. After receiving a bachelor’s degree in chemistry from Boston College (2004) and after being awarded a Marshall Scholarship, Tom completed two years of post-graduate study at Imperial College London. Returning to the United States, he began graduate studies under the direction of Prof. Charles Lieber at Harvard University and earned his PhD in 2012. Thereafter, Tom conducted postdoctoral studies in the laboratory of Prof. Daniel Nocera, first at MIT and then Harvard. Professor Kempa’s research group develops new methods to prepare and study low-dimensional (low-D) inorganic crystals from nanoparticles (0D) to few-atom thick sheets (2D) whose exceptional properties render them intriguing platforms for optoelectronic, energy conversion, and quantum science studies. Professor Kempa is the recipient of numerous awards including a DARPA Young Faculty Award, an NSF CAREER Award, a Toshiba Distinguished Young Investigator Award, a Dreyfus Foundation Fellowship in Environmental Chemistry, two Hopkins Discovery Awards, and a Hopkins Catalyst Award. He was also named an Emerging Investigator by the Journal of Materials Chemistry A and was recently selected by Matter as one of 35 early career PIs leading breakthroughs in materials science. In 2023, Tom was appointed a member of the Nano Letters Editorial Advisory Board. He is also a founder and co-director of the Hub for Imaging and Quantum Technologies, an institute at JHU.