research.md

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I am a 5th year PhD Candidate in the Stanford Materials Science & Engineering department co-advised by Professors Fang Liu and Aaron Lindenberg. My work focuses on understanding and manipulating the thermal and excitonic properties of atomically thin or "two-dimensional" (2D) materials such as Graphene, or semiconducting transition metal dichalcogenides (TMDCs) like Molybdenum Disulfide (MoS₂) and Tungsten Diselenide (WSe₂). I develop new ways to fabricate these materials and use ultrafast optical experiments combined with computational modeling to understand the physical properties of these systems. The ultimate goal is to apply these materials to microelectronic or energy conversion applications.

Tuning Thermal Transport through Morphology Engineering at Lawrence Berkeley National Laboratory

As the global energy demand rapidly increases, developing energy efficient and sustainable energy sources will play a key role in mitigating the climate crisis. Thermoelectric (TE) devices are a promising source of clean energy as they can convert thermal energy from waste heat, which comprises 72% of global energy generated, back into electric power. Expanding the availability of TE devices and applying them to existing waste heat sources such as motors, hot water pipes, industrial equipment, computer servers, and more, can help significantly increase global production of and access to sustainable energy.

Recently, Two-Dimensional (2D) materials such as monolayer transition metal dichalcogenides (TMDs), graphene, and SnSe have garnered interest for TE applications due to their low thermal conductivities, high and tunable Seebeck coefficients, tunable electrical conductivities, and relative affordability. In this project, we aim to tune the electrical and thermal conductivities of 2D materials through morphology engineering. Morphology engineering, which refers to the design and creation of nanometer sized bubbles or wrinkles, has a great potential to modulate the heat exchange, thermal insulation, and energy conversion properties of 2D materials. Our group has devised a lithography-free technique to engineer periodic nanoscale bubbles and wrinkles into monolayer materials. This designer approach can be used to control and realize new thermoelectric properties in a variety of thin materials, by controllably manipulating phonon and electron transport characteristics. The technique can be scaled for large scale production and commercialization, and will lead to the development of low-cost, flexible sustainable energy converters with the potential to be applied to a wide range of waste heat sources.

I was awarded a DOE Office of Science Graduate Student Research Award to conduct part of this research at the Molecular Foundry at Lawrence Berkeley National Laboratory from July to September 2023, working with Dr. Archana Raja. I was awarded additional funding to continue this project from the Stanford TomKat Center for Sustainable Energy.

This paper is under preparation.

Ultrafast Electron Diffraction at SLAC National Laboratory

Using ultrafast electron diffraction, I worked with a team of scientists at SLAC National Laboratory and Stanford to study thermal transport between monolayers in a multilayer stack. I fabricated large-area (mm-scale) monolayer materials and created heterobilayer stacks of these materials, which consists of one monolayer such as MoS₂ on top of another, such as WS₂. In this experiment we photoexcited the system and used ultrafast electron diffraction to understand the time-resolved lattice dynamics upon photoexcitation. In this technique we obtain a series of diffraction images as a function of delay time, which can be used to understand atomic motion after excitation. In this work we studied a range of different systems. The experiment produced over a TB of data in the form of diffraction images. For data analysis I built a python library to organize, model, and fit this data.

This work has been published here.