Welcome to the Liu Research Group

 

Dr. Liu leads an energy conversion, storage, and management research group focusing on developing computational and experimental tools for understanding nanoscale thermal transport, probing new transport phenomena in micro/nano-scale structures, and applying the results to design thermal management and energy conversion/storage systems with nano-engineered functional materials.

He is currently working on (1) developing ultrafast laser-based pump-probe system for characterizing thermal, elastic, and magnetic properties of materials (e.g. TDTR, TRMOKE, Raman); (2) developing numerical simulation tools for understanding energy transport mechanisms in soft matters and hybrid materials (e.g. molecular dynamics, density functional theory, lattice dynamics); (3) establishing novel functional thermal materials, especially soft materials and hybrid materials. Those materials serve as elementary building blocks for thermal management and energy conversion/storage devices and systems with enhanced performance.

Dr. Liu’s graduate students are motivated to learn; they are familiar with both simulation and experiment work, and tend to solve multidisciplinary, challenging problems. His students have the opportunity to learn multidisciplinary topics in optics, electronics, thermal science, materials, and solid-state physics.

Recent Research

Thermal Transport in Oriented Semicrystalline Polymers

The understanding on the thermal transport in the ultra-drawn semicrystalline polymer fibers or films is still lacking. We recently built an ideal repeating unit of semicrystalline polyethylene and studied their dependence of thermal conductivity on different crystallinity and interlamellar topology using molecular dynamics simulations. See our recent work at Journal of Applied Physics. More interesting results are to come.

Thermal Transport in 2D Materials and van der Waals Heterostructures

Thermal conductivity of 2D materials and van der Waals heterostructures is of interest for energy storage, nanoelectronics, and optoelectronics. The effect of defects and disorders is important to know. We simulated the effect of mass disorder and stacking disorder on the anisotropic thermal conductivity using MD. We also measured the effect of structural and compositional disorders by TDTR and other characterization tools. See our recent work at Nature Communications.

Anisotropic and Strain Effects in Polymers

Thermal transport in the axial direction of polymer fibers has been extensively studied, while the thermal conductivity in the radial direction remains unknown. Because polymer fiber is an important type of high anisotropic materials, we measured the strain effect of thermal conductivity in the radial direction using TDTR (ACS Macro Letters) and simulated this effect using MD(Applied Physics Letters).

More research and publications here.

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