Resnick Institute Seminar

Please join us for a seminar given by Resnick Graduate Research Fellows Navaneetha K. Ravichandran & Isaac Fees

Ravichandran's talk: "Enabling Large Scale Sustainable Lighting through Efficient Heat Dissipation in LEDs"

Light emitting diodes (LEDs) are efficient light sources that could substantially reduce our lighting energy consumption. However, inefficient dissipation of the heat generated within the LEDs significantly reduces their lifespan, thereby resulting in very high replacement costs. The origin of this inefficient heat dissipation is the high thermal boundary resistance (TBR) within the multi-layer LED structure caused by phonon reflections at the solid boundaries. Although this basic picture of the TBR is well understood, a detailed atomistic understanding of phonon boundary interactions, essential to design LEDs with better thermal properties, is still lacking. In this work, we use a novel experimental technique along with ab-initio calculations of phonon properties to directly investigate the interaction of phonons with atomistically rough boundaries for the first time. Our findings can give us direct insights into the atomistic structure of the LED boundaries that lower the TBR and improve the LED lifespan at a low cost.

Fee's talk: "Controlled Mixing of Fresh Water & Salt Water for Renewable Energy"

The mixing of fresh water and salt water involves a loss of free energy that represents a significant and as yet unharnessed renewable energy resource. Use of nano-fluidic channel architectures has emerged as a plausible technology to control this mixing process for energy capture in desalination brine disposal, municipal wastewater treatment, and at natural estuaries. We have developed an analytical model of channel electrolyte transport to predict the influence of pertinent material properties, such as the surface charge density, and system dimensions on ionic current generation when the channel is subject to imposed external pressure, salt concentration, or voltage drops. This talk will discuss the transformation of chemical energy into electrical energy for a pure salinity gradient-driven process and will also examine the impact of implementing such technology on the ability of coastal communities, e.g. Los Angeles, to become water self-sufficient.