January 24, Na Sai, University of Texas at Austin

IMG_4727.jpg3:00 PM in Room 205, 8 St. Mary’s Street

Refreshments served at 2:45 PM

New Materials for Solar Cells: From Quantum Mechanical Simulations to Computational Materials Design

Abstract: The sun delivers enormous energy to Earth that can meet our current and future demands.  Only 0.18% of the total US electricity production is currently derived from sunlight.  The enormous gap between the potential for solar energy exploitation and its utilization is due to the cost and inefficiency of existing energy conversion devices.  Third-generation solar cells are being designed to meet the grand challenge of making the conversion dramatically more affordable and efficient by innovating in the area of materials and design concepts.

Organic semiconductor solar cells offer the prospect of inexpensive and scalable production combined with mechanical flexibility.  The design of optimal organic photovoltaics (OPVs) demands elucidation of physical mechanisms in the separation of electrons and holes at organic interfaces and in the transport of charge in organic heterojunctions.  Both are critical steps in the energy conversion process and are defined by the unique active material electronic properties.  Computational investigations of OPV materials and interfaces predict key electronic properties governing the energy conversion efficiency, such as excited states, energy level alignment, interfacial charge transfer, interfacial dipoles, charge trapping, and the dependence on the molecular structure, interfacial geometry, and morphology.  I will discuss strategies for integrating theory with experiment to generate fundamental insight into the role of hot charge transfer excitons and for harnessing materials design to enhance organic photovoltaic performance.

Biography: Na Sai is a research fellow in the Department of Physics and the Institute for Computational Engineering and Sciences at the University of Texas at Austin and a Sandia National Laboratories-affiliated member of the DOE-EFRC Center on Charge Separation and Transfer at Interfaces in Energy Materials.  She received her bachelor’s degree in electronic engineering from Jilin University, China, and Ph.D. in condensed matter physics from Rutgers University.  She did postdoctoral work at the University of Pennsylvania and University of California, San Diego.  She applies a wide range of computational techniques to study electronic properties of materials, elucidating fundamental processes and mechanisms and developing insights to guide the design of new materials, most recently for solar energy conversion.  Her current research interests include organic polymers, nanostructured materials, hybrid materials, molecular electronics, multifunctional oxides for solar energy conversion and storage, nanotechnology, and next generation electronics.

Faculty Host: David Bishop

Student Host: Alket Mertiri