Nanostructure Design for Efficient Energy Devices

Dr. Yan Yao, Department of Materials Science and Engineering, Stanford University

Friday, April 27, 2012, 3:30pm

Spanos Auditorium

This seminar is part of the Jones Seminars on Science, Technology, and Society series.

Efficient energy conversion and storage play important roles in the renewable energy landscape. In developing next-generation high-performance and low-cost batteries and solar cells, significant challenges exist at both the fundamental and practical levels. In this talk, I will discuss how nanostructure design can provide us a unique opportunity to manipulate the electrons, ions, and photons to obtain remarkable device performance. In the first example, I will demonstrate a new approach to broad-band light trapping by forming whispering-gallery resonant modes inside a spherical nanoshell structure. Using nanocrystalline silicon as a model system, the absorption of a single layer of 50-nm-thick spherical nanoshells is equivalent to a 1-um-thick planar nc-Si film. Then I will show lithium-ion battery anodes made of interconnected hollow spherical structure are capable of accommodating large mechanical strain without pulverization. The structure design is theoretically guided to effectively reduce lithium-diffusion-induced stress and experimentally verified with long electrochemical cycling life. Finally, I will show the approaches of nanoscale morphology engineering for efficient polymer bulk-heterojunction solar cells.

About the Speaker

Yan Yao is a postdoctoral scholar in the Department of Materials Science and Engineering at Stanford University. His research interest is in the area of nanomaterials and nanostructures for energy conversion and storage, particularly in the field of polymer solar cells and lithium-ion batteries. Dr. Yao has published approximately 30 papers in peer-reviewed journals, and the total citations of his papers have exceeded 3000 within the past five years. Some of these works have been reported in Nature, Stanford News, Forbes, Nanowerk, etc. A native of China, Yan Yao received his B.S. and M.S. degrees in Materials Science from Fudan University, Shanghai, in 2000 and 2003, respectively, and his Ph.D. in Materials Science and Engineering from UCLA with Prof. Yang Yang in 2008. He was senior scientist at Polyera Corporation from 2008 to 2010, where he claimed 6 pending patents. His honors include the 2007 Chinese Government Award for Outstanding Students Abroad and 2008 Excellence in Graduate Polymer Research Award from the American Chemical Society.