4:10 - 4:50 p.m.
"Utilizing Conjugated Polymers for Solar Energy Harvesting: Three Vignettes"
Conjugated polymers have been mostly used as p-type organic semiconductors in the bulk heterojunction (BHJ) organic photovoltaic cells. Impressive progress has been made through synergistic efforts of chemists, physicists, and engineers. For example, the efficiency has reached 8 – 10% recently, largely through the engineering the conjugated backbone of these polymers to reach ideal energy levels and band gaps.
In this talk, I will to use three examples to explain the recent advances in using conjugated polymers for solar cells. First, we discovered that all interesting properties shown by PBnDT-FTAZ, a 7% efficiency polymer, can only be obtained with polymers of a quite narrow range of molecular weight. Second, there seems to be a lower limit on how small a band gap one can push these "low band gap" polymers to for maximizing their light harvesting ability. Third, though polymer/inorganic hybrid solar cells is a promising research direction, there are certain limitations one has to understand, esp. when GaAs is visioned as the inorganic semiconductor to pair with p-type polymers.
Dr. Wei You obtained his BS from University of Science and Technology of China in 1999. He graduated with his PhD from the University of Chicago in 2004 with Professor Luping Yu, and finished his postdoctoral training at Stanford University in 2006 with Professor Zhenan Bao. In July 2006, Dr. You joined the University of North Carolina at Chapel Hill as an Assistant Professor in Chemistry, and was promoted to the rank of Associate Professor in 2012 when he also started serving as the Associate Chair for Research in the Chemistry Department. He has published over 40 papers in leading journals such as JACS, Angew. Chem., Int. Ed., Macromolecules, Advanced Materials, among others, and has been an Associate Editor for Polymer Chemistry (RSC) since July 2013. He has received DuPont Young Professor Award (2008), NSF CAREER Award (2010), Camille Dreyfus Teacher-Scholar Award (2011), Tanner Award for Excellence in Undergraduate Teaching (2011), CAPA Distinguished Junior Faculty Award (2012), and Ruth and Phillip Hettleman Prize for Artistic and Scholarly Achievement (2013). His group is currently investigating organic solar cells, molecular spintronics/electronics and devices, new methods for nanofabrication (microfabrication), and new materials for dental applications.