报告内容摘要：
Conjugated polymers have been mostly used as p-type organic semiconductors (paired with the n-type fullerene derivatives) 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 of polymer-fullerene BHJ solar cells has breached 10% recently, enabled by the synergy between the molecular engineering of conjugated polymer, and the morphological control via fine-tuning the processing conditions.
In this talk, the design rationale of conjugate polymers for polymer-fullerene BHJ solar cells, including conjugated backbone, side chains and substituents will be summarized. First, all interesting properties shown by PBnDT-FTAZ, which can achieve over 7% efficiency with a noticeably high fill factor over 70% in its BHJ cells with a thick film of 300 nm, can only be obtained with polymers of a quite narrow range of molecular weight (~ 40 kg/mol). The molecular weight induced morphological changes in the polymer:fullerene blend provide the “missing link” that correlates the molecular weight with the photovoltaic device performance. Second, with a series of five copolymers with varying degrees of fluorination, we show that the photovoltaic properties of PBnDT-FTAZ vary depending upon the percentage of fluorine incorporation. Furthermore, increasing the fluorine content results in improved hole mobility, which appears to be the key factor for the “fluorine impact” in this series of polymers.
报告人介绍：
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 50 papers in leading journals such as Nature Photonics, 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, bio-inspired materials for biomedical applications, and new polymerization methodologies.