Department
of Materials Science and Engineering
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Materials Science
SHORT BIOGRAPHY Qibing Pei is professor of materials science and engineering specializing in synthetic polymers. He worked successively as a senior chemist at UNIAX Corporation, Santa Barbara, CA, which was later merged into DuPont Display, a senior chemist at Imation Corporation, Santa Paul, MN, and a senior research engineer at SRI International, Menlo Park, CA. He has developed a number of electronic and electroactive polymers for applications in electro-optic and electro-mechanical devices, including light emitting diodes, polymer light emitting electrochemical cells, electroactive polymer artificial muscles, and biologically-inspired robots. His research interests cover a wide range of soft materials and span from material synthesis, processing, to design of functional devices. He applies organic synthesis, polymer synthesis, solution-based processing and nanofabrication in the discovery of new polymers and multifunctional composites. RESEARCH DESCRIPTION Our Soft Materials Research Laboratory studies electronic polymers and nanostructured hybrid materials. The research focuses on molecular synthesis and nano-scale engineering for the development of new polymers and nano-structures with desired electronic, photonic, and/or mechanical properties. The applications of these materials are many folds, including flexible electronics, artificial muscles, photovoltaics, wind energy generation, radiation detection and protection, and biologically-inspired systems to name a few. Current projects include: Electroelastomer actuators and generators: These are based on dielectric elastomers exhibiting electrically-induced strains as high as 400%. The polymer transducers have such advantages as high energy and power densities, quietness, mechanical compliancy (for shock resistance and impedance matching), high efficiency, lightweight, and low cost. To improve the device performance and reliability, interpenetrating polymer networks are being studied as a new generation of electroelastomers. Fault tolerance is being introduced as a means to prolong operation lifetime. The project involves mechanical design, fabrication, and testing of polymer actuators and generators. Flexible electronics: We started a new effort in achieving electronic devices that are flexible or even stretchable. Carbon nanotubes are deposited into ultrathin coatings with modest surface conductivity and semi-transparency. Using a stretchable substrate and polymer semiconductors, flexible polymer LEDs and solar cells can be fabricated. The holy-grail is to achieve devices wherein the active area is stretchable. Nanostructured hybrid materials: Composites of inorganic compounds and conjugated polymers are prepared with controlled nanostructures for photovoltaics or radiation detection. We synthesized CdS nanorod arrays by electrochemical self-assembly, and CdS thin coating by chemical bath deposition. High-Z nanoparticle polymer composites are studied for gamma and x-ray scintillation. Synthesis of conjugated polymers: The band gap, band edges (electron affinity and ionization potential), optical absorption, photoluminescence color and quantum efficiency, and carrier mobility can be modulated through the conjugated backbone or side chains, structural regularity, molecular weight, purity, and molecular ordering. We can thus tailor conjugated polymers for different applications such as light emitting diodes, solar cells, thin film transistors, and sensors. We fabricate smiconductor devices (LEDs, solar cells) using the selected polymers.
1. “A Facile Route to Bulk High-Z Polymer Composites for Gamma Ray Scintillation,” Y.S. Zhao, Z. Yu, A. Douraghy, A.F. Chatziioannou, Y. Mo, Q. Pei, Chem. Commun., 6008–6010 (2008). 2. "Electrochemical Synthesis and Photovoltaic Property of Cadmium Sulfide-Polybithiophene Interdigitated Nanohybrid Thin Films," D. Xi, H. Zhang, B. Chen, S. Furst, Q. Pei, J. Phys. Chem. C, 112, pp19765–19769 (2008) 3. “Fault-Tolerant Dielectric Elastomers using Single-Wall Carbon Nanotube Electrodes.” W. Yuan, L. Hu, Z. Yu, T. Lam, J. Biggs, S.M. Ha , D. Xi, B. Chen, M.K. Senesky, G. Grűner, Q. Pei, Advanced Materials 20, 621–625 (2008). 4. “Operating Mechanism of Light-emitting Electrochemical Cells,” Q. Pei, A.J. Heeger, Nature Materials 7, 167 (2008). 5. “Nanoporous Carbon Nanotube Electrode for Stable Polypyrrole Actuator”, Z. Yu, D. Xi, T. Lam, Q. Pei. Proc. SPIE, Vol. 6524, 652420(2007). 6. “In-situ Preparation of Free-standing Nanoporous Alumina Template for Polybithiophene Nanotube Arrays with a Concourse Base”, D. Xi, Q. Pei. Nanotechnology, Vol. 18, 095602 (2007). 7. “Raman Studies of Optical Phonons in Vertical Cadmium Sulfide Nanorod Arrays”, D. Xi, J. Li, Q. Pei, B. Chen. J. Mater. Res. Vol. 21, 2911-2915(2006). 8. “Effects of C70 Derivative in Low Bandgap Polymer Photovoltaic Devices: Spectral Complementation and Morphology Optimization”, Y. Yao, C. Shi, G. Li, V. Shrotriya, Q. Pei, and Y. Yang. Appl. Phys. Lett. Vol. 89, 153507(2006). 9. “Regioregular Copolymers of 3-Alkoxythiophene and Their Photovoltaic Application”, C. Shi, Y. Yao, Y. Yang, Q. Pei. J. Am. Chem. Soc. Vol. 128, 8980-8986(2006). 10. “Interpenetrating Polymer Networks for High-Performance Electroelastomer Artificial Muscles”, S.M. Ha, W. Yuan, Q. Pei, R. Pelrine, and S. Stanford. Advanced Materials Vol. 18, 887–891(2006).
Openings: Prospective graduate students and postdoctoral researchers with the following specialties are welcome to apply: synthesis of conjugated polymers; solution-based nanofabrication; polymer composites; polymer processing; organic synthesis; thin film electronic devices; actuators and sensors. |
