Recipient on behalf of the Center for Organic Photonics and Electronics, the Materials Awards at the GTRC Award for Excellence in Research, Industry Engagement and Technology Transfer, 2011; Regents Professorship, Georgia Institute of Technology, 2011 – Present; Recipient of the 2011 Arthur C. Cope Scholar Award, 2010; Georgia Tech, Outstanding Award in Research Program Development, 2009
Organic Materials Research. Our research advances fundamental knowledge of organic electronic and photonic materials, and in many cases the interplay between them, through a hypothesis-driven process of molecular design, effective synthesis, and close collaboration with theoreticians and device scientists. We design molecules with controlled localization and delocalization in conjugated organic materials to probe the influence of molecular structure on bulk properties in nonlinear optics, organic electronics, and surface modification. A thorough understanding of our materials and processes is gained through collaboration with outstanding theoreticians, physicists, device scientists, and engineers at Georgia Tech and throughout the world.
Optical Materials. In this area of research, we aim to increase the third-order nonlinearity of organic materials in a manner that allows for low optical loss due to absorption, which is important in all-optical switching applications. This strategy requires careful design of chromophores that have narrow absorption bands and proper energy state spacing to exploit resonance enhancement of the third-order effect while minimizing loss due one and two-photon absorption. Other recent research includes the design and synthesis of chromophores and materials for dye-sensitized solar cells (DSSC) and organic photovoltaics (OPV). For both DSSC and OPV, we are looking at how structural changes in chromophores and donor-acceptor polymers affect device efficiency due to increased absorption, wavelength of the absorption, interactions between absorbers and other device components, and processability.
Electronics Materials. Dopants for organic electronic materials are an important and growing area of research. We design organometallic and organic p-type dopants for hole transport materials and n-type dopants for electron transport materials. Recently, an organometallic complex with high electron affinity p-doped an organic semiconductor and led to orders of magnitude increase in hole conductivity. Another organometallic complex n-doped vapor deposited electron transport materials resulted in enhanced injection efficiency and led to orders of magnitude increase in the current density. The research is being extended to air stable compounds that successfully dope a variety of electron transport materials in situ. Other research efforts are directed toward new electron transporters that are air-stable and can be ink-jet printed directly into electronic circuits.
Surface Modification. Molecules that bind to planar surfaces and nanoparticles can manipulate surface properties such as work function, wettability, stability, and processability. We have developed a series of materials that bind or adhere to the surface of inorganic and organic semiconductors, such as indium tin oxide (ITO) and poly(ethylenedioxy)thiophene (PEDOT), for modifying the semiconductor’s work function to match organic electronic materials for OLEDs, OFETs, and OPVs. Through this modification process, the surface properties can be more stable both before and after device fabrication when compared to work functions modified by other traditional treatments. Other surface modifiers allow for the processing of nanoparticles into composites, which are particularly interesting for high-density energy storage.
Advanced Functional Materials – Member, Editorial Advisory Board
Materials Horizons - Chair Editorial Board
Journal of Materials Chemistry – Member, Editorial International Board
Chemistry of Materials – Member, Editorial Board
Nonlinear Optics, Quantum Optics – Member, Editorial Board