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Welcome!
Our Research
Our research explores the chemical and physical properties of molecular, supramolecular, and nanostructured materials and assemblies and their potential applications in electronic, optoelectronic, and sensing devices. Molecule-surface and molecule-molecule interactions drive molecular organization. We exploit these chemical interactions to construct functional supramolecular and nanocrystal assemblies. Electrical measurements, optical spectroscopies, electrochemistry, and scanning probe and electron microscopies are used to probe the structure-function relationships of molecular assemblies and their interfaces with zero-, one-, and two-dimensional inorganic surfaces. These experiments provide a basis for understanding intermolecular, intramolecular, and interfacial (organic-inorganic) charge and excitonic transport and interactions. These insights are used to guide the rational design of molecular and nanostructured devices ranging from transistors to solar cells to photonics to chemical and biological sensors.
Our labs are equipped for chemical synthesis and assembly, cw and ultrafast spectroscopies with high spatial resolution, electrical measurements, and the complete fabrication of molecular and nanostructured materials in devices. Micron and nanoscale device fabrication is carried out in Penn’s Wolf Nanofabrication Facility and structural characterization is performed in Penn’s Regional Nanotechnology Facility.
Our group is interdisciplinary with students from the Departments of
Electrical and Systems Engineering,
Materials Science and Engineering, and
Chemistry. We have collaborations with groups in the Schools of
Engineering and Applied Sciences,
Arts and Sciences, and
Medicine and through Penn’s
Laboratory for the Research on the Structure of Matter and Penn’s
Energy Research Group.
Group Announcements
2/21/2012:Good Luck Sung-Hoon!
Our beloved Post-Doc, Sung-Hoon, has left us to take a job in his native South Korea. Good luck Sung-Hoon, we will miss you!
1/24/2012:
Welcome Daniel Straus!
Daniel, who is in the chemistry department and comes from the University of Chicago, has become the newest Ph.D student to join our group. Welcome!
11/16/2012:
Congratulations to Dr. Kim!
David Kim successfully defended his thesis this November, becoming the second person to earn his Ph.D. from the Kagan Group. He is now leaving for Zurich where he will work with David Norris. Good luck David!
11/1/2012:
Congratulations to Emily!
Emily Gurniak was selected to be a part of the Rachleff Scholars program, and will be completing her work for the program with our lab. Welcome, and Congratulations!
Research Highlights
1/31/2013:Nanocrystal Stoichiometric Imbalance Doping
We manipulate the stoichiometry of Pb-chalcogenide nanocrystal arrays through thermal evaporation of Pb or Se to engineer their carrier statistics. Excess Pb forms NC FETs with electron mobilities of 10 cm2/Vs and excess Se form Schottky solar cells with enhanced power conversion efficiency.
12/10/2012:Nanoimprinted Nanocrystal Metamaterials
We design optical metamaterials using colloidal gold nanocrystal building blocks, tailoring the dielectric permitivity of the solid by exchanging the nanocrystals' surface-capping molecules. Direct, wide-area nanoimprinting of subwavelength superstructures affords plasmonic resonances with tunability ranging from 660 to 1070 nm.
11/20/2012:Flexible Nanocrystal Integrated Circuits
We report solution-deposited nanocrystal integrated circuits (NCICs), showing NCIC inverters, amplifiers, and ring oscillators, constructed from high-performance, low-voltage, low-hysteresis CdSe nanocrystal field-effect transistors (FETs). We fabricated nanocrystal FETs and NCICs from colloidal inks on flexible plastic substrates that operate at low voltage.
