Cherie R Kagan Research Group

Electrical and Systems Engineering - Chemistry - Materials Science and Engineering

Group Photo 2014


The Kagan group explores the chemical and physical properties of nanostructured and organic materials and integrates these materials in electronic, optoelectronic, optical, thermoelectric and bioelectronic devices. We combine the flexibility of chemistry and bottom-up assembly with top-down fabrication techniques to design novel materials and devices. We explore the structure and function of these materials and devices using spatially- and temporally-resolved optical spectroscopies, AC and DC electrical techniques, electrochemistry, scanning probe and electron microscopies and analytical measurements.

Research Highlights

Substitutional doping in nanocrystal superlattices

In collaboration with the Murray group, we report substiutional doping of gold nanocrystals in superlattices of cadmium selenide and lead selenide quantum dots. The density of dopants is shown to be readily controllable,in analogy to atomic doping. The inclusion of dopants in the quantum dot solid is shown to vary the electronic conductivity of the film over six orders of magnitude as charge percolation pathways form in the lattice.

The effects of inorganic surface treatments on photogenerated carrier mobility and lifetime in PbSe quantum dot thin films

We used flash-photolysis, time-resolved microwave conductivity (TRMC) to probe the carrier mobility and lifetime in PbSe quantum dot (QD) thin films treated with solutions of the metal salts of Na2Se and PbCl2. The metal salt treatments tuned the Pb:Se stoichiometry and swept the Fermi energy throughout the QD thin film bandgap. The increase in TRMC mobility as the Fermi energy was shifted toward the band edges by non-stoichiometry is consistent with the QD thin film density of states.

Large-Area Nanoimprinted Colloidal Au Nanocrystal-Based Nano-antennas for Ultrathin Polarizing Plasmonic Metasurfaces

We report a low-cost, large-area fabrication process using solution-based nanoimprinting of colloidal Au nanocrystals to define anisotropic nanoinclusions for optical metasurfaces. We fabricate rod-shaped nano-antennas tailored in size and spacing to demonstrate Au nanocrystal-based quarter-wave plates that operate with extreme bandwidths and provide high polarization conversion efficiencies in the near-to-mid infrared.

Selective p- and n-Doping of Colloidal PbSe Nanowires To Construct Electronic and Optoelectronic Devices

We report the controlled and selective doping of colloidal PbSe nanowire arrays to define axial pn junctions from which we demonstrate integrated CMOS electronic circuits and fast switching photodiodes.

Binary and Ternary Superlattices Self-Assembled from Colloidal Nanodisks and Nanorods

We demonstrate novel binary and ternary superlattices self-assembled from two colloidal anisotropic nanocrystals: two-dimensional nanodisks and one-dimensional nanorods. By changing the relative size and concentration of LaF3 nanodisks and CdSe/CdS nanorods, we synthesized AB2-type, AB6-type, two AB-type binary superlattices, lamellar-type binary structure as well as an ABC-type ternary superlattice, This work demonstrates shape-engineered nanocrystals can be used to access new phases/structures, which allows for the design of novel functional metamaterials by tailoring superlattice structures.


Congratulations to our Graduating Students!

Our graduating students will be continuing their education:
  • Emily - PhD program in MSE at Univ. of Michigan
  • Devika - PhD program in MSE at UT Austin
  • Matt - PhD program in EE at UC Berkeley
  • Prashanth - PhD program in EE at Univ. of Utah
  • Chawit - PhD program in Integrated in Photonic and Electronic Systems at Cambridge University

Congratulations Yu Yao!

Yu Yao has been selected to receive the Masters Scholar Award from Materials Science and Engineering.

Congratulations Emily

Emily Gurniak has been awarded the R. M. Brick Award, named for the first chairman of the Department of Materials Science and Engineering, and awarded to the graduating senior who has demonstrated through a combination of academic performance, effort, and personal qualities that he or she will be a credit to the Department, the School, and the University.

Congratulations Cherie!!

Cherie has been been awarded the S. Reid Warren, Jr. Award for outstanding service in stimulating and guiding the intellectual and professional development of undergraduate students.

Congratulations to SJ!

SJ has just been appointed an Assistant Professor of Materials Science and Engineering at Korea University

Congratulations to Yuming!

Yuming has been awarded the S. J. Stein Prize, awarded to a Ph.D. or M.S.E. degree recipient for superior achievement in the field of new or unique materials or applications for materials in electronics. This prize acknowledges that achievement and encourages continued interest in this important field.

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Electrical & Systems Engineering, Moore Building
200 South 33rd Street, Philadelphia, PA 19104