Cherie R Kagan Research Group

Electrical and Systems Engineering - Chemistry - Materials Science and Engineering

Group Photo 2014

Welcome

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

9/1/2014:
Gate Induced Carrier Delocalization in QD FETs

Our DOE SISGR team used gate-dependent, low temperature resistance and magnetotransport measurements to study indium-doped CdSe QD FETs. We showed that with increasing gate voltage the localization product (localization length times dielectric transport) describing transport of accumulated carriers, suggests the localization length increases significantly beyond the QD diameter.

2/6/2014:
High-Performance Lead Chalcogenide Devices through Post-synthesis, Colloidal Atomic Layer Deposition

We report a simple, solution-based, post-synthetic colloidal, atomic layer deposition (PS-cALD) process to engineer stepwise the surface stoichiometry and therefore the electronic properties of lead chalcogenide nanocrystal (NC) thin films integrated in devices. We found that unlike chalcogen-enriched NC surfaces that are structurally, optically and electronically unstable, lead chloride treatment creates a well-passivated shell that stabilizes the NCs. Using PS-cALD of lead chalcogenide NC thin films we demonstrate high electron field-effect mobilities of ~4.5 cm2/Vs.

1/31/2014:
Air-Stable, Solution Processable Ag NC Materials

We describe a room-temperature, chemical process to transform silver nanocrystal solids, deposited from colloidal solutions, into highly conductive, corrosion-resistant, optical and electronic materials with nanometer-scale architectures. We show ammonium thiocyanate uniquely form low-resistivity, optically smooth thin films that can be patterned by imprint lithography to form conductive electrodes and plasmonic mesostructures with programmable resonances.

12/30/2013:
Solution-Processed Phase-Change VO2 Metamaterials

We demonstrate thermally switchable VO2 metamaterials by combining nanoimprinting and solution-based deposition of colloidal nanocrystals. We tuned the phase change temperature by W-doping the NCs and fabricated differentially-doped, multilayered materials to tailor the optical response in the near-IR and IR from that of a strong light absorber to that of a Drude like reflector with a change in temperature.

Announcements

7/21/2014:
Congratulations to SJ!

Congratulations to SJ on his PhD graduation and wishing him the best during his postdoc in the Rogers group. Also a congratulations to SJ for winning the SJ Stein Prize from the University of Pennsylvania, recognizing his PhD work for its "superior achievement in the field of new or unique materials or applications for materials in electronics," and the MRS Graduate Student Silver Award at the Spring, 2014 meeting.

7/21/2014:
Outgoing PhD Students

Congratulations to Kevin Fritz (Cornell), Michael Crump (University of Washington), Li Xie (Northeastern), Diya Li (Notre Dame), Han Wang (University of Pennsylvania) on their acceptance to PhD programs starting in Fall, 2014.

7/21/2014:
2nd Place Senior Design

Congratulations to our Undergraduate Senior Design team of Kevin, Fran and Steph on taking 2nd place in the MSE department competition.

7/21/2014:
Congratulations to Our Graduates

Undergraduate students Kevin Fritz, Francisco Lee and Stephanie Yang
Masters students Han Wang, Diya Li, Hangfei Lin, Prashanth Gopalan, Michael Crump, Qian Gao, Li Xie

7/21/2014:
2nd Place Senior Design

Congratulations to our Undergraduate Senior Design team of Kevin, Fran and Steph on taking 2nd place in the MSE department competition.

7/21/2014:
Congratulations to Ji-Hyuk Choi

Congratulations to Ji-Hyuk Choi on his new job as a research scientist at KIGAM National Lab in Korea

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Copyright © 2014 Kagan Research Group, University of Pennsylvania
Electrical & Systems Engineering, Moore Building
200 South 33rd Street, Philadelphia, PA 19104