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Materials Science and Engineering Colloquium

Event Type
Seminar/Symposium
Sponsor
Materials Science and Engineering
Location
100 Materials Science and Engineering Building
Date
Jan 29, 2018   4:00 pm  
Speaker
Cherie Kagan, Materials Science and Engineering, University of Pennsylvania
Views
85
Originating Calendar
MatSE Seminars

“Designer Materials Through Controlled Nanocrystal Coupling for Electronic and Optical Applications”

 

Semiconductor and plasmonic nanocrystals are known for their size- and shape-dependent photoluminescence and localized surface plasmon resonances respectively. In this talk, I will describe the use of semiconductor and plasmonic nanocrystals as building blocks of mesoscale materials for semiconductor electronics and optoelectronics and plasmonic optical metamaterials. Chemical exchange of the long ligands used in nanocrystal synthesis with more compact ligand chemistries brings neighboring nanocrystals into proximity and increases interparticle coupling. In semiconductor nanocrystal solids, we show strong electronic coupling in combination with doping allows us to control the carrier type and concentration and design high mobility n- and p-type materials. I will give examples where n- and p-type nanocrystal solids are used to construct field-effect transistors and integrated circuits and solar photovoltaics. In metal nanocrystals, ligand-controlled coupling allows us to tailor a dielectric-to-metal phase transition seen by a 1010 range in DC conductivity and a dielectric permittivity ranging from everywhere positive to everywhere negative across the whole range of optical frequencies. We realize a “diluted metal” with optical properties not found in the bulk metal analog, presenting a new axis in plasmonic materials design and the realization of optical properties akin to next-generation metamaterials. We harness the properties of metal NCs by using nanoimprint lithography to print large-area metamaterials on glass and plastics with widely tailorable optical properties that are used to realize near-infrared optical devices.

 

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