June 23, 2009

Nanocrystals Suitable for InkJet Printing Developed that Retain Efficient Electrical Conductance

Semiconductor nanocrystals that can be readily mass-produced and retain efficient electrical conductance, which can be used for device manufacturing via inkjet printing and other solution-based processes.

This makes them an attractive alternative to the large semiconductor crystals typically used in commercial solar cells and computer chips which are expensive and can make large-scale applications such as rooftop solar-energy collectors prohibitive. Nanocrystals were unable to efficiently transfer their electric charges to one another due to surface ligands - bulky, insulating organic molecules that cap nanocrystals. But the “electronic glue” developed in Dmitri Talapin's laboratory at the University of Chicago solves the ligand problem by substituting the insulating organic molecules with novel inorganic molecules to dramatically increase the electronic coupling between nanocrystals. Talapin believes the “electronic glue” will enable cheaper solar panels and better computer microprocessors.

Colloidal Nanocrystals with Molecular Metal Chalcogenide Surface Ligands from the Journal Science.

Similar to the way that atoms bond to form molecules and crystalline structures, colloidal nanocrystals can be combined together to form larger assemblies. The properties of these structures are determined by the properties of individual nanocrystals and by their interactions. The insulating nature of organic ligands typically used in nanocrystal synthesis results in very poor interparticle coupling. We found that various molecular metal chalcogenide complexes can serve as convenient ligands for colloidal nanocrystals and nanowires. These ligands can be converted into semiconducting phases upon gentle heat treatment, generating inorganic nanocrystal solids. The utility of the inorganic ligands is demonstrated for model systems, including highly conductive arrays of gold nanocrystals capped with Sn2S64– ions and field-effect transistors on cadmium selenide nanocrystals

30 page pdf with supplemental information.

Postdoctoral scholar Maksym Kovalenko (left) works with nanocrystals in a glovebox in the laboratory of Dmitri Talapin, assistant professor in chemistry at the University of Chicago. Working in the environmentally controlled conditions of the glovebox permits researchers to perform chemical procedures not possible under room conditions. Credit: Dan Dry

Evident Technologies has licensed the technology for thermoelectrics.

Evident Technology is a leader in commercializing quantum dot [nanocrystal] semiconductor nanomaterials and products enabled by these materials. They are pioneers in advancing quantum dot technologies for manufacturability and product development.

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