Date of Award

Summer 8-2016

Author's Department

Energy, Environmental & Chemical Engineering

Degree Name

Master of Science (MS)

Degree Type



Nanocrystal assemblies are being explored for a number of optoelectronic applications such as transparent conductors, photovoltaic solar cells, and electrochromic windows. Majority carrier transport is important for these applications, yet it remains relatively poorly understood in films comprised of touching nanocrystals. Specifically, the underlying structural parameters expected to determine the transport mechanism have not been fully elucidated. In this report, we demonstrate experimentally that the contact radius, between touching heavily doped ZnO nanocrystals, controls the electron transport mechanism. Spherical nanocrystals are considered, which are connected by a circular area. The radius of this circular area is the contact radius. For nanocrystals that have local majority carrier concentration above the Mott transition, there is a critical contact radius. If the contact radius between nanocrystals is less than the critical value, then the transport mechanism is variable range hopping. If the contact radius is greater than the critical value, the films display behavior consistent with metallic electron transport.


English (en)


Dr. Elijah Thimsen

Committee Members

Dr. Elijah Thimsen Dr. Pratim Biswas Dr. Bryce Sadtler


The following thesis has been reprinted with permission from: Contact Radius and the Insulator–Metal Transition in Films Comprised of Touching Semiconductor Nanocrystals, Deanna Lanigan and Elijah Thimsen, ACS Nano 2016 10 (7), 6744-6752, DOI: 10.1021/acsnano.6b02190