Enhanced Semiconductor Nanocrystal Conductance via Solution Grown Contacts

We report a 100000-fold increase in the conductance of individual CdSe nanorods when they are electrically contacted via direct solution phase growth of Au tips on the nanorod ends. Ensemble UV−vis and X-ray photoelectron spectroscopies indicate this enhancement does not result from alloying of the nanorod. Rather, low temperature tunneling and high temperature (250−400 K) thermionic emission across the junction at the Au contact reveal a 75% lower interface barrier to conduction compared to a control sample. We correlate this barrier lowering with the electronic structure at the Au−CdSe interface. Our results emphasize the importance of a nanocrystal surface structure for robust device performance and the advantage of this contact method.