Photogenerated Exciton Dissociation in Highly Coupled Lead Salt Nanocrystal Assemblies

Abstract
Internanocrystal coupling induced excitons dissociation in lead salt nanocrystal assemblies is investigated. By combining transient photoluminescence spectroscopy, grazing incidence small-angle X-ray scattering, and time-resolved electric force microscopy, we show that excitons can dissociate, without the aid of an external bias or chemical potential gradient, via tunneling through a potential barrier when the coupling energy is comparable to the exciton binding energy. Our results have important implications for the design of nanocrystal-based optoelectronic devices. © 2010 American Chemical Society.

Citation
Choi JJ, Luria J, Hyun B-R, Bartnik AC, Sun L, et al. (2010) Photogenerated Exciton Dissociation in Highly Coupled Lead Salt Nanocrystal Assemblies. Nano Lett 10: 1805–1811. Available: http://dx.doi.org/10.1021/nl100498e.

Acknowledgements
This work was supported by the Cornell Center for Materials Research SEED fund and KAUST-CU Center for Energy and Sustainability. GISAXS measurements were conducted at Cornell High Energy Synchrotron Source (CHESS), and we thank Detlef-M. Smilgies and Kaifu Bian for their help with these measurements. Devices were fabricated in the Cornell Nanofabrication Facility (CNF) which is funded by NSF. DFT calculations were done on the Intel Cluster at the Cornell Nanoscale Facility, part of the National Nanotechnology Infrastructure Network (NNIN) funded by the NSF. J.J.C. acknowledges support from NSF IGERT fellowship. J.L. and J.A.M. acknowledge support from NSF. Y.F.L. acknowledges a fellowship from the Agency of Science, Technology and Research (A*STAR), Singapore. L.S. acknowledges support from NYSTAR.

Publisher
American Chemical Society (ACS)

Journal
Nano Letters

DOI
10.1021/nl100498e

PubMed ID
20420458

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