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Proceedings Paper

Nanocrystal sensitized photovoltaics and photodetectors with performance enhanced using ligand engineering
Author(s): David M. Schut; George M. Williams; Stefan Arteaga; Thomas L. Allen; Thomas Novet
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Paper Abstract

Nanocrystal quantum dot photovoltaics and photodetectors with performance optimized by engineering the nanocrystals size and the optoelectronic properties of the nanocrystal's chemical coating are reported. Due to the large surface-to-volume ratio inherent to nanocrystals, the surface effects of ligands used to chemically coat and passivate nanocrystals play a significant role in device performance. However, the optoelectronic properties of ligands are difficult to ascertain, as the band structure of the ligand-capped nanoparticle system is complex and difficult to model. Using density-of-states measurements, we demonstrate that modeling of electropositive and electronegative substituents and use of the Hammett equation, are useful tools in optimizing nanocrystal detector performance. A new particle, the Janus-II nanoparticles, developed using 'charge-donating' and 'charge-withdrawing' ligands distributed over opposite surfaces of the nanocrystal, is described. The polarizing ligands of the Janus-II nanoparticle form a degeneracy-splitting dipole, which reduces the overlap integral between excitonic states, and thus reduces the probability of carrier recombination, allowing carrier extraction to take place more efficiently. This is shown to allow increased photodetection efficiencies and to allow the capture of multiple exciton events in working photodetectors.

Paper Details

Date Published: 17 May 2011
PDF: 14 pages
Proc. SPIE 8035, Energy Harvesting and Storage: Materials, Devices, and Applications II, 80351B (17 May 2011); doi: 10.1117/12.887753
Show Author Affiliations
David M. Schut, Voxtel, Inc. (United States)
George M. Williams, Voxtel, Inc. (United States)
Stefan Arteaga, Voxtel, Inc. (United States)
Thomas L. Allen, Voxtel, Inc. (United States)
Thomas Novet, Voxtel, Inc. (United States)


Published in SPIE Proceedings Vol. 8035:
Energy Harvesting and Storage: Materials, Devices, and Applications II
Nibir K. Dhar; Priyalal S. Wijewarnasuriya; Achyut K. Dutta, Editor(s)

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