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Charles A. Schmuttenmaer *
Yale University, Department of Chemistry, 225 Prospect St.,
P. O. Box 208107, New Haven, CT 06520-8107, USA
* Email: charles.schmuttenmaer@yale.edu
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Abstract: The microscopic details of carrier transport in nanocrystalline colloidal thin films is required for complete understanding of a variety of photochemical and photoelectrochemical cells utilizing interpenetrating networks. Measuring the photoconductivity and charge transport properties in these materials, however, is a challenging problem because of the inherent difficulty of attaching wires to nanometer-sized objects. Furthermore, picosecond (ps) carrier dynamics play an important role in efficient charge separation and transport, but the low temporal resolution of traditional methods used to determine the photoconductivity precludes their use in studying sub-ps to ps dynamics. Time-resolved THz spectroscopy (TRTS), on the other hand, is a non-contact electrical probe capable of measuring the photoconductivity on a sub-ps to nanosecond (ns) timescale. In this talk, TRTS is employed to determine the transient photoconductivity of ZnO nanowires, polycrystalline, and nanoparticle films, as well as dye-sensitized nanocrystalline colloidal TiO2 films. Electron injection occurs on sub-ps time scales. Decay kinetics (on hundreds of ps to ns time scales) indicate that surfaces and interfaces are the dominant sources of recombination. The photoconductivity deviates strongly from Drude behavior and is explained by disorder-induced carrier localization and/or backscattering of the photogenerated carriers. Trends as a function of material and morphology will be discussed.
Keywords: Terahertz Spectroscopy, Nanomaterials, Photoconductivity, Charge transport properties
Published: 2008-03-18
Cite this article:
Charles A. Schmuttenmaer. Using Terahertz Spectroscopy to Study Nanomaterials[J]. International Journal of Terahertz Science and Technology, 2008, Vol.1, No.1: 1-8. DOI:10.11906/TST.001-008.2008.03.01
URL: http://www.tstnetwork.org/10.11906/TST.001-008.2008.03.01
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