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Charge Transfer from PbS Quantum Dots to Insulating TiO2 Matrix

Published online by Cambridge University Press:  15 February 2011

R. Könenkamp  and
P. Hoyer
R. Könenkamp
Affiliation:
Hahn-Meitner Institut Berlin, Glienicker Str. 100, 14109 Berlin, Germany
P. Hoyer
Affiliation:
Hahn-Meitner Institut Berlin, Glienicker Str. 100, 14109 Berlin, Germany
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Abstract

We report on the photoconductivity of thin films consisting of a porous nanocrystalline TiO2 matrix and quantum size PbS clusters adsorbed on the inner surfaces of theTiO2. The PbS clusters are typically a few nm in size and are not connected. Due to quantum confinement the bandgap of the clusters is widened to around 2 eV from the 0.41 eV value for PbS bulk. The clusters thus absorb in the visible spectrum. However, due to their spatial separation, photoconductance through the film requires carrier transfer through the TiO2 matrix. Our data show this to occur only for clusters <25 Å, for which the conduction band edge lies above the TiO2 conduction band edge. For larger clusters the band alignment at the TiO2/PbS interface appears to be unfavorable for carrier transfer; these clusters do not contributeto photoconduction.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 382: Symposium G – Structure and Properties of Multilayered Thin Films , 1995 , 147
Copyright
Copyright © Materials Research Society 1995

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References

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