Carrier Multiplication and Its Reduction by Photodoping in Colloidal InAs Quantum Dots

Pijpers, J.J.H. and Hendry, E. and Milder, M.T.W. and Fanciulli, R. and Savolainen, J. and Herek, J.L. (2007) Carrier Multiplication and Its Reduction by Photodoping in Colloidal InAs Quantum Dots. Journal of Physical Chemistry C: Nanomaterials and interfaces, 111 (11). pp. 4146-4152. ISSN 1932-7447

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Abstract:	Carrier (exciton) multiplication in colloidal InAs/CdSe/ZnSe core−shell quantum dots (QDs) is investigated using terahertz time-domain spectroscopy, time-resolved transient absorption, and quasi-continuous wave excitation spectroscopy. For excitation by high-energy photons (2.7 times the band gap energy), highly efficient carrier multiplication (CM) results in the appearance of multi-excitons, amounting to 1.6 excitons per absorbed photon. Multi-exciton recombination occurs within tens of picoseconds via Auger-type processes. Photodoping (i.e., photoinjection of an exciton) of the QDs prior to excitation results in a reduction of the CM efficiency to 1.3. This exciton-induced reduction of CM efficiency can be explained by the twofold degeneracy of the lowest conduction band energy level. We discuss the implications of our findings for the potential application of InAs QDs as light absorbers in solar cells.
Item Type:	Article
Copyright:	© 2009 American Chemical Society
Faculty:	Science and Technology (TNW)
Research Group:	Optical Sciences (OS)
Link to this item:	http://purl.utwente.nl/publications/60471
Official URL:	http://dx.doi.org/10.1021/jp066709v
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