Carrier multiplication in quantum dots within the framework of two competing energy relaxation mechanisms

John T. Stewart, Lazaro A. Padilha, Wan Ki Bae, Weon Kyu Koh, Jeffrey M. Pietryga, Victor I. Klimov

Research output: Contribution to journalReview article

47 Citations (Scopus)

Abstract

The realization of high-yield, low-threshold carrier multiplication (CM) in semiconductor quantum dots (QDs) is a promising step toward third-generation photovoltaics (PV). Recent studies of QD solar cells have shown that CM can indeed produce greater-than-unity quantum efficiencies in photon-to-charge- carrier conversion, establishing the relevance of this process to practical PV technologies. While being appreciable, the reported CM yields are still not high enough for a significant increase in the power conversion efficiency over traditional bulk materials. At present, the design of nanomaterials with improved CM is hindered by a poor understanding of the mechanism underlying this process. Here, we present a possible solution to this problem by introducing a model that treats CM as a competition between impact-ionization-like scattering and non-CM energy losses. Importantly, it allows for evaluation of expected CM yields from fairly straightforward measurements of Auger recombination (inverse of CM) and near-band-edge carrier cooling. The validation of this model via a comparative CM study of PbTe, PbSe, and PbS QDs suggests that it indeed represents a predictive capability, which might help in the development of nanomaterials with improved CM performance.

Original languageEnglish
Pages (from-to)2061-2068
Number of pages8
JournalJournal of Physical Chemistry Letters
Volume4
Issue number12
DOIs
Publication statusPublished - Jun 20 2013

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ASJC Scopus subject areas

  • Materials Science(all)
  • Physical and Theoretical Chemistry

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