Can up- and down-conversion and multi-exciton generation improve photovoltaics?

Hagay Shpaisman, Olivia Niitsoo, Igor Lubomirsky, David Cahen

Research output: Contribution to journalArticlepeer-review

75 Citations (Scopus)


Photon up-conversion (UC) and photon-induced multiple-exciton generation (MEG) are proposed directions that are of increasing interest for improving photovoltaic (PV) conversion efficiencies via "photon (or light) management". Straightforward analysis of these approaches for non-concentrated single-junction cells in the detailed balance limit yields a theoretical PV conversion limit of 49%, instead of 31% without UC and MEG. With what we estimate to be optimistic, maximal realistic efficiencies (25% for UC; 70% for MEG) this limit becomes <40%, i.e., ∼1.25 times the theoretical efficiency of conventional single-band gap cells. While this result does not detract from the fascinating fundamental scientific challenge to make UC and MEG simple and cheap ways to improve PV, such reality checks should be considered when evaluating the short-term promises of these and other options, such as spectral splitting and tandem arrangements.

Original languageEnglish
Pages (from-to)1541-1546
Number of pages6
JournalSolar Energy Materials and Solar Cells
Issue number12
Publication statusPublished - Dec 2008


  • Down-conversion
  • Efficiency
  • Multiple-exciton generation
  • Photon management
  • Up-conversion

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films

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