Peak External Photocurrent Quantum Efficiency Exceeding 100% via MEG in a Quantum Dot Solar Cell

Octavi E. Semonin, Joseph M. Luther, Sukgeun Choi, Hsiang Yu Chen, Jianbo Gao, Arthur J. Nozik, Matthew C. Beard

Research output: Contribution to journalArticlepeer-review

1469 Scopus Citations

Abstract

Multiple exciton generation (MEG) is a process that can occur in semiconductor nanocrystals, or quantum dots (QDs), whereby absorption of a photon bearing at least twice the bandgap energy produces two or more electron-hole pairs. Here, we report on photocurrent enhancement arising from MEG in lead selenide (PbSe) QD-based solar cells, as manifested by an external quantum efficiency (the spectrally resolved ratio of collected charge carriers to incident photons) that peaked at 114 ± 1% in the best device measured. The associated internal quantum efficiency (corrected for reflection and absorption losses) was 130%. We compare our results with transient absorption measurements of MEG in isolated PbSe QDs and find reasonable agreement. Our findings demonstrate that MEG charge carriers can be collected in suitably designed QD solar cells, providing ample incentive to better understand MEG within isolated and coupled QDs as a research path to enhancing the efficiency of solar light harvesting technologies.

Original languageAmerican English
Pages (from-to)1530-1533
Number of pages4
JournalScience
Volume334
Issue number6062
DOIs
StatePublished - 2011

NREL Publication Number

  • NREL/JA-5900-52817

Keywords

  • MEG
  • multiple exciton generation
  • nanocrystals
  • quantum dot solar cell
  • semiconductor

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