Enhanced mobility-lifetime products in PbS colloidal quantum dot photovoltaics

Kwang Seob Jeong, Jiang Tang, Huan Liu, Jihye Kim, Andrew W. Schaefer, Kyle Kemp, Larissa Levina, Xihua Wang, Sjoerd Hoogland, Ratan Debnath, Lukasz Brzozowski, Edward H. Sargent, John B. Asbury

Research output: Contribution to journalArticle

178 Citations (Scopus)

Abstract

Figure Persented: Colloidal quantum dot (CQD) photovoltaics offer a promising approach to harvest the near-IR region of the solar spectrum, where half of the sun's power reaching the earth resides. High external quantum efficiencies have been obtained in the visible region in lead chalcogenide CQD photovoltaics. However, the corresponding efficiencies for band gap radiation in the near-infrared lag behind because the thickness of CQD photovoltaic layers from which charge carriers can be extracted is limited by short carrier diffusion lengths. Here, we investigate, using a combination of electrical and optical characterization techniques, ligand passivation strategies aimed at tuning the density and energetic distribution of charge trap states at PbS nanocrystal surfaces. Electrical and optical measurements reveal a more than 7-fold enhancement of the mobility-lifetime product of PbS CQD films treated with 3-mercaptopropionic acid (MPA) in comparison to traditional organic passivation strategies that have been examined in the literature. We show by direct head-to-head comparison that the greater mobility-lifetime products of MPA-treated devices enable markedly greater short-circuit current and higher power conversion efficiency under AM1.5 illumination. Our findings highlight the importance of selecting ligand treatment strategies capable of passivating a diversity of surface states to enable shallower and lower density trap distributions for better transport and more efficient CQD solar cells.

Original languageEnglish
Pages (from-to)89-99
Number of pages11
JournalACS Nano
Volume6
Issue number1
DOIs
Publication statusPublished - 2012 Jan 24
Externally publishedYes

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Keywords

  • charge trapping
  • colloidal quantum dot
  • mobility-lifetime products
  • photovoltaics
  • time-resolved infrared spectroscopy

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

Cite this

Jeong, K. S., Tang, J., Liu, H., Kim, J., Schaefer, A. W., Kemp, K., Levina, L., Wang, X., Hoogland, S., Debnath, R., Brzozowski, L., Sargent, E. H., & Asbury, J. B. (2012). Enhanced mobility-lifetime products in PbS colloidal quantum dot photovoltaics. ACS Nano, 6(1), 89-99. https://doi.org/10.1021/nn2039164