Micron Thick Colloidal Quantum Dot Solids

James Z. Fan, Maral Vafaie, Koen Bertens, Mykhailo Sytnyk, Joao M. Pina, Laxmi Kishore Sagar, Olivier Ouellette, Andrew H. Proppe, Armin Sedighian Rasouli, Yajun Gao, Se Woong Baek, Bin Chen, Frédéric Laquai, Sjoerd Hoogland, F. Pelayo García De Arquer, Wolfgang Heiss, Edward H. Sargent*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

45 Scopus citations

Abstract

Shortwave infrared colloidal quantum dots (SWIR-CQDs) are semiconductors capable of harvesting across the AM1.5G solar spectrum. Today's SWIR-CQD solar cells rely on spin-coating; however, these films exhibit cracking once thickness exceeds ∼500 nm. We posited that a blade-coating strategy could enable thick QD films. We developed a ligand exchange with an additional resolvation step that enabled the dispersion of SWIR-CQDs. We then engineered a quaternary ink that combined high-viscosity solvents with short QD stabilizing ligands. This ink, blade-coated over a mild heating bed, formed micron-thick SWIR-CQD films. These SWIR-CQD solar cells achieved short-circuit current densities (Jsc) that reach 39 mA cm-2, corresponding to the harvest of 60% of total photons incident under AM1.5G illumination. External quantum efficiency measurements reveal both the first exciton peak and the closest Fabry-Perot resonance peak reaching approximately 80% - this is the highest unbiased EQE reported beyond 1400 nm in a solution-processed semiconductor.

Original languageEnglish (US)
Pages (from-to)5284-5291
Number of pages8
JournalNano letters
Volume20
Issue number7
DOIs
StatePublished - Jul 8 2020

Keywords

  • blade coating
  • infrared photovoltaics
  • ligand exchange
  • quantum dots

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanical Engineering
  • Bioengineering
  • General Chemistry
  • General Materials Science

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