Mixed Lead Halide Passivation of Quantum Dots

James Z. Fan, Nigel T. Andersen, Margherita Biondi, Petar Todorović, Bin Sun, Olivier Ouellette, Jehad Abed, Laxmi K. Sagar, Min Jae Choi, Sjoerd Hoogland, F. Pelayo García de Arquer, Edward H. Sargent*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

52 Scopus citations


Infrared-absorbing colloidal quantum dots (IR CQDs) are materials of interest in tandem solar cells to augment perovskite and cSi photovoltaics (PV). Today's best IR CQD solar cells rely on the use of passivation strategies based on lead iodide; however, these fail to passivate the entire surface of IR CQDs. Lead chloride passivated CQDs show improved passivation, but worse charge transport. Lead bromide passivated CQDs have higher charge mobilities, but worse passivation. Here a mixed lead-halide (MPbX) ligand exchange is introduced that enables thorough surface passivation without compromising transport. MPbX–PbS CQDs exhibit properties that exceed the best features of single lead-halide PbS CQDs: they show improved passivation (43 ± 5 meV vs 44 ± 4 meV in Stokes shift) together with higher charge transport (4 × 10-2 ± 3 × 10-3 cm2 V-1 s-1 vs 3 × 10-2 ± 3 × 10-3 cm2 V-1 s-1 in mobility). This translates into PV devices having a record IR open-circuit voltage (IR Voc) of 0.46 ± 0.01 V while simultaneously having an external quantum efficiency of 81 ± 1%. They provide a 1.7× improvement in the power conversion efficiency of IR photons (>1.1 µm) relative to the single lead-halide controls reported herein.

Original languageEnglish (US)
Article number1904304
JournalAdvanced Materials
Issue number48
StatePublished - Nov 1 2019


  • infrared photovoltaics
  • ligand exchange
  • nanomaterials
  • quantum dots

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering


Dive into the research topics of 'Mixed Lead Halide Passivation of Quantum Dots'. Together they form a unique fingerprint.

Cite this