Optimizing Solid-State Ligand Exchange for Colloidal Quantum Dot Optoelectronics: How Much is Enough?

Ahmad R. Kirmani, Grant W. Walters, Taesoo Kim, Edward H. Sargent, Aram Amassian

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25 Scopus citations

Abstract

Progress in chalcogenide and perovskite CQD optoelectronics has relied in significant part on solid-state ligand exchanges (SSEs): the replacement of initial insulating ligands with shorter conducting linkers on CQD surfaces. Herein we develop a mechanistic model of SSE employing 3-mercaptopropionic acid (MPA) and 1,2-ethanedithiol (EDT) as the linkers. The model suggests that optimal linker concentrations lead to efficient exchange resulting in ca. 200 –300 exchanged ligands per CQD, a 50% thickness reduction of the initial film, decreased interdot spacing, a 15 nm red-shift in the excitonic absorption peak and a 10x reduction in carrier lifetime. It is a combined effect of these physico-chemical changes that have traditionally made 1% MPA and 10-2% EDT (v:v) the concentrations of choice for efficient CQD optoelectronics.
Original languageEnglish (US)
JournalACS Applied Energy Materials
DOIs
StatePublished - Apr 27 2020

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: The research reported in this publication was supported by funding from King Abdullah University of Science and Technology (KAUST). A.R.K. would like to acknowledge fruitful discussions with Matthew C. Beard, National Renewable Energy Laboratory (NREL), US.

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