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

Research output: Contribution to journalArticlepeer-review

8 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

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