Controlled Steric Hindrance Enables Efficient Ligand Exchange for Stable, Infrared-Bandgap Quantum Dot Inks
Kelley, Shana O.
Garciá De Arquer, F. Pelayo
Sargent, Edward H.
KAUST DepartmentKAUST Solar Center (KSC)
Material Science and Engineering Program
Office of the VP
Organic Electronics and Photovoltaics Group
Physical Science and Engineering (PSE) Division
Online Publication Date2019-04-30
Print Publication Date2019-06-14
Embargo End Date2020-06-14
Permanent link to this recordhttp://hdl.handle.net/10754/656427
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AbstractColloidal quantum dots (CQDs), which benefit from a size-tuned bandgap, are a solution-processed material for infrared energy harvesting. This characteristic enables the fabrication of solar cells that form tandem devices with silicon. Unfortunately, in the case of CQDs having diameters sufficiently large (>4 nm) so that the nanoparticles absorb light well beyond silicon's bandgap, conventional ligand exchanges fail. Here we report a strategy wherein short-chain carboxylates, used as a steric hindrance controller, facilitate the ligand exchange process on small-bandgap CQDs. We demonstrate that the net energy barrier to replace original capping ligands with lead halide anions is decreased when short carboxylates are involved. The approach produces more complete ligand exchange that enables improved packing density and monodispersity. This contributes to a 2-fold reduction in the trap state density compared to the best previously reported exchange. We demonstrate solar cells that achieve a record infrared photon-to-electron conversion efficiency at the excitonic peak.
CitationLiu, M., Che, F., Sun, B., Voznyy, O., Proppe, A., Munir, R., … Sargent, E. H. (2019). Controlled Steric Hindrance Enables Efficient Ligand Exchange for Stable, Infrared-Bandgap Quantum Dot Inks. ACS Energy Letters, 4(6), 1225–1230. doi:10.1021/acsenergylett.9b00388
SponsorsThis publication is based in part on work supported by the Ontario Research Fund Research Excellence Program and by the Natural Sciences and Engineering Research Council (NSERC) of Canada.
PublisherAmerican Chemical Society (ACS)
JournalACS Energy Letters