Ligand-Assisted Reconstruction of Colloidal Quantum Dots Decreases Trap State Density
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2021-03-31
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ArticleAuthors
Sun, Bin
Vafaie, Maral
Levina, Larissa
Wei, Mingyang
Dong, Yitong
Gao, Yajun
Kung, Hao Ting
Biondi, Margherita
Proppe, Andrew H.

Chen, Bin
Choi, Min-Jae
Sagar, Laxmi Kishore

Voznyy, Oleksandr

Kelley, Shana O.

Laquai, Frédéric

Lu, Zhenghong

Hoogland, Sjoerd
García de Arquer, F Pelayo

Sargent, E.

KAUST Department
KAUST Solar Center (KSC)Material Science and Engineering Program
Physical Science and Engineering (PSE) Division
KAUST Grant Number
OSR-2018-CARF/CCF-3079Date
2020-03-31Online Publication Date
2020-03-31Print Publication Date
2020-05-13Embargo End Date
2021-03-31Submitted Date
2020-02-13Permanent link to this record
http://hdl.handle.net/10754/662456
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Increasing the power conversion efficiency (PCE) of colloidal quantum dot (CQD) solar cells has relied on improving the passivation of CQD surfaces, enhancing CQD coupling and charge transport, and advancing device architecture. The presence of hydroxyl groups on the nanoparticle surface, as well as dimers—fusion between CQDs—has been found to be the major source of trap states, detrimental to optoelectronic properties and device performance. Here, we introduce a CQD reconstruction step that decreases surface hydroxyl groups and dimers simultaneously. We explored the dynamic interaction of charge carriers between band-edge states and trap states in CQDs using time-resolved spectroscopy, showing that trap to ground-state recombination occurs mainly from surface defects in coupled CQD solids passivated using simple metal halides. Using CQD reconstruction, we demonstrate a 60% reduction in trap density and a 25% improvement in charge diffusion length. These translate into a PCE of 12.5% compared to 10.9% for control CQDs.Citation
Sun, B., Vafaie, M., Levina, L., Wei, M., Dong, Y., Gao, Y., … Sargent, E. H. (2020). Ligand-Assisted Reconstruction of Colloidal Quantum Dots Decreases Trap State Density. Nano Letters. doi:10.1021/acs.nanolett.0c00638Sponsors
This work was supported by Ontario Research Fund-Research Excellence program (ORF7 Ministry of Research and Innovation, Ontario Research Fund-Research Excellence Round 7), by the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under Award No. OSR-2018-CRG7-373702 and Award No. OSR-2018-CARF/CCF-3079, and by the Natural Sciences and Engineering Research Council (NSERC) of Canada. The authors acknowledge the financial support from QD Solar.Publisher
American Chemical Society (ACS)Journal
Nano LettersAdditional Links
https://pubs.acs.org/doi/10.1021/acs.nanolett.0c00638ae974a485f413a2113503eed53cd6c53
10.1021/acs.nanolett.0c00638