TY - JOUR
T1 - Ligand-Assisted Reconstruction of Colloidal Quantum Dots Decreases Trap State Density
AU - Sun, Bin
AU - Vafaie, Maral
AU - Levina, Larissa
AU - Wei, Mingyang
AU - Dong, Yitong
AU - Gao, Yajun
AU - Kung, Hao Ting
AU - Biondi, Margherita
AU - Proppe, Andrew H.
AU - Chen, Bin
AU - Choi, Min-Jae
AU - Sagar, Laxmi Kishore
AU - Voznyy, Oleksandr
AU - Kelley, Shana O.
AU - Laquai, Frédéric
AU - Lu, Zhenghong
AU - Hoogland, Sjoerd
AU - García de Arquer, F Pelayo
AU - Sargent, E.
N1 - KAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): OSR-2018-CARF/CCF-3079
Acknowledgements: 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.
PY - 2020/3/31
Y1 - 2020/3/31
N2 - 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.
AB - 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.
UR - http://hdl.handle.net/10754/662456
UR - https://pubs.acs.org/doi/10.1021/acs.nanolett.0c00638
UR - http://www.scopus.com/inward/record.url?scp=85084695551&partnerID=8YFLogxK
U2 - 10.1021/acs.nanolett.0c00638
DO - 10.1021/acs.nanolett.0c00638
M3 - Article
C2 - 32227970
SN - 1530-6984
VL - 20
SP - 3694
EP - 3702
JO - Nano Letters
JF - Nano Letters
IS - 5
ER -