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Facet Control for Trap‐State Suppression in Colloidal Quantum Dot Solids
Author(s) -
Xia Yong,
Chen Wei,
Zhang Peng,
Liu Sisi,
Wang Kang,
Yang Xiaokun,
Tang Haodong,
Lian Linyuan,
He Jungang,
Liu Xinxing,
Liang Guijie,
Tan Manlin,
Gao Liang,
Liu Huan,
Song Haisheng,
Zhang Daoli,
Gao Jianbo,
Wang Kai,
Lan Xinzheng,
Zhang Xiuwen,
MüllerBuschbaum Peter,
Tang Jiang,
Zhang Jianbing
Publication year - 2020
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.202000594
Subject(s) - quantum dot , materials science , passivation , nanocrystal , facet (psychology) , colloid , nanoparticle , trap (plumbing) , nanotechnology , energy conversion efficiency , octahedron , kinetics , chemical physics , optoelectronics , crystal structure , crystallography , physics , chemistry , personality , meteorology , big five personality traits , quantum mechanics , psychology , social psychology , layer (electronics)
Trap states in colloidal quantum dot (QD) solids significantly affect the performance of QD solar cells, because they limit the open‐circuit voltage and short circuit current. The {100} facets of PbS QDs are important origins of trap states due to their weak or missing passivation. However, previous investigations focused on synthesis, ligand exchange, or passivation approaches and ignored the control of {100} facets for a given dot size. Herein, trap states are suppressed from the source via facet control of PbS QDs. The {100} facets of ≈3 nm PbS QDs are minimized by tuning the balance between the growth kinetics and thermodynamics in the synthesis. The PbS QDs synthesized at a relatively low temperature with a high oversaturation follow a kinetics‐dominated growth, producing nearly octahedral nanoparticles terminated mostly by {111} facets. In contrast, the PbS QDs synthesized at a relatively high temperature follow a thermodynamics‐dominated growth. Thus, a spherical shape is preferred, producing truncated octahedral nanoparticles with more {100} facets. Compared to PbS QDs from thermodynamics‐dominated growth, the PbS QDs with less {100} facets show fewer trap states in the QD solids, leading to a better photovoltaic device performance with a power conversion efficiency of 11.5%.