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Chlorine Vacancy Passivation in Mixed Halide Perovskite Quantum Dots by Organic Pseudohalides Enables Efficient Rec. 2020 Blue Light-Emitting Diodes
journal contribution
posted on 2020-02-17, 19:00 authored by Xiaopeng Zheng, Shuai Yuan, Jiakai Liu, Jun Yin, Fanglong Yuan, Wan-Shan Shen, Kexin Yao, Mingyang Wei, Chun Zhou, Kepeng Song, Bin-Bin Zhang, Yuanbao Lin, Mohamed Nejib Hedhili, Nimer Wehbe, Yu Han, Hong-Tao Sun, Zheng-Hong Lu, Thomas D. Anthopoulos, Omar F. Mohammed, Edward H. Sargent, Liang-Sheng Liao, Osman M. BakrBlue-emitting
perovskites can be easily attained by precisely tuning
the halide ratio of mixed halide (Br/Cl) perovskites (MHPs). However,
the adjustable halide ratio hinders the passivation of Cl vacancies,
the main source of trap states leading to inferior performance of
blue MHP light-emitting diodes (LEDs). Here, we report a strategy
for passivating Cl vacancies in MHP quantum dots (QDs) using nonpolar
solvent-soluble organic pseudohalide [n-dodecylammonium
thiocyanate (DAT)], enabling blue MHP LEDs with greatly enhanced efficiency.
Density functional theory calculations reveal that the thiocyanate
(SCN–) groups fill in the Cl vacancies and remove
electron traps within the bandgap. DAT-treated CsPb(BrxCl1–x)3 QDs exhibit near unity (∼100%) photoluminescence quantum
yields, and their blue (∼470 nm) LEDs are spectrally stable
with an external quantum efficiency of 6.3%, a record for perovskite
LEDs emitting in the range of 460–480 nm relevant to Rec. 2020
display standards, and a half-lifetime of ∼99 s.
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3 QDs exhibitvacancyChlorine Vacancy PassivationMHP quantum dotstrap2020 Blue Light-Emitting Diodes Blue-emitting perovskitesCl vacancieshalide ratioOrganic Pseudohalides Enables Efficient Recpassivating Cl vacanciesefficiencythiocyanate2020 display standardsLEDMHP light-emitting diodesnmDATMixed Halide Perovskite Quantum DotsSCN
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