Journal
ACS APPLIED MATERIALS & INTERFACES
Volume 12, Issue 12, Pages 14224-14232Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsami.0c02768
Keywords
light-emitting diodes; perovskites; Lewis base cyclam; self-passivation; defect states
Funding
- NSFC [51922049, 61604074]
- National Key Research and Development Program of China [2016YFB0401701]
- Natural Science Foundation of Jiangsu Province [BK20180020]
- Fundamental Research Funds for the Central Universities [30917011202]
- PAPD of Jiangsu Higher Education Institutions
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Metal halide perovskites have been focused as a candidate applied as a promising luminescent material for next-generation high-quality lighting and high-definition display. However, as perovskite films formed, high density of defects would be produced in solution processing inevitably, leading to low exciton recombination efficiency in light-emitting diodes (LEDs). Herein, a facile and novel self-passivation strategy to inhibit defect formation in perovskite films for constructing high-performance LEDs is developed. For the first time, we introduce 1,4,8,11-tetraazacyclotetradecane (cyclam) in perovskite precursor solution, and it spontaneously passivates defect states of CsPbBr3-based perovskites by coaction between amine and uncoordinated lead ions during spin-coating without an anti-solvent process. Furthermore, as a delocalized system, cyclam also possesses chemical properties that facilitate exciton transportation. The proposed passivation strategy boosts the external quantum efficiency from 1.25% (control device) to 16.24% (cyclam-passivated device). Furthermore, defect passivation is also conductive to reduce LED degradation paths and improve device stability as the extrapolated lifetime (T-50) of LEDs at an initial brightness of 100 cd/m(2) is increased from 0.9 to 127 h. These findings indicate that the introduction of cyclam is highly effective to enhance the performance of LEDs, and such a strategy in effectively reducing the defects could be also applied in other perovskite-based devices, such as lasers, solar cells, and photodetectors.
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