Structure optimization of perovskite quantum dot light-emitting diodes

Although all-inorganic perovskite light emitting diodes (PeLED) have satisfactory stability under an ambient atmosphere, producing devices with high performance is challenging. A device architecture with a reduced energy barrier between adjacent layers and optimized energy level alignment in the PeL...

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Bibliographic Details
Published in:Nanoscale 2019-03, Vol.11 (11), p.5021-5029
Main Authors: Khan, Qasim, Subramanian, Alagesan, Yu, Guannan, Maaz, Khan, Li, Delong, Sagar, Rizwan Ur Rehman, Chen, Keqiang, Lei, Wei, Shabbir, Babar, Zhang, Yupeng
Format: Article
Language:English
Subjects:
Carrier injection
Charge injection
Computer architecture
Current carriers
Current efficiency
Devices
Diodes
Electroluminescence
Electron transport
Energy levels
Nanoparticles
Optimization
Organic light emitting diodes
Perovskites
Quantum dots
Titanium dioxide
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Summary:Although all-inorganic perovskite light emitting diodes (PeLED) have satisfactory stability under an ambient atmosphere, producing devices with high performance is challenging. A device architecture with a reduced energy barrier between adjacent layers and optimized energy level alignment in the PeLED is critical to achieve high electroluminescence efficiency. In this study, we report the optimization of a CsPbBr3-based PeLED device structure with Li-doped TiO2 nanoparticles as the electron transport layer (ETL). Optimal Li doping balances charge carrier injection between the hole transport layer (HTL) and ETL, leading to superior performance in both devices. The turn-on voltages for devices with Li-doped TiO2 nanoparticles were significantly reduced from 7.7 V to 4.9 V and from 3 V to 2 V in the direct and inverted PeLED structures, respectively. The low turn-on voltage for green emission is one of the lowest values among the reported CsPbBr3-based PeLEDs. Further investigations show that the device with an inverted structure is superior to the device with a direct structure because the energy barrier for carrier injection was minimized. The inverted structure devices exhibited a current efficiency of 5.6 cd A-1 for the pristine TiO2 ETL, while it was 15.2 cd A-1 for the Li-doped TiO2 ETL, a factor of ∼2.7 enhancement at 5000 cd m-2.
ISSN:2040-3364
2040-3372
DOI:10.1039/c8nr09864f