Highly efficient and low turn-on voltage quantum-dot light-emitting diodes using a ZnMgO/ZnO double electron transport layer

Heo, Su Been; Shin, Jae Seung; Kim, Tae Yeon; Park, Sungho; Jung, Woon Ho; Kim, Hyun-Jun; Hong, Jong Am; Kim, Beom Su; Park, Yongsup; Chin, Byung Doo; Kim, Jong Gyu; Kang, Seong Jun

doi:10.1016/j.cap.2021.07.001

Cited by 16 publications

(16 citation statements)

References 38 publications

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“…37 As can be seen from Figure 1e, the binding energy peak of Zn 2p in LZO@MgO is almost unchanged relative to that of LZO, but the peak intensity is significantly weakened, which indicates that magnesium ions may not enter the interior of the ZnO NP lattice but exist on its surface. 38 Similar phenomena were also observed in Mg-doped ZnO (ZnMgO) and MgO shell-coated ZnO (ZnO@MgO) NPs (Figure S2, Supporting Information), which further confirmed that the MgO shell was coated on ZnO NPs.…”

Section: ■ Results and Discussionsupporting

confidence: 77%

Improving Performance of InP-Based Quantum Dot Light-Emitting Diodes by Controlling Defect States of the ZnO Electron Transport Layer

Ning

Cao

et al. 2022

J. Phys. Chem. C

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ZnO nanoparticles (NPs) are currently the benchmark of electron transport materials for preparing indium phosphide (InP)-based environmentally friendly quantum dot light-emitting diodes (QLEDs). However, the defect-dependent exciton quenching and charge injection limiting behavior at the ZnO/quantum dot (QD) interface seriously restrict the improvement in device performance. Herein, we report a strategy based on Li doping and MgO shell coating to regulate the defect state of ZnO to improve the performance of InP-based QLEDs. It is found that Li doping passivates the intrinsic defect states of ZnO NPs and improves the electron mobility and reduces the spontaneous charge transfer at the ZnO/QD interface and the current leakage of QLEDs. The MgO shell passivates the surface oxygen defects of ZnO NPs, thus reducing the exciton quenching and non-radiative recombination centers at the ZnO/QD interface, resulting in enhanced QLED performance. As a result, the optimized QLED prepared by Li-doped and MgO shell-coated ZnO NPs shows an external quantum efficiency of 9.7% and a brightness of 22,200 cd m–2 at 4.2 V, which are, respectively, 2.6 and 7 times higher than those of a QLED based on pure ZnO. This work shows that controlling the defect states of the ZnO electron transport layer by ion doping and shell coating provides an effective way to obtain high-performance environment-friendly QLEDs.

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Section: ■ Results and Discussionsupporting

confidence: 77%

Improving Performance of InP-Based Quantum Dot Light-Emitting Diodes by Controlling Defect States of the ZnO Electron Transport Layer

Ning

Cao

et al. 2022

J. Phys. Chem. C

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“…For electron injection, we use an indium tin oxide (ITO) cathode followed by a sol-gel ZnO ETL doped with Mg. The addition of Mg helps suppress oxygen vacancy-related defects (known QD exciton quenchers 24 ) and simultaneously partially impede electron injection (due to lowered electron mobility 25 and the increased injection barrier 26 ) to balance it with slower hole injection.…”

Section: Resultsmentioning

confidence: 99%

Two-band optical gain and ultrabright electroluminescence from colloidal quantum dots at 1000 A cm−2

et al. 2022

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Colloidal quantum dots (QDs) are attractive materials for the realization of solution-processable laser diodes. Primary challenges towards this objective are fast optical-gain relaxation due to nonradiative Auger recombination and poor stability of colloidal QD solids under high current densities required to obtain optical gain. Here we resolve these challenges and achieve broad-band optical gain spanning the band-edge (1S) and the higher-energy (1P) transitions. This demonstration is enabled by continuously graded QDs with strongly suppressed Auger recombination and a current-focusing device design, combined with short-pulse pumping. Using this approach, we achieve ultra-high current densities (~1000 A cm−2) and brightness (~10 million cd m−2), and demonstrate an unusual two-band electroluminescence regime for which the 1P band is more intense than the 1S feature. This implies the realization of extremely large QD occupancies of up to ~8 excitons per-dot, which corresponds to complete filling of the 1S and 1P electron shells.

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“…CdSe/ZnS QDs were synthesized using a two-pot synthesis method, whose details have been described in a previous study. 19,20 ZnO (N-10) was purchased from Avantama.…”

Section: Methodsmentioning

confidence: 99%

Solution-processable Li-doped transition metal oxide hole-injection layer for highly efficient quantum-dot light-emitting diodes

et al. 2022

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Highly efficient and low turn-on voltage quantum-dot light-emitting diodes using a ZnMgO/ZnO double electron transport layer

Cited by 16 publications

References 38 publications

Improving Performance of InP-Based Quantum Dot Light-Emitting Diodes by Controlling Defect States of the ZnO Electron Transport Layer

Improving Performance of InP-Based Quantum Dot Light-Emitting Diodes by Controlling Defect States of the ZnO Electron Transport Layer

Two-band optical gain and ultrabright electroluminescence from colloidal quantum dots at 1000 A cm−2

Solution-processable Li-doped transition metal oxide hole-injection layer for highly efficient quantum-dot light-emitting diodes

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