Double Metal Oxide Electron Transport Layers for Colloidal Quantum Dot Light-Emitting Diodes

Park, Myeongjin; Roh, Jeongkyun; Lim, Jaehoon; Lee, Hyunkoo; Lee, Donggu

doi:10.3390/nano10040726

Cited by 23 publications

(15 citation statements)

References 34 publications

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“…The low-binding-energy cutoff (around 4.0 eV) is relevant to the energy difference between the valence band (VB) and the E F ; therefore, the VB values of the ZnO NC films without and with PFN-Br, PFN-BF 4 , and PFN-PF 6 modification were calculated to be −7.49, −7.41, −7.52, and −7.47 eV, respectively. The obtained VB values of ZnO NC films in this study are close to the reported values in the literature. , To lead out the conduction band (CB), the energy bandgap ( E g ) of ZnO NCs without and with CPEs should be acquired first. Figure S6a shows the absorption spectra of the original and CPE-modified ZnO NC films, and the E g of ZnO NCs is estimated from the Tauc plot in Figure S6b to be 3.23 eV.…”

Section: Resultssupporting

confidence: 86%

Surface Modification of ZnO Nanocrystals with Conjugated Polyelectrolytes Carrying Different Counterions for Inverted Perovskite Light-Emitting Diodes

Chiu

Yang

2023

ACS Omega

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In this work, bromide ions (Br–) on the conjugated polyelectrolytes (CPEs) were converted to tetrafluoroborate (BF4 –) or hexafluorophosphate (PF6 –) ions through anion exchange. The three CPEs (PFN-Br, PFN-BF4, and PFN-PF6) were utilized solely for surface modification of zinc oxide nanocrystals (ZnO NCs). The ionic groups on CPEs can form permanent dipoles to facilitate charge injection from ZnO NCs to cesium lead bromide (CsPbBr3) NC emitters, therefore promoting luminescent properties of inverted perovskite light-emitting diodes (PeLEDs). The experimental results reveal that ZnO NC films were smoothened by CPEs that allowed flat deposition of the perovskite active layers; moreover, the improved contact between ZnO and perovskite layers was beneficial for reducing leakage current, as verified in the dark current measurement of devices. In addition, the incorporation of CPEs helped to passivate the defects of ZnO NC films and prolong the carrier lifetime of CsPbBr3 NCs. PeLEDs based on different CPEs were then constructed and evaluated. The device based on PFN-Br showed the highest brightness and current efficiency, and the one based on PFN-BF4 exhibited better current efficiency over PFN-Br under the low current density below 160 mA/cm2. This is the first report using fluorene-based CPEs with Br–, BF4 –, or PF6 – groups to modify the properties of ZnO and CsPbBr3 NCs for the construction of inverted PeLEDs so far. Our experiments explored new kinds of CPEs on the surface modification of ZnO NCs and device performance of PeLEDs.

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Section: Resultssupporting

confidence: 86%

Surface Modification of ZnO Nanocrystals with Conjugated Polyelectrolytes Carrying Different Counterions for Inverted Perovskite Light-Emitting Diodes

Chiu

Yang

2023

ACS Omega

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“…The degradation of the efficiency compared with the normal devices is attributed to the current crowding effect and efficiency roll-off at high current density. (25)(26)(27)(28) The leakage originates from structure variation also plays a part. The localized current density will also aggravate the Auger recombination.…”

Section: Resultsmentioning

confidence: 99%

P‐6.9: Patterning of Quantum Dots Light‐emitting Diodes Based on IGZO Films

Jia

et al. 2021

Symp Digest of Tech Papers

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Patterned quantum dots light‐emitting diodes (QLED) with sputtered IGZO films as electron transport layers are fabricated. The pattered IGZO films can define pixels ~10 μm, while accompanied by the nonuniform current spreading effect. The localized current density distribution observed by luminance distribution during the aging degrades the device seriously. In order to overcome this issue, the patterned SiO2 layer as the bank is introduced. This work also shows a potential way to tune the out couple efficiency and micro‐cavity effect (optical length) in QLED by charge transport layer thickness.

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“…In order to achieve a commercially feasible QD–LED, many studies were performed to understand the mechanisms regarding the interaction between QDs and charge transport layers [ 6 , 7 , 8 ]. During the operation of QD–LEDs, the QD active layer is generally affected by a complex combination of electric field effects and carrier charging across the device, leading to different quenching mechanisms, such as the field induced quenching, [ 9 , 10 ], interfacial charge transport [ 11 ], and charged QDs by excess charge injection [ 12 ].…”

Section: Introductionmentioning

confidence: 99%

Enhanced Electroluminescence via a Nanohybrid Material Consisting of Aromatic Ligand-Modified InP Quantum Dots and an Electron-Blocking Polymer as the Single Active Layer in Quantum Dot–LEDs

et al. 2022

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Electron overcharge causes rapid luminescence quenching in the quantum dot (QD) emission layer in QD light–emitting diodes (QD–LEDs), resulting in low device performance. In this paper we describe the application of different aromatic thiol ligands and their influence on device performance as well as their behavior in combination with an electron blocking material (EBM). The three different ligands, 1–octanethiol (OcSH), thiophenol (TP), and phenylbutan–1–thiol (PBSH), were introduced on to InP/ZnSe/ZnS QDs referred to as QD–OcSH, QD–TP, and QD–PBSH. PBSH is in particular applied as a ligand to improve QD solubility and to enhance the charge transport properties synergistically with EBM probably via π–π interaction. We synthesized poly-[N,N-bis[4-(carbazolyl)phenyl]-4-vinylaniline] (PBCTA) and utilized it as an EBM to alleviate excess electrons in the active layer in QD–LEDs. The comparison of the three QD systems in an inverted device structure without the application of PBCTA as an EBM shows the highest efficiency for QD–PBSH. Moreover, when PBCTA is introduced as an EBM in the active layer in combination with QD–PBSH in a conventional device structure, the current efficiency shows a twofold increase compared to the reference device without EBM. These results strongly confirm the role of PBCTA as an EBM that effectively alleviates excess electrons in the active layer, leading to higher device efficiency.

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Double Metal Oxide Electron Transport Layers for Colloidal Quantum Dot Light-Emitting Diodes

Cited by 23 publications

References 34 publications

Surface Modification of ZnO Nanocrystals with Conjugated Polyelectrolytes Carrying Different Counterions for Inverted Perovskite Light-Emitting Diodes

Surface Modification of ZnO Nanocrystals with Conjugated Polyelectrolytes Carrying Different Counterions for Inverted Perovskite Light-Emitting Diodes

P‐6.9: Patterning of Quantum Dots Light‐emitting Diodes Based on IGZO Films

Enhanced Electroluminescence via a Nanohybrid Material Consisting of Aromatic Ligand-Modified InP Quantum Dots and an Electron-Blocking Polymer as the Single Active Layer in Quantum Dot–LEDs

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