
Joon Hyung Lee
Visiting Professor
Materials Science and Engineering
All Publications
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Enhanced performance of Zn-modified (MnCo)1.5O4 spinel coatings: Investigating critical properties for SOFC interconnect materials
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
2025; 102: 444-451
View details for DOI 10.1016/j.ijhydene.2025.01.103
View details for Web of Science ID 001398672800001
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Enhancement of piezoelectric properties in KNN-based lead-free ceramics through controlled NaNbO<sub>3</sub> seed addition and phase structure engineering
JOURNAL OF MATERIALS SCIENCE
2025
View details for DOI 10.1007/s10853-025-10676-1
View details for Web of Science ID 001414807300001
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Self-Assembled Monolayer-Functionalized NiO Hole Injection layer for Improved Charge Injection in Quantum Dot Light-Emitting Diodes
ACS APPLIED MATERIALS & INTERFACES
2024; 17 (1): 1533-1541
Abstract
The development of quantum dot light-emitting diodes (QLEDs) represents a promising advancement in next-generation display technology. However, there are challenges, especially in achieving efficient hole injection, maintaining charge balance, and replacing low-stability organic materials such as PEDOT:PSS. To address these issues, in this study, self-assembled monolayers (SAMs) were employed to modify the surface properties of NiO, a hole injection material, within the structure of ITO/HIL/TFB/QDs/ZnMgO/Al QLEDs. Specifically, using Br-2PACz-based SAMs resulted in surface defect passivation, improved hole injection, reduced exciton quenching, and enhanced electrical characteristics. Notably, QLEDs based on (NiO+Br-2PACz) demonstrated a turn-on voltage of 2.4 V, a maximum external quantum efficiency (EQE) of 8.30%, a maximum luminance of 88,831 cd/m2, and a maximum current efficiency of 32.78 cd/A. Compared to NiO-based QLEDs, these results represent a reduction in turn-on voltage by approximately 1.5 V, a 1.99-fold increase in EQE, and a 3.63-fold increase in luminance, indicating significantly enhanced performance with notable improvements in turn-on voltage, EQE, and luminance. They also showed higher EQE and luminance than PEDOT:PSS-based QLEDs; this could be attributed to the downshifting of energy levels by Br-2PACz, which reduced the hole injection barrier, increased the conductivity, and improved charge balance. In particular, the reduction in exciton quenching and the increase in electrical conductivity contributed significantly to the overall performance enhancement of the (NiO+Br-2PACz)-based QLEDs. This paper proposes a simple method for inorganic hole injection layer functionalize and application.
View details for DOI 10.1021/acsami.4c16075
View details for Web of Science ID 001387055800001
View details for PubMedID 39780384
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Tetraoctylammonium Bromide Interlayer between NiLiO<sub> <i>x</i> </sub> and Perovskite for Light-Emitting Diodes
ACS APPLIED MATERIALS & INTERFACES
2024; 16 (46): 64210-64221
Abstract
Physical vapor deposition is a favorable technique for fabricating light-emitting diodes (LEDs) due to its scalability and reproducibility. However, the performances of LEDs fabricated via this method are worse than those prepared via solution processing owing to the generation of high defect densities. In this study, we introduce a layer of tetraoctylammonium bromide (TOABr), an interfacial-modification compound containing four long octyl chains that are symmetrically arranged around an N atom, to reduce nonradiative recombination and trap densities in CsPbBr3. We examined the impacts of adding TOABr on perovskite thin films deposited on hole injection layers made of Li-doped NiOx and poly(3,4-ethylenedioxythiophene)/polystyrenesulfonate. Our investigations reveal that TOABr addition slightly increases crystallinity, dramatically increases photoluminescence, and achieves the preferred orientation in the perovskite films. Additionally, the interfacial layer passivates defects and improves charge balance in the device, thereby enhancing performance. Consequently, perovskite LEDs with a TOABr layer exhibit a lower turn-on voltage of 3 V than their pristine counterparts, achieving a maximum luminance of 11,133 cd m-2 and an external quantum efficiency of 1.24%, whereas the pristine perovskite LEDs achieve an EQE of 0.015%. The approach proposed in this study can be used to fabricate efficient vacuum-thermal-evaporated perovskite LEDs.
View details for DOI 10.1021/acsami.4c13287
View details for Web of Science ID 001353980500001
View details for PubMedID 39530385
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Effect of magnesium doping on NiO hole injection layer in quantum dot light-emitting diodes
NANOPHOTONICS
2024; 13 (25): 4615-4624
View details for DOI 10.1515/nanoph-2024-0239
View details for Web of Science ID 001309710300001
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H<sub>2</sub>S gas sensing properties of ZnO-SnO<sub>2</sub> branch-stem nanowires grown on a copper foil
SCRIPTA MATERIALIA
2025; 255
View details for DOI 10.1016/j.scriptamat.2024.116372
View details for Web of Science ID 001314830300001
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Investigation of potassium doping and defect healing mechanism in core-shell CsPbBr<sub>3</sub>/SiO<sub>2</sub> quantum dots
JOURNAL OF MATERIALS CHEMISTRY C
2024; 12 (18): 6395-6405
View details for DOI 10.1039/d4tc00537f
View details for Web of Science ID 001214969500001
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Effect of Zn doping on the structure and electrical conductivity of Mn<sub>1.5</sub>Co<sub>1.5</sub>O<sub>4</sub> spinel
CERAMICS INTERNATIONAL
2024; 50 (6): 9744-9752
View details for DOI 10.1016/j.ceramint.2023.12.293
View details for Web of Science ID 001184546300001
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Electrophoretic deposition and low-temperature densification of Cu<sub>1.35</sub>Mn<sub>1.65</sub>O<sub>4</sub> spinel for an interconnect protective coating in solid oxide fuel cells
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
2022; 47 (78): 33410-33419
View details for DOI 10.1016/j.ijhydene.2022.07.259
View details for Web of Science ID 000895377000001
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High-Voltage, Room-Temperature Liquid Metal Flow Battery Enabled by Na-K vertical bar K-beta ''-Alumina Stability
JOULE
2018; 2 (7): 1287–96
View details for DOI 10.1016/j.joule.2018.04.008
View details for Web of Science ID 000439698900012