Academic Appointments


All Publications


  • Enhanced performance of Zn-modified (MnCo)1.5O4 spinel coatings: Investigating critical properties for SOFC interconnect materials INTERNATIONAL JOURNAL OF HYDROGEN ENERGY Kim, S., Kim, D., Oh, S., Lee, J., Heo, Y., Lee, J. 2025; 102: 444-451
  • 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 Kim, S., Oh, S., Kim, D., Lee, J., Heo, Y., Lee, J., Nahm, S. 2025
  • Self-Assembled Monolayer-Functionalized NiO Hole Injection layer for Improved Charge Injection in Quantum Dot Light-Emitting Diodes ACS APPLIED MATERIALS & INTERFACES Lim, H., Dang, T., Lee, N., Jin, S., Vo, V., Lee, J., Shin, W., Jeong, B., Heo, Y. 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

  • Tetraoctylammonium Bromide Interlayer between NiLiO<sub> <i>x</i> </sub> and Perovskite for Light-Emitting Diodes ACS APPLIED MATERIALS & INTERFACES Vo, V., Bae, S., Dang, T., Phung, D., Kim, J., Lee, S., Lee, N., Lim, H., Kim, K., Lee, J., Heo, Y. 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

  • Effect of magnesium doping on NiO hole injection layer in quantum dot light-emitting diodes NANOPHOTONICS Lee, N., Vo, V., Lim, H., Jin, S., Dang, T., Jang, H., Choi, D., Lee, J., Jeong, B., Heo, Y. 2024; 13 (25): 4615-4624
  • H<sub>2</sub>S gas sensing properties of ZnO-SnO<sub>2</sub> branch-stem nanowires grown on a copper foil SCRIPTA MATERIALIA Hung, P., Thao, D., Hung, N., Hoang, N., Hoat, P., Thin, P., Lee, J., Heo, Y. 2025; 255
  • 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 Kim, D., Jo, Y., Kim, S., Yim, S., Lee, J., Lee, C. 2024; 12 (18): 6395-6405

    View details for DOI 10.1039/d4tc00537f

    View details for Web of Science ID 001214969500001

  • 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 Kim, D., Kim, S., Lee, J., Heo, Y., Lee, J. 2024; 50 (6): 9744-9752
  • 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 Oh, S., Kim, D., Lee, I., Choi, C., Lee, J., Heo, Y., Lee, J. 2022; 47 (78): 33410-33419
  • High-Voltage, Room-Temperature Liquid Metal Flow Battery Enabled by Na-K vertical bar K-beta ''-Alumina Stability JOULE Baclig, A. C., McConohy, G., Poletayev, A., Michelson, A., Kong, N., Lee, J., Chueh, W. C., Rugolo, J. 2018; 2 (7): 1287–96