Heeyeob Chae

Quantum dots (QDs) are being highlighted in display applications for their excellent optical properties, including tunable bandgaps, narrow emission bandwidth, and high efficiency. However, issues with their stability must be overcome to achieve the next level of development. QDs are utilized in display applications for their photoluminescence (PL) and electroluminescence. The PL characteristics of QDs are applied to display or lighting applications in the form of color-conversion QD films, and

We report on an all-solution-processed fabrication of highly efficient green quantum dot-light-emitting diodes (QLEDs) with an inverted architecture, where an interfacial polymeric surface modifier of polyethylenimine ethoxylated (PEIE) is inserted between a quantum dot (QD) emitting layer (EML) and a hole transport layer (HTL), and a MoO x hole injection layer is solution deposited on top of the HTL. Among the inverted QLEDs with varied PEIE thicknesses, the device with an optimal PEIE thicknes

The performance of quantum dot light-emitting diodes (QD-LEDs) was investigated for different hole transport layers with small molecules and polymers: poly(4-butyl-phenyl-diphenyl-amine), poly-N-vinylcarbazole (PVK), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-diphenyl-4,4'-diamine, 4,4',4″-tris(N-carbazolyl)-triphenyl-amine (TCTA), and 4,4'-bis(carbazole-9-yl)biphenyl (CBP). The electroluminescence performance of QD-LEDs was considerably improved by adding small molecules (TCTA or CBP) having h

In this work, we developed a charge control sandwich structure around QD layers for the inverted QLEDs, the performance of which is shown to exceed that of the conventional QLEDs in terms of the external quantum efficiency (EQE) and the current efficiency (CE). The QD light-emitting layer (EML) is sandwiched with two ultrathin interfacial layers: one is a poly(9-vinlycarbazole) (PVK) layer to prevent excess electrons, and the other is a polyethylenimine ethoxylated (PEIE) layer to reduce the hol

Tailored-ZnMgO layers result in green-emitting InP based quantum dot light emitting diodes (QLEDs) with a maximum luminance of 13 900 cd m-2 and an external quantum efficiency (EQE) of 13.6%. This is the first report of green-emitting InP based QLEDs that exceed an EQE of 10% and a luminance of 13 000 cd m-2.

Evolution of the long-term (400 h) thermal stability of green CdSe@ZnS alloyed core/shell QDs (A-QDs) and CdSe@ZnS/ZnS (alloyed core/shell)/thick shell QDs (AS-QDs) under 85 °C, 85% relative humidity conditions in air.

Vertical graphene (VG) nanosheets are directly grown below 500 °C on glass substrates by a one-step copper-assisted plasma-enhanced chemical vapour deposition (PECVD) process. A piece of copper foil is located around a glass substrate as a catalyst in the process. The effect of the copper catalyst on the vertical graphene is evaluated in terms of film morphology, growth rate, carbon density in the plasma and film resistance. The growth rate of the vertical graphene is enhanced by a factor of 5.6

Fabrication of a multilayered quantum dot-light-emitting diode (QLED) with an inverted architecture cannot be usually fully solution-processed mainly due to the significant destruction of the pre-existing quantum dot (QD) emitting layer (EML) occurring during the subsequent solution-deposition of the hole transport layer (HTL).

High-quality CdZnSeS/ZnS alloyed core/thick-shell quantum dots (QDs) as energy donors were first exploited in Förster resonance energy transfer (FRET) applications. A highly efficient ligand-exchange method was used to prepare low toxicity, high quantum yield, stabile, and biocompatible CdZnSeS/ZnS QDs densely capped with multifunctional polymer ligands containing dihydrolipoic acid (DHLA). The resulting QDs can be applied to construct QDs-based Förster resonance energy transfer (FRET) systems b

In this study, multishelled InP-based quantum dots (QDs) were synthesized using a phosphorus source tris(dimethylamino)phosphine [(DMA)3P] and were applied to solution-processed QD light-emitting diode (QLED) devices. (DMA)3P is not only a safe phosphorus source but is also a low-cost precursor for InP QDs. The quantum yield of the QDs increased from 71.0 to 81.8% by post-treatment with hexanethiol. The efficiency of the (DMA)3P-based red InP QLEDs was enhanced by using chlorine-doped ZnMgO (Cl-

We developed a 1.0 nm thick aluminum oxide (Al₂O₃) interlayer as an electron blocking layer to reduce leakage current and suppress exciton quenching induced by charge imbalance in inverted quantum dot light emitting diodes (QLEDs).

A flexible supercapacitor was demonstrated with ‘graphene forest’ as electrodes. No capacitance loss was observed even with 100 000 times of bending.

Vertically oriented graphene (VG) with three-dimensional architecture has been proved to exhibit unique properties, and its particular morphology has been realized by researchers to be crucial for its performance in practical applications. In this study, we investigated the morphology evolution of VG films synthesized by the plasma-enhanced chemical vapor deposition process, including porous graphene film, graphene wall, and graphene forest. This study reveals that the morphology of VG is contro

Electrospray process was developed for organic layer deposition onto polymer organic light-emitting diode [PLED] devices in this work. An electrospray can be used to produce nanometer-scale thin films by electric repulsion of microscale fine droplets. PLED devices made by an electrospray process were compared with spin-coated ones. The PLED device fabricated by the electrospray process showed maximum current efficiency of 24 cd/A, which was comparable with that of the spin-coating process. The e