https://scholar.dgist.ac.kr/handle/20.500.11750/241 2026-04-05T11:52:11Z https://scholar.dgist.ac.kr/handle/20.500.11750/59986 Title: Thick ZnS Shells on CsPbBr3Quantum Dots by Colloidal-Atomic Layer Deposition for Enhanced Photoluminescence and Stability Author(s): Teku, Justice Agbeshie; Taylor, Derrick Allan; Lee, Jong-Soo Abstract: The colloidal-atomic layer deposition (c-ALD) method is employed to grow a zinc sulfide (ZnS) shell on CsPbBr3 perovskite quantum dots (PeQDs) to form CsPbBr3/ZnS core/shell heterostructures to address the intrinsic stability challenges of PeQDs. The c-ALD process offers layer by layer control over the thickness of the shell, enabling uniform and conformal encapsulation, which significantly passivates the surface defects and enhances the optical properties of the PeQDs. This approach significantly improves photoluminescence quantum yield, increases environmental stability, and prolongs the average radiative lifetime of the CsPbBr3 PeQDs. The structural and spectroscopic analysis confirms the formation of a thick and uniform ZnS shell. Furthermore, the resulting core/shell PeQDs exhibit exceptional thermal, photostability, and aqueous durability, surpassing the limitations of pristine CsPbBr3 PeQDs. This work opens new opportunities for the c-ALD method to be integrated into perovskite core/shell heterostructures for advancing optoelectronic technologies. 2025-07-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/59981 Title: Optimizing Charge Balance in Quantum Dot Light-Emitting Diodes through Benzoic Acid-Passivated ZnO Nanoparticle Layers Author(s): Cho, Sinyoung; Ahn, Jae-Hyeon; Choi, Donghyun; Chae, Weon-Sik; Ko, Keum-Jin; Lee, Jong-Soo Abstract: ZnO nanoparticles (ZnO NPs) are widely utilized as electron transport layers (ETLs) in quantum dot light-emitting diodes (QLEDs) due to their high electron mobility, wide bandgap, excellent transparency, and effective hole-blocking properties. However, their high electron mobility can lead to charge imbalance and increased leakage currents, while surface defects contribute to exciton quenching at the interface with the emissive layer (EML), limiting the overall device performance. In this study, 4-CF3BA ligands were employed to effectively passivate surface defects in ZnO NPs, reducing exciton quenching and optimizing charge transport dynamics in QLEDs. This passivation strategy resulted in a significant improvement in device performance, achieving an external quantum efficiency (EQE) of 23%. The performance improvement is attributed to the suppression of interface quenching through defect passivation, improved charge balance, and enhanced electron injection. These findings demonstrate the potential of 4-(trifluoromethyl)benzoic acid (4-CF3BA) passivation as a promising approach to improve the efficiency of QLEDs, opening the way for next-generation optoelectronic device applications. 2025-11-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/59036 Title: Hybrid Polyacrylamide-ZnO Electron Transport Layers; Enhancing Exciton Recombination and Charge Injection for High-Efficiency QLEDs Author(s): Ahn, Jae-Hyeon; Cho, Sinyoung; Choi, Donghyun; Chae, Weon-Sik; Song, Myungkwan; Ko, Keum-Jin; Lee, Jong-Soo Abstract: ZnO nanoparticles (ZnO NPs) are widely utilized as electron transport layers (ETLs) in quantum dot light-emitting diodes (QLEDs) due to their high electron mobility, wide bandgap, excellent transparency, and effective hole blocking properties. However, exciton quenching at the interface between quantum dots (QDs) and ZnO NPs and unfavorable band alignment hinder the performance of QLED devices. In this study, a straightforward and versatile approach is introduced to fabricate high-performance QLED by incorporating Polyacrylamide (polyNIPAM) with ZnO NPs. The resulting QD and hybrid-ZnO NPs films achieved a photoluminescence quantum yield (PLQY) of 57.8% and a recombination rate of 80.07%. Compared to conventional ZnO-based QLEDs, the hybrid approach led to a significant improvement in external quantum efficiency (22.34%), maximum brightness (97 593 cd m-2), and a narrow full-width at half maximum (FWHM) of 22.3 nm. The hybrid ZnO NPs exhibited favorable energy levels for electron injection, promoting exciton recombination while minimizing charge diffusion losses at the QD/ZnO NP interfaces. These findings highlight the potential of polyNIPAM-functionalized ZnO NPs for scalable, high-performance QLED fabrication. Future work will focus on optimizing hybrid material composition to further suppress electron leakage and enhance charge transport 1in large-area devices. 2025-09-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/58702 Title: RED-EMITTING QUANTUM DOTS HAVING NARROW FULL WIDTH AT HALF MAXIMUM AND EMISSION WAVELENGTH FOR APPLICATION TO HIGH-COLOR-PURITY DISPLAY, AND PREPARATION METHOD THEREFOR Author(s): 파시반; 이종수 Abstract: One embodiment of the present invention relates to a method for preparing InP-based nanoparticles for application to a high-color-purity display, and provides: a technique for synthesizing uniform core quantum dots by providing a method for preparing quantum dots, the method comprising the steps of preparing a mixture comprising InX-based quantum dot seeds, forming an InX-based core by continuously injecting a Zn(In)X-based cluster into the mixture, forming a first shell coated on the In-based core by adding a selenium compound and a zinc precursor to the mixture, and forming a second shell coated on the first shell by adding a sulfur compound and the zinc precursor to the mixture, wherein the first shell is formed from ZnSe, the second shell is formed from ZnS, and X includes phosphorus (P), arsenic (As) or antimony (Sb); and a light emitting layer of a next generation self light-emitting device, the light emitting layer having a color purity improved over that of conventional quantum dots and resolving the stability problem thereof.