https://scholar.dgist.ac.kr/handle/20.500.11750/10014 2026-10-18T14:04:44Z https://scholar.dgist.ac.kr/handle/20.500.11750/60953 Title: Facile synthesis of large-Stokes-shift giant CdHgSe/CdHgSeS near-infrared quantum dots via chlorine-mediated Ostwald ripening Author(s): Lee, Gyudong; Park, Sanghwang; Seo, Jongcheol; Lee, Wonseok; Arogundade, Opeyemi H.; Smith, Andrew M.; Choi, Jongmin; Choi, Hongsoo; Lim, Sung Jun Abstract: Giant core/shell quantum dots (GQDs) offer advantages for optoelectronics, including suppressed blinking and reduced Auger recombination, yet thick-shell growth often requires laborious successive ion layer adsorption and reaction (SILAR) cycles. Here we demonstrate a chlorine-mediated controlled Ostwald ripening strategy that transforms NIR-emitting CdHgSe/CdS core/shell seed QDs into giant CdHgSe/CdHgSeS core/gradient-shell QDs in a single post-synthetic step. Seed QDs are prepared by growing a thin (similar to 1.6-monolayer) CdS shell on CdHgSe alloy cores. Injection of CHCl3 at 240 degrees C triggers rapid ripening, in which most seeds dissolve while a minor population grows into GQDs. During ripening, the band-edge absorption feature is strongly attenuated and absorption below similar to 610 nm increases markedly, whereas NIR emission remains centered near similar to 900 nm, yielding a large effective Stokes shift that can mitigate reabsorption in luminescent solar concentrators. HAADF-STEM/EDS and XRD support a compositionally graded shell, while mass spectrometry and numerical simulations are consistent with chlorine-modified surface chemistry and altered monomer solubility/surface tension that accelerate ripening. As a proof of concept, embedding the GQDs in PMMA affords a transparent luminescent solar concentrator prototype with retained NIR emission and favorable spectral overlap with silicon photovoltaics. 2026-07-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60687 Title: Recent Progress in Surface Engineering of AgBiS2 Nanocrystals for Nontoxic and Efficient Photovoltaics Author(s): Kim, Hae Jeong; Kim, Min Yeong; Park, Jin Young; Yoon, Soojin; Choi, Jongmin Abstract: Silver bismuth sulfide (AgBiS2) nanocrystals have recently emerged as eco-friendly semiconductors, achieving power conversion efficiencies above 10%. These improvements are largely driven by surface engineering, which reduces mid-gap states and enhances charge transport and film quality. This review summarizes four major surface engineering strategies for AgBiS2 NCs solid-state ligand exchange, solution-phase ligand exchange, direct synthesis, and full passivation, highlighting their principles and representative achievements. We also discuss emerging approaches that combine chemical control with structural design, offering pathways toward scalable, stable, and high-performance AgBiS2 photovoltaics. 2026-02-28T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/59992 Title: Dopant-Chelating Polymeric Hole Transporting Material for Efficient and Humidity-Stable Quantum Dot Photovoltaics Author(s): You, Hyung Ryul; Lee, Duck Hoon; Kim, Suhwan; Park, Jin Young; Lee, Eon Ji; Kim, Hae Jeong; Ma, Hyeon Soo; Ka, Sungmin; Yong, Taeyeong; Lee, Yu Min; Kim, Younghoon; Moon, Byung-joon; Lee, Junwoo; Choi, Jongmin Abstract: Although conjugated polymers (CPs) have been extensively investigated as hole transport layers (HTLs) for optoelectronic devices, including colloidal quantum dot (CQD) photovoltaics, their stability is often limited by dopant-induced diffusion into the underlying photoactive regions. To overcome this, an ionic-electronic CP, PBTBDF-TEG, comprising benzodifuran and tetraethylene glycol (TEG)-substituted furan units is designed. PBTBDF-TEG effectively confines lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) dopants via lithium chelation by the TEG side chains, thereby suppressing dopant migration. This coordination also reduces the (010) π–π stacking distance, promoting hole transport by alleviating steric hindrance. Consequently, CQD solar cells incorporating LiTFSI-doped PBTBDF-TEG exhibited a power conversion efficiency (PCE) of 13.7%, exceeding the 11.8% achieved with the undoped counterpart. Furthermore, lithium chelation immobilizes water molecules, mitigating moisture ingress. As a result, the doped device retained over 90% of its initial PCE after 24 h under high humidity (85%–95% RH), whereas the undoped device exhibited substantial degradation. https://scholar.dgist.ac.kr/handle/20.500.11750/59901 Title: Enhancing Quantum Dot Photovoltaic Efficiency Through Defect Passivation and Triplet Energy Transfer with 9-Anthracenecarboxylic Acid Author(s): Lee, Eon Ji; Ham, Gayoung; Yun, Sunhee; You, Hyung Ryul; Yong, Taeyeong; Seo, Gayoung; Lee, Wonjong; Ma, Hyeon Soo; Park, Jin Young; Kim, Hae Jeong; Kim, Soo-Kwan; Kim, Younghoon; Lim, Jongchul; Kim, Minjun; Cha, Hyojung; Choi, Jongmin Abstract: A dual-functional electron transport layer (ETL) is reported for PbS colloidal quantum dot (CQD) photovoltaics by incorporating 9-anthracenecarboxylic acid (ACA) into a zinc oxide (ZnO) matrix. Despite its favorable electron transport characteristics and appropriate band alignment, intrinsic defects in ZnO, such as oxygen vacancies, remain a limiting factor in device performance. The carboxylate functional group of ACA effectively passivates these defects, thereby reducing trap-assisted recombination. Moreover, ACA, an acene-based π-conjugated molecule, efficiently generates triplet excitons. These triplets undergo triplet energy transfer to the PbS CQD layer, enhancing photocurrent generation. Owing to these synergistic effects, CQD photovoltaics (PVs) incorporating ACA-treated ZnO ETLs exhibit enhanced open-circuit voltage and short-circuit current density, resulting in a higher power conversion efficiency of 11.55% compared to 10.48% for control devices. This strategy highlights the combined advantages of electronic defect passivation and triplet exciton harvesting in PbS CQD PVs. © 2025 Elsevier B.V., All rights reserved. 2025-10-31T15:00:00Z