https://scholar.dgist.ac.kr/handle/20.500.11750/10496 2026-10-10T23:12:14Z https://scholar.dgist.ac.kr/handle/20.500.11750/60880 Title: Site-specific fluorination on donor-acceptor polymers enhances intramolecular charge transfer for photocatalytic hydrogen evolution Author(s): Jung, Wooteak; An, Sanghyeok; Ham, Gayoung; Choi, Geoneop; Lee, Soyeon; Park, Kyo Bin; Yang, Jiwoong; Chung, Dae Sung; Cha, Hyojung Abstract: The development of polymer photocatalysts remains a central challenge in achieving efficient solar-to-fuel conversion. A key limitation lies in the use of weak donor units, which hampers the optimization of intramolecular donor-acceptor interactions and reduces charge-transfer efficiency. Here, we report a site-specific fluorination strategy that addresses this bottleneck by introducing fluorine atoms at defined positions along the polymer backbone via a unique two-step polymerization protocol. Two representative random copolymers were synthesized: the acceptor-fluorinated polymer (PBF8BT-AF) and the donor-fluorinated polymer (PBF8BT-DF). Strikingly, PBF8BT-DF exhibited superior photocatalytic activity, while PBF8BT-AF showed inferior performance due to exciton loss through a non-productive decay pathway. A comprehensive spectroscopic analysis, supported by density functional theory (DFT) calculations, reveals that donor-site fluorination promotes exciton delocalization across the entire repeating unit, thereby facilitating efficient intramolecular charge transfer. In contrast, acceptor fluorination energetically localizes the excited state, impeding exciton migration and suppressing charge utilization. These findings underscore the critical role of site-specific exciton stabilization in determining photocatalytic efficiency and establish domain-targeted molecular engineering as a powerful design principle for next-generation polymer photocatalysts. 2026-06-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60700 Title: 이방성 나노입자의 음각 전사 방법 및 이에 의해 제조된 유연 전극 Author(s): 김혜현; 양지웅; 최문기; 김기욱 Abstract: 본 발명의 일 양태에 따르면, 나노와이어 물질을 스탬프에 도포하는 단계(S100); 상기 스탬프를 패턴이 형성된 음각 트렌치에 접촉시키고 분리시켜, 상기 스탬프에 나노와이어 물질로 형성된 패턴을 전사하는 단계(S200); 및 상기 패턴이 전사된 스탬프를 기판에 접촉시키고 분리시켜, 상기 기판에 나노와이어 물질로 형성된 패턴을 전사하는 단계(S300)를 포함하는, 음각 전사 방법이 제공된다. https://scholar.dgist.ac.kr/handle/20.500.11750/60536 Title: Nanocrystal Geometry Governs Phase Transformation Pathways in Palladium Hydride Author(s): Lee, Daewon; Oaks-Leaf, Sam; Ma, Hyeonjong; He, Jianlong; Wang, Zhiqi; Shi, Yifeng; Ahn, Eonhyoung; Bustillo, Karen C.; Song, Chengyu; Ribet, Stephanie M.; Dhall, Rohan; Ophus, Colin; Asta, Mark; Yang, Jiwoong; Xia, Younan; Limmer, David T.; Zheng, Haimei Abstract: Pathways and structural dynamics of phase transformations impact performance of materials in energy and information storage technologies. Palladium hydride (PdHx ) nanocrystals are an ideal model system for studying solute-induced phase transformations, where elastic energy from lattice mismatch between alpha-PdH, and beta-PdH, phases is often considered a key to determining the transformation pathways. alpha/beta-PdHx interfacial elastic energy is affected by the confined geometry of a nanocrystal. However, how nanocrystal geometry influences phase trans-formation pathways is largely unknown. Using in situ liquid phase transmission electron microscopy, we directly visualize hydrogenation in Pd nanocrystals with two geometries, a nanocube and a hexagonal nanoplate. Both follow similar sequences of an initially curved nucleus, interface flattening, and reverse-stage nucleation; however, their evolving alpha/beta-PdHx interfaces exhibit geometry-dependent crystallographic alignments. In nanocubes, (100)-aligned configurations conform to static elastic energy ordering, representing a pathway that maintains a local mechanical equilibrium, whereas nanoplates display both (110) and (211)-aligned interfaces. Theoretical simulations show that geometry determines the accessibility of alternative phase transformation pathways as the system is driven far from equilibrium during hydrogenation. These findings identify geometry as a fundamental parameter for directing phase transformation pathways, offering design principles for accessing atypical configurations and improving properties of intercalation-based devices. 2026-04-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60475 Title: Broadband Circularly Polarized Light Detection via Spin-Selective Charge Transport in Quantum Dot Photodiodes Author(s): Kim, Minseo; Li, Shi; Lee, Kyunghoon; Ahn, Eonhyoung; Lee, Soyeon; Kim, Kiwook; Kim, Hang; Yu, Wookyung; Choi, Changsoon; Lim, Jung Ah; Hwang, Jeeseong; Kim, Dae-Hyeong; Yang, Jiwoong Abstract: Circularly polarized light (CPL) detection provides polarization-resolved information, enabling advanced applications in quantum technologies, bioimaging, secure communications, and multi-level optical data processing. However, conventional CPL photodetectors typically rely on intrinsically chiral absorbers, restricting operation to the UV-vis range and hindering extension into the near-infrared (NIR) and shortwave infrared (SWIR), which are critical for deep tissue imaging and low-visibility sensing. Here, we demonstrate broadband CPL detection with quantum dot (QD) photodiodes that exploit the chiral-induced spin selectivity effect in chiral-ZnO charge transport layers. Chiral ligand-functionalized ZnO electron transport layers selectively transmit spin-polarized charge carriers from QDs, enabling CPL-specific photocurrent generation even in spectral regions without intrinsic chiral absorption. Heavy-metal-free Cu-In-Se QD-photodiodes exhibit outstanding specific detectivity (D *) of 1.28 x 1012 Jones without external bias and broadband CPL detection (g Iph: similar to 0.17 at 260 nm and similar to 0.13 at 780 nm), while PbS QD-devices extend CPL detection across 250-1700 nm (UV-Vis-NIR-SWIR) with superior performance (D *: 1.45 x 1012 Jones). The chiral-transport-driven strategy offers fundamental insights into CPL photodetection and establishes a scalable and optically passive platform for broadband polarization-resolved optoelectronics. 2026-02-28T15:00:00Z