https://scholar.dgist.ac.kr/handle/20.500.11750/16008 Sat, 04 Apr 2026 13:56:39 GMT 2026-04-04T13:56:39Z https://scholar.dgist.ac.kr/handle/20.500.11750/60045 Title: Impact of trivalent Sb3+-ion doping on charge carrier recombination dynamics of cesium lead bromide perovskite quantum dots Author(s): Jo, Jinwoong; Yu, Jaesang; Kim, Chanwoo; Cho, Inyoung; Lim, Kyeong Mo; Sung, Jooyoung; Oh, Juwon; Yang, Jaesung Abstract: Metal-ion doping of perovskites has proven to enhance their photoluminescence (PL) properties and stability; however, the underlying charge carrier dynamics remain unclear. We synthesized a cesium lead bromide (CsPbBr3) perovskite quantum dot (PQD) incorporating a heterovalent Sb3+ ion dopant and its pristine counterpart and performed time-resolved single-particle PL spectroscopy. The PL intensity and lifetime of the Sb-CsPbBr3 PQD were remarkably enhanced compared to those of the pristine-CsPbBr3 PQD because of diminished nonradiative charge carrier recombination dynamics. The charge carrier trapping (detrapping) rate was lower (higher) for the Sb-CsPbBr3 PQD than for the pristine-CsPbBr3 PQD, as the Sb3+ doping contributed to hindering the formation of the structural defects responsible for charge carrier trap states and increasing the exciton binding energy. The replacement of Pb2+ with Sb3+, which has a smaller ionic radius, in the CsPbBr3 structure effectively increased the tolerance factor, enabling the doped PQD to exhibit more stable local structures and, thus, suppressing its decomposition. Tue, 30 Sep 2025 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/60045 2025-09-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/57375 Title: Unveiling the humidity effect and achieving an unprecedented 12% PCE in MAPbBr3 solar cells Author(s): Kim, Mijoung; Kim, Hyojung; Sin, Jaegwan; Kim, Moonhoe; Kim, Gisung; Kim, Jaeho; Kim, Woojong; Kim, Bora; Lee, Kyoungeun; Oh, Hye Min; Sung, Jooyoung; Choi, Han-Kyu; Jeong, Mun Seok; Hong, Jinpyo; Yang, JungYup Abstract: Fabricating high-efficiency MAPbBr3 solar cells is challenging due to substantial recombination losses within the perovskite layer and at interfaces with charge transport layers. Here, we investigate the critical role of ambient humidity in improving device performance and stability. We varied humidity levels from dry N2 to 80 % relative humidity (RH) and identified that maintaining the environment at 25 % ± 0.82 % RH optimally enhances the morphological, structural, optical properties of MAPbBr3 films. Our novel analyses demonstrate that this specific humidity level significantly reduces bulk defect densities and interface recombination sites without any additive, leads to the formation of larger crystal grains, and improves optical qualities as well. Consequently, devices fabricated under these conditions achieved the highest device efficiency of 12.14 % for the MAPbBr3 solar cells. Additionally, they exhibited remarkable long-term stability, retaining nearly 90 % of the initial efficiency after 1000 h damp-heat and 100 cycles of thermo-cycling tests with encapsulated devices. © 2024 Elsevier B.V. Mon, 30 Sep 2024 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/57375 2024-09-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/48149 Title: Solvent-induced structural transformation in a one-dimensional coordination polymer Author(s): Jin, Kangwoo; Park, Nohyoon; Ahn, Yongdeok; Seo, Daeha; Moon, Dohyun; Sung, Jooyoung; Park, Jinhee Abstract: We have rationally designed a one-dimensional coordination polymer (1D CP), termed 1D-DGIST-18, that exhibits intrinsic structural flexibility. This 1D CP enables its expansion into a three-dimensional network through supramolecular interactions involving coordinated solvents and/or ligands. The strategic selection of solvents for solvent exchange, prior to drying, significantly influences the structures of 1D-DGIST-18 by removing certain coordinating solvents and modulating π-π stacking. Consequently, a hierarchical porosity emerges, ranging from micro- to meso- to macroporous structures, which is attributed to its inherent structural dynamics. Additionally, the formation of excimers endows 1D-DGIST-18, when immersed in acetone, with ‘turn-on’ fluorescence, as evidenced by fluorescence decay profiles. These structural transitions within 1D-DGIST-18 are further elucidated using single-crystal X-ray diffractometry. The insights from this study provide a foundation for the design of materials with structural dynamics and tunable properties. © 2024 The Royal Society of Chemistry. Wed, 31 Jan 2024 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/48149 2024-01-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/47584 Title: Direct Imaging of Carrier Funneling in a Dielectric Engineered 2D Semiconductor Author(s): Gauriot, Nicolas; Ashoka, Arjun; Lim, Juhwan; See, Soo Teck; Sung, Jooyoung; Rao, Akshay Abstract: In atomically thin transition-metal dichalcogenides (TMDCs), the environmental sensitivity of the strong Coulomb interaction offers promising approaches to create spatially varying potential landscapes in the same continuous material by tuning its dielectric environment. Thus, allowing for control of transport. However, a scalable and CMOS-compatible method for achieving this is required to harness these effects in practical applications. In addition, because of their ultrashort lifetime, observing the spatiotemporal dynamics of carriers in monolayer TMDCs, on the relevant time scale, is challenging. Here, we pattern and deposit a thin film of hafnium oxide (HfO2) via atomic layer deposition (ALD) on top of a monolayer of WSe2. This allows for the engineering of the dielectric environment of the monolayer and design of heterostructures with nanoscale spatial resolution via a highly scalable postsynthesis methodology. We then directly image the transport of photoexcitations in the monolayer with 50 fs time resolution and few-nanometer spatial precision, using a pump probe microscopy technique. We observe the unidirectional funneling of charge carriers, from the unpatterned to the patterned areas, over more than 50 nm in the first 20 ps with velocities of over 2 × 103 m/s at room temperature. These results demonstrate the possibilities offered by dielectric engineering via ALD patterning, allowing for arbitrary spatial patterns that define the potential landscape and allow for control of the transport of excitations in atomically thin materials. This work also shows the power of the transient absorption methodology to image the motion of photoexcited states in complex potential landscapes on ultrafast time scales. © 2023 The Authors. Published by American Chemical Society Sun, 31 Dec 2023 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/47584 2023-12-31T15:00:00Z