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631 results on '"Na, Seok-In"'

7. Optical diffraction tomography and image reconstruction to measure host cell alterations caused by divergent Plasmodium species

Author

Ong, Jessica J.Y., Oh, Jeonghun, Yong Ang, Xiang, Naidu, Renugah, Chu, Trang T.T., Hyoung Im, Jae, Manzoor, Umar, Kha Nguyen, Tuyet, Na, Seok-Won, Han, Eun-Taek, Davis, Christeen, Sun Park, Won, Chun, Wanjoo, Jun, Hojong, Jin Lee, Se, Na, Sunghun, Chan, Jerry K.Y., Park, YongKeun, Russell, Bruce, Chandramohanadas, Rajesh, and Han, Jin-Hee

Published
2023
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28. Vacuum‐Assisted Deposition of Highly Hydrophobic Self‐Assembled Monolayer for High‐Efficiency Perovskite Solar Cells.

Author

Lee, Sang‐Heon, Lee, Hyun‐Jung, Kim, Do‐Ha, Noh, Yong‐Jin, Kwon, Sung‐Nam, Kim, Do‐Hyung, and Na, Seok‐In

Subjects
SOLAR cells, MONOMOLECULAR films, PEROVSKITE, CARBAZOLE, OPEN-circuit voltage, PHOSPHONIC acids, METHYL groups
Abstract

Recently, various carbazole‐based self‐assembled monolayers (SAMs) have been investigated for use in the hole transport layer (HTL) of perovskite solar cells (PSCs). In particular, [4‐(3,6‐dimethyl‐9H‐carbazol‐9‐yl)butyl] phosphonic acid (Me‐4PACz) is attracting attention as an HTL for high‐efficiency PSC due to its potential for high open‐circuit voltage (VOC) and fill factor (FF). However, Me‐4PACz has strong hydrophobicity due to its methyl group (–CH3) and long alkyl chain (C4H8), which makes it difficult to deposit a high‐quality perovskite layer on top of conventionally coated Me‐4PACz. In this study, to overcome these limitations, a new SAM deposition method based on a vacuum‐assisted deposition (VD) process is attempted. As a result, a uniform perovskite layer is deposited on top of Me‐4PACz through a very simple VD process, achieving 20.31% efficiency, which is not only close to the highest efficiency among Me‐4PACz‐based PSCs, but also improved long‐term stability of the device. It is believed that the findings of this study can be a cornerstone for using SAM‐based HTL with high hydrophobicity in the future. [ABSTRACT FROM AUTHOR]

Published
2024
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42. Enhancing the Stability and Efficiency of Inverted Perovskite Solar Cells with a Mixed Ammonium Ligands Passivation Strategy.

Author

Lee, Hyun‐Jung, Kang, Yu‐Jin, Kwon, Sung‐Nam, Kim, Do‐Hyung, and Na, Seok‐In

Abstract

The perovskite solar cell (PSC), which has achieved efficiencies of more than 26%, is expected to be a promising technology that can alternate silicon‐based solar cells. However, the performance of PSCs is still limited due to defects and ion migration that occur at the large number of grain boundaries present in perovskite thin films. In this study, the mixed ammonium ligands passivation strategy (MAPS) is demonstrated, which combines n‐octylammonium iodide (OAI) and 1,3‐diaminopropane (DAP) can effectively suppress the grain boundary defects and ion migration through grain boundaries by the synergistic effect of OAI and DAP, resulting in improved efficiency and stability of PSCs. It has also been revealed that MAPS not only enhances crystallinity and reduces grain boundaries but also improves charge transport while suppressing charge recombination. The MAPS‐based opaque PSC shows the best power conversion efficiency (PCE) of 21.29% with improved open‐circuit voltage (VOC) and fill factor (FF), and retained 84% of its initial PCE after 1900 h at 65 °C in N2 atmosphere. Amazingly, the MAPS‐based semi‐transparent PSC (STP‐PSC) retained 94% of their maximum power (21.00% at around 10% AVT) after 1000 h under 1 sun illumination and MAPS‐based perovskite submodule (PSM) achieved a PCE of 19.59%, which is among the highest values reported recently. [ABSTRACT FROM AUTHOR]

Published
2024
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43. Enhancing Efficiency of Inverted Perovskite Solar Cells by Sputtered Nickel Oxide Hole‐Transport Layers.

Author

Kim, Jae Won, Cho, Eunmi, Lee, Hyun‐Jung, Kwon, Sung‐Nam, Park, Jin‐Seong, Kim, Mac, Kim, Do‐Hyung, Na, Seok‐In, and Lee, Sang‐Jin

Subjects
NICKEL oxide, SOLAR cells, PEROVSKITE, CARRIER density, CONCENTRATION functions, NICKEL oxides
Abstract

Perovskite solar cells (PSCs) are now approaching their theoretical limits and the optimization of the auxiliary layers is crucial for fully exploiting the potential of perovskite materials. In this study, NiOx as a hole‐transport layer (HTL) for inverted p–i–n PSCs is focused on. Sputtered NiOx is an attractive p‐type HTL owing to its facile processing, wide energy bandgap that prevents electron transfer, high transparency, stability, and effective hole extraction. Despite substantial research on sputtered NiOx, the relationship between the carrier concentration and work function is still unclear. In this study, the use of sputtered NiOx as a widely compatible HTL and the effect of its thickness on PSC device performance are investigated. Inverted PSCs with the optimal 10 nm thick NiOx achieve a remarkable power conversion efficiency of 20.54%, which is the highest reported to date for sputtered NiOx‐based PSCs. Furthermore, PSCs with various NiOx thicknesses demonstrate similar performances, demonstrating the excellent versatility of NiOx for use with different perovskite absorbers. The devices exhibit excellent thermal and photostability, retaining 97% of their initial power conversion efficiency at 65 °C and 1 sun illumination for 350 h. Sputtered NiOx HTLs have great potential for use with diverse perovskite compositions and PSC structures. [ABSTRACT FROM AUTHOR]

Published
2024
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