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33 results on '"Oh, Chang‐Mok"'

3. 4‐Phenylthiosemicarbazide Molecular Additive Engineering for Wide‐Bandgap Sn Halide Perovskite Solar Cells with a Record Efficiency Over 12.2%

Author

Pandey, Padmini, primary, Cho, SungWon, additional, Bahadur, Jitendra, additional, Yoon, Saemon, additional, Oh, Chang‐Mok, additional, Hwang, In‐Wook, additional, Song, Hochan, additional, Choi, Hyosung, additional, Hayase, Shuzi, additional, Cho, Jung Sang, additional, and Kang, Dong‐Won, additional

Published
2024
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5. Organic Surface Doping for High‐Performance Perovskite Transistors.

Author

Kim, Ju‐Hyeon, Oh, Chang‐Mok, Hwang, In‐Wook, Park, Kiyoung, and Lee, Kwanghee

Subjects
*HYBRID materials, *QUANTUM wells, *CHARGE carriers, *TRANSISTORS, *POLYMERS, *PEROVSKITE, *CARRIER density
Abstract

Quasi‐2D perovskites have attracted significant attention because of their environmental robustness and superior long‐term stability compared with their 3D counterparts. However, they typically consist of a mixture of multiple quantum wells with different optoelectrical properties, which degrades the electronic properties and hinders further electronic applications. Here, to challenge this issue, a surface p‐doping strategy involving the introduction of a thiophene‐containing polymer onto the surface of quasi‐2D tin perovskites is reported. The tin ions in the perovskites effectively interact with the sulfur atoms in the thiophene moieties, thereby generating hole carriers and inducing p‐doping. The resulting doped quasi‐2D perovskites exhibit excellent surface crystallinity, lower trap density, and enhanced charge carrier transport capability along the perovskite semiconductor channels. Consequently, the doped quasi‐2D tin perovskite‐based transistors exhibit a high field‐effect mobility of 53 cm2V−1s−1 (7 cm2V−1s−1 for the control device) and an outstanding on/off ratio (>107), together with superior operational stability. [ABSTRACT FROM AUTHOR]

Published
2024
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7. Effective Small Organic Molecule as a Defect Passivator for Highly Efficient Quasi‐2D Perovskite Light‐Emitting Diodes

Author

Li, Ying, primary, Li, Fuqiang, additional, Yu, Zhongkai, additional, Tamilavan, Vellaiappillai, additional, Oh, Chang‐Mok, additional, Jeong, Woo Hyeon, additional, Shen, Xinyu, additional, Lee, Seongbeom, additional, Du, Xiangrui, additional, Yang, Eunhye, additional, Ahn, Yoomi, additional, Hwang, In‐Wook, additional, Lee, Bo Ram, additional, and Park, Sung Heum, additional

Published
2024
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10. Bifunctional Urea–Polyethyleneimine‐Mediated Surface Engineering in SnO2 Electron‐Transport Layer for Efficient and Stable Organic Solar Cells.

Author

Kim, Dowon, Lee, Sanseong, Oh, Chang‐mok, Hwang, In‐Wook, Yoon, Changjae, Kim, Heejoo, Byeon, Jinhwan, Lee, Kwanghee, and Hong, Sukwon

Subjects
POLYETHYLENEIMINE, SOLAR cells, FRONTIER orbitals, STANNIC oxide, TIN oxides, PHOTOVOLTAIC power systems
Abstract

Because of its high conductivity, wide bandgap, and excellent photostability, tin oxide (SnO2) has long been recognized as an electron‐transport layer (ETL) in organic solar cells (OSCs). However, the energy‐level mismatch between the work function (WF) of SnO2 and the lowest unoccupied molecular orbital level of Y‐series nonfullerene acceptors (NFAs), along with the abundance of surface defects on SnO2, have limited its widespread application as ETLs in OSCs. Herein, a novel approach utilizing urea‐functionalized polyethyleneimine (PEI) materials called u‐PEIs for modifying SnO2 is introduced. This modification, which serves dual purposes of WF modulation and surface‐defect passivation, can mitigate the energy barriers of SnO2/Y‐series NFA and increase the conductivity of the SnO2 film. PM6:Y6‐based OSCs with u‐PEI‐modified SnO2 (SnO2:u‐PEI) ETLs exhibit a remarkable efficiency of 16%, which significantly exceeds that (13.5%) achieved with bare SnO2‐based OSCs, along with outstanding photo‐ and thermal stability. This study confirms the efficacy of urea‐functionalized PEI for efficient and stable OCSs, paving the way for SnO2 applications. [ABSTRACT FROM AUTHOR]

Published
2024
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14. Efficient and Stable Quasi‐2D Ruddlesden–Popper Perovskite Solar Cells by Tailoring Crystal Orientation and Passivating Surface Defects (Adv. Mater. 31/2023)

Author

Kim, Ju‐Hyeon, primary, Oh, Chang‐Mok, additional, Hwang, In‐Wook, additional, Kim, Jehan, additional, Lee, Changhoon, additional, Kwon, Sooncheol, additional, Ki, Taeyoon, additional, Lee, Sanseong, additional, Kang, Hongkyu, additional, Kim, Heejoo, additional, and Lee, Kwanghee, additional

Published
2023
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15. Efficient and Stable Perovskite Solar Cells with a High Open‐Circuit Voltage Over 1.2 V Achieved by a Dual‐Side Passivation Layer

Author

Kim, Ju‐Hyeon, primary, Kim, Yong Ryun, additional, Kim, Juae, additional, Oh, Chang‐Mok, additional, Hwang, In‐Wook, additional, Kim, Jehan, additional, Zeiske, Stefan, additional, Ki, Taeyoon, additional, Kwon, Sooncheol, additional, Kim, Heejoo, additional, Armin, Ardalan, additional, Suh, Hongsuk, additional, and Lee, Kwanghee, additional

Published
2023
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19. Improved Device Performance and Stability in Organic Solar Cells by Morphology Control via Size‐Controlled Chevron‐Shaped Blades.

Author

Song, Geon Chang, Han, Nara, Kaang, Byung Kwon, Lee, Minwoo, Moon, Yina, Yang, Dongseong, Beak, Jeongwoo, Oh, Chang-Mok, Hwang, In-Wook, and Kim, Dong-Yu

Subjects
SOLAR cells, CELL morphology, RENEWABLE energy sources, PHOTOVOLTAIC power systems, SOLAR cell efficiency, STRAY currents, SHORT circuits
Abstract

Organic solar cells (OSCs) have been studied widely as renewable energy resources for a few decades owing to their technological advantages, including low cost, light weight, flexibility, and the potential of large area printing. To upgrade the active layers of OSCs into an optimized form, a simple and straightforward strategy is demonstrated by introducing two types of size‐controlled chevron (V)‐shaped blades to delicately control PM6:Y6‐based bulk heterojunction (BHJ) films under ambient conditions. A power conversion efficiency of 15.97% is achieved from the blade‐coating methods using a small‐sized V‐shaped blade (V1), compared with 14.31% using a conventional flat blade (F). Using blade coating based on V1 improves the phase separation and molecular crystallinity in the active layer, which lead to decreased trap‐assisted recombination and leakage current, finally increasing the short circuit current and fill factor. In addition, following these morphological changes in the optimal BHJ structure, the devices printed with V1 exhibit higher stability in the long‐term shelf‐life test (320 h storage in ambient conditions). Notably, strategy is a facile layer fabrication method that adopts V‐shaped blades to achieve high device performance and stability for the practical use of large‐area OSCs. [ABSTRACT FROM AUTHOR]

Published
2023
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20. P‐Type Doping of PM6:Y6‐Based Photoactive Layer with Formic Acid.

Author

Han, Nara, Lee, Minwoo, Moon, Yina, Yang, Dongseong, Beak, Jeongwoo, Oh, Chang-Mok, Hwang, In-Wook, and Kim, Dong-Yu

Abstract

The introduction of molecular doping process is necessary to enhance the optic and electronic properties of organic semiconductors for facilitating charge transport. In particular, since the doping process has a positive influence on the charge transfer interaction between host semiconductor and dopant, improved mobility has been efficiently achieved. Despite its advantages, doping technologies in organic solar cells (OSCs) are emphasized to the development of n‐type dopants used for balancing the electron and hole. In addition, since the bulk‐heterojunction microstructure in OSCs has randomly blended phases of the donor and acceptor, it is important to optimize charge extraction without loss by controlling the morphology. Herein, OSCs by p‐type doping with formic acid (FA) into a photoactive layer is reported. The champion device yields a significantly improved power conversion efficiency from 14.3% to 15.3% with a high fill factor of 71.7%. It is found that the p‐doped photoactive layer exhibits enhanced conductivity, improved carrier mobilities, suppressed charge recombination, and lowered leakage current. The FA simultaneously acts as a film morphology controller of the photoactive layer with enhanced phase separation to transport the charge efficiently. Thus, the doping process with FA can maintain the device performance in stability tests (95.6% remaining). [ABSTRACT FROM AUTHOR]

Published
2023
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21. Conjugated Polymer Nanoparticles: Photothermal and Photodynamic Capabilities According to Molecular Ordering in Their Assembly Structures

Author

Pham, Thi-Thuy Duong, primary, Jung, Seung-Jin, additional, Oh, Chang-Mok, additional, Yang, Jin-Kyoung, additional, Lee, Dabin, additional, Kidanemariam, Alemayehu, additional, Muhammad, Arbanah, additional, Kim, Sehoon, additional, Shin, Tae Joo, additional, Park, JaeHong, additional, Hwang, In-Wook, additional, and Park, Juhyun, additional

Published
2022
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22. Elucidating the Chain-Extension Effect on the Exciton-Dissociation Mechanism through an Intra- or Interchain Polaron-Pair State in Push–Pull Conjugated Polymers

Author

Lee, Dongki, primary, Han, Se Gyo, additional, Kim, Hyojung, additional, Hwang, Hyeongjin, additional, Park, Chaneui, additional, Noh, Jaebum, additional, Mun, Jungho, additional, Nho, Hak-Won, additional, Cho, Jeong Bin, additional, Kim, Dong Hyeon, additional, Jeong, Byeong Geun, additional, Oh, Chang-Mok, additional, Yoon, Taewoong, additional, Sung, Woong, additional, Lee, Hansol, additional, Nah, Sanghee, additional, Kang, Boseok, additional, Hwang, In-Wook, additional, Jang, Joon I., additional, Kwon, Oh-Hoon, additional, Rho, Junsuk, additional, Jeong, Mun Seok, additional, and Cho, Kilwon, additional

Published
2022
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23. Efficient and Stable Perovskite Solar Cells with a High Open‐Circuit Voltage Over 1.2 V Achieved by a Dual‐Side Passivation Layer

Author

Kim, Ju‐Hyeon, primary, Kim, Yong Ryun, additional, Kim, Juae, additional, Oh, Chang‐Mok, additional, Hwang, In‐Wook, additional, Kim, Jehan, additional, Zeiske, Stefan, additional, Ki, Taeyoon, additional, Kwon, Sooncheol, additional, Kim, Heejoo, additional, Armin, Ardalan, additional, Suh, Hongsuk, additional, and Lee, Kwanghee, additional

Published
2022
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24. Pyrrolopyrrole-1,3-dione-Based Wide Band-Gap Polymeric Donors Exemplify High Voltage and Diminutive Energy Loss for Efficient Binary and Tandem Nonfullerene Organic Solar Cells with Efficiency Exceeding 15.7%

Author

Tamilavan, Vellaiappillai, primary, Lee, Jihoon, additional, Jang, Soyeong, additional, Shin, Insoo, additional, Oh, Chang-Mok, additional, Hwang, In-Wook, additional, Yang, Hyun-seock, additional, Kim, Danbi, additional, Yang, Eunhye, additional, Lee, Seongbeom, additional, Kim, Junghwan, additional, Lee, Bo Ram, additional, and Park, Sung Heum, additional

Published
2022
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25. Anion‐Induced Catalytic Reaction in a Solution‐Processed Molybdenum Oxide for Efficient Inverted Ternary Organic Photovoltaics

Author

Ki, Taeyoon, primary, Lee, Changhoon, additional, Kim, Jehan, additional, Hwang, In‐Wook, additional, Oh, Chang‐Mok, additional, Park, Kiyoung, additional, Lee, Sanseong, additional, Kim, Ju‐Hyeon, additional, Balamurugan, Chandran, additional, Kong, Jaemin, additional, Jeong, Hyeon‐Seok, additional, Kwon, Sooncheol, additional, and Lee, Kwanghee, additional

Published
2022
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33. Versatile control of concentration gradients in non-fullerene acceptor-based bulk heterojunction films using solvent rinse treatments

Author

Oh, Chang-Mok, Jang, Soyeong, Lee, Jihoon, Park, Sung Heum, and Hwang, In-Wook

Abstract

Solvent rinse treatments using polar methanol (MeOH) and nonpolar n-hexane have been developed for controlling material concentration gradients along the longitudinal direction of non-fullerene acceptor-based bulk heterojunction (BHJ) films comprised of electron donor polymer, PBDB-T and acceptor, ITIC-m. Before the used solvents (chlorobenzene with 1 vol.% DIO) were completely evaporated, ITIC-m rich domains were formed at the top surface of the BHJ films after they were rinsed with MeOH, as evidenced by water contact angle, atomic force microscopy, time-of-flight secondary ion mass spectroscopy, which led to enhanced electron transport in the conventional structure of organic solar cells (OSCs). In contrast, after rinsing with n-hexane, ITIC-m rich domains were formed at the bottom surface of the films, which improved electron transport in the inverted structure OSCs. The enhanced carrier transports increased the PCEs (11.80% and 11.15%) in both conventional and inverted OSCs by 10.29% and 10.35% compared with control devices. The versatile control of material concentration gradients is determined to be feasible owing to the chemical interaction of the used substrates (glass, PEDOT:PSS, and ZnO) and rinsing solvents.

Published
2021
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