https://scholar.dgist.ac.kr/handle/20.500.11750/16374 2026-04-04T13:36:39Z 2026-04-04T13:36:39Z Cho, Sam Yeon Yeo, Kangmo Kim, Jin Woo Kwak, Jin Ho Cho, Deok-Yong Jang, Jae Hyuck Jeong, Sukmin Choi, Yong Chan Bu, Sang Don https://scholar.dgist.ac.kr/handle/20.500.11750/57917 2025-07-25T02:43:05Z 2024-12-31T15:00:00Z

Title: Blue photoluminescence from active carboxyl adatoms on nanoporous anodic alumina films Author(s): Cho, Sam Yeon; Yeo, Kangmo; Kim, Jin Woo; Kwak, Jin Ho; Cho, Deok-Yong; Jang, Jae Hyuck; Jeong, Sukmin; Choi, Yong Chan; Bu, Sang Don Abstract: Nanoporous anodic alumina (nPAA) films formed on aluminum in lower aliphatic carboxylic acids exhibit blue self-coloring and characteristic properties such as photoluminescence (PL), electroluminescence, and electron spin resonance. The blue colors are seemingly originated from the adsorbed radicals incorporating into the oxide during the aluminum anodization. However, there is lack of reports revealing the detailed activation mechanism of the adatoms in the complexes. This study investigates the blue PL and its correlation with the atomic and electronic structures of the active aluminum surface using multiple theoretical and experimental methods. The results show that the concentration of carboxylates at the nPAA surface is highly correlated with the blue colorization and manifest that unpaired electrons in carbon (derived from the carboxylates) bridging two aluminum atoms at surface can play as an active source of the blue colorization. Therefore, it is suggested that controlling the adsorption of the carboxylate on the alumina membrane having large surface-to-volume ratio can be an efficient way to generate the blue light for the optoelectronic applications. © 2025. The Author(s).

2024-12-31T15:00:00Z Choi, Yong Chan Chung, Yeonseo Han, Ji Yoon Hyung, Ji Eun Kim, Hae-Soo https://scholar.dgist.ac.kr/handle/20.500.11750/47498 2025-07-25T02:40:27Z 2024-01-31T15:00:00Z

Title: Influence of atmospheric conditions on the formation and structural properties of two-dimensional SbSI films Author(s): Choi, Yong Chan; Chung, Yeonseo; Han, Ji Yoon; Hyung, Ji Eun; Kim, Hae-Soo Abstract: Two-dimensional heavy pnictogen chalcohalides, such as SbSI, SbSeI, and BiSI, are promising materials for solar energy harvesting (SEH) devices. In this paper, we report the influence of atmospheric conditions on the formation and structural properties of SbSI films fabricated under N2 and air atmospheres using a modified two-step method. Under N2 atmosphere, a preferentially (1 2 1)-oriented SbSI film without impurities formed. In contrast, under air atmosphere, a film with mixed crystalline phases of SbSI and secondary Sb2O3 formed. The Sb2O3 phase could be reduced by applying excess sulfur. These results provide a fundamental step toward optimizing the properties of chalcohalides for SEH device applications. © 2023 Elsevier B.V.

2024-01-31T15:00:00Z Ko, Seonkyung Yong, Taeyeong Kim, Soo-Kwan Park, Jin Young Lee, Gyudong You, Hyung Ryul Han, Sanghun Lee, Duck Hoon Choi, Seongmin Choi, Yong Chan Kim, Younghoon Lee, Nam-Suk Song, Seulki Choi, Jongmin https://scholar.dgist.ac.kr/handle/20.500.11750/45824 2025-07-24T07:23:48Z 2023-05-31T15:00:00Z

Title: A Top-Down Strategy for Reforming the Characteristics of NiO Hole Transport Layer in Inverted Perovskite Solar Cells Author(s): Ko, Seonkyung; Yong, Taeyeong; Kim, Soo-Kwan; Park, Jin Young; Lee, Gyudong; You, Hyung Ryul; Han, Sanghun; Lee, Duck Hoon; Choi, Seongmin; Choi, Yong Chan; Kim, Younghoon; Lee, Nam-Suk; Song, Seulki; Choi, Jongmin Abstract: The hole transport layer (HTL) plays a key role in inverted perovskite solar cells (PSCs), and nickel oxide has been widely adopted for HTL. However, a conventional solution-processed bottom-up approach for NiOx (S-NiO) HTL fabrication shows several drawbacks, such as poor coverage, irregular film thickness, numerous defect sites, and inefficient hole extraction from the perovskite layer. To address these issues, herein, a novel NiOx HTL top-down synthesis route via electrochemical anodization is developed. The basicity of the electrolyte used in anodization considerably influences electrochemical reactions and results in the structure of the anodized NiOx (A-NiO). The optimized A-NiO provides outstanding optoelectrical properties, including uniform film thickness, enhanced transmittance, deep-lying valance band, low trap density, and better hole extraction ability from the perovskite. Owing to these advantages, the A-NiO-based inverted PSC exhibits an improved power conversion efficiency of 21.9% compared with 19.1% for the S-NiO-based device. In addition, the A-NiO device shows a higher inlet and long-term ambient stability than the S-NiO device due to the superior hole transfer ability of A-NiO, which suppresses charge accumulation between NiOx and the perovskite interface. © 2023 Wiley-VCH GmbH.

2023-05-31T15:00:00Z Choi, Yong Chan Nie, Riming https://scholar.dgist.ac.kr/handle/20.500.11750/17506 2025-07-25T04:08:27Z 2023-03-31T15:00:00Z

Title: Heavy pnictogen chalcohalides for efficient, stable, and environmentally friendly solar cell applications Author(s): Choi, Yong Chan; Nie, Riming Abstract: Solar cell technology is an effective solution for addressing climate change and the energy crisis. Therefore, many researchers have investigated various solar cell absorbers that convert Sunlight into electric energy. Among the different materials researched, heavy pnictogen chalcohalides comprising heavy pnictogen cations, such as Bi3+ and Sb3+, and chalcogen-halogen anions have recently been revisited as emerging solar absorbers because of their potential for efficient, stable, and low-toxicity solar cell applications. This review explores the recent progress in the applications of heavy pnictogen chalcohalides, including oxyhalides and mixed chalcohalides, in solar cells. We categorize them into material types based on their common structural characteristics and describe their up-to-date developments in solar cell applications. Finally, we discuss their material imitations, challenges for further development, and possible strategies for overcoming them. © 2023 IOP Publishing Ltd

2023-03-31T15:00:00Z