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Park JS, Lee JJ, Choi YJ, Moon TW, Kim S, Cho S, Kang H, Kim DH, Park J, Choi SW. Physical Unclonable Functions Employing Circularly Polarized Light Emission from Nematic Liquid Crystal Ordering Directed by Helical Nanofilaments. ACS APPLIED MATERIALS & INTERFACES 2024; 16:7875-7882. [PMID: 38266383 DOI: 10.1021/acsami.3c17682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2024]
Abstract
This study proposes the use of physical unclonable functions employing circularly polarized light emission (CPLE) from nematic liquid crystal (NLC) ordering directed by helical nanofilaments in a mixed system composed of a calamitic NLC mixture and a bent-core molecule. To achieve this, an intrinsically nonemissive NLC is blended with a high concentration of a luminescent rod-like dye, which is miscible up to 10 wt % in the calamitic NLC without a significant decrease in the degree of alignment. The luminescence dissymmetry factor of CPLEs in the mixed system strongly depends on the degree of alignment of the dye-doped NLCs. Furthermore, the mixed system prepared in this study exhibits two randomly generated chiral domains with CPLEs of opposite signs. These chiral domains are characterized not only by their CPLE performances but also by their ability to generate random patterns up to several millimeters, making them promising candidates for high-performance secure authentication applications.
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Affiliation(s)
- Jun-Sung Park
- Department of Advanced Materials Engineering for Information & Electronics, Kyung Hee University, Gyeonggi-do 17104, Republic of Korea
- Integrated Education Institute for Frontier Science & Technology (BK21 Four), Kyung Hee University, Gyeonggi-do 17104, Republic of Korea
| | - Jae-Jin Lee
- Department of Advanced Materials Engineering for Information & Electronics, Kyung Hee University, Gyeonggi-do 17104, Republic of Korea
- Integrated Education Institute for Frontier Science & Technology (BK21 Four), Kyung Hee University, Gyeonggi-do 17104, Republic of Korea
| | - Yong-Jun Choi
- Department of Advanced Materials Engineering for Information & Electronics, Kyung Hee University, Gyeonggi-do 17104, Republic of Korea
- Integrated Education Institute for Frontier Science & Technology (BK21 Four), Kyung Hee University, Gyeonggi-do 17104, Republic of Korea
| | - Tae-Woong Moon
- Department of Advanced Materials Engineering for Information & Electronics, Kyung Hee University, Gyeonggi-do 17104, Republic of Korea
- Integrated Education Institute for Frontier Science & Technology (BK21 Four), Kyung Hee University, Gyeonggi-do 17104, Republic of Korea
| | - Seunghyun Kim
- Integrated Engineering, Department of Chemical Engineering, Kyung Hee University, Gyeonggi 17104, Republic of Korea
| | - Seungwoo Cho
- Department of e-Business, Ajou University, Gyeonggi 17104, Republic of Korea
| | - Haeun Kang
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Dong Ha Kim
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Republic of Korea
- Basic Sciences Research Institute (Priority Research Institute), Ewha Womans University, Seoul 03760, Republic of Korea
| | - Jongwook Park
- Integrated Engineering, Department of Chemical Engineering, Kyung Hee University, Gyeonggi 17104, Republic of Korea
| | - Suk-Won Choi
- Department of Advanced Materials Engineering for Information & Electronics, Kyung Hee University, Gyeonggi-do 17104, Republic of Korea
- Integrated Education Institute for Frontier Science & Technology (BK21 Four), Kyung Hee University, Gyeonggi-do 17104, Republic of Korea
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Lee JJ, Choi SW. Effect of Nematogen Doping in Bent-Core Molecular Systems with a Helical Nanofilament and Dark Conglomerate. MATERIALS (BASEL, SWITZERLAND) 2023; 16:548. [PMID: 36676284 PMCID: PMC9861025 DOI: 10.3390/ma16020548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 12/31/2022] [Accepted: 01/04/2023] [Indexed: 06/17/2023]
Abstract
Two types of binary mixtures were prepared. One consisted of a calamitic nematogen and bent-core molecule with a helical nanofilament, whereas the other contained a calamitic nematogen and bent-core molecule with a dark conglomerate. The chiroptical features of these two mixtures were investigated using polarized optical microscopy and circular dichroism. In addition, X-ray diffraction analysis was performed on the two binary mixtures. The chiroptical features of the two mixtures were remarkably different. One mixture showed enhanced chiroptical features, whereas the other did not show chiroptical features. This method may help in distinguishing between helical nanofilaments and dark conglomerates which originate from bent-core molecular systems.
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Kim JY, Lee JJ, Park JS, Choi YJ, Choi SW. Control of the Induced Handedness of Helical Nanofilaments Employing Cholesteric Liquid Crystal Fields. Molecules 2021; 26:molecules26196055. [PMID: 34641599 PMCID: PMC8512387 DOI: 10.3390/molecules26196055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Revised: 10/04/2021] [Accepted: 10/05/2021] [Indexed: 11/16/2022] Open
Abstract
In this paper, a simple and powerful method to control the induced handedness of helical nanofilaments (HNFs) is presented. The nanofilaments are formed by achiral bent-core liquid crystal molecules employing a cholesteric liquid crystal field obtained by doping a rod-like nematogen with a chiral dopant. Homochiral helical nanofilaments are formed in the nanophase-separated helical nanofilament/cholesteric phase from a mixture with a cholesteric phase. This cholesteric phase forms at a temperature higher than the temperature at which the helical nanofilament in a bent-core molecule appears. Under such conditions, the cholesteric liquid crystal field acts as a driving force in the nucleation of HNFs, realizing a perfectly homochiral domain consisting of identical helical nanofilament handedness.
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