공업화학 (Applied Chemistry for Engineering)

  • 제31권3호
  • /
  • Pages.291-298
  • /
  • 2020
  • /
  • 1225-0112(pISSN)
  • /
  • 2288-4505(eISSN)
한국공업화학회 (The Korean Society of Industrial and Engineering Chemistry)
권호 표지
DOI QR코드

DOI QR Code

투명 전도성 ZITO/Ag/ZITO 다층막 필름 적용을 위한 아크릴레이트 기반 고분자분산액정의 전기광학적 특성 최적화

Optimization of Electro-Optical Properties of Acrylate-based Polymer-Dispersed Liquid Crystals for use in Transparent Conductive ZITO/Ag/ZITO Multilayer Films

  • Cho, Jung-Dae (Institute of Photonics & Surface Treatment, Q-Sys Co. Ltd.) ;
  • Kim, Yang-Bae (Institute of Photonics & Surface Treatment, Q-Sys Co. Ltd.) ;
  • Heo, Gi-Seok (National Center for Nanoprocesses and Equipment, Korea Institute of Industrial Technology) ;
  • Kim, Eun-Mi (National Center for Nanoprocesses and Equipment, Korea Institute of Industrial Technology) ;
  • Hong, Jin-Who (Department of Biochemical & Polymer Engineering, Chosun University)
  • 투고 : 2020.04.09
  • 심사 : 2020.04.23
  • 발행 : 2020.06.10
PDF 다운로드
⟨ 이전 논문 다음 논문 ⟩

초록

본 연구에서는 RF/DC 마그네트론 증착법을 이용하여 실온에서 유리 기판 상에 ZITO/Ag/ZITO 다층막 투명전극을 제조하였다. ZITO/Ag/ZITO (100/8/42 nm)로 이루어진 다층막 구조에 대해, 면저항이 9.4 Ω/㎡이고 550 nm에서 투과도가 83.2%인 투명 전도성 필름이 얻어졌다. ZITO/Ag/ZITO 다층막 필름의 면저항 및 투과도 특성은 적외선(열선)을 효과적으로 차단할 수 있기 때문에 고분자분산액정(polymer-dispersed liquid crystal, PDLC) 기반 스마트 윈도우 적용에 매우 유용함을 알 수 있었으며 이로 인해 에너지 절약형 스마트 유리로서의 응용도 가능할 것으로 판단된다. 제조된 ZITO/Ag/ZITO 다층막 투명전극을 적용한 2관능성 우레탄 아크릴레이트 기반 PDLC 시스템에 있어서 PDLC 층 두께 및 자외선(ultraviolet, UV) 세기 변화가 전기광학적 특성, 광중합 동력학 및 표면 형태학에 미치는 영향을 조사하였다. 15 ㎛의 PDLC 층 두께를 가지며 2.0 mW/c㎡의 UV 세기로 광경화된 PDLC 셀이 우수한 off-state 불투명도, 높은 on-state 투과도 및 양호한 구동 전압을 나타냈다. 또한, 본 연구에서 제조된 최적 조건의 PDLC 기반 스마트 윈도우는 광을 효율적으로 산란시킬 수 있는 2~5 ㎛ 크기의 양호한 마이크로 구조를 갖는 액정 droplet들이 형성되었으며, 이로 인해 우수한 최종 물성을 갖는 PDLC 셀이 제조되었다.

ZITO/Ag/ZITO multilayer transparent electrodes at room temperature on glass substrates were prepared using RF/DC magnetron sputtering. Transparent conductive films with a sheet resistance of 9.4 Ω/㎡ and a transmittance of 83.2% at 550 nm were obtained for the multilayer structure comprising ZITO/Ag/ZITO (100/8/42 nm). The sheet resistance and transmittance of ZITO/Ag/ZITO multilayer films meant that they would be highly applicable for use in polymer-dispersed liquid crystal (PDLC)-based smart windows due to the ability to effectively block infrared rays (heat rays) and thereby act as an energy-saving smart glass. Effects of the thickness of the PDLC layer and the intensity of ultraviolet light (UV) on electro-optical properties, photopolymerization kinetics, and morphologies of difunctional urethane acrylate-based PDLC systems were investigated using new transparent conducting electrodes. A PDLC cell photo-cured using UV at an intensity of 2.0 mW/c㎡ with a 15 ㎛-thick PDLC layer showed outstanding off-state opacity, good on-state transmittance, and favorable driving voltage. Also, the PDLC-based smart window optimized in this study formed liquid crystal droplets with a favorable microstructure, having an average size range of 2~5 ㎛ for scattering light efficiently, which could contribute to its superior final performance.

키워드

참고문헌

  1. J. W. Doane, Polymer Dispersed Liquid Crystal Display, in: B. Bahadur (Ed.), Liquid Crystals: Applications and Uses, 361, World Scientific, Singapore (1990).
  2. P. S. Drzaic, Liquid Crystal Dispersions, World Scientific, Singapore (1995).
  3. J. B. Whitehead Jr., S. Zumer, and J. W. Doane, Light scattering from a dispersion of aligned nematic droplets, J. Appl. Phys., 73, 1057-1065 (1993). https://doi.org/10.1063/1.353292
  4. D. Kim, Study of electrochemical and electrochromic properties of 9-methy1-2,3,6,7-tetramethoxyfluorene in dichloromethane-TFATFAn( I), J. Ind. Eng. Chem., 2, 73-78 (1997).
  5. M. Moller, S. Asaftei, D. Corr, M. Ryan, and L. Walder, Switchable electrochromic images based on a combined top-down bottom-up approach, Adv. Mater., 16, 1558-1562 (2004). https://doi.org/10.1002/adma.200400198
  6. D. Barrios, R. Vergaz, J. M. Sanchez-Pena, B. Garcia-Camara, C. G. Granqvist, and G. A. Niklasson, Simulation of the thickness dependence of the optical properties of suspended particle devices, Sol. Energy Mater. Sol. Cells, 143, 613-622 (2015). https://doi.org/10.1016/j.solmat.2015.05.044
  7. T. Fujisawa, M. Hayasi, H. Nakada, S. Matumoto, Y. Tani, M. Yada, and M. Aizawa, A study of reflectivity on the liquid crystal/polymer composite films, Mol. Cryst. Liq. Cryst., 346, 229-238 (2000). https://doi.org/10.1080/10587250008023882
  8. C. E. Hoyle, T. Y. Lee, and T. Roper, Thiol-enes: Chemistry of the past with promise for the future, J. Polym. Sci. Part A: Polym. Chem., 42, 5301-5338 (2004). https://doi.org/10.1002/pola.20366
  9. S. H. Hwang, K. J. Yang, S. H. Woo, B. D. Choi, E. H. Kim, and B. K. Kim, Preparation of newly designed reverse mode polymer dispersed liquid crystals and its electro-optic characteristics, Mol. Cryst. Liq. Cryst., 470, 163-171 (2007). https://doi.org/10.1080/15421400701493653
  10. T. J. White, L. V. Natarajan, T. J. Bunning, and C. A. Guymon, Contribution of monomer functionality and additives to polymerization kinetics and liquid crystal phase separation in acrylate based polymer dispersed liquid crystals (PDLCs), Liq. Cryst., 34, 1377-1385 (2007). https://doi.org/10.1080/02678290701663936
  11. D. Hatice, M. Scott, K. Namil, H. Jun, K. Thein, V. N. Lalgudi, P. T. Vincent, and J. B. Timothy, Kinetics of photopolymerization-induced phase separation and morphology development in mixtures of a nematic liquid crystal and multifunctional acrylate, Polymer, 49, 534-545 (2008). https://doi.org/10.1016/j.polymer.2007.11.039
  12. Y. S. No and C. W. Jeon, Effect of alignment layer on electro-optic properties of polymer-dispersed liquid crystal displays, Mol. Cryst. Liq. Cryst., 513, 98-105 (2009). https://doi.org/10.1080/15421400903195759
  13. M. Kashima, H. Cao, Q. Meng, H. Liu, D. Wang, F. Li, and H. Yang, The influence of crosslinking agents on the morphology and electro-optical performances of PDLC films, J. Appl. Polym. Sci., 117, 3434-3440 (2010). https://doi.org/10.1002/app.32101
  14. K. J. Yang and D. Y. Yoon, Electro-optical characteristics of dye-doped polymer dispersed liquid crystals, J. Ind. Eng. Chem., 17, 543-548 (2011). https://doi.org/10.1016/j.jiec.2010.12.018
  15. T. Minami and T. Miyata, Present status and future prospects for development of non- or reduced-indium transparent conducting oxide thin films, Thin Solid Films, 517, 1474-1477 (2008). https://doi.org/10.1016/j.tsf.2008.09.059
  16. D. S. Liu, C. S. Sheu, C. T. Lee, and C. H. Lin, Thermal stability of indium tin oxide thin films co-sputtered with zinc oxide, Thin Solid Films, 516, 3196-3203 (2008). https://doi.org/10.1016/j.tsf.2007.09.009
  17. Y. Park, V. Choong, Y. Gao, B. R. Hsieh, and S. W. Tang, Work function of indium tin oxide transparent conductor measured by photoelectron spectroscopy, Appl. Phys. Lett., 68, 2699-2701 (1996). https://doi.org/10.1063/1.116313
  18. J. Cui, A. Wang, N. L. Edleman, J. Ni, P. Lee, N. R. Armstrong, and T. Marks, Indium tin oxide alternatives-high work function transparent conducting oxides as anodes for organic light-emitting diodes, Adv. Mater., 13, 1476-1480 (2001). https://doi.org/10.1002/1521-4095(200110)13:19<1476::AID-ADMA1476>3.0.CO;2-Y
  19. M. Bender, W. Seelig, C. Daube, H. Frankenberger, B. Ocker, and J. Stollenwerk, Dependence of film composition and thicknesses on optical and electrical properties of ITO-metal-ITO multilayers, Thin Solid Films, 326, 67-71 (1998). https://doi.org/10.1016/S0040-6090(98)00520-3
  20. J. Lewis, S. Grego, B. Chalamala, E. Vick, and D. Temple, Highly flexible transparent electrodes for organic light-emitting diode-based displays, Appl. Phys. Lett., 85, 3450-3452 (2004). https://doi.org/10.1063/1.1806559
  21. S. W. Cho, J. A. Jeong, J. H. Bae, J. M. Moon, K. H. Choi, S. W. Jeong, N. J. Park, J. J. Kim, S. H. Lee, J. W. Kang, M. S. Yi, and H. K. Kim, Highly flexible, transparent, and low resistance indium zinc oxide-Ag-indium zinc oxide multilayer anode on polyethylene terephthalate substrate for flexible organic light light-emitting diodes, Thin Solid Films, 516, 7881-7885 (2008). https://doi.org/10.1016/j.tsf.2008.06.025
  22. K. H. Choi, H. J. Nam, J. A. Jeong, S. W. Cho, H. K. Kim, J. W. Kang, D. G. Kim, and W. J. Cho, Highly flexible and transparent InZnSnOx/Ag/InZnSnOx multilayer electrode for flexible organic light emitting diodes, Appl. Phys. Lett., 92, 223302 (2008). https://doi.org/10.1063/1.2937845
  23. E. M. Kim, I. S. Choi, J. P. Oh, Y. B. Kim, J. H. Lee, Y. S. Choi, J. D. Cho, Y. B. Kim, and G. S. Heo, Transparent conductive ZnInSnO-Ag-ZnInSnO multilayer films for polymer dispersed liquid-crystal based smart windows, Jpn. J. Appl. Phys., 53, 095505 (2014). https://doi.org/10.7567/JJAP.53.095505
  24. J. D. Cho, S. S. Lee, S. C. Park, Y. B. Kim, and J. W. Hong, Optimization of LC droplet size and electro-optical properties of acrylate-based polymer-dispersed liquid crystal by controlling photocure rate, J. Appl. Polym. Sci., 130, 3098-3104 (2013). https://doi.org/10.1002/app.39558
  25. G. S. Heo, I. G. Kim, J. W. Park, K. Y. Kim, and T. W. Kim, Effects of substrate temperature on properties of ITO-ZnO composition spread films fabricated by combinatorial RF magnetron sputtering, J. Solid State Chem., 182, 2937-2940 (2009). https://doi.org/10.1016/j.jssc.2009.07.025
  26. X. Liu, X. Cai, J. Qiao, J. Mao, and N. Jiang, The design of ZnS/Ag/ZnS transparent conductive multilayer films, Thin Solid Films, 441, 200-206 (2003). https://doi.org/10.1016/S0040-6090(03)00141-X
  27. S. C. Clark, C. E. Hoyle, S. Jonsson, F. Morel, and C. Decker, Photopolymerization of acrylates using N-aliphaticmaleimides as photoinitiators, Polymer, 40, 5063-5072 (1999). https://doi.org/10.1016/S0032-3861(98)00734-4
  28. J. D. Cho and J. W. Hong, Curing kinetics of UV-initiated cationic photopolymerization of divinyl ether photosensitized by thioxanthone, J. Appl. Polym. Sci., 97, 1345-1351 (2005). https://doi.org/10.1002/app.21838
  29. J. D. Cho, H. T. Ju, and J. W. Hong, Photocuring kinetics of UVinitiated free-radical photopolymerizations with and without silica nanoparticles, J. Polym. Sci. Part A: Polym. Chem., 43, 658-670 (2005). https://doi.org/10.1002/pola.20529
  30. J. D. Nam and J. C. Seferis, Application of the kinetic composite methodology to autocatalytic type thermoset prepreg cures, J. Appl. Polym. Sci., 50, 1555-1564 (1993). https://doi.org/10.1002/app.1993.070500909
  31. F. Y. C. Boey and W. Qiang, Experimental modeling of the cure kinetics of an epoxy-hexaanhydro-4-methylphthalicanhydride (MHHPA) system, Polymer, 41, 2081-2094 (2000). https://doi.org/10.1016/S0032-3861(99)00409-7
  32. N. S. Allen, M. S. Johnson, P. K. T. Oldring, S. Salim, in: P. K. T. Oldring (Ed.), Chemistry & Technology of UV & EB Formulation for Coatings Inks & Paints, Vol. 2, 237, SITA Technology, London (1991).