Journal of IKEEE (전기전자학회논문지)

Institute of Korean Electrical and Electronics Engineers (한국전기전자학회)
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Environmental Friendly Out-Coupling Film to Enhance the Efficiency of Organic Light Emitting Diode with UV protection

자외선 차단이 가능한 유기발광다이오드의 효율 향상을 위한 친환경 아웃 커플링 필름

  • Hyunjun Jang (Department of Creative Convergence Engineering, Hanbat National University) ;
  • Baeksang Sung (Department of Creative Convergence Engineering, Hanbat National University) ;
  • Sora Han (Department of Creative Convergence Engineering, Hanbat National University) ;
  • Jooho Lee (Department of Creative Convergence Engineering, Hanbat National University) ;
  • Yong Hyun Kim (Department of Smart Green Technology Engineering, Pukyong National University) ;
  • Jae-Hyun Lee (Department of Creative Convergence Engineering, Hanbat National University) ;
  • Jonghee Lee (Department of Creative Convergence Engineering, Hanbat National University)
  • 장현준 ;
  • 성백상 ;
  • 한소라 ;
  • 이주호 ;
  • 김용현 ;
  • 이재현 ;
  • 이종희
  • Received : 2014.09.02
  • Accepted : 2024.09.14
  • Published : 2024.09.30
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Abstract

Organic light emitting diode(OLED) is distributed in layers with different refractive index, which leads to total internal reflection and low light extraction efficiency. As a result, light extraction technologies have been investigated that include structures such as MLA. However, technologies such as MLA are using petroleum-based polymers, which cause environmental problems during disposal. Therefore, this study investigates the use of eco-friendly polymers hydroxyethyl cellulose(HEC) and tannic acid(TA) to produce external light extraction films. HEC is biodegradable and has high transparency, making it suitable for eco-friend external light extraction films. The TA used as an additive is a polyphenolic molecule, which is expected to form strong hydrogen bonds with HEC. In addition, TA can protect OLED from damage by UV light through its phenolic groups. HECTA MLA films were produced by dissolving HEC and TA in water without using additional solvents and then imprinting them on MLA mould. When the HECTA MLA film was attached to the outside of the OLED and analysed, it showed a high Haze of more than 80%, and the external quantum efficiency and current efficiency of the OLED were improved by 38% and 39%, respectively, compared to the reference.

유기발광다이오드(OLED)는 층간 굴절률 차이로 내부 전반사가 발생하며 낮은 광추출 효율의 원인이 된다. 그 결과, MLA와 같은 구조체를 활용하는 광추출 기술들이 연구되고 있다. 하지만 MLA와 같은 석유계 고분자를 활용한 기술들은 폐기 과정에서 환경 문제를 야기한다. 따라서 본 연구에서는 친환경 고분자 hydroxyethyl cellulose(HEC)와 tannic acid(TA)를 활용하여 외부 광추출 필름을 제작하고자 한다. HEC는 생분해가 가능하며 높은 투명도를 가져 친환경 외부 광추출 필름으로 제작하는데 적합하다. 첨가제로 사용된 TA는 폴리페놀 화합물로 HEC와 견고한 수소결합을 형성할 것으로 예상된다. 또한, TA는 페놀 그룹을 통해 자외선으로부터 OLED가 손상되는 것을 방지할 수 있다. HECTA MLA 필름은 추가적인 용매를 사용하지 않고 물에 HEC와 TA를 용해시킨 후 MLA 몰드에 임프린팅 하여 제작하였다. HECTA MLA 필름을 OLED 외부에 부착하여 분석한 결과, 80% 이상의 높은 흐림도를 보였으며 OLED의 외부 양자 효율과 전류 효율이 기준 대비 각각 38%, 39% 향상되었다.

Keywords

Acknowledgement

This research was conducted with the support of the Korea Institute for Advancement of Technology funded by the government (Ministry of Trade, Industry and Energy) in 2024 (Project No. P0023691, Specialized Workforce Development Program for Space Materials, Parts, and Equipment) and with the support from the Basic Science Research program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2018R1A6A1A03026005).

References

  1. S. Han, B. Sung, H. Jang, J. Lee, S. Woo, D. Kim, J. Kim, H. R. Joe, J. W. Han, Y. H. Kim, J. H. Lee, J. Lee, "Spontaneously formed cellulose-based random micro-textured film for light extraction in organic light-emitting diodes," Journal of Information Display, pp.1-8, 2024. DOI: 10.1080/15980316.2024.2325357
  2. B. Sung, C. W. Joo, J. C. Yang, A. Gasonoo, S. W. Woo, J. H. Lee, S. Park, J. Lee, "Application of optical property-enhancement film to improve efficiency and suppress angle dependence of top-emitting organic light-emitting diodes," Journal of Information Display, vol.24, no.1, pp.71-79, 2023. DOI: 10.1080/15980316.2022.2127950
  3. S. W. Woo, J. Lee, B. Sung, A. Gasonoo, J. Cho, S. Y. Lee, S. J. Lee, Y. S. Lee, S. Y. Baek, J. Kim, Y. H. Kim, J. H. Lee, M. H. Kim, J. Lee, "Improved out-coupling efficiency of organic light-emitting diodes using micro-sized perovskite crystalline template," Organic Electronics, vol.108, 2022. DOI: 10.1016/j.orgel.2022.106580
  4. H. J. Jang, J. Y. Lee, G. W. Baek, J. Kwak, J. H. Park, "Progress in the development of the display performance of AR, VR, QLED and OLED devices in recent years," Journal of Information Display, vol.23, no.1, pp.1-17, 2022. DOI: 10.1080/15980316.2022.2035835
  5. S. J. Zou, Y. Shen, F. M. Xie, J. D. Chen, Y. Q. Li, J. X. Tang, "Recent advances in organic light-emitting diodes: toward smart lighting and displays," Materials Chemistry Frontiers, vol.4, no.3, pp.788-820, 2020. DOI: 10.1039/c9qm00716d
  6. R. Shinar, J. Shinar, "Light extraction from organic light emitting diodes (OLEDs)," Journal of Physics: Photonics, vol.4, no.3, 2022. DOI: 10.1088/2515-7647/ac6ea4
  7. K. Saxena, V. K. Jain, D. S. Mehta, "A review on the light extraction techniques in organic electroluminescent devices," Optical Materials, vol.32, no.1, pp.221-233, 2009. DOI: 10.1016/j.optmat.2009.07.014
  8. C. H. Shin, E. Y. Shin, M. H. Kim, J. H. Lee, Y. Choi, "Nanoparticle scattering layer for improving light extraction efficiency of organic light emitting diodes," Optics express, vol. 23. no.3, pp.133-139, 2015. DOI: 10.1364/OE.23.00A133
  9. S. Yuan, Y. Hao, Y. Miao, Q. Sun, Z. Li, Y. Cui, H. Wang, B. Xu, "Enhanced light out-coupling efficiency and reduced efficiency roll-off in phosphorescent OLEDs with a spontaneously distributed embossed structure formed by a spin-coating method," RSC advances, vol.7, no.69, pp.43987-43993, 2017. DOI: 10.1039/c7ra06921a
  10. A. Salehi, X. Fu, D. H. Shin, F. So, "Recent advances in OLED optical design," Advanced Functional Materials, vol.29, no.15, 2019. DOI: 10.1002/adfm.201808803
  11. A. Kim, G. Husynova, J. Lee, J. H. Lee, "Enhancement of out-coupling efficiency of flexible organic light-emitting diodes fabricated on an MLA-patterned parylene substrate," Organic Eltronics, vol.71, pp.246-250, 2019. DOI: 10.1016/j.orgel.2019.05.025
  12. J. H. Han, J. Moon, D. H. Cho, J. W. Shin, H. Y. Chu, J. I. Lee, N. S. Cho, J. Lee, "Luminescence enhancement of OLED lighting panels using a microlens array film," Journal of Information Display, vol.19. no.4, pp.179-184, 2018. DOI: 10.1080/15980316.2018.1531073
  13. M. I. Vladu, ""Green" electronics: biodegradable and biocompatible materials and devices for sustainable future," Chemical Society Reviews, vol. 43. no.2. pp.588-610, 2014. DOI: 10.1039/c3cs60235d
  14. Z. Fang, H. Zhang, S. Qiu, Y. Kuang, J. Zhou, Y. Lan, C. Sun, G. Li, S. Gong, Z. Ma, "Versatile wood cellulose for biodegradable electronics," Advanced Materials Technologies, vol.6, no.2, 2021. DOI: 10.1002/admt.202000928
  15. R. Mori, "Replacing all petroleum-based chemical products with natural biomass-based chemical products: a tutorial review," RSC Sustainability, vol1, no.2, pp.179-212, 2023. DOI: 10.1039/d2su00014h
  16. N. S. El-sayed, H. Awad, G. M. El-sayed, Z. A. Nagieb, S. Kamel, "Synthesis and characterization of biocompatible hydrogel based on hydroxyethyl cellulose-g-poly (hydroxyethyl methacrylate), Polymer Bulletin, vol.77, pp.6333-6347, 2020. DOI: 10.1007/s00289-019-02962-1
  17. Y. Han, C. K. Moon, K. Kim, H. Lee, J. J. Kim, "Random organic nano-textured microstructures formed by photoexcitation for light extraction of blue OLEDs, "Organic Electronics, vol.87, 2020. DOI: 10.1016/j.orgel.2020.105892
  18. S. Chandrasekaran, A. C. Izquierdo, R. Castaing, B. Kanola, J. L. Scott, "Facile preparation of flame-retardant cellulose composite with biodegradable and water resistant properties for electronic device applications," Scientific Reports, vol.13, no.1, 2023. DOI: 10.1038/s41598-023-30078-0
  19. Z. Lu, J. Huang, S. E, J. Li, L. Si, C. Yao, F. Jia, M. Zhang, "All cellulose composites prepared by hydroxyethyl cellulose and cellulose nanocrystals through the crosslink of polyisocyanate," Carbohydrate polymers, vol.250, 2020. DOI: 10.1016/j.carbpol.2020.116919
  20. S. K. Kwon, J. H. Baek, H. C. Choi, S. K. Kim, R. Lampande, R. Pode, J. H. Kwon, "Degradation of OLED performance by exposure to UV irradiation", RSC advances, vol.9, no.72, pp. 42561-52568, 2019. DOI: 10.1039/c9ra09730a
  21. A. Turak, "Interfacial degradation in organic optoelectronics,"RSC Advances, vol.3, pp.6188-6225, 2013. DOI: 10.1039/c2ra22770c
  22. Y. N. Chen, C. Jiao, Y. Zhao, J. Zhang, H. Wang, "Self-assembled polyvinyl alcohol-tannic acid hydrogels with diverse microstructures and good mechanical properties," CS omega, vol.3, no.9, pp.11788-11795, 2018. DOI: 10.1021/acsomega.8b02041
  23. H. Sun, X. Fang, Y. Zhu, Z. Yu, X. Lu, J. Sun, "Highly tough, degradable, and water-resistant bio-based supramolecular plastics comprised of cellulose and tannic acid," Journal of Materials Chemistry, vol.11, no.13, pp.7193-7200, 2023. DOI: 10.1039/d3ta00351e
  24. M. A. Gwak, B. M. Hong, W. H. Park, "Hyaluronic acid/tannic acid hydrogel sunscreen with excellent anti-UV, antioxidant, and cooling effects," International Journal of Biological Macromolecules, vol.191, pp.918-924, 2021. DOI: 10.1016/j.ijbiomac.2021.09.169
  25. F. Galeotti, W. Mroz, G. Scavia, C. Botta, "Microlens arrays for light extraction enhancement in organic light-emitting diodes: a facile approach," Organic Electronics, vol.14, no.1, pp.212-218, 2013. DOI: 10.1016/j.orgel.2012.10.034
  26. G. Zahi, W. Zhu, L. Huang, C. Yi, K. Ding, "Enhanced light extraction from green organic light-emitting diodes by attaching a high-haze random-bowls textured optical film," Journal of Physics D: Applied Physics, vol.53, no.43, 2020. DOI: 10.1088/1361-6463/ab9fc3
  27. S. Han, B. Sung, D. Kim, J. Kim, S. Woo, J. Lee, S. Y. Baek, M. Won, C. W. Joo, J. W. Han, Y. H. Kim, D. Kim, J. H. Lee, J. Lee, "Eco-friendly External Light Extraction Films for Enhanced Out-Coupling Efficiency of Organic Light Emitting Diodes," Journal of IKEEE, vol.27, no.2, pp.9-17, 2023. DOI: 10.7471/ikeee.2023.27.2.135