• Title/Summary/Keyword: ETRI

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Surface Control of Planarization Layer on Embossed Glass for Light Extraction in OLEDs

  • Cho, Doo-Hee;Shin, Jin-Wook;Moon, Jaehyun;Park, Seung Koo;Joo, Chul Woong;Cho, Nam Sung;Huh, Jin Woo;Han, Jun-Han;Lee, Jonghee;Chu, Hye Yong;Lee, Jeong-Ik
    • ETRI Journal
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    • v.36 no.5
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    • pp.847-855
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    • 2014

  • We developed a highly refractive index planarization layer showing a very smooth surface for organic light-emitting diode (OLED) light extraction, and we successfully prepared a highly efficient white OLED device with an embossed nano-structure and highly refractive index planarization layers. White OLEDs act as an internal out-coupling layer. We used a spin-coating method and two types of $TiO_2$ solutions for a planarization of the embossed nano-structure on a glass substrate. The first $TiO_2$ solution was $TiO_2$ sol, which consists of $TiO_2$ colloidal particles in an acidic aqueous solution and several organic additives. The second solution was an organic and inorganic hybrid solution of $TiO_2$. The surface roughness ($R_a$) and refractive index of the $TiO_2$ planarization films on a flat glass were 0.4 nm and 2.0 at 550 nm, respectively. The J-V characteristics of the OLED including the embossed nano-structure and the $TiO_2$ planarization film were almost the same as those of an OLED with a flat glass, and the luminous efficacy of the aforementioned OLED was enhanced by 34% compared to that of an OLED with a flat glass.

  • https://doi.org/10.4218/etrij.14.0113.0845 인용 PDF KSCI KPUBS