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Journal Article
Surface Control of Planarization Layer on Embossed Glass for Light Extraction in OLEDs
- Authors
- Doo-Hee Cho, Jin-Wook Shin, Jaehyun Moon, Seung Koo Park, Chul Woong Joo, Nam Sung Cho, Jin Woo Huh, Jun-Han Han, Jonghee Lee, Hye Yong Chu, Jeong-Ik Lee
- Issue Date
- 2014-10
- Citation
- ETRI Journal, v.36, no.5, pp.847-855
- ISSN
- 1225-6463
- Publisher
- 한국전자통신연구원 (ETRI)
- Language
- English
- Type
- Journal Article
- Abstract
- We developed a highly refractive index planarization layer showing a very smooth surface for organic lightemitting 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 TiO2solutions for a planarization of the embossed nano-structure on a glass substrate. The first TiO2solution was TiO2sol, which consists of TiO2colloidal particles in an acidic aqueous solution and several organic additives. The second solution was an organic and inorganic hybrid solution of TiO2. The surface roughness (Ra) and refractive index of the TiO2planarization 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 TiO2planarization 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.
- KSP Keywords
- Aqueous solution, Colloidal particles, Coupling layer, Flat glass, Glass substrate, Highly efficient, J-V characteristics, Organic additives, Organic-inorganic, Smooth surface, Surface roughness