연구홍보포털

논문 초록 (Abstract)

Conventional optical structures for enhancing the light-extraction efficiency of organic light-emitting diodes (OLEDs) require toxic solvents, non-recyclable synthetic resins, and high-cost, complex fabrication processes. These factors increase the environmental impact of these structures and hinder the development of sustainable next-generation display technologies. To address these limitations, in this study, an eco-friendly light-extraction template for OLEDs was developed, with deionized water as the sole solvent and incorporating the naturally derived oligosaccharide β-cyclodextrin (β-CD) and water-soluble polymer hydroxyethyl cellulose (HEC). Through chemical interactions between the β-CD and HEC, rod-shaped crystal structures with suppressed aggregation formed on the template surface. Both the crystal morphology and distribution varied with the presence or absence of HEC. Furthermore, a shift in the O–H stretching band observed in the FT-IR spectra indicated that the hydrogen-bonding and hydration environment was modified upon mixing the β-CD and HEC. The proposed template was replicated in PDMS to obtain the rod-shaped crystalline structure (RCS) w/ HEC film, which was laminated onto an OLED device through an index-matching oil layer. This device exhibited a 60% enhancement in light-extraction efficiency over the entire emission hemisphere. These results demonstrate that a light-extraction microstructure of practical performance can be obtained from a master template prepared in water alone, without organic solvents or a separate patterning step, thereby offering a viable platform for next-generation OLED displays and lighting.