Transparent organic light-emitting diodes with different bi-directional emission colors using color-conversion capping layers

Abstract

We report a study on transparent organic light-emitting diodes (OLEDs) with different bidirectional emission colors, enabled by color-conversion organic capping layers. Starting from a transparent blue OLED with an uncapped Ag top electrode exhibiting an average transmittance of 33.9%, a 4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM)-doped tris-(8-hydroxy-quinolinato)-aluminium (Alq3) capping layer is applied to achieve color-conversion from blue to orange-red on the top side while maintaining almost unchanged device transmittance. This color-conversion capping layer does not only change the color of the top side emission, but also enhances the overall device efficiency due to the optical interaction of the capping layer with the primary blue transparent OLED. Top white emission from the transparent bi-directional OLED exhibits a correlated color temperature around 6,000K-7,000K, with excellent color stability as evidenced by an extremely small

Simplified Bilayer White Phosphorescent Organic Light-Emitting Diodes

“…The chemical structures of the materials and energy level diagrams used in this study are shown in Figs. 2 and 3 (the energy levels are taken from the literature) [8]- [10], respectively. ITO was cleaned using a standard oxygen plasma treatment.…”