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

Research output: Contribution to journalArticle


Jonghee Lee, Tae-Wook Koh, Hyunsu Cho, Tobias Schwab, Jae-Hyun Lee, Simone Hofmann, Jeong-Ik Lee, Seunghyup Yoo, Karl Leo, Malte Christian Gather

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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)-4Hpyran
(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 variation in color coordinate of ∆(x,y) = (0.002, 0.002) in the forward luminance range of 100-1000 cd m-2. At the same time, the blue emission color of bottom side is not influenced by the color conversion capping layer, which finally results in different emission colors of the two opposite sides of our transparent OLEDs



Original languageEnglish
Pages (from-to)180-184
JournalJournal of Luminescence
Early online date25 Feb 2015
Publication statusPublished - Jun 2015

    Research areas

  • Down-conversion white OLED, Color conversion capping layer, Transparent OLED, Bi-directional OLED

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