Stacked inverted top-emitting green electrophosphorescent organic light-emitting diodes on glass and flexible glass substrates

• Stacked inverted top-emitting green organic light-emitting diodes.
• Devices are demonstrated on flexible glass substrates (Corning® Willow™ Glass).
• A maximum current efficacy of 205 cd/A at 103 cd/m2 is achieved.
• Double-unit OLED acts like two single-unit OLEDs electrically connected in series.
• Interconnecting unit consists of thin layers of HAT-CN/Al/LiF.

Stacked inverted top-emitting green electrophosphorescent organic light-emitting diodes (OLEDs) are demonstrated on glass and flexible glass substrates. A single-unit OLED is shown to have a current efficacy of 46.8 cd/A at a luminance of 1215 cd/m2. When two of these OLEDs are stacked, the double-unit OLED exhibits a current efficacy more than twice that of the single-unit OLED, with a current efficacy of 97.8 cd/A at a luminance of 1119 cd/m2. With the addition of an optical outcoupling layer of N,N′-Di-[(1-naphthyl)-N,N′-diphenyl]-1,1′-biphenyl)-4,4′-diamine (α-NPD) on top of the semitransparent gold anode, the double-unit stacked OLED achieves a maximum current efficacy of 205 cd/A at a luminance of 103 cd/m2, maintaining a high current efficacy of 200 cd/A at a luminance of 1011 cd/m2. These stacked inverted OLED combine the advantages of inverted OLEDs with the benefits of having a stacked architecture.

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