Angle-stable inverted top-emitting white organic light-emitting devices based on gradient-doping electron injection interlayer

• White inverted top-emitting organic light-emitting devices were demonstrated.
• Bphen:Ag interlayer was used to enhance the electron injection.
• Ag–Ge–Ag capping with light outcoupling layer was used as anode.
• The device shows stable spectra with voltage and viewing angle.

By adopting an 4,7-diphenyl-1,10-phenanthroline (Bphen):Ag interlayer with the gradient structure between the cathode and electron injection layer, the electron injection of white inverted top-emitting organic light-emitting devices (WITOLED) was enhanced. The structure of Ag–Ge–Ag anode capping with light outcoupling was used to ensure the spectral stability with the angles. The structure of the emission layer was carefully designed to guarantee the spectral stability with the voltages. The highest current efficiency of the WITOLED can reach 21.7 cd/A. The CIE 1931 coordinates varies only 0.022 in X and 0.015 in Y (0o–60o).

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