High-efficiency and superior color-stability white phosphorescent organic light-emitting diodes based on double mixed-host emission layers

•The key feature of the concept is to introduce double blue mixed-host EMLs with an orange ultrathin layer.•The white device without spacer or interlayer achieves superior color-stability.•The peak efficiencies of 40.8 lm/W and low turn-on voltage of 2.71 V are realized.•The double mixed-host EMLs concept proves to be quite useful in achieving excellent device performance.

We demonstrate high-efficiency and superior color-stability white phosphorescent organic light-emitting diodes based on double blue mixed-host emission layers (EMLs) with different mixed ratios. The key feature of the concept is to introduce double blue mixed-host EMLs with an orange ultrathin layer sandwiched between them. The improved white device without spacer or interlayer achieves superior color-stability and reduced efficiency roll-off, which are consistent with the good ambipolar conductivity of the mixed-host layer. Moreover, peak efficiency of 40.8 lm/W and low turn-on voltage of 2.71 V are realized. The double mixed-host EMLs concept proves to be quite useful in achieving excellent device performance.

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