Highly efficient orange-red organic light-emitting diode using double emissive layers with stepwise energy-level architecture

This study demonstrates a highly efficient orange-red organic light-emitting diode with a double emissive layer architecture that exhibits a record-breaking power efficiency of 47 lm W −1 at 100 cd m −2 , or 32 lm W −1 at 1 000 cd m −2 . Two factors may contribute to the high efficiency. First, the device architecture has a stepwise energy-level, leading to a significantly reduced energy-barrier for both hole and electron to transport, revealed by the relatively low driving voltage. Second, employing a hole-transporting host and an electron-transporting host leads to a nearly perfect balanced injection of hole and electron to the emissive zones, indicated by the obtained external quantum efficiency that reaches the 20% theoretical limit. A highly efficient orange-red organic light-emitting diode with a double emissive layer architecture that exhibits a record-breaking power efficiency of 47 lm W −1 at 100 cd m −2 , or 32 lm W −1 at 1 000 cd m −2 is presented.