Novel Cs2CO3:Ag2O electron injection layer for high-efficiency organic light-emitting devices

Highly efficient organic light-emitting devices containing a novel composite electron injection layer (Cs2CO3:Ag2O) were fabricated for this study. Compared with the maximum current efficiency and luminance of the control device with a 1 nm Cs2CO3 structure, a maximum current efficiency of 6.45 cd/A and a maximum luminance of 23,320 cd/m2 were obtained, at a Ag2O mass fraction of 20 % and a Cs2CO3:Ag2O layer thickness of 2 nm, which is an increase by a factor of 1.80 and 2.36, respectively. The reason for the high performance can be attributed to the effective reduction of the electron injection barrier at the cathode/organic layer interface by the Cs2CO3:Ag2O electron injection layer, facilitating electron injection. In addition, it is found that the electrical conductivity was increased as well by a factor of 2.54 (1.6 s/m for the Cs2CO3:Ag2O (20 %) layer and 0.63 s/m for the 1 nm Cs2CO3 layer), indicating that the good device performance partly originated from the high electrical conductivity.