Increasing the Efficiency of the Blue OLED Device with a Double-Emitting Layer Structure

Without changing the host–guest materials of the optimized single-emitting layer (S-EML), a series of double-emitting layer (D-EML) was constructed by the same host material and the same guest material to improve the exciton distribution of the EML; thereby, a better performance of the D-EML blue device was obtained. The best D-EML device showed that the luminance and the current efficiency were enhanced, respectively, to 1437 cd/m2 and 6.92 cd/A at the current density 20 mA/cm2, which was 22.9