Realization of high-performance blue organic light-emitting diodes using multi-emissive layers

High-performance blue organic light-emitting diodes(OLEDs) are developed.A concept of using multiple-emissive layer(EML) configuration is adopted.In this letter,bis(2-methyl-8-quinolinolate)-4-(phenylphenolato)Al(BAlq) and 9,10-di(naphtha-2-yl)anthracene(ADN),which serve n- and p-type EMLs,respectively,are used to evaluate and demonstrate the multi-EML concept for blue OLEDs.The thickness effect of individual EMLs and the number of EMLs,e.g.,triple and quadruple EML components,on the power efficiency of blue OLEDs are systematically investigated.To illustrate the point,the total thickness of the emissive region in different blue OLEDs are kept contact at 30 nm for comparison.The power efficiency of blue OLEDs with a quadruple EML structure of BAlq/ADN/BAlq/ADN is about 40% higher than that of blue OLEDs having a single EML unit.The Commission Internationale deL'eclairage color coordinates of multi-EML OLEDs have values that represent the average of blue emissions from individual EMLs of BAlq and ADN.