High‐Performance Red Quantum‐Dot Light‐Emitting Diodes Based on Organic Electron Transporting Layer

Abstract High‐performance red quantum dot light‐emitting diodes (QLEDs) are demonstrated based on nitrogen heterocycle‐containing compounds as the organic electron transporting layer (ETL). Unlike ZnO, the adoption of organic ETL can eliminate unwanted photoluminescence quenching of colloidal quantum dots (QDs) due to the prevented electron transfer between QDs and organic ETL. Most importantly, when the central core is varied from benzene and pyrimidine to triazine, their lowest unoccupied molecular orbital energy levels are found to be well tuned to facilitate electron injection. Consequently, a triazine‐cored organic ETL (denoted as TmPPPyTz) achieves a restored charge balance, giving a record‐high external quantum efficiency of 13.4% (18.8 cd A −1 , 23.9 lm W −1 ) and Commission Internationale de l'Eclairage coordinates of (0.68, 0.32). The obtained state‐of‐art performance clearly indicates the great potential of organic ETL towards efficient QLEDs.