Effect of inorganic interfacial modification layer on the performance of quantum-dots light-emitting diodes

Efficiency and operational durability are crucial characteristics for the high-performance quantum-dots light-emitting diodes (QLEDs). In order to improve the efficiency and the stability of the QLEDs, we have inserted an inorganic Al2O3 interfacial modification layer (IML) next to the electron transport layer (ETL) using atomic layer deposition (ALD). We conducted a comparative analysis of two different positions of Al2O3 IML inside the device, inserting IML before ETL and after ETL, to find an optimized structure for the efficient QLEDs. As a result, when Al2O3 IML was located after ETL, reduction of oxygen vacancy in the ZnO layer was occurred due to the reaction of O2 plasma reactant that used during the ALD process. It can have the effects of decreasing the exciton quenching phenomenon and balancing the charge injection. Therefore, improved device performances were observed, and the maximum luminance was 56 108 cd m−2 when 1 nm Al2O3 IML was deposited after ZnO ETL. These results suggest Al2O3 IML deposition would provide a useful way to improve the performance of QLEDs.