We report a large-area quantum dot light-emitting diode (QLED) with sputtered Zn 0.85 Mg 0.15 O (ZMO) as an electron transportlayer (ETL). Uniform ZMO is applied as ETL of the inverted structured QLED and the adjustment of Ar/O 2 ratio ondevice characteristics is studied in detail. Compared to pristine ZMO, ZMOs with O 2 gas are found to be benefi cial to thecharge balance in the emitting layer of QLEDs mainly by their upshifted conduction band minimum, which in turn limitsan electron injection. Additionally, it is found that oxygen vacancies in the ZMO, acting as the exciton quenching sites, areresponsible for the device stability. QLEDs with 6:1 ZMO produce a maximum luminance of 136,257 cd/m 2 and externalquantum effi ciency of 5.15%, which are the best device performances to date among QLEDs with sputtered ETLs. Theseresults indicate that the sputtered ZMO shows great promise for use as an inorganic ETL for future large-area QLEDs.