The　emerging　multilayer　colloidal　quantum　dot　light　emitting　diodes　(QLEDs)　comprise　excellent　intrinsic　properties,　such　as　narrow　emission　bandwidth,　wide　color　gamut　and　solution　processability,　all　of　which　is　consistent　with　the　requirement　of　advanced　panel　display　device　and　their　low-cost　production　process.　But　inferior　blue　QLEDs　performance　has　impeded　the　commercialization　of　QLED　display　panel.　Herein,　polyvinylpyrrolidone　(PVP)　was　doped　into　the　electron　transport　layer　where　PVP　functions　as　electron　blocking　material　and　separates　zinc　oxide　nanoparticles　(ZnO　NPs)　from　each　other　to　reduce　electron　injection,　achieving　charge　balance　in　blue　QLED　emitting　layer.　With　this　method,　the　device　performance　obtained　significant　improvement.　The　maximum　brightness　of　the　devices　reached　22800　cd　m−2,　and　the　external　quantum　efficiency　reached　2.95%.　©　2018　Elsevier　B.V.