CuInS2-based　quantum-dots　(QDs)　have　been　highlighted　as　promising　photoelectric　materials　for　their　low　toxicity　and　color　adjustable　emissions　as　well　as　stability.　Here,　multi-shell　CuInS2/ZnS/ZnS　QDs　with　high　PLQY　of　76%　were　synthesized　by　employing　a　high　temperature　and　long-time　growth　strategy　while　highly　bright　and　efficient　quantum-dot-light-emitting　diodes　(QLEDs)　were　fabricated　by　using　these　multi-shell　QDs　as　an　emission　layer　and　polyethylenimine　(PEI)　as　an　insulating　layer,　respectively.　By　introducing　PEI　between　the　QDs　and　ZnO　EML　layers　of　the　QLEDs,　the　balance　of　the　carriers　within　the　QDs　layer　injected　from　HTL　and　ETL　was　greatly　improved.　As　a　result,　comparing　to　the　QLEDs　without　PEI,　the　greatly　improved　efficiency　(1.9　times　as　high　as　that　of　the　QLEDs　without　PEI)　has　been　achieved　in　the　optimized　QLEDs　with　PEI.　These　QLEDs　exhibits　an　outstanding　performance　with　the　maximum　EQE　of　1.56%　and　the　maximum　brightness　of　5825　cd/m2.　©　2020　Elsevier　B.V.