Althoughsignificantprogresshas been madein the developmentof green,red,and near-infraredperovskitelight-emittingdiodes(PeLEDs),blue PeLEDsexhibitinferiorperformance,owingto variousdefectsand poorcarrierinjectionin solution-processedperovskitefilms.Thus,this studyincorporatesdual-passivationadditivediphenylphosphina-mide(DPPA)into perovskitefilms,and throughdensityfunctionaltheorycalculationsandexperimentalcharacterizations,DPPAhas beenprovento be an effectivepassivator.Itsphosphineoxidegroupcoordinateswith unsaturatedlead ions, passivatingperovskitedefects,whilethe aminogroupformshydrogenbondswith adjacenthalideions, suppressingtheirmigrationand furtherstrengtheningthe passivationeffect.Bluequasi-two-dimensionalPeLEDsbasedon DPPA-modifiedperovskitefilms achievedan externalquantumefficiencyof12.31%with an emissionpeak at 486 nm. Moreover,the deviceoperationallifetimewasextendedby 32% with morestablespectraowingto the decreaseddefectdensityand suppressedion migrationin theperovskitefilm