Regarding　conventional　quantum　dot　light-emitting　diodes　(QLEDs)　fabricated　by　using　the　spin-coating　(SC)　technique,　voids　and　interstitial　spaces　are　inevitable　due　to　unordered　quantum　dots　(QDs)　stacking,　generating　device　leakage　current　under　an　external　bias.　In　the　present　study,　we　fabricated　an　ultra-homogeneous　and　highly　ordered　QD　monolayer　by　adopting　the　Langmuir-Blodgett　(LB)　technique.　The　QD　monolayer　was　transferred　as　a　emissive　layer　with　a　horizontal　lifting　(HL)　method　to　a　red　QLED,　which　exhibited　high　performance　with　an　external　quantum　efficiency　(EQE)　of　19.0%　and　lifetime　(T95@100　cd　m−2)　of　13,324　h.　When　compared　with　the　SC-based　device,　the　EQE　and　lifetime　were　improved　by　15%　and　183%　due　to　the　compact　and　ordered　QD　monolayer　that　lowered　the　leakage　current.　Moreover,　white　QLEDs　with　stacked　QD　monolayers　could　be　obtained　at　a　low　voltage　of　4　V　because　LB　technique　is　an　organic-solvent-free　approach　avoiding　interlayer　mixing　and　controlling　the　QD　layer　thickness　precisely.　In　addition,　we　successfully　fabricated　an　ultra-homogeneous　large-area　QD　monolayer　on　a　rectangular　substrate　with　a　size　of　9　cm　×　5　cm,　indicating　the　promising　size　scalability　of　the　LB-HL　strategy.　©　2021,　Science　China　Press　and　Springer-Verlag　GmbH　Germany,　part　of　Springer　Nature.