Lead-free　double　perovskites　(DPs)　are　emerging　highly　stable　emitters　with　efficient　broadband　self-trapped　exciton　(STE)　photoluminescence　(PL),　but　their　low　electroluminescent　(EL)　efficiency　is　a　critical　shortcoming.　This　work　promotes　the　external　quantum　efficiency　(EQE)　and　luminance　of　DP-based　white　light-emitting　diode　(wLED)　with　a　normal　device　structure　to　0.76%　and　2793 cd　m−2　via　two　modifications:　This　work　prevents　the　formation　of　adverse　metallic　silver,　spatially　confined　STE,　and　lowers　local　site　symmetry　in　Cs2Na0.4Ag0.6In0.97Bi0.03Cl6　DP　by　terbium　doping;　and　this　work　develops　a　guest–host　strategy　to　improve　film　morphology,　reduce　defect　density,　and　increase　carrier　mobility.　These　alterations　cause　substantial　increase　in　STE　radiative　recombination　and　charge　injection　efficiency　of　perovskite　layer.　Finally,　pure　white　EL　with　ideal　color　coordinates　of　(0.328,　0.329)　and　a　record-breaking　optoelectronic　performance　is　achieved　by　introducing　additional　green　carbon　dots　in　LED　to　fill　the　deficient　green　component.　©　2023　Wiley-VCH　GmbH.