Owing　to　their　composition-tunable　and　narrow　emissions　and　high　photoluminescence　quantum　yield　(PLQY),　inorganic　halide　perovskite　quantum　dots　(IPQDs)　are　a　promising　option　for　wide　color　gamut　displays.　However,　their　practical　applications　have　been　limited　by　their　lattice　structure　instability　and　surface　defect　states.　Herein,　CsPbBr3:KBF4@SiO2　with　improved　stability　and　optical　properties　is　successfully　synthesized　with　a　two-step　optimization　of　fluorine　(F)　anion　doping　and　SiO2　in　situ　coating.　Compared　with　bromide　(Br),　higher　electronegativity　and　a　smaller　radius　of　F　lead　to　stronger　binding　energy　with　Pb2+.　Also,　F　anions　can　occupy　surface　Br　vacancies.　Then,　benefiting　from　the　acidic　environment　provided　by　BF4-　hydrolysis,　tetraethyl　orthosilicate　(TEOS)　can　be　more　easily　hydrolyzed　on　the　CsPbBr3:KBF4　surface　to　generate　SiO2　coating,　thus　further　passivating　lattice　defects　and　improving　environmental　stability.　Importantly,　the　PLQY　of　CsPbBr3:KBF4@SiO2　achieves　85%,　and　the　stability　has　been　greatly　improved　compared　with　pure　CsPbBr3.　Finally,　CsPbBr3:KBF4@SiO2/PDMS,　CsPbI3/PDMS,　and　CsPbCl3/PDMS　composites　with　narrow　emissions　are　applied　to　replace　traditional　phosphors　as　color　converters　for　direct-view　light-emitting　diode　(LED)　displays　or　liquid　crystal　display　(LCD)　backlights.　The　color　gamut　reaches　118.22%　under　the　NTSC　standard.　Concerning　the　display　field,　it　suggests　likely　applications　in　the　future.