Ionic　liquids　are　effective　additives　to　enhance　the　performance　and　stability　of　perovskite　optoelectronic　devices.　Because　of　the　diverse　types　of　ionic　liquids,　their　role　for　device　improvement,　especially　in　perovskite　light-emitting　diodes　(PeLEDs),　still　needs　to　be　investigated.　To　answer　this　question,　we　studied　the　performance　of　quasi-two-dimensional　(quasi-2D)　PeLEDs　doped　with　two　different　kinds　of　ionic　liquids,　BMIMBF4　and　BMIMBr.　Our　results　show　that　the　optimization　of　the　PeLED　performance　arises　from　the　modification　of　the　crystallization　process　of　quasi-2D　perovskite　films.　After　doping　with　the　ionic　liquid,　the　distribution　of　the　low-dimensional　perovskite　phases　becomes　gradient.　This　gradient　phase　distribution　forms　an　energy　funnel,　which　could　boost　the　charge　transfer　and　facilitate　the　luminescence　efficiency.　Further　comparative　investigation　shows　that　the　BF4-　anion　is　more　effective　than　Br-　in　the　optimization　of　the　crystallization　process.　These　results　provide　better　understanding　of　the　role　of　anions　in　ionic　liquid　additives　and　the　ways　to　enhance　the　performance　of　perovskite　light-emitting　devices.　©　2023　American　Chemical　Society.