Four　o-carborane-based　aggregation-induced　emission　molecules　with　ultra-large　Stokes　shifts　were　designed　and　synthesized.　To　explore　the　origin　of　the　ultra-large　Stokes　shifts　(Δλ　≈　268–294　nm)　of　the　four　target　molecules,　a　new　molecule　named　CZ-Ph-PO　was　synthesized　by　replacing　the　o-carborane　unit　in　CZ-CB-PO　with　a　benzene　ring.　It　was　found　that　the　ultra-large　Stokes　shift　was　the　result　of　the　combined　action　of　diphenylphosphinyl　and　o-carborane,　in　which　o-carborane　was　the　key　group.　In　addition,　combined　with　the　single　crystal　structure　analysis,　the　effect　of　halogens　on　molecular　photophysical　properties　was　investigated.　Our　work　provides　a　reference　for　the　design　and　synthesis　of　o-carborane-based　fluorescent　molecules　with　ultra-large　Stokes　shifts.　©　2023　Wiley-VCH　GmbH.