In　this　study,　a　low　steric　hindrance　spiro-type　diimine　ligand,　which　possesses　long　afterglow,　has　been　prepared　to　design　Ag(i)　complexes.　By　achieving　coordination-induced　thermally　activated　delayed　fluorescence　(TADF),　the　excited　state　energy　level　of　the　spiro-type　diamine　ligand　is　regulated,　and　a　small　ΔEST　is　obtained.　Thus,　a　reverse　intersystem　crossing　(RISC)　process　is　facilitated　and　an　highly　efficient　TADF　is　achieved　in　these　Ag(i)　complexes.　This　mechanism,　illustrated　in　this　study,　contributes　to　an　in-depth　understanding　of　transformations　in　different　radiative　decay　pathways.　©　2022　The　Royal　Society　of　Chemistry.