Ⅰn　this　study,　a　Cu(Ⅰ)　complex　luminescent　material　Cu-P-Spiro2N　with　thermally　activated　delayed　fluorescence　(TADF)　properties　was　successfully　designed　by　combining　the　donor-acceptor　(D-A)　type　ligand　10-phenyl-10H-spiro[acridine-9,9＇-(4,5-diazafluorene)]　(Spiro2N)　with　long　afterglow　emission　properties　and　the　auxiliary　phosphine　ligand　bis(2-diphenylphosphinophenyl)　ether　(POP).　The　molecular　structures　of　the　Cu(Ⅰ)　complex　were　confirmed　by　nuclear　magnetic　resonance　spectroscopy,　and　the　crystal　structure　of　the　Cu-P-Spiro2N　complex　was　further　characterized　by　X-ray　single　crystal　diffraction.　Cu-P-Spiro2N　belongs　to　the　triclinic　crystal　system　with　cell　parameters　α＝90.14(2)°,　β＝115.43(3)°,　γ＝115.55(3)°,　a＝15.10(6)　nm,　b＝15.15(4)　nm,　c＝16.62(6)　nm.　Due　to　the　two　mutually　orthogonal　π-conjugated　planar　structures　of　the　ligand　molecule　Spiro2N,　its　highest　occupied　molecular　orbital　(HOMO)　and　lowest　unoccupied　molecular　orbital　(LUMO)　are　well　separated,　but　with　a　relatively　large　singlet-triplet　energy　gap　(∆EST).　After　coordination　of　the　metal　Cu(Ⅰ)　fragment　with　the　ligand　Spiro2N,　the　energy　gap　between　HOMO　and　LUMO　is　further　reduced,　and　the　charge　transfer　(CT)　state　energy　level　is　further　lowered,　which　makes　the　complex　Cu-P-Spiro2N　have　a　very　small　∆EST　of　0.05　eV.　The　small　∆EST　facilitates　the　reverse　intersystem　crossing　process,　thereby　achieving　TADF　emission.　The　emission　of　this　complex　mainly　comes　from　the　D-A　ligand　Spiro2N,　which　exhibits　metal　perturbation　intramolecular　ligand　charge　transfer　(ⅠLCT)　properties.　At　room　temperature,　in　the　doped　polymethylmethacrylate　(PMMA)　film　(10%　(w)),　the　Cu-P-Spiro2N　complex　exhibits　strong　yellow　light　emission　with　an　emission　peak　at　551　nm,　a　photoluminescence　quantum　efficiency　of　49%,　and　an　excited　state　lifetime　of　6.3　μs.　The　results　of　this　study　indicate　that　by　coordinating　with　Cu(Ⅰ)　ions,　the　excited　state　energy　level　of　the　ligand　molecule　can　be　modulated,　reducing　∆EST　and　thus　achieving　TADF　emission.　©　2024　Shanghai　Ⅰnstitute　of　Organic　Chemistry,　Chinese　Academy　of　Sciences.