Photoluminescence Properties of Silver(I) Complexes: From Extremely Long-Lived Phosphorescence to Ultrashort-Lived TADF

High Resolution Image Download MS PowerPoint Slide We review Ag(I) complexes with organic ligands that show ambient-temperature phosphorescence or thermally activated delayed fluorescence (TADF). Criteria for the assignment of the emission character are given. Two materials are highlighted: [Ag(dmp)(DPEPhos)]PF 6 A (dmp: 2,9-dimethyl-1,10-phenanthroline, DPEPhos: bis[(2-diphenylphosphino)phenyl]ether), featuring an exceptionally long decay time of τ(phos) = 110 ms at Φ PL (phos) ≈50%, shows phenanthroline ligand-centered 3 LC → S 0 phosphorescence. The resulting large Δ E (S 1 –T 1 ) gap (640 meV) inhibits the efficient thermal population of the S 1 state. In contrast, the rationally modified Ag(dbp)(P 2 -nCB) B (dbp: 2,9-dibutyl-1,10-phenanthroline, P 2 -nCB: strongly electron-donating diphosphine ligand comprising a negatively charged nido -carborane cage) features low-lying states of (ligand + metal)-to-ligand charge transfer ( 1,3 (L + M)L’CT) character. This reduces Δ E (S 1 –T 1 ) to 80 meV, enabling fast and bright ambient-temperature TADF (radiative decay time: 1.4 μs at Φ PL (TADF) = 100%) with the decay time of more than 5 orders of magnitude shorter than that of A . The radiative properties of both compounds are outstanding compared to other pseudotetrahedrally coordinated metal complexes. In a second part, we extend the reviewed work by investigating both compounds by detailed DFT and TD-DFT calculations, including spin–orbit coupling. The results reflect the experimental trends. A is a potential highly sensitive oxygen sensor, while B might represent a new type of efficient OLED emitter material.