Heteronuclear Complexes Containing Pt(II) and Ag(I) Centers: Application to Efficient Light-Emitting Electrochemical Cells

We report the synthesis of novel ionic heteronuclear Pt(II)-Ag(I) complexes derived from Pt(NCN)-C≡CR precursors (R = aryl), where Ag⁺ ions coordinate to the acetylene groups. The photophysical investigation reveals a complex interplay of emissions: ³MLCT and ³LC states from the Pt(NCN) units, ³LC emissions from the R aryl groups, and ³MMLCT emissions arising from aggregated Pt(NCN)-X units in the solid state. These complexes exhibit photoluminescence in the range of 650-750 nm, predominantly from ³MMLCT states facilitated by short Pt···Pt contacts. Utilizing complex 4c (R = phenanthryl) as the ionic emitter in proof-of-concept LEECs, we achieved a maximum EQE of 4.1% and a luminance of nearly 2000 cd m^-2. These results represent one of the highest-performing LEECs incorporating Pt(II)-based phosphorescent complexes, underscoring their potential in light-emitting applications.