Deep Blue Phosphorescence in Polystyrenes Enabled by Gold(I) N-Heterocyclic Carbene Acetylide Complexes

We synthesized and characterized two novel phosphorescent gold(I) N-heterocyclic carbene (NHC) acetylide complexes and four corresponding copolymers featuring these emissive units as pendant groups on a polystyrene backbone. The molecular complexes exhibit deep-blue phosphorescence (λ_max ∼ 420 nm) with structured emission and long excited-state lifetimes (τ ∼ 50 μs), attributed to ligand-centered ³(π → π*) transitions, as supported by density functional theory calculations. Incorporation of these complexes into a polystyrene matrix preserves their phosphorescent properties, enabling the generation of emissive polystyrenes. The copolymers display similar solid-state photoluminescence, with gold loading influencing spectral shape and aggregation. A proof-of-concept organic light-emitting diode (OLED) device fabricated with one of the molecular complexes demonstrated electroluminescence at 408 nm and an external quantum efficiency of 3.3%. This work highlights the potential of NHC-Au(I) acetylide motifs as versatile building blocks for integrating tunable phosphorescence into simple polymer frameworks, opening new avenues for developing functional luminescent materials.