High-Performance Multicolor Organic Light-Emitting Diodes Based on a Pt(II) Carbene Complex Featuring Hemiligand Interaction

Utilizing a single organic light-emitting diode (OLED) architecture for multicolor emissions can significantly simplify manufacturing progress and broaden applications. Here, we report on a carbene-based Pt(II) complex, designated as <b>Pt(pyiOppy)</b>, which exhibits an unusual dimeric packing mode solely by hemiligand π···π stacking. This feature is distinct from the well-known Pt···Pt or Pt···ligand interactions. The dimer persists in new types of orbital combinations, along with its triplet transition state, which are evidenced for the first time. <b>Pt(pyiOppy)</b>, under various doping concentrations in a solid matrix, demonstrates multicolor emissions ranging from green to red, all exhibiting high photoluminescent quantum efficiencies (48-97%). The devices incorporating <b>Pt(pyiOppy)</b> can emit green, yellow, orange, and red lights, covering a CIE coordinate range of (0.28-0.65, 0.61-0.34). All the devices also achieve appreciable maximum external quantum efficiencies (9.4-17.2%) and impressive lifetimes of hundreds of hours (LT₇₀ at 1000 cd/m²). These findings showcase a new type of Pt(II) aggregate enabling well-controlled, multicolor high-performance phosphorescent OLEDs.