Wide-colour gamut emission tuning of platinum(ii) complexes via multi-quantum state coherence†

The commercialization of organic light emitting diodes (OLEDs) depends significantly on the stability and performance of phosphorescent organic metal emitters. Although platinum (Pt) complexes hold potential as alternatives to iridium based emitters, their luminescence mechanisms are not fully understood, and the development of high performance Pt-based phosphorescent materials remains a challenge. In this study, we designed and synthesized a series of tetradentate cyclometalated Pt(II) complexes based on the PtON7 framework, incorporating a multi quantum state coherence (MQC) model to effectively modulate the luminescent quantum states. Through systematic ligand adjustments, we successfully controlled the emission characteristics of these complexes, achieving full color luminescence across the visible spectrum in dichloromethane solution. Theoretical and experimental results show that substituents on the pyridine ring of the Pt(II) complexes result in a wide color gamut, with emission wavelengths ranging from 480 nm to 617 nm. Notably, introducing conjugated groups at the para-position of the pyridine nitrogen induces a red shift and significantly enhances the photoluminescence quantum yield (PLQY), which can be up to 50% higher than that of PtON7. This work not only demonstrates the potential of Pt(II) complexes for full spectrum emission but also provides valuable insights into the design and optimization of metal complexes for enhanced luminescent performance, offering a promising pathway for the development of efficient, long lifetime emitters for OLEDs.