A Multi‐Luminescent Platinum Emitter for Broad‐Spectrum Warm‐White Emission

ABSTRACT

Broad‐spectrum emission from a single coordination complex remains a formidable challenge, yet its potential to simplify white organic light‐emitting diodes (WOLEDs) continues to motivate the search for single‐emitter alternatives to multi‐component systems. Herein, we present a step‐wise molecular engineering approach that systematically transforms an inefficient design into a high‐performance white‐light emitter. Starting from Pt‐1 (PLQY 1%), which suffered from dominant intra‐ligand charge‐transfer ( ³ ILCT) quenching, we introduced a strong‐field NHC ligand to create Pt‐2 (PLQY 63%), successfully suppressing the ³ ILCT state. A final structural reconfiguration yielded PtNex , a tetradentate complex with four distinct Pt–C/N bonds that integrate monomer phosphorescence and excimer emission. This architecture generates high‐performance Warm‐white light spanning 420–770 nm with a PLQY of 66.5%, a short lifetime of 5.01 µs, and a radiative decay rate of 1.33 × 10 ⁵ s ⁻¹ . Single‐emitter WOLEDs based on PtNex achieve a maximum external quantum efficiency (EQE) of 26.2% (38.7% with outcoupling enhancement), a power efficiency of 54.4 lm W ⁻¹ , and CIE coordinates of (0.42, 0.49). This multi‐luminescent design concept offers a versatile platform for advanced optoelectronics.