Precise Modulation of Sterically Shielded Pt (II) Complex for Deep Blue OLED Enabled Long Lifetime with High Efficiency

Abstract

The limited operational stability of blue phosphorescent organic light-emitting diodes (PhOLEDs) remains a major challenge for next-generation display technologies. Herein, a highly stable deep blue PhOLED is reported, enabled by a newly designed Pt (II) complex, PtON-2,6-TPI, developed through a combination of density functional theory (DFT) calculations and automated quantitative structure-activity relationship modeling (Auto-QSAR). PtON-2,6-TPI exhibits enhanced exciton stability and broad recombination zone, attributed to its deep highest occupied molecular orbital (HOMO) level and sterically engineered ligand environment. Devices based on PtON-2,6-TPI demonstrate a twofold improvement in operational lifetime (LT90 120 h at 1000 cd m-2) compared to the benchmarked PtON-TBBI. A top-emission OLED employing deuterated hosts and PtON-2,6-TPI achieves a narrow full-width half maximum (FWHM) of 15 nm and extended operational stability with BT.2020 blue coordinates of (0.13, 0.05) (LT95 193 h at 1000 cd m-2). Furthermore, a phosphorescent-sensitized TADF (PST) device incorporating PtON-2,6-TPI as a sensitizer and a multiple-resonance emitter as the terminal emitter delivers a record-high external quantum efficiency (EQE) of 34.5% and a narrow FWHM of 16 nm in the deep-blue region. This work highlights the critical role of DFT and machine learning-assisted ligand design, offering a viable pathway toward commercially viable blue PhOLEDs.