A new design strategy for high color-purity blue emission with suppressed vibronic coupling in lutidine-based tetradentate Pt(II) complexes

초록

Realization of efficient and pure deep blue phosphors with color purity remains one of the great challenges in the development of organic light-emitting diodes (OLEDs) due to intrinsic vibrational sideband and aggregation-induced broadening. In this work, we report the design and synthesis of three tetradentate-ligand-based Pt(II) complexes, namely, Pt-Py-CH3, Pt-Py-dtb, and Pt-Lut-dtb, by incorporating pyridine into the phenyl-carbazole ether ring nitrogen atom of pyridine at the para position on the carbon where the tetradentate ligand binds to the platinum atom. These emitters exhibit deep blue photoluminescence with a peak emission of similar to 455 nm and an extremely low full width at half maximum (FWHM) of <21 nm in toluene, along with a high photoluminescence quantum yield (PLQY) of 88-96% in the doped film. When incorporated into OLED devices, the device based on Pt-Lut-dtb emitter shows better performance at an external quantum efficiency (EQE) of 15.3% and CIEy coordinates of 0.123. Furthermore, a phosphorescence-sensitized fluorescence (PSF) device was fabricated, which maintained deep-blue emission with better device performance, with EQE of 28.2%.

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