Enhancing Phosphorescence and Electrophosphorescence Efficiency of Cyclometalated Pt(II) Compounds with Triarylboron

A synthetic strategy for the preparation of cyclometalated platinum(II) acetylacetonate (acac) complexes functionalized with triarylboron is achieved. This method is used to synthesize a series of triarylboron‐functionalized phosphorescent Pt(acac) compounds, which are characterized by NMR spectroscopy, X‐ray crystallography, and theoretical calculations. These complexes exhibit a range of bright phosphorescent colors spanning the green to red region of the visible spectrum (λmax = ∼520–650 nm) in solution and the solid state. Functionalization with a triarylboron group leads to significant enhancement in quantum yield for several of these complexes relative to the non‐borylated Pt(II) parent chromophores, which may be attributed to the increased mixing of 1MLCT and 3LC states. The phosphorescent enhancement, electron transport capabilities, and steric bulkiness offered by the triarylboron group can be used to significantly enhance the performance of electrophosphorescent devices based on Pt(II) emitters. A high efficiency green electrophosphorescent device is fabricated with a maximum external quantum efficiency of 8.9%, luminance efficiency of 34.5 cd A−1, and power efficiency of 29.8 lm W−1, giving significantly improved performance over control devices in which the Pt(II) emitter lacks the boron functionality. Triarylboron is found to greatly enhance the photoluminescent quantum yields, electrophosphorescence efficiencies, and electron transport capabilities of cyclometalated N,C‐chelate Pt(II) complexes, which leads to significant improvements in the performance of electroluminescent devices based on doped Pt(II) emitters.