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 (lambda(max) = similar to 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 (MLCT)-M-1 and (LC)-L-3 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.