High-efficiency blue phosphorescence devices with external quantum efficiencies above 25% are developed using a new bipolar host material, diphenyl(10-phenyl-10H-spiro[acridine-9,9-fluoren]-2-yl)phosphine oxide (POSTF), which is constructed in orthogonal molecular structure with a spiro-coree. The separation of bipolarity from effective spiro-fluorene-triphenylamine (STF) structure is elucidated and its versatility in device is evaluated by two kinds of sky-blue phosphors. Noticeably, large-size white light-emitting panel (150 mm x 150 mm) is fabricated with max power efficiency of 75.9 l m W-1 using this new host.