Highly Efficient Deep‐Blue Electrophosphorescence Enabled by Solution‐Processed Bipolar Tetraarylsilane Host with Both a High Triplet Energy and a High‐Lying HOMO Level

A new bipolar tetraarylsilane derivative with both a sufficiently high triplet energy and a high-lying highest occupied molecular orbital energy level is presented as an excellent host for the deep-blue phosphor. A solution-processed FIr6-based deep-blue phosphorescent organic light-emitting diode (PhOLED) is realized with high efficiency and low efficiency roll-off.