Bipolar Host Materials Based on 1,3,5‐Triazine Derivative for Green Phosphorescent Organic Light‐emitting Diode

We designed and synthesized new bipolar host materials 2–4, through microwave‐assisted Suzuki‐coupling reaction with 1,3,5‐triazine unit and carbazole/fluorene group. The photophysical and thermal properties of the synthesized 1,3,5‐triazine derivatives 2–4 were investigated by ultraviolet–visible (UV–vis) spectrometer, spectrofluorometer, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The 1,3,5‐triazine derivatives 2–4 have suitable energy bandgap (Eg = 3.15–3.35 eV) and high triplet energy level (ET, 2.63–2.87 eV) for phosphorescent green host. Device performance of 2–4 materials shows that maximum luminescence efficiency (LE) and external quantum efficiency (EQE) of green device A–C were 29.25, 49.67, and 48.74 cd/A and 8.68, 14.52, and 14.30%, respectively.