Thianthrene 5,5,10,10-tetraoxide-based phosphorescent platinum(II) complexes for solution-processed organic light-emitting diode (OLED) with external quantum efficiency approach 25 %

Pt(II) complexes have great potential in realizing high efficiency OLED luminous materials, and the development of achieving high quantum efficiency in solution-processed OLED is a great challenge. Here, we designed and synthesized three efficient emitters by combining isoquinoline, thiophene and pyridine groups with thianthrene 5,5,10,10-tetraoxide group. With the introduction of thianthrene 5,5,10,10-tetraoxide group, these Pt(II) complexes show improved electron injection/transport capabilities. A range of emission energies that can be tuned from green to red was realized by solution-processed OLEDs. Their electrochemical and photophysical properties were explored and analyzed. The structure of Pt-SOPy complex was also characterized by X-ray crystallography. Importantly, the green OLED using Pt-SOPy as an emitter shows excellent performance with a peak external quantum efficiency (EQE) of 24.7 %. As far as we known, the value sets a new record for solution-processed green OLEDs based on Pt(II) complexes.