Efficient dinuclear Pt(ii) complexes based on the triphenylphosphine oxide scaffold for high performance solution-processed OLEDs

Dinuclear Pt(ii) complexes have the potential to achieve high electroluminescence (EL) performance because of the enhanced phosphorescence emission induced by the extra metal center. However, to date, organic light-emitting devices (OLEDs) utilizing dinuclear Pt(ii) complexes as emitters usually show low EL performance with external quantum efficiencies (EQE) less than 10%. In this work, with the triphenylphosphine oxide group as the scaffold core and different N-heterocycles (pyridine, thiazole, and quinoline) as the end-groups, dinuclear Pt(ii) complexes PyPODPt, ThPODPt, and QuPODPt are synthesized to show bright emissions peaking at 500, 543, and 586 nm in solutions. The photoluminescence quantum yields are measured to be up to 0.96. More importantly, the solution-processed orange-red device based on QuPODPt exhibits outstanding EL performance with the EQE reaching 11.2%, which is among the highest EQEs reported for OLEDs employing dinuclear Pt(ii) complexes. The superior device performance demonstrates the promising potential of triphenylphosphine oxide-based dinuclear Pt(ii) complexes for OLED applications.