Strategy for the Realization of Efficient Solution-Processable Phosphorescent Organic Light-Emitting Devices: Design and Synthesis of Bipolar Alkynylplatinum(II) Complexes

A new class of highly luminescent bipolar alkynylplatinum­(II) complexes has been synthesized, characterized, and applied as phosphorescent dopants in the fabrication of solution-processable organic light-emitting devices (OLEDs). Through the incorporation of a delicate balance of electron-donating carbazole moieties and electron-accepting phenylbenzimidazole or oxadiazole moieties into the platinum­(II) core, the platinum­(II) complexes have been demonstrated to exhibit bipolar charge transport character with high photoluminescence quantum yields of up to 0.75 in thin films. The introduction of <i>meta-</i>linkages into the complexes further helps weaken the donor–acceptor interactions, facilitating better carrier-transporting abilities. More importantly, high-performance solution-processable green-emitting OLEDs with maximum current efficiencies of up to 57.4 cd A^–1 and external quantum efficiencies of up to 16.0% have been realized. This is among the best performances for solution-processable phosphorescent OLEDs reported based on platinum­(II) complexes as well as bipolar metal complexes