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

摘要

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 phenyl-benzimidazole or oxadiazole moieties into the platinum(II) core, the platinum(II) complexes have been demonstrated to exhibit bipolar charge transport character with high photo-luminescence quantum yields of up to 0.75 in thin films. The introduction of meta-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.