Elaborate Design of Ag8Au10Cluster [2]Catenane Phosphors for High-Efficiency Light-Emitting Devices

In this work, rational design of highly soluble and phosphorescent Ag–Au cluster complexes with exceptional [2]catenane structures is conducted using 1,8-diethynyl-9H-carbazole (H3decz) as a rigid U-shaped ligand with a distinguished hole-transport character. The self-assembly reaction of H3decz, Au+, and Ag+generated phosphorescent Ag4Au6cluster 1(Φem= 0.22 in CH2Cl2) with H2decz–having a free ethynyl (−C≡CH) group. When the four free C≡CH groups in the Ag4Au6complex 1are further bound to four (PPh3)Au+and four (PPh3)Ag+moieties through M–acetylide linkages, the formation of Ag8Au10cluster 2not only eliminates nonradiative ethynyl C–H vibrational deactivation process but also improves dramatically the molecular rigidity so that the phosphorescent efficiency of the Ag8Au10cluster 2(Φem= 0.63) is nearly 3 times that of the Ag4Au6cluster 1. The Ag8Au10cluster structure is further rigidified using diphsophine Ph2P(CH2)4PPh2(dppb) in place of PPh3so that the phosphorescence of the Ag8Au10cluster 3(Φem= 0.77) is more efficient than that of 2. Making use of the Ag8Au10clusters as phosphorescent dopants, high-efficiency solution-processed organic light-emitting diodes (OLEDs) were achieved with current efficiency (CE) and external quantum efficiency (EQE) of 47.2 cd A–1and 15.7% for complex 2and 50.5 cd A–1and 14.9% for complex 3.