A novel near-infrared-emitting cyclometalated platinum (II) complex with donor–acceptor–acceptor chromophores

A novel near-infrared-emitting cyclometalated platinum (II) complex of (TPA-BT-Q)Ptpic with a donor–acceptor–acceptor (D–A–A) chromophores was synthesized and characterized, in which the TPA-BT-Q unit is a cyclometalated ligand of N,N-di(4-octyloxyphenyl)-4-(7-(quinolin-2-yl)-benzo[c][1,2,5]thiadiazol-4-yl)-phenylamine and pic is picolinate anion. Its optophysical, electrochemical and electroluminescent characteristics were primarily studied. An intense UV–vis absorption peak at 540 nm and a strong near-infrared emission peak at 759 nm were observed for (TPA-BT-Q)Ptpic in dichloromethane. Using (TPA-BT-Q)Ptpic as a single dopant and a blend of poly(vinylcarbazole) and 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole as a host matrix, the single-emissive-layer polymer light-emitting devices exhibited a near-infrared emission peaked at 760 nm with the maximum external quantum efficiency of 0.12% at 16.6 mA cm−2 and a radiance intensity of 112 μW cm−2 at 11.7 mA cm−2 at the doping concentrations of 2.0 wt%. This work provides an efficient approach to realize near-infrared electrophosphorescent emission with high radiance intensity by employing platinum (II) complex with the D–A–A structure.