Organic Light-Emitting Diodes Fabricated by a Solution Process and Their Stress Tolerance

Polymeric organic light-emitting diodes (PLEDs) were fabricated by solution process, and their stress tolerance were studied by continually pressing the PLEDs fabricated on polymeric substrates. Two types of host materials, poly(nvinylcarbazole) (PVCz) and starburst small-molecule 1,3,5tris[4-(diphenylamino)phenyl] benzene (TDAPB) were employed as host for the PLEDs doped with phosphorescent materials. Two iridium complexes are employed as dopants, fac-tris(2-phenyl- pyridine) iridium [Ir(ppy) ₃] and tris(1-phenylisoquinoline) iridium (III) [Ir(piq)₃] for green-emitting and red-emitting phosphorescent materials, respectively. The external quantum efficiency and power efficiency were 8.2% and 17.3 lm/W, and 6.3% and 3.0 lm/W for a device with Ir(ppy)₃ doped TDAPB and Ir(piq)₃ doped PVCz-TDAPB mixture host, respectively. Pushing tolerance tests were performed for PLEDs fabricated on polymeric substrates. The device continued to emit light after a pushing test consisting of more than 20 000 steps. In this paper, we discuss the fabrication and characteristics of PLEDs prepared using starburst TDAPB and phosphorescent materials for green and red emissive materials by a solution process. We discuss the pushing tolerance for PLEDs fabricated on a polymeric substrate