Fab-compatible nano-lens array integration for optically efficient flexible top-emitting organic light-emitting diodes

This work extends the kinds of organic materials that can form nano-lens arrays (NLAs). We have previously addressed fabrication of a N, N'-di(1-naphthyl)-N, N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (NPB) NLA and explained the formation mechanism as NPB crystallization and the resulting increase in surface tension. Here, we report a Tris(8-hydroxyquinolinato)aluminum (Alq(3)) NLA fabricated by the same deposition method as a NPB NLA. Grazing-incidence small-angle X-ray scattering experiments indicate that the formation mechanism of the Alq(3) NLA is the same as that of the NPB NLA. Furthermore, this study broadens the application of NLAs from rigid to flexible organic light-emitting diodes (OLEDs). Here, flexible stainless steel-based devices using a low-temperature thermal release film, atomic layer deposition and NPB NLA processes are fabricated and characterized. With a NLA, current efficiency is increased 1.4 times, indicating that fab-compatible NLA technology is also available for flexible OLEDs. (c) 2019 The Japan Society of Applied Physics