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

Abstract

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(1naphthyl)-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.

12‐3: A Highly Mass‐producible Nano‐lens Array Technology for Optically Efficient Full‐color Organic Light Emitting Diode Display Applications

“…N,N′-di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (NPB) powders (sublimed, purity: >99.9%) were loaded in the vaporizer to fabricate NPB NLAs. The detail procedures of OVPD were described in our previous reports [10][11][12]. The current density-voltage-luminance (J-V-L) characteristics were measured by using a Keithley 2400 programmable source meter.…”

“…1a) make manufacturers reluctant to use MLA in the industry. Very recently, we have developed a nano-lens array (NLA, lens size: <1 um) technology and obtained high-performance green [10][11] and blue OLEDs [12] by using an organic vapor phase deposition (OVPD) method. Nano-lenses having round surfaces caused OLEDs to show the significant increase in light extraction efficiencies and the improvement of color stability.…”