Fine control of optical scattering characteristics of porous polymer light-extraction layer for organic light-emitting diodes.

Abstract The optical scattering properties of porous polyimide (PI) films were investigated for the light-extraction layer in organic light-emitting diodes (OLEDs). By adjusting mixing ratios of different non-solvents during the immersion precipitation process, the light scattering at the generated porous PIs can be precisely tuned. Analyzed from the final OLED devices based on prepared scattering substrates, we found that the light-output characteristics of fabricated devices are correlated with the optical scattering properties, which depends on both the size of generated pores inside porous PIs and the surface roughness at the air-interface. From the help of Mie scattering and Surface scattering simulations, a systematic approach has been performed to explain the influence of the generated micro-structure on both the optical scattering and OLED-performance. Graphical abstract Image 1 Highlights • Porous light-extraction layers for OLEDs with coated polyimides by immersion precipitation. • Fine control of optical scattering properties through tuning mixing ratios of two non-solvents. • Tuning capabilities of light-outcoupling efficiency and angular emission property in OLEDs. • Systematic approach to correlate optical scattering of porous films with OLED performance. • Analysis of influences of the pore-structures using both Mie scattering and surface scattering. [ABSTRACT FROM AUTHOR]