One-dimensional micro-scale patterned conjugated polymer structures in bilayer architecture and light emitting diode application

Abstract

To maximize luminescent brightness in organic light-emitting diode (OLED) systems, charge transport dynamics of emissive layer is needed to be controlled. Herein, we pattern aligned micrometer scale conjugated polymer structures using a solution based processing method. Super yellow (SY)-polyethylene oxide (PEO) nanofibers were electrospun using simple uniaxial electrospinning method. A hybrid bilayer of SY-PEO fiber and poly (9,9-dioctylfluorene) derivative PFO film was formed by the sequential deposition of the electrospun fiber and spin-coated film. The maximum brightness of hybrid LED devices was increased over 1.7 fold to that of film-film bilayer device possessing same average film thickness. Besides, optical properties such as absorption/luminescence of SY were modulated by the rapid crystallization and solvent evaporation during electrospinning process compared to the spin-coated film. The electroluminescence enhancement and color control was attributed to balanced charge transport and enhanced Förster resonance energy transfer (FRET). A patterned hybrid bilayer was formed by the combination of the SY-PEO fiber and PFO thin film via solution based sequential deposition methods, including electrospinning and spin-coating. Thanks to the molecular packing and increment of conjugation length in electrospun SY-PEO nanofibers, such nanofibers exhibited distinct optical properties in comparison with SY thin film. Micro-dimensional alignment of conjugated polymer fiber-film bilayer device exhibited superior electroluminescent brightness besides color tunability of constructed LED device. Such enhancements were attributed to balanced charge transport and enhanced Förster resonance energy transfer in fiber-film hybrid emissive bilayer. • Aligned conjugated polymer fibers by electrospinning process. • Electrospun super yellow -polyethylene oxide nanofibers. • One-dimensional conjugated polymer microstructures in fiber-film hybrid bilayer architecture. • Utilization of conjugated polymer nanofibers in light emitting devices.