Enhancing waveguided light extraction in organic LEDs using an ultra-low-index grid

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• Organic Light-Emitting Diodes (OLEDs) suffer from limited light outcoupling due to refractive index mismatch.
• Efficient light extraction is crucial for improving OLED performance and reducing energy loss.

Purpose of the Study:

• To demonstrate improved light outcoupling in OLEDs using a novel ultra-low index porous silicon dioxide grid (UltraLIG).
• To enhance the efficiency and power conversion of OLED devices through advanced nanostructure fabrication.

Main Methods:

• Fabrication of a porous SiO(2) grid with an ultra-low refractive index (n=1.15) using glancing-angle deposition.
• Integration of the UltraLIG structure with electrophosphorescent tris(2-phenylpyridine) iridium [Ir(ppy)(3)]-based OLEDs.
• Characterization of light outcoupling efficiency and device performance at various luminance levels.

Main Results:

• A 48% increase in light outcoupling into substrate modes was observed for OLEDs with UltraLIG compared to conventional devices at 100 cd/m(2).
• UltraLIG devices achieved peak external quantum efficiencies (eta(EQE)) of 22.5% and power efficiencies (eta(P)) of 64 lm/W.
• These efficiencies represent a nearly threefold improvement over analogous conventional OLEDs.

Conclusions:

• The ultra-low index porous SiO(2) grid (UltraLIG) is an effective strategy for enhancing light outcoupling in OLEDs.
• This approach significantly boosts OLED efficiency and power conversion, paving the way for more advanced display and lighting technologies.