High Efficiency Organic Light Emitting Devices for Lighting

Technical Report · Sun Sep 01 04:00:00 EDT 2013

DOI:https://doi.org/10.2172/1111142· OSTI ID:1111142

So, Franky ^[1]; Tansu, Nelson ^[2]; Gilchrist, James ^[2]

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1. Univ. of Florida, Gainesville, FL (United States); University Of Florida
2. Lehigh Univ., Bethlehem, PA (United States)

We fabricated OLEDs on microlens array substrates. We developed an imprinting process to fabricate OLEDs on 0.5 μm and 1.0 μm microlens array substrates. With a perfect self-assembled micro sphere array to form the grating structure for light extraction, it is expected that the light emission profile is wavelength dependent with a strong angle dependence. Because of the defects present in the microlens array, the light emission profile from the resulting OLEDs is almost lambertian due to the so-called “defective grating”. As a result, we were able to obtain an enhancement of 2X in power efficiency. Using a macro lens to further extract the substrate mode, we were able to obtain a 3X enhancement in light extraction. The optimized OLEDs with phosphorescent dopant of Ir(ppy)₃ showed 49 cd/A and 33 lm/W in current and power efficiencies. With the 0.5-μm-diamter silica array, the current and power efficiencies were improved to 78 cd/A and 72 lm/W, giving rise to 60% and 120% enhancements, respectively. With a hemisphere lens, the total power efficiency of the grating device was enhanced by a factor of ~3.7. With the 0.4-μm-diamter silica array, the grating devices showed the lower enhancement of 46% in the current efficiency over the reference than the 0.5 μm grating device due to the lower depth of the corrugated structure.

• Research Organization: Univ. of Florida, Gainesville, FL (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE)
• DOE Contract Number: EE0001522
• OSTI ID: 1111142
• Report Number(s): DOE-UF--01522
• Country of Publication: United States
• Language: English

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32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION