Deep-blue PHOLEDs get very efficient

While red- and green-emitting phosphorescent organic light-emitting diodes (PHOLEDs) have made progress in the ten years since their discovery, blue PHOLEDs still are not efficient enough to find use in full-color displays and lighting applications.

Nov 1st, 2008

While red- and green-emitting phosphorescent organic light-emitting diodes (PHOLEDs) have made progress in the ten years since their discovery, blue PHOLEDs still are not efficient enough to find use in full-color displays and lighting applications. Now, materials engineers at the University of Florida (Gainesville, FL) have reported very-high-efficiency PHOLEDs with deep-blue emission at a peak wavelength of 458 nm. The deep-blue PHOLEDs are based on a fluoro-iridium complex called FIr6, incorporated into a dual-emissive-layer structure p-i-n device.

Sang-Hung Eom and colleagues found that at a turn-on voltage of only 3.2 V, the peak power efficiency improved more than 300% over that of conventional devices: from 8 ± 1 lm/W to 25 ± 2 lm/W at a luminance of 100 cd/m2, an ideal luminance for displays. An efficiency of 20 lm/W at 1000 cd/m2, ideal for lighting, was achieved with the same turn-on voltage. A maximum external quantum efficiency of 17 ± 1% was a five-point improvement, while the electroluminescence spectra of the p-i-n devices are nearly identical to that of conventional PHOLEDs. Contact Jiangeng Xue at jxue@ufl.edu.

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