Dye Improves Efficiency of Organic LEDs

A team of researchers from Princeton University in New Jersey has improved the efficiency of electroluminescent organic light-emitting diodes (LEDs) by introducing a fluorescent dye.
Fluorescence emissions occur when electrons become excited, jumping first to a singlet spin state. These electrons represent only 25 percent of the total excited state population, with the remainder in the triplet state, a higher state of excitation.
The team discovered that, by adding a fluorescing dye, they achieved emissions in both the singlet and triplet states. After doping the electroluminescent device, the researchers generated saturated red emissions with peak external and internal quantum efficiencies of 4 and 23 percent, respectively. The luminescent efficiencies attainable with phosphorescent dyes may lead to new applications for organic materials.