OLED breakthrough could boost smartphone battery life

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Researchers at the University of Michigan have extended the lifetime of blue OLEDs by a factor of 10.

The breakthrough, they say, could enable smartphones to hold their battery up to 20% longer, and reduce power consumption in next generation TVs. Building on earlier work to establish why the lifetime of blue OLEDs is so short, the researchers began by spreading out the light producing energy within a blue PHOLED consisting of a thin film of light emitting material sandwiched between two conductive layers – one for electrons and one for holes. The team found that if the light-emitting molecules were evenly distributed, the energetic electron-hole pairs tended to accumulate near the layer that conducts electrons, causing damaging energy transfers. As such, they arranged the molecules so that they were concentrated near the hole-conducting layer and sparser toward the electron conductor. This drew electrons further into the material, spreading out the energy. The new distribution alone extended the lifetime of the blue PHOLED by three times. Then, the team split their design into two layers, halving the concentration of light-emitting molecules in each layer. This configuration increased the lifetime tenfold. "This exciting result is an important step towards a full commercial phosphorescent RGB solution," said Julie Brown, senior vice president and chief technical officer of Universal Display.