USC Dornsife scientists have found a cheaper material in copper to light up smartphone and TV screens instead of the traditionally-used iridium, without compromising visual quality.
“The current technology that sits in every Samsung Galaxy phone, high-end Apple iPhone and LG TV relies on iridium compounds for colour and light on OLED screens. We have been using it because of its highly-efficient light emission, but [the problem is] iridium is the rarest naturally-occurring element on Earth,” said Mark E. Thompson, USC Dornsife College chemist.
Iridium is currently in high demand, due to the popularity of the gadgets it lights up. Also, OLEDs have started to replace LED LCD screens in consumer electronics, and in an OLED screen, each pixel generates light, unlike in an LCD where pixels are illuminated by a backlight.
The scientists have now turned to copper to light up OLED screens, even though to date copper complexes have shown weaker structures and unstable molecules, with shorter lifetime than that of iridium compounds. Copper solves the problem of availability since it is readily mined, whereas iridium exists only in few places, mostly South Africa and parts of Asia. There’s a hypothesis behind its scarcity that suggests its origins to be from the same meteor that wiped out the dinosaurs 65 million years ago.
In addition to being more readily available, copper is also better at generating blue light. Its new, more-rigid molecular complex also matches iridium’s rate of light emission, so energy is converted efficiently into light and colour.
“Achieving efficient blue emission out of copper compounds opens up entirely new possibilities for tackling the problem of short lifetimes in blue devices,” said Rasha Hamze, the study’s lead author.