Jian Shen of the Oak Ridge National Lab and colleagues used the magnetic nanoparticles to dope the structure of a polymer-based organic light-emitting diode (OLED). The technique not only opens up a way to get more light out of an OLED, but also allows the OLED intensity to be controlled by an external magnetic field.

A typical polymer-based OLED structure contains three layers: a thin light-emitting layer held between a hole-transport layer and an electron-transport layer. The emissive layer should be thin enough to allow the electrons and holes from the transport layers to meet and recombine.

Shen and colleagues fabricated their device by using an ultrasound method to mix cobalt ferrite (CoFe) nanodots into chloroform solutions of polymers. The researchers spin-cast the CoFe-doped polymers onto a conducting glass substrate to form the OLED. They then measured the electroluminescence intensity of the doped OLED and compared it with that of a non-doped OLED.

full article optics.org