Organic electronics beyond cell phone screens

November 21, 2017 // By Jean-Pierre Joosting
Researchers from Princeton University, the Georgia Institute of Technology and Humboldt University in Berlin have made a breakthrough that points the way to more widespread use of an advanced technology generally known as organic electronics.

Organic semiconductors are prized for their applications in emerging technologies such as flexible electronics, solar energy conversion, and high-quality color displays for smartphones and televisions. The advance should particularly help with organic light-emitting diodes that operate at high energy to emit colors such as green and blue.

"Organic semiconductors are ideal materials for the fabrication of mechanically flexible devices with energy-saving low temperature processes," said Xin Lin, a doctoral student and a member of the Princeton research team. "One of their major disadvantages has been their relatively poor electrical conductivity. In some applications, this can lead to difficulties and inefficient devices."

The research, published in the journal Nature Materials, describes a new approach for greatly increasing the conductivity of organic semiconductors, which are formed of carbon-based molecules rather than silicon atoms. The dopant, a ruthenium-containing compound, is a reducing agent, which means it adds electrons to the organic semiconductor as part of the doping process. The addition of the electrons is the key to increasing the semiconductor's conductivity. The compound belongs to a newly-introduced class of dopants called dimeric organometallic dopants. Unlike many other powerful reducing agents, these dopants are stable when exposed to air but still work as strong electron donors both in solution and solid state.


Researchers used ultraviolet light to excite molecules in a semiconductor, triggering reactions that split up and activated a dopant. Image courtesy of Jing Wang and Xin Lin.