The researchers at Stanford University along with SLAC National Accelerator Laboratory have developed a printing process they call FLUENCE—fluid-enhanced crystal engineering, resulting in thin films capable of conducting electricity 10 times more efficiently than those created using conventional methods.
Researchers have made major improvements to organic electronics – a technology in demand for lightweight, low-cost solar cells, flexible electronic displays and tiny sensors. The new printing method FLUENCE is fast and works with a variety of organic materials to produce semiconductors of strikingly higher quality than what has so far been achieved with similar methods.
“Even better, most of the concepts behind FLUENCE can scale up to meet industry requirements,” said Ying Diao, a SLAC/Stanford postdoctoral researcher and lead author of the study, which appeared in Nature Materials.
Stefan Mannsfeld, a SLAC materials physicist and one of the principal investigators of the experiment, said the key was to focus on the physics of the printing process rather than the chemical makeup of the semiconductor. Diao engineered the process to produce strips of big, neatly aligned crystals that electrical charge can flow through easily, while preserving the benefits of the “strained lattice” structure and “solution shearing” printing technique previously developed in the lab of Mannsfeld’s co-principal investigator, Professor Zhenan Bao of the Stanford Institute for Materials and Energy Sciences, a joint SLAC-Stanford institute.
Diao designed a printing blade with tiny pillars embedded in it that mix the ink so it forms a uniform film. A series of cleverly designed chemical patterns on the substrate suppress the formation of unruly crystals that would otherwise grow out of alignment with the printing direction. The result is a film of large, well-aligned crystals.
Principal investigators Bao and Mannsfeld say the next step for the group is pinning down the underlying relationship between the material and the process that enabled such a stellar result. Such a discovery could provide an unprecedented degree of control over the electronic properties of printed films, optimizing them for the devices that will use them.