Researchers in California have made improvements to a printing process for that is used to fabricate organic electronics. The printing method is fast and works with a variety of organic materials to produce semiconductors of higher quality than what has so far been achieved with similar methods. Organic electronics have great promise for a variety of applications, but even the highest quality films available today fall short in how well they conduct electrical current. The researchers have developed a printing process they call FLUENCE (fluid-enhanced crystal engineering) that for some materials results in thin films capable of conducting electricity 10 times more efficiently than those created using conventional methods. Most of the concepts behind FLUENCE can scale up to meet industry requirements. The key to developing the new technique was to focus on the physics of the printing process rather than the chemical makeup of the semiconductor. The researchers engineered the process to produce strips of 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. To make the advance, the researchers focused on controlling the flow of the liquid in which the organic material is dissolved. If the ink flow does not distribute evenly, the semiconducting crystals will be riddled with defects. The researchers designed a printing blade with tiny pillars embedded in it that mix the ink so it forms a uniform film. They also engineered a way around another problem: the tendency of crystals to randomly form across the substrate. A series of chemical patterns on the substrate suppress the formation of the crystals that would otherwise grow out of alignment with the printing direction. The result is a film of large, well-aligned crystals.
www.eurekalert.org/pub_releases/2013-06/dnal-pip053113.phpwww.eurekalert.org
