PORTLAND, Ore.University researchers have reported a breakthrough that could help organic semiconductors bridge the considerable performance gap with silicon chips.
Organic semiconductors offer easier low-temperature processing than silicon, resulting in lower cost semiconductors with highly tunable properties. Unfortunately, the poor carrier mobility of organic materials makes their performance characteristics lag behind traditional inorganic semiconductors by a thousand times or more.
The researchers at McGill Universtiy (Montreal) demonstrated a method of endowing organic semiconductors with the performance characteristics of inorganic materials by copying their highly ordered nanoscale structure with bottom-up self-assembly techniques.
"What we show in this work is that we can take a crystalline that is perfectly ordered inorganic materialhere single crystal copperand translate its order into that of an organic layer," said McGill professor Dmitrii Perepichkal, who performed the work with professor Federico Rosei at the Institut national de la recherche scientifique. "Specifically, we demonstrate perfectly ordered arrays of one of the most important organic conducting polymer, PEDOT [polyethylenedioxythiophene]."
|Polymers created at a resolution of fve nanometers by copying the crystalline template of inorganic copper.|
The researchers attained five nanometer resolution for lines of PEDOT by copying the already perfect crystalline structure of thin-film copper, using a simple low-temperature deposition technique whereby "monomers" self-assembled into polymers atop the inorganic material.
"When these small monomer moleculesthe constituents of a polymerreach the surface of a crystal, they polymerize in such a way that the direction of the resulting polymer lines is defined by the crystal itself," said Perepichkal.
The crystalline monolayers of PEDOT hold the potential of enabling organic transistors to be ten time smaller than today's semiconductors, but with performance that rivals inorganic materials like silicon.
Although their work is still in the early stages, the researchers claim their technique could eventually be adapted to a wide variety of organic semiconductors including wide-area computer displays and highly efficient but inexpensive plastic solar cells.
So far the researchers have only demonstrated the effect in one dimensional, but are currently working to show it can be duplicated in traditional two-dimensional sheets, resulting in organic monolayers from which traditional electronic circuits can be fabricated.