“We found that polarisation induced energy level shifts from the edge of these materials to the interior are significant and can’t be neglected when designing components,” said researcher Katherine Cochrane.
The researchers looked at ‘nano islands’ of clustered organic molecules deposited on a silver crystal coated with a layer of salt just two atoms deep. The salt prevents electrons in the organic molecules from interacting with those in the silver.
Not only did the molecules at the edge of the nano islands have different properties than in the middle, the variation in properties depended on the position and orientation of nearby molecules.
“While we were expecting some differences, we were surprised by the size of the effect and that it occurred on the scale of a single molecule,” added assistant professor Sarah Burke, an expert on nanoscale electronic and optoelectronic materials.
“Herbert Kroemer said in his Nobel Lecture that ‘The interface is the device’ and it’s equally true for organic materials,” she continued. “The differences we’ve seen at the edges of molecular clusters highlights one effect that we’ll need to consider as we design new materials for these devices, but it’s likely there are many more surprises waiting to be discovered.”
