After we previously demonstrated, that controlling the ink-flow with our FLUENCE technique leads to massive improvements in the film structure and performance for small organic semiconductor inks, a new paper, published in Nature Communications, describes our modification of the FLUENCE approach to work with conjugated semiconducting polymers.
The question here was: can we achieve similar control over the morphology of polymer films as we achieved for the small molecules. The answer is yes, but in order to work for polymers, the structures controlling the ink flow needed to be shrunk from tens of micrometers down to as small as possible. New shearing blades with photo-lithographic structured pillars of 1-2 micrometer diameter and pitch were produced. These specially structured blades improved the morphology of printed polymer films for organic solar cells and enhanced all metrics of solar cell device performance across various printing conditions, specifically leading to higher short-circuit current, fill factor, open circuit voltage and significantly reduced device-to-device variation.