a1 Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308, Australia.
a2 CSIRO Energy Centre, Mayfield West, NSW 2304, Australia.
Organic photovoltaic (OPV) devices were fabricated using a novel draw bar premetered coating technique, whereby a meniscus of fluid is dragged across a substrate to leave a trailing wet film. The results showed that coating thickness could be controlled by varying the coating speed, rod diameter, gap height, amount of solution injected, rod diameter, rod composition material and number of layers. Devices on PET with active areas of 10 cm2 and active layer thicknesses ranging from 35 to 475 nm were produced using the technique. Active layers of 160 nm were the optimum of thicknesses trialled, achieving typical best efficiencies around 0.4 %. Devices with films thinner than 90 nm did not function due to short-circuiting. The draw-bar coating method has the advantage of allowing controlled deposition of a wide range of film thicknesses with no solution wastage.