Abstract: The invention relates to a method and apparatus for the application of material to form a layer of an organic electroluminescent device. The material is sputter deposited typically from at least one target of material held in respect to a magnetron in a coating chamber. The magnetrons used can be unbalanced magnetrons and/or are provided with other magnetrons and/or magnet arrays in a closed field configuration. The material is found to be deposited in a manner which prevents or minimises damage to the device and hence reduces or removes the need for a barrier layer to be applied.