The spray coating allows the precise, thin and cohesive application required to create thin displays on irregular surfaces without having to use a masking technique.
For an EL display to emit light it requires four layers: a conductive bottom electrode, an insulating dielectric layer, an insulating light-emitting layer, and a conductive top electrode. The bottom electrode is often made from a highly conductive metal, such as copper or silver ink. The dielectric layer is an electrical insulator, and must spread beyond the electrode layers to prevent short circuits between the top and bottom of the structure. The light-emitting layer is EL phosphor suspended in solvent. The top conductive layer must be transparent as with some polymers or metal oxides. To light up, an alternating current of around 200V operates between the electrodes, across the dielectric layer, energizing the light-emitting layer.
Using conductive channels rather than ‘on surface’ electrodes has a number of advantages to object design. Using 3D printed channels allows digitisation of the process for defining cell shape, increasing the potential for fully automating the process. Routing a conductive pathway inside the object also allows the only points on the surface to be the EL cells and the electrode attachment points, without the need for an on-surface conductive trace between the two. As a result, base electrode channels can cross each other in ways they wouldn't be able to in 2D.
This gives a wider range of possible cell placement and opens design options and gives a potential for higher resolution of display due to denser cell placement, since space on the surface is no longer required for base electrodes merely for the attachment sites. It also allows easier electrode attachment points can be 3D printed in a wider range of potential locations, being less dependent on segment sizes/shape/location.
Automating the printed base electrodes through 3D printed conductive channels, means that the EL fabrication approach is