Patent ID: 8684779

Claim:
A method of patterning a top conductive layer on a substrate containing an array of organic thin film transistors, as active electronic devices, said patterned top conductive layer to form pixel electrodes for the array of organic thin film transistors in a multilayer device structure, the method comprising: depositing a layer of insulating dielectric material on the active electronic devices to provide a dielectric layer, the layer of insulating dielectric material having a thickness of greater than 3 microns; and depositing a layer of conducting material over the dielectric material to provide the top conductive layer, the layer of conductive material being a metal layer of thickness less than 100 nm; the method characterised by: irradiating portions of the substrate with ultraviolet laser light, whereby portions of the top conductive layer are selective removed by melting or ablation from said irradiated substrate portions, the laser light being of a wavelength absorbed by dielectric material, such that a surface region of the layer of dielectric material is removed and significant degradation of the underlying array of the organic thin film transistors as active electronic devices, due to irradiation by the light, is prevented, and the dielectric layer remaining under the pixel electrodes as part of the multilayer device structure.