A process for the production of an optoelectronic device, such as a photovoltaic cell or a light emitting diode is disclosed. The process comprises providing a substrate having a conductive coating on at least one surface, the conductive coating having an initial roughness and at least one or more spikes, and applying a functional component to the coated surface of the substrate. The surface of the substrate having the conductive coating has been subjected to a polishing step using at least one brush to reduce the height of the spikes inherent to the conductive coating and to give the conductive coating a final roughness. By reducing the spikes there is less potential for the optoelectronic device to suffer from electrical shunts which reduce the efficiency of the device.