Selective nickel oxide solar absorber coatings electroplated with pulsed currents

Abstract

Electroplated nickel oxide layers are often proposed as selective solar absorber coatings. The solar absorptance of these layers can be improved by superposing an appropriate surface structure. The growth conditions of the nickel crystallites can be influenced by the current density. The high current densities required for the deposition of suitable structured surfaces can be realized using short current pulses instead of direct current. The effect of the deposition parameters on the surface structure and the optical properties of the coatings were studied by scanning electron microscopy and by radiometric and spectrophotometric measurements.