CuInSe₂ thin-film deposition on flexible plastic substrate: electrolyte recirculation rate and deposition potential effects

Abstract

Copper indium diselenide (CuInSe₂; CIS) layer was electrolytically plated from an aqueous medium at room temperature onto electroless nickel deposited on flexible plastic (Kapton). The CIS depositions were carried out under constant deposition potentials (−0.5 to −1.1 V vs. Ag/AgCl) and at various electrolyte flow rates (0.3 to 1.5 ml/s) under constant applied current. The resulting thin films were characterized using atomic force microscopy, energy-dispersive X-ray spectroscopy, environmental scanning electron microscopy, and X-ray diffraction. The surface morphology and the atomic composition of the deposited CIS film were found to be influenced by the deposition potential under potential control and the electrolyte recirculation rate under current control. Low electrolyte flow rates under constant current control and high cathodic deposition potential under voltage control favor the deposition of indium. CIS films of uniform deposit, smoother surfaces, and with better adhesion properties are favored by moderate electrolyte recirculation rate. At a current density of 0.6 mA/cm², the electrolyte recirculation rate required to achieve ideal CIS atomic composition was found to be 1.0 ml/s in such a setting. The crystallinity of the film improved after annealing for 2 h at 390 °C under argon atmosphere.